Cereals And Bakery Products
( Originally Published 1939 )
Cereal products such as wheat, corn, rice, oats, rye, and barley constitute a very large part of our food supply. The great bulk of wheat is prepared as refined flour, corn as corn meal and starch, and rice as the milled and polished grain. In recent years, all the above grains have been used in the preparation of scores of breakfast foods. Wheat flour is made into numerous bakery products, chief of which are bread and biscuits, cake, various pastries, and the alimentary pastes.
Bread. Although bread is basically made from flour, water, salt, and yeast, commercial practice has introduced other ingredients to improve the food value, flavor, and appearance of the loaf. Chief among these are malt syrup, certain salts, sugar, shortening, and milk (or its normal equivalent in skim-milk powder and butter). Flour is often a blend of several varieties to impart the texture desired with a given dough formula and bakery practice. Changes in costs of certain ingredients may compel a baker to alter his formula to meet competition. All ingredients must be weighed. The baking quality of a flour depends on its gluten strength and content, and not merely on its nitrogen content. The amount of water used varies, depending on the absorption property of the dough.
The use of milk strengthens the gluten, increases the volume of loaf, adds to food value, and improves the texture, flavor, and appearance of the bread. Salt also strengthens the gluten, and at the same time regulates the activity of yeast fermentation. Sugar is added to supplement the sugar formed by the action of diastase on starch; it furnishes more gas for raising the dough and also adds flavor. Malt syrup not only supplies malt sugar and enzymes to convert starch to sugar and dextrose, but also proteins and mineral salts as useful foods for the yeast. Shortening improves the texture and eating qualities of the bread. Yeast ferments the carbohydrates and produces gas which raises the dough and makes the bread palatable.
Mixing the dough. Two general types of dough are used in commercial bread baking, namely, straight dough and sponge dough. Straight dough contains all the ingredients mixed in one operation. Sponge dough, amounting to possibly about two-thirds of the total amount of the batch, is first mixed to form the sponge which is fermented rapidly to a given degree, then is mixed with the remainder of the dough and fermented to the final point.
Mixing machines come in different makes, according to the type of bread to be produced. The effect of mixing on the dough is determined by the construction of the mixer, the number of revolutions per minute of the mixing arms, and the temperatures at which the doughs come out.
Fermentation of dough. Dough is usually fermented in a dough trough—a long rectangular-shaped, metallic box, open at the top, and set on wheels for moving about the dough fermentation room. Some-times the air is humidified to maintain a proper degree of moisture. After a preliminary fermentation, the dough is "punched" or folded over by pulling it from the sides and ends into the center of the trough to mix it thoroughly. It is divided into pieces, each of which when baked will give a loaf of the desired weight. Sometimes this dividing is done by hand, but machines are now available to do it more quickly and accurately.
After this relatively rough handling, the pieces of dough must be allowed to rest or be given an opportunity to recover from the dividing process. This is called the short proof or sometimes the inter-mediate, preliminary, or first proof. For about 10 to 15 minutes, the dough is protected from chilling, and the yeast brings about improvement in texture and quality of the piece. It is then ready to be flour-dusted and molded into a dough loaf. Each piece is placed in a lightly greased pan. These pans should be kept clean and free from dust, grease, burned crumbs, flour, and other residues. After this panning, the dough must be allowed to "proof" or attain proper lightness. This is done in a chamber with a humidity of about 80 to 85 percent and a temperature of 95° to 98° F. (35-37° C.) to produce loaves of uniform and satisfactory quality.
Baking. During the first few minutes of baking, the dough continues to rise rapidly. This is called oven spring. The heat of the oven sets the dough and brings about the chemical and physical changes familiarly known as baking. The temperature of the air of the oven is about 400° F. (204° C.), but the interior of the loaf does not reach a temperature much above 212° F. (100° C.). In general, 1-pound loaves require a baking temperature of about 425° F. (218° C.) for 1/2 hour, although this varies with the composition of the dough and the individual bakeshop practice. Loaves must be gradually cooled to prevent temperature shock.
Wrapping. Bread wrapping with semi-porous waxed or paraffined paper is now being very extensively practiced. It protects the bread from contamination by dirt and infection, and prolongs the period of its salability.
Milk bread. The use of milk solids in commercial bread-making has had a rapid growth. Formulas for white pan bread have gradually increased the content of dry skim milk from 2 percent to 4 percent in 1930, and to 5 percent in 1931. At present 6 percent is the average. This is calculated on the basis of weight of the flour used. A 12 per-cent milk solids content has been recommended for school lunches, but this bread now appeals to a wider market. If a bread is to be labeled milk bread, it must contain milk with content of milk solids and butterfat in normal proportions which average about 8 3/4 and 3½ parts respectively, or about 21/2: 1. Skim-milk powder and butter are used in bakeshop practice because of the greater ease of handling them and lower price as compared with locally produced liquid milk. Whole milk powder becomes rancid so quickly that bakers generally use skim-milk powder and its proportionate amount of butter. The following are typical formulas of straight and milk-improved doughs:
STRAIGHT WATER DOUGH MILK-IMPROVED DOUGH
200 lb. Flour 200 lb.
124 lb. Water 136 lb.
4 lb. Yeast 5 lb.
8 oz. Yeast food 8–12 oz.
41b. Salt 4 lb.
10 lb. Sugar 10 lb.
6 lb. Shortening 8 lb.
8 oz. Malt 1 lb.
0 Milk solids 12 lb.
78° Dough temp 79°
1 3/4 hr First turn 1 3/4 hr.
1/2 hr. Second turn 1/2 hr.
1/4 hr. Makeup 1/4 hr.
Use of milk necessitates a corresponding increase in water to prevent binding of the dough with its attendant impairment of quality. This added water does not reduce the total solids content because it is equal to the increase in milk solids. The great value of milk solids is to enrich the nutritive quality of bread and to improve its flavor and texture.
Alimentary pastes. This class of cereal products includes macaroni, spaghetti, vermicelli, and noodles. They are made from the semolina (middlings) or a specially hard or "durum" wheat (containing a strong gluten) by removing the husks by wetting, heating, grinding, and sifting. This produces a coarse meal of round glazed particles. The meal makes a very stiff dough which is formed into the characteristic shape of the commercial product by being forced under pressure through dies. The strands or ribbons are very care-fully dried to impart the desired toughness and brittleness. The use of eggs in the dough imparts a yellow color which is sometimes fraudulently simulated by artificially coloring inferior water doughs.
Diabetic bread. Producers of this class of foods cater to needs of persons suffering from diabetes by preparing bakery products which contain little or no starch or other carbohydrates. Biscuits may be made of gluten, soybean flour, or other such ingredients. Unfortunately, these specialty products are not always free from starch or sugar. Inasmuch as their market is sick persons, it is incumbent on producers and regulatory officers to use adequate measures to insure compliance with claims.
Breakfast foods. The grains most commonly used are oats, wheat, corn, rice, and to a smaller extent barley and rye. Most of them are changed only in the physical form of the grains. Some breakfast foods consist of the whole grain. In others, more or less bran and germ is removed. A few are finely bolted and ground, and a small number are malted. Various flavoring agents, such as salt, sugar, and honey, are added to some.
In the oat foods, various percentages of hull are removed, and the kernel is slightly steamed, then rolled or crushed. Quick-cooking rolled oats are manufactured by making the flakes thinner and smaller or by puffing them to cause more intimate contact with the cooking liquors. They are flaked by softening under steam pressure and rolling between revolving rolls.
Wheat breakfast foods quite generally retain the germ and bran,. except the farina and gluten preparations. Wheat that is moderately crushed is known as wheat grits or cracked wheat. Shredded wheat is made by cooking whole wheat under steam pressure, shredding on grooved rolls, and pressing into biscuit forms which are toasted and. dried. One popular brand consists of wheat freed from the outer bran layers and then toasted to drive off moisture and darken the particles. Puffed wheat (and other grains) are softened under high pressure, which is suddenly released to explode or expand the cells and impart porosity for easy digestibility.
Corn flakes are made by steaming the grain to soften and remove the germ and hull. The resultant hominy grits, which constitute the endosperm, are mixed with flavoring materials (such as malt extract, salt, or sugar) and cooked under steam pressure in rotary cookers, then dried, flaked between revolving rolls, toasted in ovens, cooled, and packed into the cartons. Corn meal is always degerminated to remove the oil which becomes rancid quickly and spoils the product.
In making rice flakes, milled rice is cooked in a rotary pressure cooker, with various flavors and nutrients, dried with air, flaked, toasted, cooled, and packaged. Rice grains are dehulled, degerminated, and usually polished to impart a pearly luster.
Various specialty products are made of mixtures of numerous nutrients, cooked under steam pressure in gas-fired ovens, and then rolled, flaked, or crushed. One large company enriches its products with vitamin D, to improve their calcifying properties, by irradiating its rolled oats with ultra-violet light, and its wheat products by ad-mixing a standard amount of irradiated yeast.
Custard-filled pastry. Some popular types of pastry such as eclairs and cream puffs are made by filling custard into baked shells. These are then dipped into chocolate or sugared. A standard custard is made by dissolving sugar in milk, bringing the mixture to a boil, and then adding starch, eggs, milk, and flour. These ingredients are intimately mixed, boiled, and then set aside to cool. The product is often put into cans, covered,-and set in the refrigerator to be used at a later time. After the shells are baked, the custard is introduced by spoon, pastry bag, or filling machine.
Custards and other thickened pastelike products give off their heat very slowly. In addition, many small bakeshops are located in poorly ventilated rooms, often exposed to wind-blown street and alley dust, and sometimes not effectively screened to keep out flies. Workmen may handle the products with their bare hands, often unclean. Proximity to stables exposes them to infestation from roaches, rats, and other vermin. Under such conditions, it is easily possible for cans of eggs, milk, or custard to become infected with microorganisms, and if this happens, the conditions may be propitious for their extensive incubation. Many bakeries now pasteurize their custard products, and others keep them under refrigeration until delivered to the consumer.
RELATION TO THE PUBLIC HEALTH
Composition. Sherman 3 has compiled excellent tables of the composition of different cereal grains, the various grades of flour and meal, several breakfast foods, and a wide range of crackers and bread, some of which are listed in Table XXXI. As a class, whole grains are low in moisture, fat, and protein; good in mineral content; and high in carbohydrates. Starch is the principal carbohydrate of grains, although variable amounts of cellulose (fiber), hemicellulose, and other unassimilables are present. Most of the. grains undergo more or less milling to improve their merchantability, palatability, or keeping quality. These treatments change the percentage composition, usually by reducing fiber, minerals, and vitamins, and increasing starch.
The outer parts of cereal grains after dehusking contain the hull or bran layers. These have a high percentage of fiber (cellulose) and more or less hemicellulose, quite unavailable for assimilation by the body but valuable because of their property of absorbing water and of stimulating peristalsis. These layers are usually removed in the milling of rice, wheat, and corn in order to give a lighter-colored and more attractive-looking product, such as polished rice, patent flour, and light corn meal, respectively.
By grinding the gluten fraction, flour low in carbohydrate is made for use by persons suffering from diabetes. Analyses by Bailey 5 are shown in Table XXXIV.
Wheat germ contains high percentages of oil, minerals, and protein. Oil has a tendency to become rancid quickly so that its removal is necessary to give the milled product good keeping qualities (and, in wheat flour, also to remove some of the coloring constituents). In rye and oats the greater part of the germ and a considerable portion of the outer layers remain with the finished product. It is possible that the well-known antioxidative constituents of the oat kernel protect the fat from decomposition. The fat of the wheat germ contains some vita-min A and is particularly rich in vitamins B and E.6 Oat fat has even less vitamin A than wheat fat. Yellow corn contains a large quantity of vitamin A which is not confined to the oil. The valuable vitamin B in rice is located almost entirely in the germ and some in the bran so that their removal strips this grain of a valuable nutrient constituent indispensable to those persons who are restricted to a rice diet.
Nutritional value. From time immemorial, bread and other bakery products have constituted an important part of human diet. Bread is, in fact, the oldest prepared food, and has been known for centuries as the "staff of life."
Despite a somewhat prevalent idea that white bread is an inferior food, deficient in minerals, vitamins, and roughage, the modern white bread made by bakers is a valuable foodstuff that furnishes an economical and readily digestible source of carbohydrate and food energy, as well as proteins of excellent quality, some minerals, and small amounts of certain vitamins.
Bread is also thought by many persons to be fattening, although bread and cereals are obviously no more fattening than equal amounts of carbohydrate, fat, and protein from other foodstuffs. No single food causes overweight when it is part of a well-balanced daily diet. It is also generally recognized that no single food is perfect from the standpoint of human nutrition, but that a variety of protective and energy-bearing foods must be chosen by the average person for nutriment and gustatory appeal.
The desirability of bread in the diets of growing children is indicated by its inclusion in the so-called "Oslo breakfast," devised originally in Norway, and now employed in many other countries. This meal consists of uncooked protective foods, including milk, bread, butter, and raw fruit or vegetables, which need no preparation and are served to children before the day's activities.
Proteins of the whole wheat kernel are a little more efficient for promoting growth than the same amounts of protein from milk and eggs,' but there is great variability of quality in different lots. Wheat, maize, and oat proteins have about the same value in human nutrition. The digestibility of the proteins in their ordinary products is some-what lower than when they are free. This is probably caused by the cell walls and their associated products.
The coefficient of digestibility of patent, entire wheat, and Graham flours has been shown to be about equal when these products are compared on the basis of equal protein content. The proteins of white, whole-wheat, and rye breads were assimilated 7 by young rats only to the extent of 74, 73, and 66 percent respectively, but by mature rats to 83, 80, and 82 percent. Five human subjects averaged 83 percent assimilation for each of the breads, although the figures for each individual differed markedly from those of the others.
Cereal proteins are not fully adequate for the best nutrition because their paucity of some of the essential amino acids requires their use in relatively large amounts. Sherman showed, however, that a diet of two-thirds whole-wheat or patent flour and one-third dried whole milk was adequate for normal growth and reproduction of rats. The proteins are so constituted that, when they are adequately supplemented with the proper amount of milk, the combination is so well balanced nutritively that Sherman says: "The dietary should be built around bread and milk."
Whole grain cereals are excellent sources of carbohydrates, phosphorus, and the blood-forming minerals iron, copper, and manganese; they are good sources of vitamin B and proteins. They are relatively poor in calcium and the vitamins A, C, D, and G, although some of these factors are added when bread is made with milk.
The chief nutritive value of the cereals lies in their carbohydrate content, constituting the largest source of our supply of calorific energy. Starches are considered to be superior to sugars in general nutrition, because their relatively slower digestion rate prolongs their assimilation and utilization.' When normal male adults 23 to 36 years old were fed respectively bread, sucrose, glucose, and invert sugar in water, the rate of rise in blood and urine sugar of those who ate bread was least, thus demonstrating a maximum tolerance for bread. This brought about a more uniform, or rather, a much less flooded, distribution of energy, and flattened the curve of the rate of assimilation.
The whole grain contains calcium, phosphorus, iron, manganese, copper and other minerals, but most of these are lost in milling operations, especially in the production of white patent wheat flour. Iron of whole wheat and bran has been shown by Rose and associates to be well utilized in the formation of hemoglobin. The actual content of minerals is not a constant figure but varies with the moisture and soil on which the cereal is grown.
Food fads and other erroneous notions have frequently been concerned with cereals. A current one holds that carbohydrates and proteins must not be eaten at the same time because carbohydrates re-quire an alkaline medium and the proteins an acid medium for their digestion. Evidence is lacking that there is any incompatability between protein and carbohydrate in digestion 11 Milk, the food that nature provides for the young of all mammals, contains both protein and carbohydrate in substantially similar amounts.
Acid residues from the eating of cereals are not noticeable in a mixed diet containing fruits, vegetables, and milk. Bread and cereals represent only about 17 percent of the cost of food, but provide about 40 percent of the energy, and 25 percent of the protein of our diet, a quarter of the phosphorus and iron, and an appreciable amount of vitamin B in whole grains. Bread and cereals are still the backbone of our nutrition.
Cereals and rickets. Mellanby has reported 12 that development of rickets in puppies was intensified when the proportion of cereals in the diet was increased. These findings were later confirmed on rats and children, and were attributed to the decalcifying effect of some unknown substance in cereals which he called a toxamin. Its effect was overcome by means of other foods that contained a calcifying sub-stance or vitamin D. These findings were confirmed by several other workers. Some producers of breakfast foods have fortified their products with the addition of vitamin D substances or have irradiated them with ultra-violet light. This treatment changes their effect from a slightly negative calcifying to a slightly positive one.
American workers have emphasized the disproportion between the amounts of calcium and phosphorus and the absence of vitamin D as the sole cause of the development of rickets. Shohl found that whereas normal Ca/P has heretofore been defined as 2 : 1 to 1 : 2, in his experiments a Ca/P ratio of 1 : 16 produced no rickets when the feeding level was high enough. Concentration of the calcium and phosphorus in the diet is just as important as the ratio of the two in determining the degree of rickets produced.
The Council on Foods of the American Medical Association, after an extensive review of the experimental work, concludes that 15 there is no evidence for the existence of a decalcifying factor in cereals, and that there is no necessity to irradiate cereals or to add vitamin D sub-stances to cereal products to overcome this alleged harmful effect of a hypothetical toxamin.
From the foregoing considerations, it is clear that cereals should not be charged with being rachitogenic any more than any other food. Cereal breakfast foods are particularly safe because they are usually eaten with milk which amply supplements the mineral content.
Milk bread. White flour contains about 4 times as much phosphorus as calcium whereas the optimum calcium-phosphorus ratio is generally considered to be about 2 to 1. The addition of milk to bread adjusts the mineral content to what is thought to be more nearly the optimum figure. When a bread is made with 6 pounds of skim-milk powder to 100 pounds of white flour, the dough will contain 0.1004 pound of calcium and 0.1388 pound of phosphorus. When 12 percent of milk solids are added, a 1-pound loaf would contain 0.482 gram of calcium and 0.527 gram of phosphorus, although these figures vary somewhat according to the mineral content of the other ingredients,' thereby reducing the calcium-phosphorus ratio from 1 : 1.38 to 1 : 1.09. Moreover, the general food value of the bread is. enhanced by this addition of proteins, minerals, and vitamins.
Roughage. Use of refined foods is thought to be one of many causes that have led to widespread prevalence of constipation and other forms of intestinal trouble. Weight of fecal material and number of bowel movements daily are dependent largely on bulk in the diet. In normal adults, and in some sufferers from constipation, intestinal hygiene can be improved by incorporating in the dietary an increased proportion of unassimilable products. These contribute bulk to the intestinal contents and stimulate peristalsis (the normal healthy action of the intestines in eliminating its content of digested food).
Cereal products contribute these desirables by virtue of their con-tent of fiber (cellulose) and various other inert products like the pentosans. These substances can be increased in food by selecting cereals which have not been so highly refined as to remove fiber and other unassimilable products, and also by adding bran directly. Wheat bran consists of the outer coat of the wheat grain and is usually separated from the germ in various grades of flour during milling operations. The commercial product contains some wheat embryo and a small amount of endosperm (the starchy interior body of the kernel). Bran contains a high percentage of fiber and other unassimilable carbohydrates; much iron and protein; and some vitamin B. Iron is as productive of hemoglobin in man as the iron equivalent of egg yolk. On the other hand, calcium and protein are not so well utilized when a large amount of fiber is present. Bran fiber is more resistant to decomposition in the alimentary tract than fiber of many ordinary foods. It may irritate a sensitive or diseased colon and actually create constipation. No evidence is available to show a relation between bulk and constipation in children, and McCance warns that children are intolerant of high-cellulose diets.
Bran in moderation may be helpful, but bulk is better obtained by alternating bran with agar and other allied products that are less coarse than bran alone.
Breakfast foods. Some of the more common cereals, especially wheat, oats, corn, and rice, and to a smaller extent barley and rye, have been prepared in various combinations with other products for marketing in dried forms in cartons as breakfast foods, to be consumed dry or cooked. Emphasis is placed on rapidity of preparation XXXV. Vor table use. The composition of several is given in Table
The cooking of cereals gelatinizes the starch, proportional to the amount of water present and the degree of fineness of the cereal. Murlin and associates 20 studied nutritive values of six widely used oat, wheat, and corn breakfast foods. The utilization of the protein varied from 84 percent in rolled oats to 94 percent in wheat endosperm; that of fat was constant at 90 percent; and carbohydrates, 96-97 per-cent. Carman and associates 21 reported that digestion in vitro showed that precooking by steaming or roasting affected favorably the digestion of starch, more especially for corn and oats than for wheat. Cooking (boiling) improved digestion of starch less than that of protein; and clumping of cereal such as occurs in single boilers interfered greatly with the breakdown of cellulose walls, and retarded protein more than starch digestion. In experiments on rats, Mattill and Smith 22 showed that cooked cereal left the stomach more quickly when finely ground than when in the granular manufactured form, and bran seemed to accelerate the passage of compact cereal preparations through the stomach. In human subjects, Blough, Carman, and Austin found 23 that rates of stomach evacuation were about 83 per-cent for wheat endosperm after 2 hours and 76 percent for whole oats, and incorporation of bran had practically no effect in influencing the evacuation time of the stomach. Mattill and Clayton found 24 that the biological values of several breakfast cereals and milk were as follows: milk 89 percent, precooked oats 82 percent, wheat endosperm 73 per-cent, and whole wheat 72 percent. Roasted cereals contained a sub-stance that weakly increased the tonus of the smooth muscle of the intestine. Morgan and associates found that cooking with water increased the biological value of protein. Values for wheat protein were 64 percent raw, 67 percent for water-cooked, and 52 percent for toasted.
In general, cereal breakfast foods have an abundance of starch, some protein that is not quite the equal of animal proteins in biological value, and, when prepared with the germ and bran, a good content of iron and some vitamin B (BI).
Epidemiology. The attention of food-control officials has been attracted to a considerable number of food-poisoning outbreaks which have been clearly traced to bakery products, chiefly involving such cream-filled confections as chocolate eclairs, Boston cream pies, and custard-filled puffs. The ingredients, sugar, milk, eggs, and starch, when improperly handled, are favorable media for bacterial growth.
Cream pastry. A pastry, containing a cooked cream filling, was reported in 1936 by Staff and Grover 26 to have caused an outbreak of 208 cases, resulting in 3 deaths. Symptoms of acute gastroenteritis developed in 2 to 20 hours after the eating of some commercial pastry. Sudden chill, diarrhea, vomiting, fever, abdominal cramps, and prostration pointed to a typical food poisoning. The officials made the naïve observation that inspection "revealed nothing grossly out of the ordinary, it being typical of the average small bakery." Rat and human excreta were abundant in an alley at the rear. Salmonella enteritidis organisms were isolated from numerous specimens of the pastry (mostly chocolate eclairs), from the stools of recovering patients, from the organs of 2 patients who died, and from the colon of a rat that was trapped in the bakery. These investigators gave a good review of the literature in the role of rodents as carriers of infection in food-poisoning outbreaks.
Cream-filled bakery products have been incriminated in 10 out-breaks of food poisoning listed by Denison. He reports in detail investigations attendant on an outbreak in Birmingham where 94 students were made ill by eating cream puffs infected with Staphylococcus aureus. The pastry was baked in a shop where conditions were filthy and revolting. Cultures of staphylococci were isolated in large numbers from the throat of one of the bakery employees, and from various parts of the machinery.
The extent to which an outbreak of infected cream or custard filling can cause illness is illustrated by an outbreak in Westchester County, New York, in 1935, involving more than 1000 cases. Typical food-poisoning symptoms set in within 2 to 8 hours after eating.
Recovery was uneventful in 24 to 36 hours, although several cases of respiratory and sinus infections followed. Staphylococcus aureus was found in large numbers in the filling, but the source of the contamination was never determined. Numerous other outbreaks of staphylococci infection of such fillings are reported in the literature.
Cream puffs have also been incriminated in a recent typhoid-fever epidemic. Epidemiological investigation eliminated milk, water supplies, and fresh fruit. Lavan reports that 9 persons in Grand Rapids, in the county, and in a town 21 miles away ate cream puffs from a bakery where an intermittent typhoid carrier filled cream from a bag into baked shells. Icings were mixed without heating and then applied to cake, cream puffs, and other products. The batters and cream were made largely from condensed and powdered milk, and were said to be boiled. There were no more cases after the carrier was removed and production of cream puffs was discontinued.
Two outbreaks of illness, involving 124 persons, within a year and a half, all from eating cream puffs produced by the same bakery, indicated bacterial intoxication by reason of the suddenness of the onsets within 1 to 4 hours after eating, and the elimination of metals, fluoride roach poison, and alkaloids. The path of entry of the organism was not definitely found, but cultures of it were taken from various parts of the room in which the material was prepared. No paratyphoid organisms were found in the cream or in stools. Eight samples contained 10 to 68 million bacteria per gram, one had 2 million, and one only 16,000. From seven other bakeries, counts ranged from 2000 to 74,000 on agar plates; and after 48 hours' incubation at room temperature, 30,000 to 1,500,000 organisms per gram. Suspected puffs contained many aerogenes, a few coliform, sarcina, and many cloacae strains. Cooking was uncertain, cooling uncovered, and shallow pans and empty cans lying around were used as dippers. The room was open to much dirt from an adjacent alley, and the handling of products was grossly insanitary. Employees lifted cans of cream filling from the floor by grasping the cans around the bottom, set them on the work benches, and then wiped out adhering portions of batter with their bare hands. The findings indicated a dirt rather than a fecal contamination from an organism resembling the cloacae.
Other bakery products. An outbreak of illness affecting 60 persons and causing 4 deaths was traced to the infection of pie dough with Salmonella schottmülleri (B. paratyphosus B) .31 There was no unusual taste or odor. Symptoms developed in some persons in 41/2 hours but most of them appeared in 12 to 19 hours after eating. The organism found possessed the morphologic, cultural, pathogenic, and immunologic character of the Salmonella group, and its identification was proved by agglutination. Its path of entry into the dough was not traced.
A typhoid-fever outbreak involved 93 cases of illness and 3 deaths, caused by an infected sauce. This was made with milk, butter, and tomato sauce, neutralized with baking soda, and spread over spaghetti for baking. The temperature of baking was insufficient to kill any of the organisms but really incubated the infection.
A typhoid-fever outbreak involving cases is reported by Hinton to have broken out in the Elgin (Illinois) State Hospital. It was apparently caused by a typhoid carrier who sliced the bread. She was transferred to work which involved no handling of uncooked food, and cases of typhoid ceased to appear.
Another typhoid-fever outbreak is reported to have been caused by a kitchen worker who sliced bread for an institution. The man frequently visited and nursed a brother who was ill with typhoid fever. When he was dismissed, there were no more cases.
An outbreak of Flexner dysentery in a prison, involving 946 per-sons, was attributed to a carrier of Flexner's bacillus. The man cut bread for the mess. Inoculations on bread were viable for 11 days, grew to a maximum in 48 hours, and then decreased. The other food was stated to have been well cooked, and "little" of it came in contact with human hands.
Another extensive food-poisoning outbreak involved 206 persons. Onset of illness occurred about 2 1/2 hours after eating meat sandwiches, and the symptoms were typical of food poisoning, namely: epigastric distress, vomiting, diarrhea, and marked prostration lasting several hours. Although bread was not the original source of infection (as shown by absence of illness in those persons who ate sandwiches other than meat), yet the organism grew well on bread after it was infected by meat. In this outbreak, Kelly and Dack 37 showed that food-poisoning staphylococci could elaborate an enterotoxic substance in sandwiches from either meat or bread. Although Stone 38 stated that protein was a food constituent in every outbreak, Jordan and Bur-rows 39 showed that starch favors production of enterotoxic substances, even to the extent of restoring this property to strains which had originally been positive but had long given negative results. They also show that monkeys are not so susceptible to food infected with this organism as humans, and warn that this animal should not be used to test such suspected food.
Tanner states 40 that investigators have found that the temperature of the interior of a loaf of bread during baking does not rise much above 100° C. (212° F.). He quotes the work of Auché that tubercle bacilli, introduced into a dough, were dead in the finished bread, al-though that investigator believed that pathogenic organisms may survive the baking process. It is generally known that spore-forming organisms may survive baking.
Howell found that when 100 loaves of bread, collected from all over Chicago, were bacteriologically examined, the unwrapped loaves were more or less thickly covered with bacteria in much larger number than the wrapped loaves. The count was lower on loaves from clean shops than from dirty shops. Barnard and Bishop 42 quote the work of Sadtler that colon bacilli were found on 17 percent of the samples of an investigation on unwrapped bread, and in addition 121/2 percent showed the presence of large numbers of organisms. These findings indicated that. the bread was of doubtful quality. Samples of wrapped bread had a low microbic content and no pathogenic organisms.
Selenium-containing grains. From time to time since 1857, reports of a mysterious disease which affects livestock have been appearing from scattered localities over a wide area of the north central plains of the United States. The disease in forage animals was called "alkali disease"; when acute, it was known as "blind staggers." Franke and his collaborators showed that the etiologic agent is the element selenium in some organic combination with protein. Vegetation takes it up from the soil. In wheat, nearly all the selenium is concentrated in the gluten fraction. Selenium has been found also in corn, barley, and emmer from seleniferous areas. Hens fed a toxic grain laid eggs that contained selenium, divided equally between the white and the yolk. Their own flesh contained rather high proportions of selenium. The cereals are of special importance, and next follow the food concentrates such as egg powder, milk powder, cheese, gluten, and the flesh of chickens, cattle, hogs, and other flesh-producing animals. Vegetables and fruits both may become increasingly involved through the development of irrigation districts watered from seleniferous sources, and by the widening use of seleniferous sprays.
When tested on white rats, seleniferous wheat was more toxic than selenious acid containing the same amount of selenium. When the diet contained 1.5 p.p.m. or less, there was no detectable effect on growth or reproduction, but when this was at a level of 3.0 p.p.m. and higher, the toxic effects were proportional to the amount of selenium supplied. This element was not stored in the body and hence its effect was not cumulative, but the lesions were permanent after the seleniferous supply was withdrawn.
In spite of the widespread toxic effects on animals, including in-sects, no human death from eating seleniferous food is known. An investigation has been made of the physical condition and health of some of the rural population of the most severely affected parts of Wyoming, South Dakota, and Nebraska to determine the possibility of selenium intoxication through the consumption of selenium-containing foodstuffs produced locally on seleniferous soils. The typical symptoms of "alkali" disease in livestock were found on 11 farms. Nearly all the farms investigated had very definite past histories of this disturbance. Many more or less vague symptoms of poor health were found, but none were clearly traced to ill effects from the ingestion of selenium. Urines from 92 percent of the 127 persons examined contained from 2 to 133 micrograms of selenium per 100 milliliter, indicating absorption of this element by some of the rural population. (The urines of 3 horses and a colt in various stages of "alkali" disease ranged from 33 to 170 micrograms per 100 milliliters.) Physical ailments associated with these higher urinary contents (20 or more micrograms per 100 milliliters) were pathological conditions of the nails, gastrointestinal disorders, and an icteroid skin.
A review of the selenium problem has been published by Manville [Am. J. Pub. Health 29, 709 (1939) ]. In general, it has been observed that acute effects of the ingestion of soluble selenium compounds may be summarized as consisting primarily of early cellular destruction of the liver with later pathological changes throughout the organism. The ingestion of small amounts of selenium compounds over a long period results in retrograde changes in the liver and kidneys accompanied by a general debility. The lethal dose for animals is approximately 2 milligrams per pound of animal. A tentative limit of 4 p.p.m. has been suggested as the tolerance limit of selenium in human food. There is no evidence that the disease presents public health hazard over the country at large because of the great dilution of foodstuffs from these lands with those from unaffected areas. However, in those sections of the country where selenium occurs in relatively large amounts, the problem is more immediate.
Ergot. Grain such as wheat, rye, and oats may be infected with the fungus Claviceps purpurea. The mycelium replaces grain in the head of rye or wheat. When such grain is milled, the flour is discolored and has a sour odor. It produces symptoms of spasms or convulsions, accompanied by great pain described as being "like fire." This condition is virtually unknown in America.
Bleached flour. Public demand for a white flour has led to the use of several different chemicals for bleaching flour, chiefly chlorine, nitrosyl chloride, nitrogen trichloride, and benzoyl peroxide. These not only bleach the color but also bring about other chemical changes. Numerous investigators have studied the toxicity of bleached flour. The majority of them seem to indicate that bleaching improves the baking and digestibility of flour rather than harming these properties 46 Studies on the digestibility of bread made from bleached flour have shown that the effects, if any, are too slight to be noticeable. These studies are old and were done before the present-day knowledge of vitamins and minerals had developed. Poor results may have been due to vitamin or mineral deficiency, not toxicity.
Some recent Hungarian investigations have shown 47 that, when experimental rats are fed a properly balanced ration containing flour to which various oxidizing agents were added, there were no noticeably positive harmful effects, eventhough these "improvers" were added in strength 100 times greater than customary. The effects were the same whether the flour was treated or untreated—the rats developed avitaminosis. These products destroy the traces of carotene that remain in flour, but inasmuch as refined flour does not contain appreciable amounts of either vitamin A or D, the effects are immaterial, especially in view of man's mixed diet. These traces of vitamin A are sacrificed for the improved attractiveness of the flour.
Spoilage. Flour particles are ground to pass through silks of 100 to 200 mesh to the inch, and so possess a very great surface in proportion to their bulk. This enhances susceptibility of flour to absorb taints from its surroundings, and also to oxidize, sometimes with disastrous explosive violence. Mustiness may develop in flour left over until the following spring; it is associated with high mold content. Foreign seeds may impart an off-flavor. Sometimes the flour is "bin burnt," with a darker color and a heated taste.
Small packages of flour may undergo a loss in weight from evaporation of moisture. Lumps may form from excess of moisture. Rancidity is rare, but acid conditions may develop on long standing under unfavorable conditions.
Insects may infest flour to such extent as to impart a purplish hue. If a sample is flattened with a spatula, it may soon become roughened from the movement of the maggots. These conditions are aggravated by high temperature and moisture. Moths lay their eggs in crevices in the plants or carriers. Caterpillars hatch in a few days, and may spin silk in sufficient amount to clog machinery. Rat and mouse droppings may also contaminate flour.
Bread may be spoiled in storage by development of organisms which produce a mucilaginous product described as "rope." The odor at first is reminiscent of over-ripe fruit but becomes repugnant on further development. Wrapping of bread before it is cooled, or close-stacking to preclude rapid cooling, contribute to its spoilage. Staling of bread is erroneously thought by the public to be caused by drying out as evidenced by increased hardness and dryness of the crumb, but the real reason is obscure. Bread can be restored to temporary freshness by reheating for a few minutes in the oven.
Definitions and standards. The federal standards in 1936 for several of the more commonly used breads are as follows:
Corn meal, maize meal, Indian corn meal. Meal made from maize grain. It contains not more than 14 percent of moisture, not less than 1.12 percent of nitrogen, and not more than 1.6 percent of ash.
Oatmeal. Meal made from hulled oats. It contains not more than 12 percent of moisture, not more than 1.5 percent of crude fiber, not less than 2.24 percent of nitrogen, and not more than 2.2 percent of ash.
Flour, wheat flour, white flour. The fine ground product obtained in the commercial milling of wheat, consisting essentially of the starch and gluten of the endosperm. It contains not more than 15 percent of moisture, not less than 1 percent of nitrogen, not more than 1 percent of ash, and not more than 0.5 percent of fiber.
Whole-wheat flour, entire-wheat flour, Graham flour. The product made by grinding wheat, and containing in their natural proportions all the constituents of the cleaned grain.
Gluten flour. The product made from wheat flour by the removal of a large part of the starch. It contains not more than 10 percent of moisture and, calculated on the water-free basis, not less than 7.1 percent of nitrogen, not more than 56 percent of nitrogen-free extract (using the protein factor 5.7), and not more than 44 percent of starch (as determined by the diastase method).
Ground gluten. The product made from wheat flour by the almost complete removal of starch. It contains not more than 10 percent of moisture and, calculated on the water-free basis, not less than 14.2 percent of nitrogen, not more than 15 percent of nitrogen-free extract (using the protein factor 5.7), and not more than 5.5 percent of starch (as determined by the diastase method).
Bread. The product made by baking a dough consisting of a leavened or unleavened mixture of ground grain and/or other edible substances.
White bread. The product, in the form of loaves or smaller units, obtained by baking a leavened and a kneaded mixture of flour, water, salt, and yeast, with or without edible fat or oil, milk, or a milk product, sugar and/or other fermentable carbohydrate substance. It may also contain diastatic and/or proteolytic ferments and such minute amounts of unobjectionable salts as serve solely as yeast nutrients. The flour ingredient may include not more than 3 percent of other edible farinaceous substance. White bread contains, 1 hour or more after baking, not more than 38 percent of moisture. The name "bread" unqualified is commonly understood to mean white bread.
Whole-wheat bread, entire-wheat bread, Graham bread is defined like white bread in every respect except that it is made from whole-wheat flour instead of flour.
Milk bread is like white bread in every respect except that milk (or its equivalent in proportions normal to milk) is used in place of water in making the dough. The milk may be reconstituted from a milk powder, with sufficient butter added to give a butterfat content equal to that of the normal amount of milk.
Raisin bread is like white bread except that there is no moisture limit, and the finished product must contain 3 ounces of raisins to the pound.
Boston brown bread is the product obtained by steaming or baking a leavened mixture of rye flour or meal, a white flour, molasses, salt, water, and/or a milk product, with or without raisins. Leavening is commonly effected with baking powder or sodium bicarbonate and sour milk.
Macaroni is the shaped, dried dough made by mixing water with semolina, farina, or wheat flour; the finished product does not exceed 13 percent moisture.
Noodles are made from doughs prepared with wheat flour and eggs. They are usually ribbon-shaped and contain not more than 13 per cent moisture and not less than 5.5 percent of egg solids (whole egg or egg yolk) on the dry basis.
Plain noodles contain no eggs, and the moisture does not exceed 13 percent.
Mixed flour. The federal statute of June 13, 1898, amended by the Act of April 12, 1902,5° defines mixed flour to be any milled food product containing 50 percent or more of wheat flour, grain products other than wheat, and any other material except "any material, not a product of grain, commonly used for baking purposes." It also includes any milled food product containing not more than 50 percent of wheat or wheat flour, and any other grain or its product, sold as a "flour," but does not refer to the mixtures sold as such. This operation is taxed at the rate of 4 cents per package of more than 98 pounds, paid by the mixer for coupon stamps from the Commissioner of Internal Revenue. There is also a special tax of $12 a year. The package shall be marked in black letters not less than 2 inches in height with the words "mixed flour," together with the weight, the names of the ingredients, and the name and address of the packer. A card not less than 2 by 3 inches bearing the same information must be inside each package.
Regulations for custard-filled pastry. Pursuant to numerous out-breaks of illness from eating infected cream pastries, some health officers have placed this industry under special surveillance. The West-chester County (New York) Department of Health has added regulations to its sanitary code which places any baker of custard pastry under permit, revocable Tor cause by the Commissioner of Health. Mix must be heated at a temperature of 200° F. (93° C.) for not less than 10 minutes, and then placed in a cooling room at a temperature of not more than 50° F. (10° C.) within an hour. At all times, it must be adequately protected against contamination. Utensils must be sterilized before each use. Persons suffering with skin infections are prohibited from preparing or handling the products. Temperature records must be kept on a form furnished by the department of health, including information about time of heating, cooling, and the filling operation. Products must be packaged to protect them from contamination, and labeled to declare the name of the manufacturing baker, the day of manufacture, and the statement: Refrigerate and consume today. They must be sold only on the day they were manufactured. Between the months of May and September, they must be kept refrigerated at a temperature not above 50° F. (10° C.) until delivery to the consumer.
The Baltimore City Department of Health requires that such pastry be heated 52 so that the custard reaches a temperature of 180° F. (82° C.). The time of heating and "riding down" to 150° F. (65.5° C.) after removal from the oven varies with the oven, thickness of pastry shell, and formula. Stritar and associates 53 have shown that custard-filled puffs and eclairs can be heated for 30 minutes at oven temperatures ranging from 190.6° to 218.3° C. (375° to 425° F.) with-out spoiling the quality and yet killing all harmful staphylococci. The outer covering of chocolate-coated products like eclairs can be added subsequent to any rebaking process.
Sanitary requirements. Many cities and states have enacted legislation to require sanitation in bakeshop practice. These requirements comprise the following items:
Bakeshops must be kept separate from living quarters.
All doors and windows must be adequately screened.
Adequate washing facilities must be accorded.
Water must be sanitary and potable.
Premises must be kept clean.
Toilet facilities must be adequate and sanitary.
Plumbing must be sanitary.
Walls and ceilings must be kept painted.
Floors must be impervious for flushing.
Light and ventilation must be adequate.
No animals are allowed in bakeries.
No sitting, lying, nor lounging on work benches is allowed.
No smoking or spitting is tolerated.
Employees must be free from communicable disease.
Employees must wash their hands and arms to elbows and clean under their fingernails whenever they begin work or leave the toilet.
Delivery vehicles must be kept clean.
Shelves, cases, refrigerators, showcases, and other receptacles must be kept clean and free from contamination by animals, flies, or vermin.
No products shall be touched or handled by customers.
All equipment must be cleaned daily.
No bakery products may be returned to sale after exposure unless wrapped in the same container originally used when first delivered. Refuse shall be kept well covered and removed daily.
Only clean fresh wrappings shall be used.
All ingredients must be pure and wholesome.
Not all these provisions collectively have been found in any one set of bakery regulations, but every provision occurs in at least some one official code.
Types of adulteration. Grain may be smutty or moldy, may contain ergot, or may carry an unusually large percentage of selenium. Wheat flour may be mixed with that from some other grain or vegetable product without declaration. Undeclared bleaching agents may be present. The flour itself may contain ergot. Weevils and other insects may infest it, and animal refuse and other dirt may contaminate it. Bacterial spores and vegetative cells may infect it. Flour may be spoiled by souring, molding, acquisition of off-flavors from storage, or lumping from excess moisture. Bread may fail to comply with legal standards of composition, particularly in content of moisture, or in some added ingredient such as milk. Artificial coloring may be introduced to deceive in the absence of some expected ingredient such as eggs in noodles. Any bakery products may contain micro-organisms of mixed flora which may come from insanitary bakery practices, or they may have become infected with pathogenic organisms.
Chemical tests. Sampling. Grain is sampled by probing bulk shipments with a double-shell compartment trier 60 inches long, taking at least 5 samples. Flour is sampled from sacks in number equivalent to the square root of the total number in the lot, but not less than 10, and selected progressively in increasing degree of exposure. The samples are concentrated by blending and quartering, and storing in air-tight containers.
Bleaching agents. Chlorine is determined by extracting the care-fully dried flour with anhydrous, alcohol-free ether, evaporating to dryness, extracting with dilute nitric acid, and determining the chlorine gravimetrically or volumetrically by titration with silver nitrate.
Nitrite determination is made colorimetrically by suspending 2 grams of the flour in nitrite-free water in 100 milliliter volumetric flasks, and comparing the color formed by the addition of sulfanilic acid and alpha-naphthylamine hydrochloride with tubes containing known amounts of nitrites.
Organic peroxides produce a blue color when treated with gum guaiac, approximately proportional to the amount of peroxide present.
Ergot. Ergot in flour is indicated by the absorption of the stain anilin violet by the damaged particles of grain. When a hot alcoholic extract of the flour is treated with dilute sulphuric acid in a test tube, a red color indicates the presence of ergot.
Selenium. Selenium is determined in wheat 54 by weighing the finely divided product into a mixture of sulphuric and nitric acids, gently heating, treating with hydrobromic acid, and distilling. When hydroxylamine is added, the selenium comes down as a pink precipitate which is weighed, or compared colorimetrically with standards of known selenium strength.
Bread. Bread is sampled by cutting slices about 1 cm. in thickness. The slices are allowed to air-dry overnight, then ground, and stored in an air-tight container.
MOISTURE DETERMINATION. Approximately 2 grams of the well-mixed sample are weighed into a flat bottom dish, heated in an oven, cooled in a desiccator, and weighed.
MILK SOLIDS IN BREAD. The percentage of milk solids in bread is determined indirectly by two available methods, namely, by the properties of the fat, and by the amount of citric acid. In the former, the Reichert-Meissl and Polenske values of the fat are determined, and from these data the butterfat and milk solids can be calculated by an appropriate formula which accompanies the description of the analytical method. The citric acid method is based on the digestion of the bread with an alcoholic-sulphuric acid-phosphotungstic acid solution, treatment of the filtrate with suitable reagents, and weighing the resultant pentabromacetone. A formula enables the analyst to calculate the percentage of whole milk solids in the moisture-free bread.
Carbohydrates in diabetic foods. Starch, sugar, and dextrin are determined by means of diastase. The finely ground sample is gelatinized on a water bath, and then treated with a malt extract until negative to the iodine test. The dextrose is determined by weighing copper oxide. The factor 0.9 converts the content of dextrose to starch.
Eggs in alimentary paste. The egg content in alimentary paste can be quantitatively measured by determining phosphorus in the lecithin-phosphoric acid 56 fraction by precipitating with molybdic acid and magnesia mixture. Also, the content of fat is indicative of the presence of eggs. Leach shows the effect of different amounts of eggs on the composition of noodles. The official method for deter-mining fat in these products provides that a 2-gram sample is to be shaken in a Rohrig or Mojonnier fat-extraction tube with alcohol and ether, the solutions evaporated to dryness, and the residues of fat weighed.
Pigments added to alimentary paste. Coloring matter in alimentary paste is determined by digesting the sample with ammoniacal alcohol, filtering, boiling off the alcohol, acidifying with acetic acid, and dyeing on wool. The official method 55 gives detailed directions for differentiating the colors.
Soybean flour. The presence of soybean flour in macaroni is indicated by the high fat and nitrogen contents. Rice, rye, and potato flours are revealed by microscopic examination of the starch cells.
Microbiological examination. Bacteria in flour are determined by plating 1-milliliter portions of the flour suspension on nutrient agar in a standard sterile petri dish. The colonies are counted after incubation at 37° C. (98.6° F.) for 24 and 48 hours.
Contamination with rat or mouse droppings is likely to give a high count of coliform organisms.
Bacterial spores in flour may be counted by suspending 20 grams of flour in 100 milliliters of sterile water, and pipetting 1-milliliter samples into tubes of melted nutrient agar. The tubes are placed in a boiling water bath for 20 minutes, and then the contents are poured into petri dishes. These are incubated at 37° C. (98.6° F.) and counted after 24 hours.
Rope spores. Hoffman and associates have worked out a method 58 for determining the spores of rope-forming organisms in flour or grain. They weigh 2 grams of the finely divided product into a glass-stoppered bottle, add 96 milliliters of distilled water, and shake with 10 grams of sea sand. Dilutions are made in sterile nutrient broth, heated in an Arnold sterilizer to destroy the vegetative forms, and incubated for 48 hours at 37.5° C. (99.5° F.). The presence of a pellicle on the surface of the liquid in the tubes is presumptive evidence of the presence of rope-forming organisms. The number of rope spores per gram of material tested is taken as the reciprocal of the highest dilution giving a positive result. They consider that, for practical purposes, counts are objectionably high when there is an excess of 20 per 100 grams of flour, 100 per gram of yeast or salt, and 10 per gram of the other ingredients.
Smut. Smut on wheat is determined directly by weighing out 50 grams of the sample, and then picking out and weighing all smut balls. A drop of the aqueous suspension of this fraction is quickly mounted on a hemacytometer, and the spores counted in the squares of the ruling. If the sample contains more than 0.02 gram of smut for a 50-gram sample (0.04 percent) , the wheat will grade smutty.
Insect parts. For the determination of insect parts, rodent hair, and other such insoluble filth in flour, a 50-gram sample is suspended in a saturated salt solution in a 2-liter Erlenmeyer flask. A layer of gasoline (sometimes carrying a wetting agent such as a drop or two of triethanolamine) is added to concentrate the extraneous material. This material is collected on a filter disk in a Buchner suction funnel, and examined under a low-power microscope at a magnification of 20-30.59
Supervisory procedure. The operation of a bakery must be kept on a high plane of sanitation if the products are to be clean, uncontaminated with harmful products of any kind, and uninfected with injurious microorganisms. The only way to insure compliance with such a desideratum is to inspect the premises regularly and to examine the products.
Premises should be free from infestation by vermin. Rat and mouse excreta and tracks give some idea of the number of these animals. Roaches, flies, and ants can be readily seen. Systematic mea-sures should be in operation to control all these pests.
Toilet and lavatory facilities should be amply provided to accommodate the size of the establishment. Floors should be non-absorbent, and pitched to a drain for flushing and sterilizing. Soap, hot water, and individual towels should be convenient for use before operators enter workrooms. Signs should be prominently displayed to remind employees to wash their hands before returning to their work. Plumbing throughout the plant should be sanitary, and protected from cross connections with the sewerage. Cobwebs should be kept down, dust and dirt removed, waste materials destroyed, equipment kept clean, windows clear, and floors scrubbed, and ample scalding water should be available for general clean-up. Piles of rubbish in the yard or anywhere on the premises can be expected to harbor vermin. Delivery equipment must be kept clean.
Employees should be medically examined at the time of employment, and periodically thereafter. Every day, the personnel should be inspected for cleanliness of finger nails and freedom from abscesses or skin diseases of any kind. No one with any fever, head cold, or cough should be allowed to handle products. Any workman who has been in contact with anyone having a communicable disease should be employed on jobs which do not expose the food to infection.
All operations in departments where cream pastries are made should be carefully examined to prevent practices which induce spoil-age or contamination. Refrigeration or other provisions must be ac-corded to prevent microbic growth. All equipment must be thoroughly scrubbed each day, and all utensils and tanks should be sterilized.
The baked foods themselves should be sampled from time to time to ascertain their compliance with local standards. This is especially necessary for therapeutic foods. Cream pastry must be carefully examined bacteriologically for staphylococci, salmonella, and coliform organisms. No carriers of typhoid organisms should handle finished products.
Bleaching of flour is considered to be an adulteration under the Food and Drugs Act if bleaching reduces quality and conceals inferiority or damage. It must be labeled to indicate that it has undergone this treatment.
To control insect infestation in the warehouse, floors should be kept swept, and all rubbish removed, burned, or fumigated in a vault. Freshly milled flour should not be stacked near old stock or feed. Fumigation with hydrocyanic acid is effective where gas penetrates, but it reaches the center of a bag very slowly by diffusion. Dosage should be determined by tightness of building, amount of stock, and stacking of bags. A recent case of poisoning from excessive residues of hydrocyanic acid used in fumigation of dried fruits indicates the potential danger of this powerful fumigant. Returned goods and used bags may also introduce infestation. Sometimes infestation may occur in a railway car during transit. Insects are found in accumulations of grain in cracks of the sides and bottoms of cars, and especially back of car linings. Sweeping is not always remedial, but fumigation with a gas is very effective. Infestation can occur on docks, especially when flour is stacked close to infested cottonseed meal and rice.
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50. Act of June 13, 1898, as amended by Act of April 12, 1902, relating to mixed flour. Internal Revenue. Section 1020, Title 26 U. S. C. A. See Regulations 25 Relating to the Tax on Mixed Flour. Bur. Inter. Rev., U. S. Treasury Dept., revised, Aug. 30, 1932.
51. Westchester (N. Y.) County Sanitary Code, Sec. 6, Article III, Effective March 15, 1936.
52. Baltimore Health News, 13, 65 (1936).
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58. C. HOFFMAN and associates, Ind. Eng. Chem., 29, 464 (1937).
59. Mimeograph release from Microanalytical Laboratory, U. S. Food and Drug Administration, Sept. 17, 1937.
60. Service and Regulatory Announcements, U. S. Dept. Agr., Bur. Chem. 26, Dec. 30, 1920.
61. G. A. DEAN and associates, U. S. Dept. Agr. Circular 390, 1936.
62. Report of the Chief of the Food and Drug Administration 1937, p. 3.