AUGUST, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
In emergencies the utilization of both chlorine and copper sulfate is a frequent practice. During slime troubles, where bacterial counts are uniformly high, appropriate control measures invariably result in marked reductions of microorganisms. Figure 2 illustrates the average counts secured under ordinary mill conditions. Results were obtained by the plating method, using standard agar and incubating for 48 hours a t 3OOC. Although plant conditions (as shown in Figure 2) may not permit complete control of organisms to a state of practical sterility, it is possible for many mills to manufacture pulp which is relatively free from microorganisms. For example, a t bull screens (stage 2, Figure 2) colonies have been reduced to 8 per cc. Counts a t groundwood deckers (stage 5 ) were reduced a t the same time from 320,000 to 1,500. Contamination in a sulfite mill was almost completely eliminated ; less than twenty colonies per cc. of white water or stock were obtained in this part of the system. Progress in effective control is reflected in the production of
951
stock which is relatively free from bacteria, offensive odors, and dirt. This is the quality of paper recommended for food wrappers and containers. I n cases of contamination of stock by spore-forming bacteria, it should be possible to reduce the number of viable spores in newly made sheets to less than 100 per gram of stock (Figure 3). Further contacts while paper remains exposed in paper mills tend to recontaminate it with spores, growth fragments, and bacteria-laden dirt. I n order to avoid contamination following sheet formation, wrapper and container stock should be immediately encased and sealed in uncontaminated paper wrappers, providing complete protection a t ends of rolls or sheeted stock. It is particularly important to eliminate, as far as possible, direct human contacts. Detailed studies of microorganisms present in paper containers for milk suggest that, in order to obtain paper of satisfactory quality for contact with foods, it will be necessary to enlist the aid of sanitary procedures during every step in its fabrication. RECEIVED December 28, 1936.
Oat Flour as an Antioxidant
F
ROBERT C. CONN' AND ROBERT E. ASNISZ I N E LY ground oat flour, Table I records the values for known as Avenex, has been Musher Foundation,Inc., New York, N. Y. treated and untreated chips taken recommended as a suitable over a period of 42 days. Other inhibitor of rancidity in oil- and series were run with similar refat-containing foodstuffs; it has the advantages of availasults. Slight differences in the peroxide values were observed bility, blandness of flavor, absence of color, and acceptwhich could not be correlated with either the length of time ance as a food (9,4, 7). Experiments are reported here the chips remained under test or with organoleptic rancidity. which deal with the dusting of Avenex over the surface of Other unusual variations in the peroxide value were frepotato chips. Other studies were undertaken to determine quently observed, such as the reduction in peroxides of the the effectiveness of oat flour in reducing the rapid oxidation fat from treated chips between the 10- and 21-day periods. of fats at the surface of wrapping materials such as parchment Food-Packaging Materials paper, wax paper, and cardboard containers. These processes are referred to broadly in certain United States patents (6, 6). For such products as crackers, potato chips, nuts, etc., the fat of the product is adsorbed a t the surface of the packaging Potato Chips material, whereas for butter, lard, oleomargarine, etc., the fat is always in direct continuous contact with the packaging Potato chips were freshly prepared and dusted with 5 per cent of Avenex. The desirability for the elimination of the material. Consequently, it was desirable to determine the degree of rancidity protection afforded by the use of oat-flourprooxygenic actinic rays in the storage of potato chips was previously reported (1,s). However, because of the fact that treated (Avenized) packaging materials as would be obtained exposure of potato chips to ultraviolet light or to direct sununder normal commercial conditions. Avenized parchment paper was prepared by surface-water light does not simulate average commercial conditions, it was considered advisable to store them in the dark and a t sizing with oat flour following the parchmentizing operation; room temperature. the normal appearance of the paper is not changed by this Peroxide determinations following the Wheeler method (8) treatment. were made to determine development of rancidity. The following procedure gave consistent results : TABLEI. PEROXIDE NUMBBRS OF TREATED AND UNTREATED POTATO CHIPS~ AFTER STORAGE AT ROOM TEMPERATURE IN Twenty-five grams of crushed chips were thoroughly extracted THE DARK by shaking with 50 ml. of chloroform in a tightly stoppered bottle. The contents of the bottle then were transferred to a dry, previTreatment Peroxide Number after: of Chips 0 days 3 days 10 days 21 days 32 days 42 days ously weighed folded filter, and the bottle was washed out with an additional 25 ml. of chloroform which was likewise added to the Untreated 2.1 3.8 4.4 12.6b 20.9 35.7 Dusted with 5% filter. The filtrate was collected, and the filter plus the extracted Avenex 2.1 2.8 3.8 3.0 10.6 15.3C chips was thoroughly dried and weighed. By difference the weight a Cooked in refined cottonseed oil. of the extracted oil was obtained. Titration of aliquot portions b Distinct organoleptio rancidity. of the total filtrate gave the perogide number of the oil. TenC Slightly rancid. milliliter portions were usually taken for titration. Forty per cent of glacial acetic acid was added together with 1 ml. of saturated potassium iodide solution. After standing for exactly 1 Avenized greaseproof wax papers were prepared by mixing 35 minute, 50 ml. of water and a few drops of starch solution were per cent Avenex with 65 per cent paraffin in the waxing trough added, and the solution was immediately titrated with 0.001 N and applying sodium thiosulfate. ... - the paraEn-Avenex mixture to the paper in the normal manner. Appearance of the paper was not- changed, 1 Present address, Calco Chemical Company, Bound Brook, N. J but moisture resistance was decreased by this procedure. 2 Present address, Conshohocken, Pa.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
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VOL. 29, NO. 8
F COATED ( 5 % AVENEX) XPARAFFIN-COATED CONTROL AAVENEX-PARAFFIN COATED (IO% AVENEX)o OPARAFFIN-00ATED CONTROL
loo OAVENEX-PARAFFIN
XUNTREATED WRCHMENT PAPER
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FIGURBI1. PARCHMENT PAPEREXPERIMENT
Avenized cardboard containers were prepared by surfacewater sizing or as otherwise described in Figure 3. That a marked degree of protection was afforded could be simply demonstrated by thinly coating pieces of the Avenized papers and their respective controls with lard, placing them in tightly closed jars, and opening the jars a t regular intervals to note any changes in the odor of their contents. The jars containing the controls were found to have a definitely perceptible rancid odor for an appreciable length of time before those containing the Avenized papers. To demonstrate chemically and quantitatively, however, the exact amount of inhibitory protection afforded, the following method, which was found to be the most convenient for this purpose, was adopted : Exactly 1 ml. of molten lard held at 35" t o 40" C . was run from a volumetric pipet onto a piece of tthe paper measuring a b o u t 5.5 x 4 inches (14 X 10 om.). The paper was then tilted up and down until the lard was fairly evenly spread over its surface. The papers thus coated with lard were set aside, and care was taken to place all under exactly identical light and temperature conditions. In these FIGURE 3. CARDBOARD experiments the p a p e r s CARTON EXPERIMENT were kerJt in uniform darkness at -room temperature. Substantially the Wheeler peroxide titration method (8) was used as before: The piece of paper containing the lard to be tested was folded to a convenient size or cut into strips and placed in a 125-ml. Erlenmeyer flask. To the flask containing the paper were added about 10 ml. of a fat solvent, consisting of a mixture of 60 per cent glacial acetic acid and 40 per cent chloroform. The flask was then allowed to stand for about 5 minutes with occasional shaking. At the end of this time, 0.2 ml. of saturated potassium iodide was added, and the solution allowed to stand exactly 1 minute. Ten milliliters of distilled water and a few dro s of a 0.2 per cent starch solution were immediately added, a n f the solution was immediately titrated with 0.01 N sodium thiosulfate solution. The parchment and wax paper experiments were carried out in the Princeton University Chemical Laboratory. Figures 1 and 2 show the degree of rancidity protection obtained with these types of Avenized papers. Since a peroxide number of 20 is generally considered to indicate the approximate rancid point of lard, it is shown in the figures in that manner. The rapidity of the oxidation of lard spread on the surface of the control papers may be noted; the lard reaches a peroxide value of 20 a t the end of 3 days in the case of the parch-
A
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FIGURE 2. GREASE-PROOF WAXPAPER EXPERIMENT
ment paper and a t the end of about 5 days in the case of the waxed papers, whereas the oat-flour-treated parchment required 13.75+ days, and the treated wax paper required about 11 and 20 days, depending upon the concentration of oat flour on the paper. Similar tests were made in the laboratory of Musher Foundation with treated and untreated cardboard packaging materials and are recorded in Figure 3. The decrease in the initial peroxide number of the lard with increasing concentration of oat flour indicates a destruction of the peroxides initially present by the oat flour. A uniform increase in protection is obtained as the concentration of oat flour is increased. As indicated in Figure 3A, 4 per cent of oat flour was sufficient in these experiments to keep the per*CONTROL BOARD X A V E N U WATER WASH OslLlCATED BOARD-CONTROL A SIUCATED BOARD-AVENEX WATER WASH
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oxide number below 20 for a period of about 70 days. The control reached this level in 19 days. These results indicate that it is possible to secure substantial inhibiting effect to formation of peroxides in the fat of (1) potato chips by dusting 5 per cent Avenex over their surfaces, and (2) parchment paper, wax paper, and board materials surface-coated with lard, by treatment of such packaging materials with Avenex.
Acknowledgment The authors acknowledge the cooperation of the Kalamazoo Vegetable Parchment Company, Paterson Parchment Paper Company, Riegel Paper Corporation, Gair Cartons, Inc., and Chicago Carton Company for the processing of the paper and boards used for these experiments.
Literature Cited (1) Coe and Le Clero, IND.ENG.CHEM.,26, 245 (1934). (2) Harrison, Lowen, and Anderson, Ibid., 29, 151 (1937). (3) Morgan, Ibid., 27, 1287 (1935). (4) Musher, S.,Food Industries, 7,329 (1935). (5) Musher, S.,U. 5. Patent 2,026,697(Jan. 7. 1936). (6) Ibid., 2,038,752(April 28, 1936). (7) Peters, F. N., and Musher, S.,IND.ENG.C H ~ M29, . , 146 (1937). (8) Wheeler, D.H., Oil & Soap, 9, 89 (1932). RH~CEIV April ~ D 6,1937.
