Mushrooms, pearl onions, and cherry peppers were packed with either citric acid or acetic acid to determine the time required for the pH inside the particulates to decrease to 4.8 or less. The blanched products were packed into home canning jars, covered with acidified brine, and pasteurized in steam at 100°C. After storage at 25°C, pH measurements were taken on samples of drained brine, individual particulates, and a puree of all particulates. With acetic acid, equilibrium pH was achieved in approximately 1, 15, and 30 d for mushrooms, onions, and peppers, respectively. Longer times would be required to achieve equilibrium pH for each product with citric acid. The time required for the pH inside the particulates to decrease to 4.8 or less was a function of acid type, initial acid concentration, and the product being acidified. With sufficient acidulant to achieve an equilibrium pH of 4.6 or less, the time required for particulates of mushrooms, onions, or peppers to decrease to pH 4.8 or less was 7 d or less in all instances. Since studies (inoculated packs) of similar products have shown that a minimum of about 10 d is required for Clostridium botulinum growth at a pH of 5.0, the rate of acidification for these products was sufficient to prevent growth of C. botulinum.

A proposed method for determining pH of acidified foods has been developed and subjected to collaborative study. The method appears to be both accurate and precise. Five samples consisting of pimientos, marinated pimientos, 2 pH buffer solutions, and chocolate syrup were sent to each of 12 collaborators along with a copy of the method. Two of the collaborators were FDA District laboratories while the remainder were representatives from industry, universities, and state health agencies. Many different types of pH meters and combinations of electrodes were used by the collaborators. The tabulated results from the collaborators are presented. The method has been adopted official first action.

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Within recent years many synthetic pesticides have been developed and used for the protection of food crops. These powerful pest control agents have received much attention from investigators both as to their toxicological nature and their ability to alter food flavor.The influence of pesticide residues on food fermentations has not been so widely studied as the flavor effect. The problem has, however, received the attention of Adams (1) who, working with the fungicide captan, found that yeast fermentation of cherry juice was delayed 24 hours and 30 days by 7 and 10 p.p.m., respectively, of the material.Lindane, the gamma isomer of hexachlorocyclohexane, is a very effective insecticide in controlling certain cucumber insects. A metabolic relationship between lindane and i-inositol has been reported by several investigators for yeasts (11, 13, 15), mold (3, P), other organisms (4, 10) and enzymes (7,12,14). The study reported here was made to ascertain the influence of lindane residue on the cucumber fermentation and on certain species of the microflora. EXPERIMENTAL Materials and methods.To study the effect of lindane spray residue on cucumber fermentatiorf, the lindane was introduced by 3 methods : spraying harvested cucumbers just prior to brining; using recommended insect control schedules with lindane on replicated experimental field plots; and adding known amounts of pure lindane and i-inositol to highly defined liquid media for growing pure cultures of micro-organisms.For the first method (1953), harvested cucumbers were divided into two approximately equal lots. One lot was used for the controls. The other lot was sprayed with lindane (1 lb. 25% wettable per 100 gal.) as follows : cucumbers were spread one layer thick on a tarpaulin and the spray was applied uniformly over the sample by single passes of the nozzle held about 18 inches above the cucumbtrs. The control lot was sprayed with tap water only. Three replications of each treatment were made. One hundred pounds of cucumbers were weighed into each 21-gallon keg and covered with 10 gallons of brine. The concentration of the brine for the first replication was 45" Salometer; this brine density was maintained by addition of salt during the active fermentation period.Brine concentration for the second replication was also 45", but in this case it was permitted to equalize with the cucumbers. Cucumbers in the third replication were covered with a 35" Salometer brine which was permitted to equalize with the cucumbers during the fermentation period. The growth of film yeasts during the active fermentation was suppressed by a G-E Sun lamp and the ambient air temperature of the room was not controlled.Cucumbers from replicated insect-disease control field plots were used for the second method (1954). Four treatment schedules and a control were employed ; namely, Block I

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