Willis A. Gortner

A study of the determination of peroxides in fats

SummaryThe Kokatnur-Jelling method as modified by Lingenfelter for the determination of peroxides in animal fat has been found to agree satisfactorily with other methods now in use. The modified method involves a microtitration in a homogeneous medium (isopropanol) and has the additional advantages of being both simple and rapid.A statistical analysis of the peroxide values shows that the reaction time and temperature and the sample size must be standardized to obtain reproducible and reliable results. Close adherence to reaction specifications such as five minutes at 80°C. or seven minutes at 75°C. is necessary. Three minutes is too short a reaction time. The individual fat sample should contain no more than 50 microequivalents of peroxygen to avoid depression of the peroxide value.

Studies on the Relation of Chemical Structure to Plant Growth-Regulator Activity in the Pineapple Plant. V. Post-Harvest Delay of Senescence of Pineapple Fruit

The results of testing 369 compounds for post-harvest delay of senescence of pineapple fruit have been presented. Included were 94 phenoxyacetic acids, 43 other phenoxy acids, 23 phenylacetic acids, 15 hydrocinnamic acids, 20 compounds related to phenoxy acids, nine benzoic and seven salicylic acids, 48 naphthalene derivatives, 22 indole acids, five hydrazine derivatives, and eight cinnamic acids. Some 76 of the chemicals tested showed activity, and 29 were highly active in delaying senescence. The relationship of some of the chemical structures to senescence inhibition as a manifestation of plant-growth regulator activity is discussed. In the phenoxyacetic acid series, high activity was obtained from several of the halogen-substituted acids and not among the methyl-substituted acids. A few of the methyl-substituted acids did have moderate activity, however. In the phenoxy-a-propionic acid series, high activity was observed not only for a number of halogen-substituted acids but also for those with methyl substitution. None of the substituted phenoxy acids other than acetic and a-propionic showed even moderate activity. An appreciable number of the chlorine-substituted phenylacetic acids and two benzoic acids showed activity. None of the phenylalkyl-carboxylic acids other than acetic showed even moderate activity. None of the salicylic, phthalic, or phthalamic acids showed any activity. The hydrazine derivatives tested were all inactive. Only five chemicals other than the derivatives of phenoxy acids, naphthalene compounds, or phenylacetic acids were found to have at least moderate activity. The amides, nitriles, simple esters, and salts of active acids that were tested all proved effective in delaying senescence of pineapple fruit.