L. R. Dugan

A distillation method for the quantitative determination of malonaldehyde in rancid foods

SummaryAn improved distillation method is described for the quantitative determination of malonaldehyde in foods containing oxidized fats. The procedure is compared with other methods in current use for the determination of malonaldehyde. A high correlation of TBA numbers with rancid odor in cooked meats was established.

Butylated hydroxyanisole as an antioxidant for animal fats

SummaryButylated hydroxyanisole has been developed as a new and very effective antioxidant for animal fats. It is readily soluble in fats, and practically insoluble in water. It exhibits synergism with acids, hydroquinone, methionine, lecithin, and thiodipropionic acid. It is very effective in protecting foods made with lard against rancidity.In combination with small quantities of hydroquinone or propyl gallate and an acid synergist, it imparts to animal fats high AOM stability and shelf life and is very effective in protecting foods made with lard (crackers, pastry, etc.) against rancidity.Extensive pilot plant and commercial tests have demonstrated the practical usefulness of the antioxidant.Extensive toxicological tests with rats have failed to demonstrate any physiological effects when the antioxidant is used daily in food, even in amounts several hundred times the maximum amount permitted by the regulations of the Meat Inspection Division.

An infrared absorption study of autoxidized methyl linoleate

SummaryA study has been made of the infrared absorption spectra of autoxidized methyl linoleate in samples ranging from PV 1 to PV 940 m.e./kg. Principal changes occur in the frequency range 3400–3550 cm−1 where bonded−OH groups absorb and at 1650–1775 cm−1 where >c=0 groups absorb.Two maxima were observed in oxidized samples in the −OH absorption range: one sharp and distinct at 3467–70 cm−1 which increased in intensity with increase in PV and a broad band which increased with increasing PV until it resolved into a true maximum at 3430 cm−1. Reduction of typical oxidized samples with KI reagent resulted in disappearance of the 3430 cm−1 band and appearance of a new band above 3500 cm−1. The band at 3430 cm−1 was attributed to −OOH groups associated by hydrogen bridging. The band at 3467 cm−1 and the band appearing above 3500 cm−1 were attributed to −OH groups, the band at the higher frequency resulting directly from reduction of a hydroperoxide.Absorption due to ketone and aldehyde carbonyl groups appeared only as an indefinite shoulder on the band due to the ester carbonyl. These were resolved by using the intensity of the sample with PV 1 as Io and that for the oxidized samples as I. A plot of Log Io/I then revealed three maxima. These indicate the presence of two and possibly three carbonyl containing substances other than the ester carbonyl in autoxidized methyl linoleate.Absorption in the two critical frequency ranges of fractions of autoxidized methyl linoleate eluted from an adsorption column correlate with interpretations made from ultraviolet absorption studies of the same substances.

Kinetic investigation into glucose-, fructose-, and sucrose-activated autoxidation of methyl linoleate emulsion

Autoxidation of methyl linoleate emulsions in aqueous phosphate buffer solutions in the presence of glucose, fructose, and sucrose has been studied by the rate of oxygen uptake. Oxidation rates increased with increasing concentration of sugars in the system. At comparable molar ratios of sugar to methyl linoleate the rate of oxidation in the presence of fructose was greater than with glucose which, in turn, was greater than with sucrose. Oxidation rates increased with pH until a maximum rate was reached at pH 8.00. There was less conjugation and more CO2 with fructose than with glucose at a comparable level of oxygen uptake and pH value. This suggested concurrent oxidation of methyl linoleate and sugars; fructose is the most readily oxidized of those studied.Sugars seemed to be effective only in combination with the resulting methyl linoleate hydroperoxide. The effect of sugars rests in an activation of the decomposition of the linoleate hydroperoxide, and on the acceleration of the autocatalysis.The activation energy values for the autoxidation of methyl linoleate emulsions in the presence of sucrose, glucose, and fructose are 14.9, 10.6, and 10.6 K. Cal./mol. at pH 5.50; 16.0, 10.8, and 10.4 K. Cal./mol. at pH 7.00; and 14.4, 10.2, and 8.8 K. Cal. at pH 8.00, respectively.Addition of ascorbic acid to the system at zero time or after 2 hrs. increased oxygen absorption. It appeared that oxidized methyl linoleate caused co-oxidation of the ascorbic acid. Additions of nordihydroguaiaretic acid, propyl gallate, and hydroquinone to the system were ineffective in stopping oxidation when they were added after oxidation had commenced. They reduced effectively the rate of oxidation when added at zero time.

Tocopherols as carry-through antioxidants

Summary1. Tocopherols have been found to be carry-through antioxidants in lard.2. Gamma tocopherol, which is a better antioxidant than alpha tocopherol, is also a better carry-through antioxidant.3. Higher levels of tocopherol provide increased carry-through stability although the AOM stability of lard is decreased.4. Combinations of BHA with tocopherol in lard provide increased carry-through stability but do not increase the AOM stability.

Some differences in composition of covering fat, intermuscular fat, and intramuscular fat of meat animals.

A method is described for rapid, reproducible extraction of total lipids from adipose and muscle tissues. The distribution of polyunsaturated fatty acids in the depot fats and intramuscular lipids in loin or rib roasts of pork, beef, lamb, and veal has been determined. The phosphatides of the muscle were found to contain a greater amount of polyunsaturated fatty acids than the neutral fats of the intramuscular lipids.

Influence of high energy radiation on oxidation of oleic acid and methyl oleate

Summary1. Gamma radiation from Cobalt 60 influences the oxidation of oleic acid and methyl oleate even at low temperatures.2. Determination of peroxide values, carbonyl values, and the E1cm1%. values at 224 mµ revealed that high peroxide values could be obtained but that secondary products are formed in appreciable quantities.3. The products causing absorption at 224 mµ may be α,β-unsaturated ketones. The level of these substances can be increased by irradiation-oxidation in the presence of metal soaps such as cobalt stearate.4. Irradiation-oxidation of methyl oleate through a series of temperature ranges from 7.5°C. to 55°C. reveals a marked thermal activation effect. Peroxide values of 2000 me/kg or greater are obtained in 100 hrs. of reaction time.

Influence of high energy radiation on the oxidation of oleic acid and methyl oleate. II. Sites of oxygen attack

Summary1.The hydroperoxides formed by the γ-irradiated autoxidations of methyl oleate at 7.5°C. and 56°C. have been characterized. The mono- and dicarboxylic acids produced by γ-irradiated autoxidation at 56°C. and by cobalt-catalyzed γ-irradiated autoxidation at 73°C. have also been examined.2.The hydroperoxides were found to be a mixture of the 8-, 9-, 10-, and 11-hydroperoxidoöleates in both samples. They were present in the order 10>11> 9>8.3.Evidence is presented for the presence of octanoic, nonanoic, octandioic, and nonandioic acids in the 56°C. autoxidation. Octanoic and nonanoic acids were also present in the cobalt-catalyzed autoxidation.4.No significant departure from non-irradiated autoxidations was found.

Study of carcass fats of beef animals. I. The composition of beef brisket fat

SummaryThe iodine value, titer, and unsaturated fatty acid composition of a number of beef brisket fats have been determined.Beef brisket fats have been found to differ from beef tallows representing composites of fats from other portions of the carcass. The variations are manifested in a higher iodine value, lower titer, lowersaturated fatty acid, and a higher monoethenoid fatty acid composition. The outer brisket fat seems to differ from composite tallows more than the inner brisket fat. This observation, previously unreported, does not apparently conflict with Shorlands designation of beef tallows as “heterolipids.”

The composition of fat from icterus swine

SummaryThe fatty acid composition of depot fats from 18 “icterus swine” has been determined. These fats represented back, belly, and abdominal fats. Depot fats from comparable carcass locations in nine normal swine were examined in the same manner. The fatty acid composition of depot fats from “icterus swine” corresponds well with that from the same carcass location of normal swine. The yellow fat in “icterus swine” is believed to be due to bile pigments or similar substances deposited by the pig under the conditions of disease existing in the animal. This yellow fat (from diseased swine) differs from that observed by Beadle,et al. (1), in that it has an apparently normal linolenic acid content whereas they found an abnormal linolenic acid content which they ascribed to dietary effects.