Autoxidation in milk rich in linoleic acid. I. An objective method of measuring autoxidation and evaluating antioxidants

Autoxidation was studied in milk obtained from cows fed on formaldehyde-treated casein-safflower oil supplement. The fat of this milk contained high levels of linoleic acid. A rapid disappearance of dissolved oxygen (DO), measured by using a oxygen electrode, from milk samples stored at 0 degrees C in tubes without head-space, coincided with the development of oxidized flavours detected organoleptically. A correlation coefficient of 0.9 with 69 degrees of freedom (P smaller than 0.001) was obtained between the amount of DO disappearing and the taste panel scores for oxidized flavours. Butylated hydroxyanisole, sesamol, nordihydroguaiaretic acid, ethoxyquin, or butylated hydroxyanisole with propylgallate or tocopherols, when added in emulsified form to the milk at the rate of 10-15 mg/l milk checked the development of oxidized flavours and the rapid disappearance of DO. Other antioxidants tested were either ineffective or imparted off-flavours to milk. Samples of mare's milk neither developed oxidized flavours nor showed rapid disappearance of DO over a test period of 8 d. The oxygen electrode provides a convenient and sensitive method for studying autoxidation and evaluating antioxidants in milk.

The effect of intravenous infusions of sterculic acid on milk fat synthesis

1. The effects of intraduodenal infusions of sterculic acid, a naturally occurring inhibitor of desaturase activity, on the yield and composition of milk were examined in a lactating goat.

2. Sterculic acid administration increased the percentage of stearic acid in milk fat, reflecting inhibition of mammary desaturase activity. Milk yield was not affected, but milk fat output decreased. Possible explanations are discussed.

3. No evidence was obtained for an alternative pathway of oleic acid synthesis from acetate.

Strontium, calcium, magnesium, and phosphorus content of rat incisors as determined by electron microprobe analysis

Divalent cation and phosphorus content of normal and strontium-laden rat maxillary incisors was determined by electron microprobe analysis. A high positive correlation of magnesium and strontium distributions was found. Where strontium was elevated, calcium was only slightly depressed. Phosphorus appeared to be distributed randomly.

Jet-injection technique applied to preventive dentistry

A method developed to demonstrate desirable dispersion patterns of jet-injected solutions is presented.

The biosynthesis of cyclopropane and cyclopropene fatty acids in plant tissues

The biosynthesis of cyclopropane and cyclopropene fatty acids was investigated in seeds of several species of the order Malvales, including species with a high content of sterculic acid, a high content of malvalic acid, and a low content of these cyclopropene fatty acids. The fatty acid composition of the lipids in young and developing seeds is compared with particular attention to variations in cyclopropane and cyclopropene fatty acid contents.Incubation studies employing several(14)C compounds indicate that the methyl group of methionine is the most likely precursor of the ring-methylene carbon. A pathway for the synthesis of the cyclopropane and cyclopropene fatty acids is postulated. The origin of malvalic acid is also considered.

Strontium incorporation into dental enamel

Rats were raised on diets either rich or poor in strontium. Powder x-ray diffraction patterns suggest that isomorphous substitution of strontium for calcium occurs in the apatite of tooth enamel, and that strontium may form Sr(6)H(3)(PO(4)) * 2H(2)O, a compound hitherto unreported in biologic systems.

Authentic Vanilla Extracts: Comparison of Analyses of Commercial Samples with Their Laboratory-Prepared Analogs

Analytical indexes and profiles for 13 commercial and laboratory-made vanilla extracts were compared in a collaborative study. Experimental data are presented and discussed, indicating limits of comparability for the two types of extracts. Agreement in analytical values for corresponding commercial and laboratory-prepared extracts was satisfactory.