Oxidation Of Milk Fat Research Articles

The Effects of Amino Acids on Milk Fat Oxidation

The Effects of Amino Acids on Milk Fat Oxidation

Role of Milk Fat Globule Membrane in Autoxidation of Milk Fat

ABSTRACTThe influence of the milk fat globule membrane (MFGM) on oxidation of milk fat under various conditions was monitored by fatty acid analysis and oxygen consumption at 50°C. The rate of copper‐catalyzed oxidation of cream containing the membrane was faster than when the membrane was removed. In the dry state, the isolated MFGM, membrane lipids (ML) and the nonlipid membrane solids (NLMS) inhibited oxidation at 50°C and 95°C. In the presence of water, however, all membrane components enhanced oxidation at 50°C. The balance between the accelerating effects of membrane components and the inhibiting influence of other factors appeared to depend on processing conditions.

The role of amino acids in the autoxidation of milk fat

The effects of amino acids and their analogs on milk fat oxidation were examined under various conditions by measuring oxygen consumption and total unsaturated fatty acids. All the amino acids tested acted as antioxidants, characteristically extending the induction period (IP). Not only primary amino groups are responsible for the antioxidative activities of amino acids, but also the side‐chain groups contribute, at least partially, to the protective effects of L‐cysteine, L‐tryptophan and L‐tyrosine. In aqueous and HCL solutions, the antioxidative effects of L‐alanine were significantly reduced. The freeze‐dried L‐lysine‐HCL and L‐alanine‐HCL accelerated, while the corresponding control amino acids inhibited, milk fat oxidation.

Thermal behaviour of milk powders studied by differential thermal analysis and heat flow calorimetry

The technique of heat flow calorimetry was used to study the thermal behaviour of different milk powders above 20°C. Exothermic reactions of different types occurred when measurements were made with the samples in sealed cells. According to our interpretation of the calorimetric curves, these reactions correspond to: crystallization of amorphous lactose, Maillard reaction between milk proteins and lactose, oxidation of milk fat and decomposition of lactose. Their relative importance is discussed. In addition, the technique of high-pressure differential thermal analysis was used for studying spontaneous ignition and combustion of milk powders, under a large oxygen excess. The role of fat, carbohydrate and protein decomposition is underlined. Some self-ignition temperature values are given.

Light-induced Oxidation in Milkfat

Solutions of milkfat in hexane exhibited light absorption only in the near ultraviolet and in the region about 450nm. However, milkfat oxidation was promoted by narrow wavebands of light in all except the red end of the visible spectrum. In contrast, milkfat that had been treated with activated charcoal showed marked stability to oxidation during exposure to all except the blue and near ultraviolet part of the spectrum. It appears, therefore, that when milkfat is exposed to suitable wave lengths of visible light unknown constituents are capable of initiating oxidation reactions.

Studies on Buffalo milk fat oxidation. 1- The induction period as measured by peroxide value and TBA test, and its relation to iodine value, total carbonyls, and conjugated fatty Acids

Studies on Buffalo milk fat oxidation. 1- The induction period as measured by peroxide value and TBA test, and its relation to iodine value, total carbonyls, and conjugated fatty Acids

Studies on Buffalo milk fat oxidation. II. The variation on peroxide, T.B.A., and iodine values, and other constituents of Buffalo milk fat during autoxidation

Studies on Buffalo milk fat oxidation. II. The variation on peroxide, T.B.A., and iodine values, and other constituents of Buffalo milk fat during autoxidation

Studies on Buffalo milk fat oxidation. III. Isolation and identification of the carbonyl compounds from oxidized buffalo milk fat

Studies on Buffalo milk fat oxidation. III. Isolation and identification of the carbonyl compounds from oxidized buffalo milk fat

食品中の脂肪とThiobarbituric Acid (TBA) との反応について

(1) After a procedure for application of Thiobarbituric acid (TBA) test to milk fat was examined (Fig. 1, 2 and 3), TBA values of several kinds of milk products were measured (Table 1). (2) Sweetened milk products which showed high TBA value were found to have been influenced by added sucrose content (Table 2 and Fig. 4). (3) The influences of the methods of storage of modified powdered milk enriched with vitamin A on oxidation of milk fat and retention of vitamin A were studied. It was found that aeration (oxygen) had more influence on oxidation of fat in powdered milk than temperature. On the contrary, the former was less influence on retention of vitamin A than the latter (Fig. 5).

食品中の脂肪とThiobarbituric Acid (TBA) との反応について

(1) After a procedure for application of Thiobarbituric acid (TBA) test to milk fat was examined (Fig. 1, 2 and 3), TBA values of several kinds of milk products were measured (Table 1). (2) Sweetened milk products which showed high TBA value were found to have been influenced by added sucrose content (Table 2 and Fig. 4). (3) The influences of the methods of storage of modified powdered milk enriched with vitamin A on oxidation of milk fat and retention of vitamin A were studied. It was found that aeration (oxygen) had more influence on oxidation of fat in powdered milk than temperature. On the contrary, the former was less influence on retention of vitamin A than the latter (Fig. 5).

Studies on Oxidized Milk Fat. III. Chemical and Organoleptic Properties of Volatile Material Obtained by Fractionation with Various Solvents and Girard's Reagent

Summary The predominant odor compounds from the oxidized milk fat used in this study were ketones. None of these ketones were methyl ketones and a large proportion of them were unsaturated. Presumptive evidence has been presented which suggests that lactones are to be found in the volatile material and these have been correlated with the fruity and coconut odor of certain fractions of the distillate. The flavor of oxidized milk was closely simulated when the ketone fraction and non-carbonyl neutral fraction were mixed in milk in the proper proportions. It has been shown that in the advanced stages of milk fat oxidation it is possible to isolate flavor fractions which are typical of earlier stages in the oxidation and that the change in organoleptic character of milk fat during oxidation is due to a blending of different flavor compounds. The prolonged distillation of oxidized milk fat resulted in the formation of an α , β -unsaturated carbonyl compound of the formula C 10 H 18 O and the properties of its 2,4-dinitrophenylhydrazone have been presented.

2-Thiobarbituric Acid as a Reagent for Detecting Milk Fat Oxidation

Summary Malonic dialdehyde has been shown to yield a red color when heated with 2-thiobarbituric acid (TBA) reagent. Spectral analysis of this color has revealed it to be identical with that obtained similarly from oxidized milk fat and to closely resemble colors secured in like manner from a number of oxidized lipid materials and animal tissues containing unsaturated fatty acids. Thus, malonic dialdehyde may be a compound of significance in both food fat rancidification and the biological oxidation of unsaturated fatty acids. A preliminary study concerning the use of TBA to measure oxidative deterioration in pure milk fat has indicated that this reagent is more sensitive than conventional tests such as iodine value and the Kreis test. A procedure for empirical measurement of milk fat oxidation with the TBA reagent is presented. It seems probable that the TBA test could be used advantageously in measuring oxidative deterioration in a wide variety of fats and fat-containing foods.

Factors Influencing the Initial Induction Period in the Oxidation of Milk Fat

Factors Influencing the Initial Induction Period in the Oxidation of Milk Fat