Lard oxidation

Table 9.15. Antioxidant activities of flavonols (0.01%) in lard oxidized at 60°C ...

Alford et al. [94] have reported on the action of various nticroorganisms on lard oxidation. They found 10 of the 28 nuCToorganisms studied destroyed the low levels of peroxide in fresh lard. Fourteen of the 28 had no effect on peroxides in the lard, while five strains of streptomyces increased peroxides by threefold. Pseudomonas ovalis increased peroxides by 8-fold, and Micrococcus freudenreichii increased peroxides 14-fold. The extent of oxidation observed in the lard was found to be very dependent upon the microtlora present in the lard. 

The raw materials for the manufacture of soap, the alkali salts of saturated and unsaturated C10-C20 carboxylic acids, are natural fats and fatty oils, especially tallow oil and other animal fats (lard), coconut oil, palm kernel oil, peanut oil, and even olive oil. In addition, the tall oil fatty acids, which are obtained in the kraft pulping process, are used for soap production. A typical formulation of fats for the manufacture of soap contains 80-90% tallow oil and 10-20% coconut oil [2]. For the manufacture of soft soaps, the potassium salts of fatty acids are used, as are linseed oil, soybean oil, and cottonseed oil acids. High-quality soap can only be produced by high-quality fats, independent of the soap being produced by saponification of the natural fat with caustic soda solution or by neutralization of distilled fatty acids, obtained by hydrolysis of fats, with soda or caustic soda solutions. Fatty acids produced by paraffin wax oxidation are of inferior quality due to a high content of unwanted byproducts. Therefore in industrially developed countries these fatty acids are not used for the manufacture of soap. This now seems to be true as well for the developing countries. 

MAHGOUB s E o and HUDSON B J F (1985) Inhibition of the pro-oxidant activity of copper by primary antioxidants in lard, Food Chem, 16, 97-101. 

Oleic acid may be obtained from glycerol trioleate, present in many liquid vegetable and animal nondrying oils, such as olive, cottonseed, lard, by hydrolysis. The crude oleic acid after separation of the water solution of glycerol is cooled to fractionally crystallize the stearic and palmitic acids, which are then separated by filtration, and fractional distillation under diminished pressure. Oleic acid reacts with lead oxide to form lead oleate, which is soluble in ether, whereas lead stearate or palmitaie is insoluble, prom lead oleate oleic add may be obtained by treatment with IL 5 (lead sulfide, insoluble solid, formed). With sodium oleate, a soap is formed. Most soaps are mixtures of sodium stearate, palmitate. and oleate. 

Certain protein hydrolyzates can be used for their antioxidant properties. Thus, a hydroly-zate of egg white slowed oxidation when added to a sample of cookies containing lard (28c). The rise in stability was proportional to the amount of protein hydrolyzate added. Dipeptides were... 

Kupranycz et al. (60) reported the presence of dimeric triglycerides in various butterfat samples oxidized at 185°C in the presence of air for 8 and 16 h. Nonpolar and polar dimeric TGs were found in lard samples used in deep fat frying (61). 

Contrary to our results, other workers (4, 9, 20, 36) state that in the stabilization of carotene, paraffin wax, and lard the activity of pyrocatechol is favorably affected by substitution at position 4, not only by normal but by tertiary alkyl groups as well. Disparate influences of substitution are not surprising when comparing the activity in different substrates owing to the possibility of directive influences in the process of inhibited oxidation. The participation of phenolic antioxidants in the inhibition of autoxidation can be demonstrated (1, 2, 3) simply as a reaction between the molecule of antioxidant AH and the alkylperoxy radical ROO formed duririg the autoxidation of the substrate RH. During this process, an aryloxy radical (A ) is first generated. 

Pastes Ointment-like mixtures of starch, dextrin, zinc oxide, sulfur, calcium carbonate, or other medicinal substances made into a smooth paste with glycerin, soft soap, petrolatum, lard, or other fats, and medicated with antiseptic or astringent agents, designed for external use. Early pastes, such as Pasta Glycyrrhizae and Pasta Althaeae, were internal preparations, most of which were of gum-like consistency. The modern pastes were introduced by the noted... 

Ascorbic acid was used to prevent the oxidation of olive oil, milk, arachis nut oil, lard, ethyl ester of lard, cottonseed oil, pork, and beef fat (4) data showing activity alone and as a synergist are reviewed. Ascorbyl laurate, myristate, palmitate, and stearate were similarly active, although only AP is listed as a preservative in GFR. Ascorbic acid synergy with tocopherol was also reviewed. 

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