Drying oils peroxide value

Fig. 6.38 I nfluenceofwater activity (relative humidity) on the peroxide value (POV) of bulk flaxseed oil (O) and of flaxseed oil encapsulated in spray-dried WPI ( ) after 9w of storage at 37°C.

Feeding menhaden (fish) oil at 2% of the dry matter intake of the diet also lowered milk fat concentrations. The level of CL A was increased by approximately 3.6 fold, but there was also a concurrent 4-5 fold rise in the level of vaccenic acid. Increasing the oil intake to 3% had no additional effects. The level of n-3 fatty acids in the milk was increased, mainly due to increased levels of eicosapentaenoic acid (EPA 20 5n-3), as was the level of total trans monoenes. The effects of pasteurization and oxidation on the raw milk were examined but no significant changes were observed and the CLA isomer profile was unchanged. There were no significant flavour differences found between the milk (and butter made from the milk) of cows fed 2% menhaden oil and control samples. The higher polyunsaturated fat content of the butter meant that it was softer at 4°C and 20°C, but the acid value and peroxide value of the butter were similar to those of control samples even after 3 months. A consumer evaluation of milk from cows fed a fish oil diet found no difference in acceptability compared with the control milk (Ramaswamy et al, 2001). 

Crude lecithin is mixed with 2-14% hydrogen peroxide and 1% lactic acid at 50-60 °C. The lactic acid reduces the pH, which facilitates the reaction. Residual water is removed by drying. During the reaction the coloured components are bleached, which yields a light coloured lecithin. Hydroxylated lecithin is superior for emulsification of oil-in-water emulsions. It easily disperses in cold and water as a whitish emulsion. This is already a good indication that the HLB value increased significantly. 

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