Lipid Deterioration in Dairy Products. The Stability of Milk Fat and Fat-Soluble Vitamins as Determined by the Re-Emulsification Test

Krukovsky, Vladimir N.; Guthrie, E.S.; Whiting, F.

doi:10.3168/jds.s0022-0302(48)92283-8

Cited by 9 publications

(7 citation statements)

References 12 publications

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“…The nutritional significance of this loss of vitamin C has been disputed (Lechner, 1977;Wartenberg, 1977), but that of folic acid may be regarded as serious (Ford, 1967). Losses of vitamins B 12 , A and E also depend on the O 2 content of milk (Ford, 1967;Krukovsky et al 1948).…”

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confidence: 99%

Effect of oxygen on the keeping quality of milk: I. Oxidized flavour development and oxygen uptake in milk in relation to oxygen availability

Schröder¹

1982

Journal of Dairy Research

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Oxidized flavour developed in whole milk only through the catalytic effect of either Cu or light. The O 2 requirement for the 2 processes differed as did the characteristics of the off-flavours produced. Cu-induced oxidized flavour was described as 'cardboardy' and light-induced oxidized flavour was 'painty'. Light-induced oxidized flavour increased in intensity with O 2 loss, and could be prevented in stored milk by restricting access of O 2 . In UHT milk with a dissolved O 2 content of 66 mg/1, and in the absence of access of further O 2 , light-induced oxidized flavour did not develop; similarly, O 2 uptake of 7 -5 mg/1 in in-bottle sterilized milk exposed to fluorescent light did not result in flavour formation. When light-induced oxidized flavour developed consistently in whole milk none developed in skim-milk, indicating the lipid source of the flavour. In contrast Cu-induced oxidized flavour development was not associated with high O 2 uptake. Although nearly complete deoxygenation of whole pasteurized milk contaminated with Cu prevented the formation of the flavour, moderate deoxygenation resulted in even greater flavour intensity than non-deoxygenation. The 2 oxidized flavours also differed in relation to ascorbic acid (AA) oxidation. Light-induced oxidized flavour developed only after AA oxidation was complete, whereas Cu-induced flavour developed with AA still present. AA oxidation was greatly accelerated through the effects of both Cu and light. In milk free from Cu contamination and protected from light, after AA oxidation (plus SH group oxidation in the case of UHT milk) was complete, no further loss of O 2 occurred, even during prolonged storage at 5 °C, despite the presence of large O 2 concentrations. However, at 20 °C, a small consumption of O 2 was measured, and this was associated with stale flavour.

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confidence: 99%

Effect of oxygen on the keeping quality of milk: I. Oxidized flavour development and oxygen uptake in milk in relation to oxygen availability

Schröder¹

1982

Journal of Dairy Research

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“…The deaeration of raw milk also extends the protective influence against photochemical inactivation of milk lipase (27). In the presence of occluded oxygen the enzyme sensitivity to light varies appreciably, however, among samples of milk from individual cows (27).…”

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confidence: 99%

“…Lipase can be inactivated irreversibly and completely by heating milk at 58°t o 630 C. for 30 minutes in the presence of occluded oxygen (35), by rennet and acids at the isoelectric point of casein (20), and by preformed FLO» added in amounts needed to oxidize all of the ascorbic acid in the milk to dehvdroascorbic acid (27).…”

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confidence: 99%

“…In the presence of occluded oxygen the enzyme sensitivity to light varies appreciably, however, among samples of milk from individual cows (27). The origin of bitter flavor in rancid milk was traced by us to the gravity cream layer of raw milk (27). Since the milk fat agglutinin concentrate (22) obtained by the author via reseparation of gravity cream at 37°to 40°C.…”

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confidence: 99%

“…However, the fat does deteriorate when milk products are used after prolonged storage, persistent metallic-to-fishy flavors develop, and in fat soluble vitamins are lost (Figure 5 and Table III). The likelihood of deterioration depends on the type of product held and upon production, processing, and storage conditions 27). Fat also deteriorates when whole milk is permitted to oxidize with 5 to 10 p.p.m.…”

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confidence: 99%

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