Cholesterol oxidation during storage of UHT-treated bovine and caprine milk

Effect of industrial processing and storage procedures on oxysterols in milk and milk products

“…1,2 However, a few more recent studies, with the development of more sensible methods for cholesterol oxides determination, have disclosed their presence in raw milk, both of cow and human origin. 6,13 While earlier studies reported that no or only limited amounts of oxysterols were formed during heating of milk under commercial pasteurization or UHT-treatments, a more recent study has shown that pasteurization and UHT treatments increase the amount of COPs significantly, up to 58% in bovine milk and 42% in caprine milk, when compared to raw milk. [13][14][15] These discrepancies may be attributed, at least in part, to the lack of a generally accepted standardized method for determining COPs in different food matrices.…”

“…6,13 While earlier studies reported that no or only limited amounts of oxysterols were formed during heating of milk under commercial pasteurization or UHT-treatments, a more recent study has shown that pasteurization and UHT treatments increase the amount of COPs significantly, up to 58% in bovine milk and 42% in caprine milk, when compared to raw milk. [13][14][15] These discrepancies may be attributed, at least in part, to the lack of a generally accepted standardized method for determining COPs in different food matrices. The variability of indicators such as linearity range, detection limit, repeatability and recovery rate of the various analytical methods that have been developed for quantifying COPs in food surely increases entropy.…”

“…16 The major oxysterol species found in animal products are 7α-hydroxycholesterol (7αOHC), 7β-hydroxycholesterol (7βOHC), 7ketocholesterol (7KC) 5,6β-epoxycholesterol (β-epoxy), 5,6α-epoxycholesterol (α-epoxy), cholestan-3β,5α,6β-triol (Triol), 25hydroxycholesterol (25OHC). 13,17,18 Some of these compounds have received particular attention due to their potential toxicity:…”

“…7βOHC and 7KC were selected as the most trustable indices of cholesterol autoxidation not only because the most represented in both liquid and powdered milk and derivatives, 12,13,17,18 but also because much less affected by the quite complex analytical determination procedures than other oxysterols such as β-epoxides. 28 Moreover, a large body of literature specifically points to the potential broad cytotoxicity of 7βOHC and 7KC, when present in excess amounts.…”

Simultaneous Analysis of Cholesterol Oxidation Products (COPs) in Powdered Milk Using HPLC/UV-Vis

“…24 The established derivatized method of cholesterol and COPs for HPLC/UV-Vis proved that reliable quantitation of COPs at the typical level (in the range of ppb (μg/kg) or ppm (mg/kg)) found the egg yolk, 16 milk and other dairy products 26,27 is possible. The accuracy (as a relative recovery) and the precision (as RSD%) of the COPs in the concentration range of 0.059-56 mg/kg in the spiked powder milk were 78.1-116.7% and 1.1-9.9%, respectively.…”