Tocopherol Distribution in Milk Fractions and Its Relation to Antioxidant Activity^a

Abstract

SUMMARY Studies were made of the distribution of tocopherol between the lipid in the fat globule membrane and inside the milk fat globule, and the relation of that distribution to the loss of tocopherol during lipid oxidation. Two fractionation procedures were used, one based on churning of cream, the other on washing cream by repeated dilution with sucrose‐saline solution and separation, followed by treatment with sodium deoxycholate. The tocopherol concentration was at least three times higher in the lipid of the fat globule membrane than inside the fat globule. During lipid oxidation, the tocopherol associated with the fat globule membrane was lost more rapidly. The results demonstrated that, in determining the oxidative stability of milk, the membrane tocopherol is more important than that inside the fat globule.

Effect of forage type and supplemental dietary vitamin E on milk oxidative stability

“…(Erickson et al 1964). The amount of a-tocopherol (vitamin E) associated with the membrane is considered to be the main determinant of the oxidative stability of the milk (Erickson et al 1964). …”

Composition, Properties and Nutritional Aspects of Milk Fat Globule Membrane – A Review

“…Alternatively, MFGM can directly be released from washed cream by the use of polar aprotic solvents [Bingham & Malin, 1992;Dapper et al, 1987], bile salts [Erickson et al, 1964;Snow et al, 1980], or nonionic detergents [Patton, 1982]; in addition these authors reported that direct extraction normally results in a lower yield, and a certain difference in composition depending on the concentration of the applied chemicals, the time and temperatures of extraction.…”

“…Only 4% of phospholipids compared with 16% of the MFGM proteins were lost during the washing process [Anderson & Brooker, 1975]. Washing also causes losses of tocopherol, an antioxidant in the MFGM [Erickson et al, 1964].…”

“…The larger fat globule surface area is likely to enhance aroma perception due to a greater contact surface of fat in the mouth [Michalski et al, 2003]. Due to the high amount of unsaturated FAs, MFGM phospholipids are susceptible to oxidation and may provoke a soapy-rancid flavor [Erickson et al, 1964;Lopez et al, 2007]. …”

“…First, cream can be separated from milk by a laboratory centrifuge or in a large scale, bench-top cream separator. Next, the separated cream is washed two [Ye et al, 2002], three [Fong et al, 2007;Kanno & Kim, 1990] or more number of times [Asker, 1974;Mangino & Brunner, 1975] in 3-15 fold volumes of distilled or deionized water [Kanno & Kim, 1990;Newman & Harrison, 1973], sucrosesaline solution with [Erickson et al, 1964;Mather et al, 1977;Nejjar et al, 1986;Snow et al, 1977] or without [Dowben et al, 1967] pH buffering, pH buffered sucrose solution [Khodaparast-Sharifi & Snow, 1989], isotonic phosphate buffer solution [Nielsen & Bjerrum, 1977], phosphate-saline buffer [Innocente et al, 1997], or simulated milk ultrafiltrate [Ye et al, 2004]. In some cases, detergents [Diaz-Maurino & Nieto, 1976;Mather et al, 1977] or dissociating agents [Ye et al, 2002] are added to facilitate the washing.…”