Identification and quantification of cholesterol oxides in grated cheese and bleached butteroil

Abstract

Butteroil samples bleached with benzoyl peroxide (BP) and 17 commercial cheeses were screened for oxidized sterols by thin layer chromatography (TLC). Ungrated cheeses made from bleached milk and freshly bleached butteroil contained no detectable oxidized sterols. Oxidized sterols were detected in stored, bleached butteroils and in grated cheeses. Four major oxidation products were the isomeric 5,6‐epoxycholesterols and the epimeric 7‐hydroxycholesterols identified by TLC, high performance liquid chromatography (HPLC) and mass spectrometry (MS). Additional sterol oxides (tentatively identified and not quantified) present in these samples included low levels of 7‐ketocholesterol and cholesta‐3,5‐dien‐7‐one. The epimeric 7‐hydroxycholesterols were detected in bleached butteroils stored in air (BP‐A) and nitrogen (BP‐N) for 22 days at 15 C. Butteroil, after 90 days of storage at 15 C, had 30 (BP‐N) and 60 (BP‐A) µg total oxides/g of bleached oil and, after 1‐year at −20 C, had 70 (BP‐N) and 180 (BP‐A) µg/g butteroil. A grated, unbleached cheese packaged in clear glass contained the most oxidized sterols (44 µg/g). Sterol oxides were not detected in bleached cream using a simulated industrial process.

Oxidised cholesterol in milk and dairy products

“…In the opinion of Nourooz-Zadeh and Appleqvist (1988b), the analytical data of Fischer, Laskawy, and Grosch (1985) who saponified total lipids, include esterified sterol oxides as some artefacts were generated. The method (TLC analysis) used by Finocchiaro, Lee, and Richardson (1984) also appears to yield values which are higher than results using other methods.…”

“…In the first 20 days, only a small amount of COPs was found in grated cheese under fluorescent light, the formation of 7-ketocholesterol was faster than 7a-and 7b-hydroxycholesterol whereas aand b-epoxide remained nearly constant for 72 days (Nielsen et al, 1995). According to Finocchiaro et al (1984), the levels of 5,6-epoxycholesterol, 7a-and 7b-hydroxycholesterol were higher in grated Parmesan cheese packaged in glass than the same grated cheese packaged in a cardboard box. Exposure of cheese powders to fluorescent light (1611 lux) for 12 weeks increased the levels of a-epoxide and 7-ketocholesterol, Table 7 COP levels (mg kg À1 fresh product) in stored butter after exposure to light at cooling and room temperature (Hiesberger & Luf, 2000) Butter with the levels being highest after 3 weeks and then decreasing throughout the remaining weeks to about half (Sander et al, 1989b).…”

“…Rose-Sallin et al (1995); (2) van deBovenkamp et al (1988); (3)Angulo et al (1997); (4)Calvo et al (2003); (5) Nourooz-Zadeh and Appleqvist (1988a); (6)Nielsen et al (1996a);(7); (8) Nourooz-Zadeh and Appleqvist (1988b); (9)Sander et al (1988); (10)Pie et al (1990); (11)Finocchiaro et al (1984); (12)Rose-Sallin et al (1997); (13)Sander et al (1989b); (14)Kristensen et al (2001);(15)Angulo et al (1998) 1 mg kg À1 lipid; 2 values for week 0 are in…”

Effects of Antioxidants and Packing on Cholesterol Oxidation in Processed Anchovy during Storage

“…Cholesterol oxides are usually found to accumulate at a relatively high level in commercially available fish products (1,2), and similarly in other processed foods such as spray-dried egg and milk products (3,4), heated oils and fats (5)(6)(7)(8)(9)(10) and processed meat products (11,12). We have studied the mechanism involved in cholesterol oxidation in fish products, and reported that there was a significant correlation between the peroxide values and the levels of cholesterol oxides in an oxidized mixture of cholesterol and purified fish oils.…”

Validação da metodologia para determinação simultânea, por CLAE, de colesterol e óxidos de colesterol em produtos cárneos processados

“…Embora seja eficiente para separar alguns produtos da oxidação do colesterol, a CG pode também destruir termicamente o colesterol e os hidroperóxidos [6,31]. A cromatografia gasosa com espectrometria de massas (CG-MS) é também uma técnica particularmente eficaz para a confirmação dos óxidos de colesterol [16,20,24].…”