Assessment of α-tocopherol content in cow and goat milk from the Serbian market

Slavica Sunaric,Jelena Zivkovic,Natasa Trutic,Gordana Kocic,Slavoljub Zivanovic,Radmila Pavlovic

doi:10.2298/hemind111116006s

Abstract

The present paper reports determination of ?-tocopherol in commercial cow, raw cow and goat milk, as well as estimation of its nutritive value based on ?-tocopherol content. Quantification was done by reversed-phase HPLC with fluorescence detection (ex 295 nm, em 330 nm) and with UV detector set at 286 nm and 292 nm. The method of milk sample preparation consisted of alkaline saponification with 30% KOH, denaturation of lipoproteins with methanol followed by liquid-liquid extraction with diethyl-ether. Recovery values of the extraction method were 78.5, 86.7 and 91.0% for three standard addition levels. Analyzed commercial low-fat milk samples had significant lower ?-tocopherol levels than milk with higher fat content. ?-tocopherol concentration below 0.30 ?g/ml in low-fat cow milk and 0.83-0.86 ?g/ml in whole milk were detected. Raw goat milk had much more ?-tocopherol (1.25 ?g/ml) compared with commercial and raw cow milk with similar fat content.

Highlights

The present paper reports determination of α-tocopherol in commercial cow, raw cow and goat milk, as well as an estimation of its nutritive value based on α-tocopherol content
Vitamin E is only biosynthesized by plants and distributed in milk principally as α-tocopherol
Occurring antioxidants have a potential for use as components in functional foods or nutraceutical which are fortified, enriched or enhanced with particular compounds. α-Tocopherol is often added to milk for a number of purposes: to restore its content where this has been reduced during technological, storage or handling procedures, to enhance nutritive value or to prevent lipid oxidation, reaction which leads to oxidative rancidity of milk and dairy products

Summary

Introduction

The present paper reports determination of α-tocopherol in commercial cow, raw cow and goat milk, as well as an estimation of its nutritive value based on α-tocopherol content. Α-Tocopherol is often added to milk for a number of purposes: to restore its content where this has been reduced during technological, storage or handling procedures, to enhance nutritive value or to prevent lipid oxidation, reaction which leads to oxidative rancidity of milk and dairy products. For this purpose, Regulation (EC) No 1925/2006 of the European Parliament and of the Council allows addition of α-tocopherol, α-tocopheryl acetate and α-tocopheryl acid succinate [2]. Stock standard solution of α-tocopherol (0.908 mg/ml) was prepared by dissolving (±)-α-tocopherol (Fluka Analytical BioChemika 1.1 units/mg) in absolute ethanol. Working solutions (100 μg/ml) were prepared daily from the stock standard solutions

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