Journal of Dairy Research

Table of Contents - 2004 - Volume 71, Issue 01  


Oxidative stability of buttermilk as influenced by the fatty acid composition of cows' milk manipulated by diet

Dorthe Kristensen a1, Rikke V Hedegaard a1, Jacob H Nielsen a2c1 and Leif H Skibsted a1
a1 Food Chemistry, Department of Dairy and Food Science, Royal Veterinary and Agricultural University (KVL), Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
a2 Department of Food Science, Danish Institute of Agricultural Sciences, Research Centre Foulum, PO Box 50, DK-8830 Tjele, Denmark

Article author query
kristensen d   [PubMed][Google Scholar] 
hedegaard r   [PubMed][Google Scholar] 
nielsen j   [PubMed][Google Scholar] 
skibsted l   [PubMed][Google Scholar] 

Abstract

Milk from cows fed a low-fat diet high in cereals designed to stimulate fat synthesis de novo was lower in unsaturated fatty acids (21·3%) than milk from cows fed a diet high in fat, mainly from roasted soy beans (41·3% unsaturated fatty acids). Buttermilk from the more unsaturated milk was less oxidatively stable during storage (at 4 °C, followed for 11 d) than buttermilk from the more saturated milk, as monitored both by primary lipid oxidation products (lipid hydroperoxides) and by the secondary lipid oxidation product, hexanal. Fat-soluble antioxidants, β-carotene and α-tocopherol, analysed by HPLC, were not consumed during storage for either of the two types of buttermilk. In contrast, the antioxidative capacity of the serum phase decreased during storage as evaluated in a radical scavenging assay based on the semi-stable water-soluble radical nitrosodisulphonate (Fremy's salt). The time course for the decrease in water-soluble antioxidants was very similar for the two types of buttermilk suggesting that oxidation is initiated in the serum phase independently of fatty acid composition.

(Received October 30 2002)
(Accepted February 7 2003)


Key Words: Buttermilk; oxidation; free radicals; fatty acid composition.

Correspondence:
c1 e-mail: jacobh.nielsen@agrsci.dk