Volatile 4-alkyl-branched chain fatty acids in New Zealand sheep milk

Sheep milk contains higher levels of major nutrients including protein, fat, minerals and vitamins than cow milk. However, the perceived goaty-sheepy flavour may limit the consumer interest in sheep milk and/or sheep milk products. Volatile free fatty acids, and especially volatile branched chain fatty acids (vBCFAs), contribute to the typical goaty-sheepy flavour in sheep and goat milk. 4-Ethyloctanoic acid (4-Et-8:0) plays a predominant role for this unique favour attribute of sheep and goat milk along with 4-methyloctanoic acid (4-Me-8:0) and 4-methylnonanoic acid (4-Me-9:0) when they are present in free from. The free vBCFAs include the native nonesterified fatty acids in milk and those hydrolysed from lipid such as triacylglycerols. The flavour intensity of sheep and goat milk is not only linked to the concentrations of vBCFAs, but also to their sensory thresholds which is the concentration where 50% of the trained panellists could correctly identify the vBCFA as being present. Odour activity values (OAVs) of volatiles derived from their concentrations relative to their odour thresholds can therefore be used to estimate the flavour perception of milk and dairy products.