Changes of free fatty acid composition and number of lactic acid bacteria in three functional goat and sheep milk products fortified with inulin or fish oil

Abstract

Inulin and fish oil rich in omega-3 fatty acid were applied to yoghurt, kefir, and smearcase made from goat and sheep milk, and their impact on fatty acid composition was investigated at 8°C throughout 40 days. The number of lactic acid bacteria (LAB) was significantly diminished within 16 days, and by the end of the storage period the population size was decreased by 3 orders of magnitude in fish oil fortified samples. In inulin-fortified samples, a significant decrease in LAB number (by 2.5–3 orders of magnitude) was observed just by the end of the storage time, while the amount of unsaturated free fatty acids was increased. The extent of lipolysis and the resulted amount of free fatty acids exhibited varying feature depending on the composition of the product. Goat and sheep milk products exhibit analogous trends in terms of change in fatty acid composition with one exception: the ratio of free C16:0 was increased by 10% for goat milk products, while for the sheep milk products only by 3%. Ratio of C16:0 did not change during storage of sheep yoghurt as a result of inulin fortification. In contrast, 13% increase of this parameter was observed in case of the product variant prepared with fish oil addition. It might be stated that fortification with prebiotics can be regarded as a better way to improve the biological value of dairy products than that with fish oil.

Keywords

• functional dairy products
• fortification with inulin and fish oil
• fatty acid composition
• lab number
• diverse packaging methods