Comparative physico-chemical properties, amino acids and volatile components of yoghurt produced from cow, goat, and camel fresh milk

Abstract

The study evaluated and compared the physicochemical properties, amino acid profiles, volatile compounds, and organoleptic characteristics of yoghurts produced from fresh camel, sheep, and cow milk to determine their respective quality profiles. Fresh milk was obtained from camels, sheep, and cows, then pasteurized and processed into yogurt using a Yogourmet® starter culture containing active bacterial cultures (Lactobacillus bulgaricus, Streptococcus thermophilus, and Lactobacillus acidophilus). The yogurts were analysed for physicochemical properties (pH, Brix, specific gravity, viscosity, total solids, moisture, and lactic acid), amino acids, sensory attributes, and volatile compounds using standard methods. The physicochemical parameters ranged as follows: pH (4.32- 4.50), specific gravity (1.030 – 1.038), brix (18.20 – 21.00%), moisture (71.00 – 74.20 %), total solids (25.80 – 29.00 %), lactic acids (0.85 – 0.95 %), and viscosity (4450 – 4000 mPa.s). Camel milk yoghurt showed highest proportions of most of the essential and non-essential amino acids. The volatile compounds identified in the yogurts were classified as alcohols, aldehydes, acids, esters, and aromatic compounds. Specifically, aldehydes (including furan, hexanal, heptanal, octanal, and decanal) and esters (such as ethyl acetate, ethyl propionate, ethyl hexanoate, ethyl octanoate, and ethyl butyrate) were primarily responsible for the flavor profiles of the yogurts, based on their relative proportions. Ethyl pyrazine, 2 – Acetyl – 1 – pyrroline, Benzyl alcohol were aromatic compounds identified. Sheep milk yoghurt was the most viscous, smooth, and spreadable with a robust flavour, while cow milk yoghurt achieved the highest overall acceptability due to its balanced flavour and absence of off-flavours. Camel milk yogurt was characterized by a thinner, more watery consistency and a more pronounced sourness, but sweet than the other samples. All the samples were acceptable.