Development of new probiotic yoghurt with a mixture of cow and sheep milk: effects on physicochemical, textural and sensory analysis

Abstract

The purpose of the present study is to develop a new probiotic yoghurt with a mixture of cow and sheep milk and evaluate on physicochemical, textural and sensory parameters of these products. For each trial (n=3), cow (CM) and ewe (EM) milk were used to manufacture yoghurts with either cow (Y1), ewe (Y5) or mixtures of cow to ewe milk ratios of 3:1 (Y2), 1:1 (Y3), and 1:3 (Y4). Physicochemical (pH, titratable acidity, contents of total solids, protein, lipid, ash, water-holding capacity – WHC, and spontaneous syneresis), textural (firmness and apparent viscosity), microstructural and sensory (appearance, aroma, flavour, and consistency) properties were evaluated. In general, Y5 and Y4 exhibited increased (P<0.05) proximate composition values, with greater (P<0.05) firmness, WHC, apparent viscosity and lower (P<0.05) spontaneous syneresis values than Y1 and Y2; Y3 demonstrated intermediate values in textural parameters. Yoghurt micrographic structures supported that the greater ewe milk content the denser is the gel structure (Y5) as a result of more interconnected protein clusters. No apparent differences among mixed probiotic yoghurt microstructures were observed. While Y1 demonstrated the lowest (P<0.05) consistency, overall impression, appearance and purchase intention scores; Y3 was the only treatment exhibiting ideal consistency. Therefore, the probiotic yoghurt mixture containing equal proportion of cow and ewe milks represents an advisable technological alternative for dairy industries.