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

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. (C) 2017 Elsevier B.V. All rights reserved.