Impact of Glycomacropeptide and Crude Virgin Olive Oil on Properties of Bio-Yoghurt

Abstract

In this study, bio-yoghurt was manufactured using cow milk and addition of 1% Bifidobacterium bifidum Bb12 to yoghurt culture consist of 2% (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) (1:1) The study also concerned with improving the viability of the used bacteria by adding 0.01% glycomacropeptide (GMP) and 0.1% crude virgin olive oil (CVOO) to milk prepared for yoghurt industry. The effect of these additions on microbiological, chemical, rheological and sensory properties has been studied of the final product during storage period for 21 days at 5°C. The results revealed that, numbers of bacteria Lb. bulgaricus, S. thermophiles, B. bifidum and total bacterial count were increased in treated yoghurt more than control during storage period. Yeasts and moulds were appeared in yoghurt fortified with 0.01% GMP and control after 15 days of storage. All yoghurt treatments as well as control were completely free from coliform group during storage period. Values of pH for all yoghurt samples, decreased generally while the content (%) of acidity, total solid (TS), Total protein (TP), water soluble nitrogen (WSN) and fat increased during progress of storage period and all treatments have values more than control. Syneresis decreased during progress of storage period. Hardness, Cohesiveness, Gumminess and Chewiness increased for all treatments during storage while Springiness decreased for all treatments during storage period. Yoghurt fortified with GMP (T1) had the highest total acceptance during storage for 21 days at 5°C.