IMPROVEMENT OF THE RHEOLOGICAL AND PHYSICAL PROPERTIES OF NON-FAT YOGURT USING MICROBIAL TRANSGLUTAMINASE, EXOPOLYSACCHARIDES PRODUCING CULTURE AND COMMERCIAL STABILIZERS

Abstract

The aim of this study was to improve the rheological, physical and organoleptic properties of non-fat yogurt using microbial Transglutaminase (MTGase), Exopolysaccharides producing culture (EPS) and two commercial stabilizers based on pectin and gelatin. Results showed that non-fat yogurt samples produced by textural impotents haven't significant differences with control full-fat yogurt sample in moisture content at fresh, while there were significant differences between these samples and control non-fat yogurt sample. Moisture content significantly decreased in all yogurt samples except in control full and non-fat yogurt samples after 10 days of storage period. Non-fat yogurt EPS sample had the highest percentage moisture content compared with control (full-fat and non-fat) yogurt samples and experimental non-fat yogurt (MTGase, commercial pectin and gelatin) samples throughout storage. Pro/D.M was higher in control non-fat yogurt, non-fat yogurt EPS and non-fat yogurt produced by commercial gelatin compared with non-fat yogurt (MTGase, commercial pectin) and full-fat yogurt samples at fresh. There were no significant differences in Fat /D.M % between non-fat yogurt C2 and non-fat samples containing textural improvements, while there were significant differences between them and control full-fat yogurt C1 at fresh or during storage period. There were no significant differences in acidity among all treatments. Hardness was significantly lower in the EPS non-fat yogurt compared with the other treatments throughout storage period. The non-fat yogurt containing EPS producing culture and non-fat yogurt containing commercial stabilizers had a lower level springiness, Chewiness and gumminess than the full-fat yogurt sample and non-fat yogurt containing MTGase. Adhesiveness significantly increased during storage period for all treatments. There were no significant differences in syneresis percentage among all treatments. Non-fat yogurt produced by Exopolysaccharides producing culture, microbial Transglutaminase and commerial gelatindemonstrated rheological and physical properties were closer to that of control full-fat yogurt.