Quality evaluation of low-fat buffalo milk yogurt using ultrasound combined with microbial transglutaminase treatment

Buffalo milk is widely consumed in many regions and is known for its high nutritional value. In this study, low-fat buffalo milk yogurt was developed to address coagulation issues and whey separation problems. The aim was to enhance the texture of the yogurt using a combination of ultrasound and microbial transglutaminase (mTGase). Results showed that yogurt treated with 450 W ultrasound and 0.2 g/L mTGase had a smooth texture, no whey separation, and a balanced sweet-sour taste. The yogurt exhibited significantly improved physicochemical properties: water-holding capacity reached 89.9 % (a 2.27 % increase vs control), hardness increased to 972.947 g (15.7 % higher), while pH decreased to 4.34 (control: 4.44). While rheological measurements indicated higher storage modulus (G'), loss modulus (G″), and viscosity. Scanning electron microscopy showed a denser microstructure, while secondary structure analysis revealed an increase in α-helix and β-sheet content, indicating a more ordered and stable protein structure. Electronic tongue measurements indicated reduced bitterness, astringency, and aftertaste, with increased sourness. Electronic nose analysis showed increased levels of flavor compounds, including alkanes, alcohols, aldehydes, ketones, certain aromatic compounds, further enhancing the taste of the yogurt. This study provides theoretical insights into using ultrasound and mTGase to improve low-fat yogurt.