Physicochemical, rheological and antioxidant profiling of yogurt prepared from non-enzymatically and enzymatically hydrolyzed potato powder under refrigeration

Abstract

Evidences show that the storage period greatly affects the quality of yogurt. In this study, three types of yogurt: control yogurt (CY), non-hydrolyzed potato powder yogurt (PPY) and enzymatically hydrolyzed potato powder yogurt (EHPPY) were prepared at 42 °C for 5 h and stored for 28 days at 4 °C. The yogurts were evaluated for quality characteristics at different storage periods. Negligible differences in pH values, titratable acidities and viable counts were detected in all three types of yogurt during storage. However, compared to other yogurts, EHPPY exhibited desirable water holding capacity, throughout the storage period. Apart from this, sensory properties and antioxidant activities (2-diphenyl-1-picryl-hydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP)) of EHPPY were also significantly improved during the storage period. Furthermore, the storage (Gʹ) and loss (Gʺ) modulus of PPY, EHPPY were lower than CY at 4 °C while a hysteresis loop was shown by all yogurts at the temperature range of 4–50 °C indicating higher Gʹ (elasticity) than Gʺ (viscosity). Based on our findings, EHPP could be an important functional ingredient in improving the quality and storage stability of yogurt for its production at an industrial level.

Keywords

• Storage stability
• Potato powder
• Yogurt
• Rheology
• Microbiology
• Antioxidant activity