Effect of type and quality of milk on heat induced protein-protein interactions in khoa

Associated Changes in the Structural and Antioxidant Activity of Myofibrillar Proteins via Interaction of Polyphenolic Compounds and Protein Extracted from Lentil (Lens culinaris)

This study evaluated the effects of different concentrations of green lentil acetone extract (GLA) (250, 500, 750, and 1000 μg/mL) and protein of green lentil (PGL) (1, 2, 3, and 4 g/100 g MP) on the functional attributes of myofibrillar protein (MP). GLA extract and PGL significantly affected the structure of MP by decreasing the carbonyl and sulfhydryl contents. Intrinsic fluorescence quenching studies showed that static quenching was involved in MP-GLA extract and MP-PGL complexes. Compared to the control (MP), the addition of GLA extract and PGL decreased the surface hydrophobicity, which correlated with the decrease in protein solubility. The MP-GLA and MP-PGL had lower cooking losses and slightly higher water-holding capacities $\left(P<0.05\right)$ . FTIR spectroscopy demonstrated changes in MP secondary structure with the addition of GLA extract and PGL. GLA extract and PGL also decreased the thermal stability of MP and showed significant synergism in enhancing the radical scavenging activity of MP. Taken together, the results indicated that a high concentration of GLA extract (1000 μg/mL) and PGL (4 g/100 g MP) improved the functional properties of MP, and GLA extract was the most effective.

Change in the structural and functional properties of goat milk protein due to pH and heat

This study was carried out to investigate the effects of pH and heat on the structure and function of milk proteins by comparing goat milk treated under different pH and temperature conditions. The results showed that pH had a significant effect on the thermal stability of goat milk proteins, and the proteins were least thermally stable at pH 7.7. Except for the pH 6.9 goat milk, the surface hydrophobicities of the milk proteins at various pH values reached their maxima at 85°C. The particle size, zeta potential, and content of regular secondary structure also decreased significantly at 85°C, and the turbidity of milk proteins under alkaline pH conditions was lower than that under acidic conditions. It was concluded that alkaline conditions resulted in better emulsion stability and oil-holding capacity, and acidic conditions offered better foaming ability, foam stability, and water-holding capacity for goat milk protein during heat processing. It can also be seen that 85°C was the key temperature for milk proteins after changing the pH of the milk. This paper provides a theoretical basis for optimizing the processing conditions for goat milk and the applications of goat milk proteins.

Effect of quality of milk on physico-chemical characteristics of buffalo milk concentrate (khoa) during storage

The present work was conducted to evaluate the quality of milk (fresh/acidic/neutralized) on the physico-chemical, textural and fatty acid profile of khoa prepared from buffalo milk and stored in poly-alu-poly laminates for 30 °C/7 days and 5 °C/21 days, respectively. The degree of deterioration of common quality parameters was rapid during storage at 30 °C as compared to storage at 5 °C. Khoa stored at 30 °C showed greater variation in various physico-chemical and textural parameters as compared to khoa stored at 5 °C. Acidity, ash, tyrosine value, furosine, HMF, FFA, peroxide value, TBA value, butyric acid and stearic acid showed an increasing trend whereas, decrease in pH and oleic acid was observed as storage period progressed. Noticeable changes were observed in textural attributes of khoa during storage. However, the SDS-PAGE pattern of caseins from different types of khoa showed almost negligible deviation during storage.