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

Abstract

The present study was carried out to evaluate the effect of developed acidity and subsequent neutralization of milk (cow/buffalo) on heat induced protein-protein interactions occurring at various stages during preparation. Protein-protein interactions were studied in terms of surface hydrophobicity (F), sulfhydryl (-SH) group and SDS PAGE. As milk progressed to boiling stage, increase in F and decrease in -SH content was observed. prepared from cow milk had comparatively higher values for F and lower values for -SH group. F was observed to be highest in acidic samples followed by neutralized and fresh samples. While considering -SH group, maximum values were observed in neutralized samples followed by acidic and fresh samples of both milk and . However, no visible difference was observed in SDS PAGE patterns of casein fractions isolated from different types of samples. The bands of β-lg and α-la did not resolve clearly in the samples due to high heat treatment involved in its preparation, indicating intense denaturation of whey proteins especially in neutralized samples where an alkaline medium resulted in strong binding between casein and whey proteins. The quality of milk also resulted in altered heat induced protein-protein interactions in .

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

“…Khoa is a fat and protein rich product with quite high water activity which makes it more prone to proteolytic and oxidative changes adversely affect its storage stability. India is a tropical country and due to its comparatively higher atmospheric temperature, development of acidity is one of the most common reasons of milk getting sour easily (Choudhary et al 2018). Such milk is not suitable for thermal processing (Choudhary et al 2017a, b).…”

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

“…Tis might be due to the conversion of the SH group to disulfde (SS), resulting in protein-protein interaction between PGL and MP. Choudhary et al [33] reported that polymerization and formation of covalent disulfde bonds after protein-protein interaction reduced total SH content.…”

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

“…As shown in Figure 3A, the surface hydrophobicity of the goat milk protein treated at 85°C and above was significantly greater (P < 0.05) than that of the CG and reached maximum at 85°C, indicating that the hydrophobic groups exposed on the surface of the milk protein increased when the heating temperature was increased to 85°C. This may be explained by the fact that when the temperature was lower than 85°C, the heating caused exposure of the thiol group, the whey protein conformation changes and the protein structure unfolds, resulting in the exposure of the hydrophobic site, and thus the surface hydrophobicity is increased (Vasbinder and de Kruif, 2003;Choudhary et al, 2018). With increasing heating temperature (85-125°C), interaction between β-LG and cysteine containing whey protein such as α-LA led to the formation of whey protein aggregates, and β-LG and ĸ-casein formed casein-whey protein aggregation by thiol-disulfide bond exchange reactions, which resulted in irregular surface structures of the casein and improvements in surface hydrophobic- (Vasbinder and de Kruif, 2003;Choudhary et al, 2018).…”