Yeşil Çay Polifenollerinin Kazein ile Β- Laktoglobulin Etkileşimleri Üzerine Etkisi

Abstract

Within the scope of the thesis, it has been tried to determine the interactions of Betalactoglobulin (BLG) and Kappacasein (KCN), which are aimed at different degrees of denaturation at different heat treatment norms, and in which direction these interactions will be affected by polyphenol-protein interactions. In this sense, the effect of green tea polyphenols on the coagulation process and the relationship of this effect with heat treatment were evaluated in rennet gels obtained from raw milk, which were heat treated at 65 °C/30 min, heat treated at 85 °C/30 min. As a result of the analysis of the effect of green tea extract (GTE) addition on the rennet coagulation process of milk, it was observed that the total duration of the rennet coagulation process increased with the addition of GTE, that is, the processes slowed down with the addition of GTE. When the effect of the addition of YÇE on the formation of caseinomacropeptide (CMP) was examined, it was not seen in CMP experiments, but it was thought that the interactions of BLG and KCN were effective in slowing the rate of CMP formation, especially in milk samples that were heat treated at 85°C/30 min. In the results of the trial performed with circular dichroism (CD) spectroscopy, the BLG structure was denatured at 85 °C and an increase in the number of different secondary structures was observed. The difference clearly revealed by the interaction with GTE was observed in near-visible region studies, especially in the presence of BLG-KCN interactions at 85°C, and it was observed that the GTE effect caused tertiary structure changes in both forms of heat treatment. In the Native-PAGE study, it was determined that the interaction of GTE phenolics with BLG and BLG-KCN complex increased with increasing degree of denaturation of BLG. In the measurements made with the gel formed in the texture analysis, the hardness of the raw milk and 65°C heat-treated gel with the addition of GTE decreased. In gels made with raw milk and milk that was heat treated at 65°C/30 min, the parameter affecting the reduction of hardness was heat treatment, not the addition of GTE. Based on the inference made in the texture analysis, it was thought that the effect of GTE on the water holding capacity was masked by the heat treatment in this experiment. When all the analysis results within the scope of the thesis are reviewed, it has been clearly demonstrated that the addition of GTE has an effect on the BLG-KCN interactions that occur as a result of the heat treatment. This effect was such that with BLG denaturation, BLG-KCN interactions could make it difficult to reach the chymosin substrate, and in parallel with the addition of GTE, casein (CN) and phenolics interacted and made it difficult for chymosin to reach the substrate. The denaturation of BLG was marked by the effect of GTE. In Native PAGE analyzes, it was observed that large aggregates formed by heat treatment did not form in the presence of GTE, and it was observed that GTE had an effect on protein-protein interactions in this direction. It has been concluded that the addition of heat treatment and GTE will change the properties of cheese gels, especially at temperature norms where BLG is denatured.