Improved Solubility And Thermal Stability Of Whey Protein By Glycosylation With Galactooligosaccharide And Development Of Sports Drinks

Whey protein is a kind of protein with high yield and high quality,which is widely used in food.In protein drinks,whey protein acid drinks on the market contain up to 4% whey protein.We hypothesized that glycosylation of whey protein leads to higher net charge,enhanced thermal stability,increased structural rigidity and reduced buffering capacity through early Maillard reaction,so as to produce high protein content acidic beverage(> 4.2% protein).Therefore,the following research is carried out and the results are as follows:Firstly,the glycosylation conditions of whey protein isolate and galactooligosaccharide were optimized.The results showed that the optimum condition of dry heat method was 60 ° C for 96 h.The unreacted galactooligosaccharides were removed by hydrophobic chromatography.When the elution time was 95-130 min,the eluted protein contained whey protein isolate(WPI)and partially glycosylated whey protein(PGW-G).Secondly,the glycosylation degree,browning rate,lysine blocking rate,free amine loss rate and in vitro digestibility of pgw-g were monitored.The Maillard reaction was confirmed by SDS-PAGE gel.The p I of PGW-G was 4.38,lost only 2.49% of free amino groups,and the digestibility of PGW-G was11.20% higher than that of WPI.Thirdly,the solubility and thermal stability of PGW-G and WPI before and after heat treatment were compared at different protein concentrations and pH values.Differential scanning calorimetry(DSC)and SDS-PAGE were used to monitor the initiation of denaturation and polymerization,respectively.The thiol exposure and surface hydrophobicity of WPI and PGW-G were monitored.It was found that the solubility of pgw-g was improved at higher protein concentration and wider pH range.Finally,a sports drink was developed with pgw-g.The optimal formula was 4.5% PGW-G and45% lactic acid ° T.10% sucrose and 0.35% low-fat pectin.The final product has moderate sweet and sour,high protein content and high transparency.In brief,the results showed that galactooligosaccharide partially glycosylated whey protein isolate could improve the solubility and thermal stability of protein,and its buffering capacity decreased.PGW-G is suitable for drinks with low pH and high protein.