Stabilization Of Collagen Peptide-Cranberry Juice Drink By Polysaccharides And Its Mechanism

Collagen peptides are often used as the raw material of functional drinks because of rich functional properties,small molecular weight and easy absorption.However,collagen peptides are generally fishy and fruit juices are often added to improve the taste of collagen peptide drinks.Collagen peptide-juice drinks may cause turbidity and precipitation during preparation and storage,which greatly affects the acceptance of consumers.Therefore,this subject discussed the composition and characteristics of the precipitation of collagen peptide-juice drink during storage,and explore the regulation process and mechanism of three polysaccharides(β-glucan,hypomethoxy-pectin,chitosan)on its stability,in order to provide theoretical basis for solving this industrial problem.Firstly,the main components of precipitation in the shelf life of a beverage were studied.A fish collagen peptide-cranberry juice drink was stored at 25℃ for 16 weeks,and the supernatant and precipitated components were analyzed.The results showed that the main components of the precipitation were collagen peptides and polyphenols,which accounted for53.231±2.538% and 6.841±0.213%,respectively.The precipitated polyphenols were mainly procyanidins,accounting for about 55.5% of insoluble polyphenols.Collagen peptides with a molecular weight of 1000-10000 Da gradually precipitated during storage.The precipitation contained a high content of 9 amino acids.Compared with supernatant,proline(Pro)in precipitation increased by 6.25%,which was the most increased amino acid.Secondly,the efficiency and mechanism of β-glucan(BG),hypomethoxy-pectin(LMP)and chitosan(CS)in improving the stability of a fish collagen peptide-cranberry juice drink were investigated..The effects of mixing sequence,mixing temperature,p H,and polysaccharide concentration on stability were studied by conducting centrifugal precipitation rate,turbidity,relative turbidity,Zeta potential,rheology,confocal laser scanning microscopy,and storage(4℃,25℃,40℃,14 d)experiments.The results showed that all three polysaccharides effectively improved the stability of the drink mixture,but to different extents,as the stability was highly dependent on p H and the type and concentration of the polysaccharide.Among them,BG had the best stability.Steric hindrance,electrostatic repulsion,and increased viscosity were the main reasons underlying the improvements in the stability of the system.The stability mechanisms were also related to a competition or ternary complex mechanism.The results of storage experiment showed that the storage stability of these three polysaccharides was different at different temperatures.CS only had the ability to stabilize the system at 25℃,but only for a short period of 2 d.BG could stabilize the system continuously for 14 days only at 4℃ and LMP at 4℃ and 25℃.None of them had storage stability at 40℃.Finally,the intervention mechanism of β-glucan(BG)on collagen peptide(CP)and oligopoly proanthocyanidin(OPC)aggregates was explored.By analyzing turbidity,relative turbidity,Zeta potential,fluorescence quenching spectrum,binding constant and thermodynamic parameters,circular dichroism spectrum and fourier infrared spectrum,the instability mechanism of OPC on CP and the influence of BG and heating(85℃,10 min)were discussed.The results showed that OPC formed insoluble complex with CP mainly through hydrophobic interaction,which was promoted by heating.OPC increased the microenvironmental polarity of tryptophan and tyrosine,but heating inhibited the effect of OPC at high concentrations(OPC:CP=1:80 and 1:40).Only under heating conditions,the secondary structure of CP was changed by OPC,which gradually changed from random curling to α-helix..The addition of BG to the CP solution alone had a certain adverse effect on the stability,but heating promoted the stability of the binary system.BG had quenching effect on the fluorescence of tryptophan and tyrosine,but did not change the polarity of the microenvironment,and had no effect on the secondary structure of CP.BG interfered in the formation of aggregates by forming a soluble ternary complex with OPC and CP,and inhibited the effects of OPC on the microenvironmental polarity of tryptophan and tyrosine and the secondary structure of CP.Heat promoted the formation of soluble ternary complexes.