Study On The Preparation,Modification And Application Of Whey Protein Aerogel

Aerogel,a porous solid with high specific surface area and big pore volume,can serve as carriers of bioactive ingredient.Whey protein can be made into bio-compatible and bio-degradable aerogel using heat-induced gel and freeze drying.However,whey protein aerogel made by freeze drying has negative features with loose structure and nonuniform pore distribution,which is easy to be damaged.In this study,we aimed at improving the applicability of whey protein aerogel to provide theoretical basis for its application in food aspects.Firstly,effects of different gelling conditions on compressive modulus and loading rate of whey protein aerogel were investigated.Whey protein aerogel,prepared with protein(0.250 g/m L)and NaCl(110.0 mmol/L,p H 8.0)at 77~oC for 30 min,had a compressive modulus of 8.86 MPa and loading rate of 68.54%and 107.20%for linoleic acid and cinnamaldehyde,respectively.The compressive modulus and loading rate were significantly increased(p?0.05)through modify with MCC(6.0 mg/mL)and TGase(4.0 mg/m L).The structure and property of modified whey protein aerogel were analyzed.The SEM result presented that pores uniformity was improved.Moreover,the pores of MCC-modified aerogel were bigger than that of TGase-modified aerogel.In addition,TGase-modified aerogel has a better storage performance due to low hygroscopicity.Then,the protection ability and gastrointestinal controlled-release effect for bioactive ingredient were researched through in vivo releasing model.Accelerated oxidation experiments showed that the oxidation of linoleic acid was markedly inhibited via preparation of TGase-modified aerogel and whey protein aerogel.Moreover,the peroxide value of linoleic acid was decreased by coating whey protein.Those results of digestion presented that the releasing rates of linoleic acid in aerogel were around 30%for 2 h in gastric fluid,while the releasing rate reached more than 80%for 2 h in intestinal fluid.So,it was deduced the aerogel could maintain a relatively complete structure in gastric fluid,which had an advantage on the release of bioactive ingredient to the target.The volatile and antibacterial compound cinnamaldehyde was loaded in whey protein aerogel to study its comtrolled-release effect.The volatilization rate of cinnamaldehyde in aerogel was lower than non-loaded cinnamaldehyde at 37~oC,25~oC,4~oC,resepectively.The TGase-modified aerogel had a more sustained release of cinnamaldehyde and the best controlled-release effect.Aerogel coating with surfactant Span80 had lower cinnamaldehyde release speed at high temperature.Finally,the cinnamaldehyde loaded aerogel was used to preserve cherry tomatoes.After 15days perservation,the decay rate of cherry tomatos in aerogel loaded cinnamaldehyde decresed markedly from 48.89%to 24.44%(p<0.05),compared with non-loaded cinnamaldehyde group.Besides,aerogel loaded cinnamaldehyde could slow the decrease of the weight-loss ratio,firmness,and titratable acid content of cherry tomatoes,and facilitate the maintenance of their quality.Overall,the preparation,modification and application of whey protein aerogel were studied in this research.Those results confirmed that whey protein aerogel had potential functional features including fixed-point release,controlled release and preservation,which holds a promise for application as a carrier of bioactive ingredient.