Effect Of Whey Protein Combined With High Hydrostatic Pressure Treatment On Color And Flavor Of Garlic Puree

Garlic(Allium sativum L.),has a unique pungent flavor and a variety of physiologically active functions that are beneficial to humans,making it an important dual-use flavoring vegetable.Allicin,the main source of flavor and physiological activity of garlic,is extremely unstable and prone to flavor deterioration during processing,and the commercial value of garlic is greatly reduced due to the involvement of allicin in the greening reaction.In this paper,we investigated the color,volatile flavor substances and total bacterial colony of garlic puree by high hydrostatic pressure combined with whey protein treatment to address the problems of greening and flavor loss in the processing of garlic puree,and the main results are as follows:(1)Effect of pretreatments on the quality of garlic pureeDifferent pretreatment tests showed that the highest allicin content of 7.20±0.20 mg/g was found in fresh garlic homogenized for 180 s.The allicin content in garlic puree was7.70±0.19 mg/g at p H 5.8 and temperature of 35°C.Then,the effects of ascorbic acid,citric acid,L-cysteine,and whey protein on the color and allicin content of garlic puree were compared,and the results showed that the addition of 1.0% L-cysteine and 2% whey protein,the a* values in the garlic puree were-2.53±0.21 and-3.36±0.08,both of which had a better effect of inhibiting the green change of garlic puree.The allicin content in the puree with the addition of 2% whey protein was 3.40±0.14 mg/g,but the addition of 1% L-cysteine completely eliminated allicin from the garlic puree,resulting in a serious loss of the unique pungent flavor of the puree.The free sulfhydryl content was 4.297±0.08 μmol/g after pretreatment of whey protein for 15 min at 60°C with ultrasonic temperature and 25 W/L power,and the p H of garlic puree was adjusted to 4.0 with ascorbic acid,and the a* value of garlic puree was-1.8±0.21,and the allicin content was 0.88±0.09 mg/g,which effectively inhibited the green change of garlic puree and maintained the pungent flavor.(2)Effect of high hydrostatic pressure combined with whey protein on the quality of garlic pureeHigh hydrostatic pressure combined with whey protein treatment inhibits greening of garlic puree,balancing the flavors in the masala to maintain its pungent flavor and extend shelf life.The treatment with 500 MPa holding pressure for 5 min reduced the colony in whey protein-garlic paste from 3.88±0.22 Log CFU/g to 2.94±0.08 Log CFU/g,with an a* value of0.13±0.17,which effectively inhubited microorganisms while maintaining the color of garlic puree.The volatile flavor compounds in the garlic puree before and after combined HHP treatment were analyzed by GC-MS.Compared with the original garlic puree,the relative contents of 3-vinyl-4H-1,2-dithiene and 3-vinyl-5H-1,2-dithiene in the HHP-whey protein garlic puree decreased by 51.51% and 47.95%,and the relative contents of diallyl disulfide with pungent flavor characteristics increased by 49.33%,while the relative content of methallyl disulfide with garlic odor characteristics decreased by 85.04%.Using the total number of colonies as indicators,the SGompertz equation was used to fit the microbial growh of garlic puree during storage.The model equation of HHP-whey protein garlic puree at 4°C storage condition is: Y=0.8601*exp{-exp[-0.1592*(t-12.9969)]}.(3)Mechanism of the effect of high hydrostatic pressure treatment combined with whey protein on allicinThe aqueous solution model of whey protein-allicin was used to study the changes of hydrophobicity,particle size and potential of whey protein before and after the interaction with allicin.The surface hydrophobicity of whey protein was 44325±2182,and after the combination of allicin and whey protein,the surface hydrophobicity increased to442,096±6920.The ultrahigh pressure treatment changed the structure of whey protein,and the number of hydrophobic groups decreased and reduced the surface hydrophobicity of the bound material to 371372±7293.The absolute value of the zeta potential of whey protein was12.27±0.29.Ultrahigh pressure affected the electrostatic and hydrophobic interactions of the protein dispersion system to reduce the homogeneous charge,while the reaction of allicin with sulfhydryl groups in the protein reduced the other reactions with the protein,and the absolute values of zeta potential of the conjugates in whey protein solution and aqueous solution of allicin-lactalbumin conjugate treated with ultrahigh pressure were 12.27 ± 0.29 and 10.34 ± 0.27;the particle sizes were 361.73 ±1.06 nm,321.43 ±1.68 nm.