Preparation Of Glycosylated Pea Protein Isolate And Its Stabilization In Nanoemulsions And Non-dairy Whipping Cream As Fat Substitution

Pea protein isolate(PPI)has the advantages of low allergenicity and low cost.And it is considered to be a good source of protein-based fat substitutes.In this study,PPI and xylan(X)were used as raw materials to obtain PPI-X conjugate(PXC)by glycosylation modification.Then preparation of PXC-based nanoemulsions using ultrasonic homogenization(UPXC-NEs)and the corresponding structure and environmental stability were investigated.Finally,the PXC as substituted fat was added to prepare low-fat non-dairy whipping cream,and the possibility of PXC as a fat substitution in the development of low-fat non-dairy whipping cream was investigated.The main findings are as follows:1.The preparation conditions of PXC optimized by the response surface methodology and the corresponding structural and functional properties were investigated in this study.Results showed that the optimal preparation conditions were as follows:sample solution pH 8.15,heating temperature 60℃,and incubation time 160 min,under which the degree of grafting of the obtained conjugate was 60.92%.The electrophoretic analysis confirmed the formation of conjugate based on the appearance of protein band with high molecular weight.The changes in infrared absorption indicated the grafting of xylan chains changed the secondary structure of PPI.The intrinsic fluorescence results reflected the tertiary structure of PPI was changed to reduce the fluorescence intensity.Compared to the native PPI,the PXC exhibited an enhanced solubility under acidic conditions.For instance,the solubility was increased from 3.26%to 9.08%at pH 4 and from 2.10%to 7.63%at pH 5.The emulsifying properties were also improved according the increase in the emulsifying activity index from 20.97 to 40.23 m2/g and the emulsifying stability index from 11.23 to 65.51 min.2.Preparation of pea protein isolate-xylan conjugate-based nanoemulsions with ultrasound homogenization(UPXC-NEs)and the corresponding structure and environmental stability were investigated in this study.Conditions used to prepare UPXC-NEs were optimized using a response surface methodology as follows:protein concentration 8.86 mg/mL,ultrasound amplitudes 57%(370.5 W),and ultrasound time 16 min.UPXC-NEs formed under these conditions exhibited less mean droplet size(189.4 nm),more uniform droplet distribution,greater absolute value of zeta-potential(44.8 mV),and higher protein adsorption content(48.18%)compared with pea protein isolate-based nanoemulsions with ultrasound homogenization(UPPI-NEs).UPXC-NEs also exhibited even particle distribution and dense network structure,which might be reasons for the observed high interfacial protein adsorption content of conjugate-stabilized NEs.Moreover,better stability against environmental stresses,such as thermal treatment,freeze-thaw treatment,ionic strength and type,and storage time was also observed for the conjugate-stabilized nanoemulsions,indicating that this type of nanoemulsions possess a potential to endure harsh food processing conditions.3.PXC was applied to replace soybeanoil in the preparation of low-fat non-dairy whipping cream,and the effects of substitution amounts of 0,10%,25%,50%,75%and 100%on the low-fat non-dairy whipping cream were investigated.The results showed that the particle size of emulsions before churning decreased significantly when the substitution amount over 50%.The turbidity of the pre-churned emulsions decreased significantly(p<0.05)and the content of trans fatty acids decreased gradually.The viscosity of non-dairy whipping cream after churning was close to 1000 MPa.s with no significant changes when the substitution amounts were 0,10%and 25%.In addition,the sensory qualities of taste and odor,tissue state,spreadability and color sense of the low-fat non-dairy whipping cream with different substitution amounts were compared,and it was found that this samples with 10%and 25%substitution amounts were close to the control.