Factors Influencing The Release Of Strawberry Flavor In Formulated Soy Beverage

Soy protein is widely applied in food industry due to its high nutritional value and excellent processing functionalities.The soy protein beverages have also become the main stream products.However,the flavor deterioration and unbalance of soy protein beverages occurred because the off-flavor existed in soy protein and the binding ability of soy protein with flavor compounds was different.In addition,the interaction between flavor compounds and soy protein was affected to some extent by the addition of ingredients such as hydrocolloids,emulsifiers and lipids in beverages.Thus,finding the effective way to control the perception of flavor in soy beverages was important to deal with the problem of flavor unbalance in soy beverages.The strawberry flavoring and natural soy protein isolate(SPI)were used in this study and the neutral protein beverage system was simulated.Factors influencing the release of strawberry flavor compounds in formulated soy beverage were investigated.Major contents and results were as follows.The flavor compounds of present popular strawberry flavoring were determined by gas chromatography-mass spectrometer(GC-MS).Combined with the strawberry flavoring composition of fresh strawberry and strawberry flavoring of references,twelve compounds were chosen as the strawberry flavor compounds.Seven strawberry flavor compounds(limonene,ethyl hexanoate,(z)-3-hexenyl acetate,ethyl 2-methylbutanoate,ethyl butanoate,(z)-3-hexenol and diacetyl)of twelve flavor compounds could be detected by headspace-gas chromagraphy(HS-GC)and hence defined as volatiles.The gas-matrix partition coefficients in different matrices were analyzed in detail.Five undetected compounds(?-decalactone,methyl cinnamate,hexanoic acid,2-methyl butyric acid and furaneol)were defined as less-volatiles.(Z)-3-hexenol,limonene and diacetyl were defined as non-ester volatiles.The influence of structure and properties(chain length,functional group and the hydrophobicity value)of compounds on the release of flavor compounds were investigated.The results were as follows.An enhancement of the retention of flavor compounds was observed with increasing the chain length in different component of soy beverages.The retention ability of aldehydes were the strongest in SPI solution.The retention of flavor compounds was reduced to different extent in the matrices which usually used in beverage with the increase of hydrophobicity value.The effect of ingredients which were widely used in protein beverages on the interaction between individual flavor compound and SPI was researched.The results were as follows.No influence was observed for the effect of viscosity and droplet size on the release of flavor compounds.The charge and side chain of hydrocolloids had no effect on the retention of flavor compounds when xanthan gum,carboxymethyl cellulose(CMC)and locust bean were added in SPI,separately.The retention of(z)-3-hexenol,limonene and diacetyl significantly changed(p<0.05)with increasing xanthan gum concentrations.There was no influence for ester compounds except ethyl butanoate when soybean oil and palm oil were added in SPI,while significant difference was observed for(z)-3-hexenol,limonene and diacetyl.Increasing soybean oil concentration affected the retention of flavor compounds significantly(p<0.05).The behavior of esters and limonene in the emulsions containing sucrose ester and tween 80 was obviously different from the emulsion containing monoglyceride.The release of ethyl butanoate,limonene and diacetyl was highly affected with the concentrations of sucrose ester increasing.The influence of coexistence complex flavor compounds on the interaction between SPI and flavor compounds were investigated.Presence of any other esters led to suppression of the release of ester compounds in water,SPI and the mixture of SPI,xanthan gum,sucrose ester and soybean oil.The less-volatiles accelerated the release of ester compounds to some extent in different matrices.In the mixture of flavor compounds,the release of(z)-3-hexenol was promoted in the mixture of SPI,xanthan gum and soybean oil,while the release was restrained in the mixture of SPI,xanthan gum,sucrose ester and soybean oil.Based on the interaction between individual compound and protein and the interaction between SPI and flavor compounds in the presence of complex flavor compounds,the effective way to control the strawberry flavor unbalance in soy protein beverage,namely the addition of less-volatiles,was obtained.The above thinking were verified in the actual beverage system.According to the sensory assessment,the addition of methyl cinnamate(final concentration was 10 mg/L)or furaneol(final concentration was 20 mg/L)in SPI solution could control the unbalance of strawberry flavoring.The addition of furaneol(final concentration was 20 mg/L)in the mixture of SPI,xanthan gum,sucrose ester and soybean oil could control the unbalance of strawberry flavoring.