Flavor formation of Maillard reaction intermediates and milk fat

• 1、State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122

Abstract：The effects of lipase concentration, enzymatic hydrolysis temperature and enzymatic hydrolysis time on the enzymatic hydrolyzed-oxidized degree of milk fat were investigated by evaluation indexes including acid value and peroxide value, and the milk fat with three different enzymatic hydrolyzed-oxidized degrees were prepared. The glutamic acid-galactose Amadori rearrangement product (ARP) was prepared by method of aqueous Maillard reaction coupled with vacuum dehydration, and its structure was identified by NMR. Three kinds of milk fat with different enzymatic hydrolyzed-oxidized degrees were mixed with glutamic acid-galactose ARP for thermal reactions under different processing conditions. The volatile flavor compounds of thermal treatment products were analyzed by HS/SPME-GC/MS. It was found that medium enzymatic hydrolyzed-oxidized degree milk fat with lipase concentration of 2000 U/g, enzymatic hydrolysis temperature of 45℃, enzymatic hydrolysis time of 3 h, acid value of 3.897 mg/g and peroxide value of 0.257 mmol/kg exhibited the optimal flavor formation ability. The high temperature was more favorable for milk fat degradation products to participate in Maillard reaction. The concentration and composition of frankincense characteristic flavor compounds formed at 120℃ for 80 min were optimal with the most abundant scent types with aldehydes 4.711 μg/kg, alcohols 2.224 μg/kg, ketones 60.230 μg/kg, nitrogen-containing compounds 196.342 μg/kg, furans 487.618 μg/kg, acids 354.635 μg/kg, esters 3.109 μg/kg. Partial least squares regression analysis was used to analyze the correlation between process parameters and frankincense characteristic flavor compounds. Results revealed that the formation of nitrogen-containing compounds, furans and acids in the system could be promoted by increasing the lipase concentration, thermal reaction temperature and thermal reaction time, and the frankincense and sweet flavor could be improved simultaneously.

Keywords： Milk fat Enzymatic hydrolysis Amadori rearrangement product Characteristic Volatile flavor compounds Partial least squares regression analysis