| The characteristics of low solubility is a big limitation for the comprehensive utilization of wheat gluten and one of the best way to solve this problem is to use enzymatic hydrolysis to prepare bioactive peptides. The peptides with good functional properties and physiological functions can be used in food, feed, health products, pharmaceuticals industries and many other fields which could greatly increase the added value of wheat gluten. This paper aims to prepare peptides derived from wheat gluten in a continuous enzymatic membrane reactor (EMR) which let the low molecular weight peptides separated from hydrolysates in time, thus avoiding the disadvangtages of batch reactor such as low enzyme activity and substrate-product inhibition.The original wheat gluten is easily to block the membrane, therefore, raw materials must be modified in order to achieve the process of continuous enzymatic membrane reaction. From the comparison of the membrane ultrafiltration between wheat gluten and its peptides, it can be concluded that the major factors for membrane fouling are the exist of lipid and starch in wheat gluten. Hence, the original wheat gluten must be modified to remove the components that cause the severe fouling of the membrane in order to achieve the process of continuous enzymatic membrane reaction. By comparison of four modification methods including heat treatment, limited hydrolysis in organic solvents, acidified alcohol treatment and hydrolysis in acid condition, it was found that modification with acidified alcohol was the most effective, because it not only significantly reduced the content of the lipid and starch in raw materials, but also greatly improved the solubility of wheat gluten, so as to establish the foundation of achieving continuous enzymatic membrane reaction.The effect of three variables including substrate concentration (S), enzyme concentration (E) and operating pressure (P) on average permeate flux (Javerage) and conversion were investigated in EMR using a 10 kDa nominal molecular weight cut-off (NMWCO) membrane filter. The optimum working conditions for Alcalase to hydrolyze modified wheat gluten to produce peptides were:substrate concentration= 2% (w/v), E/S= 5400 (U/g Protein), operating pressure= 0.04 MPa, temperature= 40℃, pH 9.0. The peptides (mainly<1000 Da) were homogeneous and stable, showing antioxidant activity. The reducing power, DPPH radical scavenging ability and iron chelation ability were determined respectively. The results indicated that the antioxidant activity of peptides increased with the increase of sample concentration.Operation stability of EMR (including Jresiduai, Aresiduab productivity and capacity) were evaluated and it can be concluded that EMR was superior to the batch reactor. The results indicated that EMR can not only retain a higher enzyme activity, but also maintain a steady production of peptides for a long period of time and had higher Jresiduai and capacity.The kinetics characteristics of wheat gluten in the batch reactor was studied by discussing the influence of different substrate concentration and enzyme concentration on the degree of hydrolysis. Through the experiment, we not only established the kinetic models of both hydrolysis rate and degree of hydrolysis, but also discussed the critical substrate concentration and enzyme concentration, and simultaneously calculated the Michaelis constant Km=13.211 g·L-1. It was found that the deviation between the theoretical values and experimental values was very small, which indicated that the model had a good practical application value. Furthermore, the mechanism of controlled enzymatic hydrolysis in the batch reactor was probed including substrate-product inhibition and the loss of enzyme activity.In the process of preparing peptides in EMR, the equation of degree of hydrolysis was established. A simple theoretical kinetic model was successfully applied for the enzymatic hydrolysis of wheat gluten in EMR and kinetic constants were calculated including Km= 2.11 g·L-1 and Vmax= 0.0153 g·L-1·min-1. The deviation between the theoretical values and experimental values was very small, providing a theoretical basis for industrial production.
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