Preparation And Characterization Of The Limited Enzymatic Hydrolysates Of The Protein In Lotus-seed

Lotus seed,the mature seeds of Nymphaeaceae plant lotus(Nelumbo nucifera),can be found in many places in China,such as Fujian,Zhejiang,Hunan,Hubei,Jiangsu,Hebei and so on.Due to its abundant nutritional and medicinal value,it is widely regarded as Chinese favorite medicine and food nutrition.Because of the lack of the related research,the development of lotus seed food is restricted and the food variety on the market is unitary.Protein is not only one of the important factors that affect nutritional food,also is the important factor of food processing,whereas enzymatic modification is an important means of improving functional characteristics of food protein.In this paper,limited enzymatic hydrolysis conditions of protein in lotus seed was established and the research of functional characteristics on the hydro lysates was also made in order to provide certain scientific basis of the development and deep processing of health lotus seed food.The main results were as follows:1.Lotus seed proteins were extracted by using alkaline sodium chloride solution and the content of protein extracted was as high as 82.52%.The enzymolysis of alkaline protease,neutral protease and trypsin were studied and the effect of trypsin was the best.Optimization conditions test was carried out by choosing the single trypsin and the related analysis of orthogonal experiment was also done.The optimun enzymolysis conditions determined were:pH 8,temperature 45 ?,substrate concentration 3%,hydrolysis time 5 h,the amount of enzyme 7000 U/g.2.Under the optimal condition of trypsin enzymolysis,the protein in lotus seed was digested into enzymatic antioxidants.The features of the limited enzymatic hydrolysates were studied.3.Research on the features of limited enzymatic hydrolysates of protein in lotus seed mainly included:DPPH radical scavenging activity,iron ion reducing power,metal ion chelating ability,hydroxyl radical scavenging activity,superoxide anion scavenging activity,solubility,foaming and emulsification.The research results showed that compared with the original protein,limited enzymatic hydrolysates of protein in lotus seed had better free radical scavenging activity,solubility,emulsibility and foaming ability.DPPH radical scavenging activity of limited enzymatic hydrolysates of the protein in lotus seed is 13.58%-56.28%,higher than the original protein in lotus seed.Iron ion reducing power of limited enzymatic hydrolysates of the protein in lotus-seed is 2.3-2.9 times of the original protein in lotus seed.Metal ion chelating ability of limited enzymatic hydrolysates of the protein in lotus-seed is 3 times more than the original protein in lotus seed.When concentration of protein is 10 mg/mL,hydroxyl radical scavenging activity of limited enzymatic hydrolysates of the protein in lotus-seed is even up to 79.46%,66.54%higher than the original protein in lotus seed.When concentration of protein is 10 mg/mL,superoxide anion scavenging activity of limited enzymatic hydrolysates of the protein in lotus-seed is much higher than the original protein in lotus seed.4.UV wavelength scanning was used to the controlled enzymatic antioxidants of protein in lotus seed.Also,by using dextran gel(Sephadex G-25),the limited enzymatic hydrolysates of protein in lotus seed were preliminarily separated and the separated components were studied for antioxidant activity.Research results showed that DPPH radical scavenging activity of the first peak is as high as 91.83%,2.8 times more than the hydrolysates before separation,iron ion reducing power is 1.8 times as the antioxidants before hydrolysis.5.SDS-PAGE protein analysis was carried out about the peak 1.The results showed that the main substance were two kinds of the highest concentrations of protein fractions,whose molecular weight were about 20 KDa and 10 KDa.The results showed that the limited enzymatic hydrolysates of protein in lotus seed were found.It has good antioxidant activity,solubility and emulsification.The results offer a certain reference for further development and utilization of lotus-seed functional food.