Enzymatic Preparation And Function Improvement Of Protein From Hot-pressed Peanut Meal

The peanut production is about16million tons per year in China, in which about10million tons were pressed for oil and producing about6million tons hot-pressed peanut meal. There is abundant protein resource accountingfor50%of hot-pressed peanut meal. However, affected by high temperature, high pressure and organic solvents, the peanut protein was denatured seriously and can be used as feed ingredients with low price. In this study, high purity and function peanut protein were prepared with enzymatic methods taking hot-pressed peanut as material which can be widely used in food and beverage industry. This study provided a new way of utilization of hot-pressed peanut meal as food resource.Cellulose and polysaccharide, as the two other main components in heat pressed peanut meals, were removed out by biological enzyme method, so as to obtain peanut protein with a high purity. Through experiments of single factor and response surface method, the optimal conditions for enzyme preparation were that:cellulase1%, ratio of solid to liquid1:4, pH4.8,50℃, hydrolysis for10h; medium temperature-amylase0.55%, ratio of solid to liquid1:8, pH6.0,60℃, hydrolysis for1h. The purity of peanut protein reached81.38%.Solubility and related characteristics of different protein hydrolysates (including acid protease, neutral protease, alkaline protease, protease and papain) were analyzed to select optimum proteases to improve solubility of peanut protein, that for neutral, alkaline with the highest solubility, about80%; that for neutral, alkaline, papain with the better emulsification, that for neutral protease reached99.09%; that for neutral, alkaline, papain with the better foamability, but without foam stability; that for neutral, alkaline, papain with the better oil holding; all with a bad water retention; that for neutral and alkaline with a good thermal stability; that for papain with the highest DPPH semi scavenging, followed by that for alkaline, neutral, compound protease, the lowest for enzymatic protease. To sum up, that for alkaline, neutral protease, papain were improved obviously, and used in further optimization of function improvement.Conditions of each protease were firstly optimized, then order of multi enzyme enzymes was to compared, so as to gain peanut protein with a high solubility. Because of high function for all hydrolysates, and the hydrolysis rate was regarded as the index. The optimum conditions of each protease were that:alkaline protease2.0%, the ratio of material to liquid1:20,55℃, pH8.0, hydrolysis for5h; the amount of enzyme was; neutral protease2.0%, the ratio of material to liquid1:20,55℃, pH6.0, hydrolysis for5h; papain1.5%, the ratio of material to liquid1:20,70℃, pH7.0, the hydrolysis for5h. Through analysis of different orders for alkaline protease, neutral protease, papain, screening, it’s found that the order play a less effect, hydrolysis rate fluctuated from32%to35%, the optimal order was that:the first for alkaline protease, the second for papain, the last for neutral protease, hydrolysis rate reached35.25%.