Study On Processing Technology Of Antioxidant Polypeptide From Agaricus Bisporus

Agaricus bisporus,a common edible,medicinal,belongs to kingdom of Eumycophyta,phylum of Basidiomycotina,class of Basidiomycotina,order of Agaricales,family of Tricholomataceae,genus of Tricholoma.Agaricus bisporus not only has delicious taste and soft texture,but also has very high nutritional value.It is a kind of ideal and health food with rich protein,low fat and low calorie.Bispora mushroom has high protein content,fresh weight content as high as 3.5-4.5%,which is several times to dozens of times more than ordinary vegetables,and itis in the forefront among edible fungi foods.Agaricus bisporus is a kind of potential protein resource and has the reputation of “plant meat”.It also contains 17 kinds of amino acids,rich in 8 kinds of essential amino acids for human body.In recent years,the cultivation industry of Agaricus bisporus in China has developed rapidly and its output has increased year by year.However,the development of its deep processing technology has lagged behind seriously.Most ofproducts are sold ormade into cans locally,with low added value and weak comprehensive utilization ability.At present,there is little research on the polypeptide of Agaricus bisporus in China.In this research,the optimum extraction technology of antioxidant peptides from fruiting bodies of Agaricus bisporus was investigated.The main results are as follows:Single-factor experimental results of ultrasound conditions showed that the protein extraction rate increased first and then decreased with the increase of ultrasonic power,ultrasonic time,ultrasonic temperature and material-liquid ratio.The result by an orthogonal experiment indicated thatthe effect of various factors on the extraction rate of proteins from Agaricus bisporus was as follows:ultrasonic time > ultrasonic temperature > ultrasonic power > ratio of material to liquid.The optimum parameters of ultrasonic-assisted extraction of protein from Agaricus bisporus were as follows: ratio of material to liquid 1:35,ultrasonic time 20 min,ultrasonic power 300 W,ultrasonic temperature 30 ?.Under these conditions,the extraction rate of protein from Agaricus bisporus was 27.42%.Studied on the effect of pH on the functional properties of Agaricus bisporus protein.The trend of solubility,water holding capacity,oil holding capacity,foaming capacity,foam stability,emulsifying activity index and emulsifying stability index of Agaricus bisporus proteinwere similar with the increase of pH,and both showed a trend of decreasing first and then increasing,and they get the lowest valuenear near the isoelectric point of Agaricus bisporus protein,which were 12.22%,162.87%,164.5%,24.44%,65.14%,36.56% and63.44%.The effects of trypsin,alkaline protease,neutral protease,papain,compound protease,flavor protease and bromelain on the enzymatic hydrolysis of Agaricus bisporus protein were compared.Taking the scavenging rate of DPPH free radicals by enzymatic hydrolysate as an index,the optimal hydrolytic enzyme was determined as alkaline protease.Antioxidant peptides were prepared by enzymatic hydrolysis of Agaricus bisporus protein with alkaline protease.Single factor experimental results showed that the optimum parameters of each factor were: substrate concentration 2%,enzyme dosage 4%,enzymatic hydrolysis temperature 50 ?,enzymatic hydrolysis pH 9.5.The scavenging rate of DPPH free radicals by enzymatic hydrolysate increased first and then decreased with the increase of each factor.On the basis of single factor experiment,four factors and three levels of response surface experiment were carried out.The results showed that the optimum conditions for the preparation of antioxidant peptide from Agaricus bisporus were as follows: substrate concentration 2.03%,enzyme dosage 4.67%,enzymatic hydrolysis temperature 50.19 ?,pH9.23.Under these conditions,the theoretical value of DPPH free radical scavenging rate of enzymatic hydrolysate reached 68.72% after 2.5 hours of enzymatic hydrolysis.Verification experiment with slight adjustment according to actual operation showed that the DPPH free radical scavenging rate of the enzymatic hydrolysate was 67.84%,which was similar to the theoretical value.