Study On The Extraction Of Cicada Pupa Protein And The Antioxidant Activity Of Protein Hydrolyzate

Cicada pupa mostly distributes in the northern region of China, and it is well known for its delicious taste. But up to now, cicada pupa has not been conducted systematic study; and its value can not be fully utilized and resources are wasted.ObjectiveTo observe cicada pupa’s main nutritional components, and to provide the basis for the development of new resource food, and to provide a new raw material for the production of antioxidant peptides.MethodsThe cicada pupa as a research object, its nutritional components were analyzed according to national standards. Cicada pupa protein was extracted by alkaline extraction and acid precipitation. Single factor test and response surface optimization design were applied to determine the optimum extraction conditions. Cicada pupa protein was hydrolyzed by protease; then single factor experiment and orthogonal test design was utilized to determine the optimal hydrolysis conditions. The in-vitro antioxidant activities of protein hydrolyzates were evaluated by a variety of free radical scavenging experiments.ResultsCicada pupa’s moisture and ash contents were5.61%and4.05g/100g. Its protein and fat contents were68.83g/100g and9.15g/100g, and it was rich in mineral elements. Cicada pupa contained seven kinds of fatty acids, the unsaturated fatty acids occupied77.27%, monounsaturated fatty acid content of68.84%. Cicada pupa contained17kinds of amino acids, the total content of63.54g/100g, its EAA/TAA was0.42, and its EAA/NEAA was0.72, which was higher than the FAO/WHO standards. Cicada pupa’s EAAI was104.65according to the FAO/WHO standard, its EAAI was78.69according to the whole egg standard, it demonstrated that cicada pupa essential amino acids balance was better.The optimum conditions for cicada pupa protein alkaline extraction and acid precipitation were as following:extraction time was1.0h and temperature was61.4℃, alkali concentration was1.2%, the ratio of cicada pupa protein and water was1:23.7, the largest dissolution rate of cicada pupa protein was46.07%. The optimal protease for cicada pupa protein hydrolysis from the alkaline protease, neutral protease and papain was alkaline protease. Its degree of hydrolysis was14.63%, and the DPPH radical scavenging rate was64.3%. The optimal hydrolysis conditions determined by the single factor and orthogonal experimental design was that temperature was55℃, pH was8.5, enzyme concentration was4500U/g, the ratio of cicada pupa protein and water was4%and the hydrolysis time was3h.Stronger or a certain degree of antioxidant activities of hydrolysate of cicada pupa protein were demonstrated in4antioxidant system. The scavenging ability of DPPH free radicals, OH free radicals, ABTS free radicals and reducing activity were in dose-dependent manner with concentration and the IC50was2.33mg/ml、15.21mg/ml、2.86mg/ml.ConclusionsCicada pupa have rich protein, many kinds of amino acids and fatty acids and mineral elements, it’s one kind of nutritious food. Hydrolysate of cicada pupa protein have stronger antioxidation activity, it provides the basis for the preparation of antioxidant peptide.