The enzymatic hydrolysis conditions of almond protein were optimized by orthogonal rotation combination design.The orthogonal regression model of hydrolysis degree(Y)and four factors of temperature(X1),substrate concentration(X2),enzyme-substrate ratio(X3),hydrolysis time(X4)was established:Y=23.73865-3.16060X1-1.54037X2+2.07211X3+3.48164X4-3.31615X21-0.97209X22-0.40641X23-1.28322X24-0.21875X1X2+0.07125X1X3-0.26375X1X4-0.26375X2X3+0.07125X2X4-0.21875X3X4. It was concluded from the model that when temperature,substrate concentration,enzyme-substrate ratio,hydrolysis time were 50℃,2%,4% and 180min,the hydrolysis degree(Y)was the maximal 27.22% and consistent with the confirmatory experiment result.

The response surface method was used in optimizing the enzymatic hydrolysis methods of Sweet almond oil.Box-Behnken design was adopted.Statistics analysis system8.0 was used in analyzing the influence of the enzymatic time,the enzymatic temperature,and the quantity of the enzyme on the oil yield.The result showed the optimal conditions were as follows:the enzymatic time 3.0 h,the enzymatic temperature 54.95 ℃,the dosage of the enzyme 3.22%,and the enzymatic extraction ratio of sweet almond oil was up to 42.34%.

The response surface was used in optimizing the extraction of sweet almond oil. Box-Behnken design was adopted. Regression analysis with statistics analysis system was used in analyzing the influence of the solid-liquid ratio,the solvent time,the solvent temperature on the oil yield. The result showed that when the solid-liquid ratio was 1∶8.25,the solvent time was 4.98h,the solvent temperature was 68.45℃,the extraction ratio of sweet almond oil was up to 96.82%.

There are many bioactive polypeptides in bio-organisms with different structures and functional activities.Peptides were mainly absorbed as hydrolyzed proteins in the body.Polypeptides have double function on regulating cells:physiological and nutritionally.Many kinds of functional polypeptides were discovered in plants and animals,and their characters,preparation process,separation and purification methods,determination techniques,functional activities and application were studied extensively.In this article recent researches of biological polypeptides were reviewed,several kinds of functional activities of polypeptides were analyzed,and different preparation methods were introduced.The development perspectives on polypeptides in the fields of food,medicine,biology was also prospected.