| Our country is a sericulture country, with an annual output of silkworm pupa weight more than 300000 t. The protein content is very rich in silkworm pupa, the protein content of dry silkworm pupa is up to 65%-71.9%, amino acid composition is reasonable, balanced proportion, according with the ideal amino acid pattern of the recommendation FAO/WHO, and has the development and utilization of high value. But for a long time, because of silkworm pupa exists serious odor, and the limitations of silkworm pupa processing technical, they caused the silkworm pupa of high added value utilization rate is extremely low. In this study after degreasing and deodorizing silkworm pupa as raw material, the pupa protein was modified by transient ultrasonic cavitations. Based on single factor experiment, the process conditions of ultrasonic modified silkworm pupa protein is optimized to use thru method of response surface analysis, then before and after modification, the functional properties physicochemical properties and amino acid composition of silkworm pupa protein are tested, and its biological activity was evaluated.Solubility was taken as index, the protein concentration, ultrasonic power, temperature and time of four single factor experiments are completed. On this basis, response surface analysis is used to optimize the conditions of ultrasonic modification for silkworm pupa protein. The best technological conditions are as follows: ultrasonic power 81.6%, protein concentration of 10.84%%,temperature 37.3℃, time 96.4min.Under the best condition, the modified silkworm pupa protein is prepared, solubility emulsifying and foaming properties of silkworm pupa protein are 4.02 times, 1.87 times and 1.41 times before treatment. Through the determination of the microstructure, IR spectra, UV spectra, sulfhydryl and disulfide bond of two, compare and analysis the change of structure of silkworm pupa protein after modification.The results found, before and after modification structure of silkworm pupa protein has a change in the very great degree, so that the functional properties have different improvement.Silkworm pupa protein antioxidant and antihypertensive activities showed that biological activity of silkworm pupa protein has a largely positive change after modification, antioxidant activity and antihypertensive activity has been greatly improved. Amino acid composition of the silkworm pupa protein before and after modification were analyzed and compared. The results showed amino acid components of silkworm pupa protein was more reasonable after modification, the total amino acid and essential amino acid content increased, the content of essential amino acids increased by 14.69%. To illustrate, ultrasonic modification can help to improve the nutritional value of silkworm pupa protein. |
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