Study On Simultaneous Separation Of Hami Melon Seed Oil And Protein By Ultrasonic-assisted Aqueous Enzymatic Method

In recent years,the out put of cantaloupe in China has been increasing.The seeds of cantaloupe are rich in oil and protein,but most of them are discarded,resulting in the waste of oil and protein resources.The technology of simultaneous separation of oil and protein by aqueous enzymatic method has the advantages of mild conditions,preservation of nutrients in oil,environmental protection and so on.The application of ultrasonic-assisted technology can promote the dissolution of effective components in oil,improve the extraction rate of oil and improve the functional characteristics of protein.Therefore,in this study,using Hami melon seeds as raw materials,the technology of simultaneous separation of Hami melon seed oil and protein by ultrasonic-assisted aqueous enzymatic method was established through single factor and response surface design.The effects of ultrasonic-assisted aqueous enzymatic method on the composition,physical and chemical characteristics and nutritional components of Hami melon seed oil were studied,and the effects of ultrasonic-assisted aqueous enzymatic method on the structure and functional characteristics of Hami melon seed protein were also studied.The research results provided theoretical basis for the effective utilization of Hami melon seeds and the simultaneous separation of oil and protein by ultrasonic-assisted aqueous enzymatic method.The main results are as follows:(1)Through single factor and response surface experiment,the technology of simultaneous separation of Hami melon seed oil and protein by ultrasonic-assisted aqueous enzymatic method was established.The results showed that the average extraction rate of Hami melon seed oil was 76.72%under the conditions of ultrasonic time 54 min,ultrasonic temperature 51°C,power density p H 4.7 w/cm~3,solid-liquid ratio 1:8 and enzyme dosage 3%(v/w),which was 7.05%higher than that of aqueous enzymatic method.The content of Hami melon seed protein in water phase is23.88%,and that in slag phase is 69.67%.The influence of various factors on the extraction rate of Hami melon seed oil is p H,ultrasonic temperature,ultrasonic time and ultrasonic power density in turn.(2)The effects of ultrasonic-assisted aqueous enzymatic method on the composition,physicochemical and nutritional characteristics of Hami melon seed oil were studied.The results showed that compared with the oil prepared by aqueous enzymatic method,the main fatty acids(linoleic acid,oleic acid,palmitic acid and stearic acid),the sn-2 fatty acids(α-linolenic acid,linoleic acid,oleic acid and stearic acid)and triglycerides(LLL、LLP、LLO、LOP、LOO、OOO、POO、SOO)extracted by ultrasonic-assisted aqueous enzymatic method were higher.The color,rheological properties,acid value,peroxide value,iodine value and saponification value of Hami melon seed oil were analyzed.The results showed that compared with the oil prepared by aqueous enzymatic method,ultrasonic-assisted aqueous enzymatic method reduced the oxidation induction time and yellow color of oil,but the peroxide value of oil increased,and there was no significant difference in rheological properties,acid value,iodine value and saponification value of oil.By studying the contents of total phenols,total flavonoids,sterols and vitamin E in Hami melon seed oil,it was found that compared with the aqueous enzymatic method,the ultrasonic-assisted aqueous enzymatic method increased the total phenols content in the oil,but had no significant effect on the total flavonoids content,but the contents of active substances such as vitamin E and sterols decreased.The ultrasonic action destroyed sterols and vitamin E in the oil,which reduced the oxidative stability of the oil.(3)The effects of ultrasonic-assisted aqueous enzymatic hydrolysis on the structural characteristics of Hami melon seed protein were studied.The results showed that compared with aqueous enzymatic hydrolysis protein(EAP)and residue protein(ESP),the contents of amino acids such as aspartic acid(Asp),glutamic acid(Glu)and arginine(Arg)in ultrasonic-assisted aqueous enzymatic hydrolysis protein(UEAP)and residue protein(UESP)were no significant differences.Compared with EAP and ESP,theα-helix content in UEAP and UESP decreased,but theβ-sheet content increased.The wavelengths of UEAP and UESP were both red-shifted at the maximum light intensity,and the hydrophobic groups inside are exposed.Meanwhile,the particle size of UEAP and UESP decreased and distributed more evenly,and the absolute value of Zeta potential increased.(4)The effects of ultrasonic-assisted aqueous enzymatic method on the functional properties of Hami melon seed protein were studied.The results showed that compared with EAP,UEAP’s solubility,water-holding capacity,oil-holding capacity,emulsifying activity,emulsifying stability,foamability and foam stability were significantly improved.Compared with ESP,the emulsifying activity,emulsifying stability and foamability of UESP are significantly improved,but there is no significant difference in solubility,water holding capacity,oil holding capacity and foam stability.The research results provide theoretical basis for the development and utilization of Hami melon seeds and ultrasonic-assisted aqueous enzymatic technology.