Aqueous Enzymatic Extraction Of Seed-watermelon Seed Oil And Protein Hydrolysates

The seed-watermelon seed contains a large amount of oil and protein. Oleic acid and linoleic acid accounting for more than80%, whose content are about15%and65%. So the seed-watermelon seed oil is nutritious oil. The content of protein is about35%in the seed, which is rich in amino acid. In this dissertation, the suitable process and the optimum aqueous enzymatic extraction cionditions for seed-watermelon seed oil and protein hydrolysate were studied. Compared with conventional methods,aqueous enzymatic extration technology has some advantages as:shorter process, simple and safe operations without pollution to the environment.The seed-watermelon seed oil and protein hydrolysis were produced using aqueous enzymatic method, alkaline protease was used as extraction enzyme reagents. The oil and protein hydrolysate extraction experiment show that the level of the impact factors affect the oil yield:protease concentration> time> temperature> ratio of material to water. The optimum extraction conditions were alkaline protease of2.96%, temperature of44.4℃, time of2.86h, and ratio of material to water of1:5.74with the extraction rate of76.3%. The protein hydrolysate optimum extraction conditions were alkaline protease of2.92%, temperature of42.9℃, time of2.97h, and ratio of material to water of1:5.93with the extraction rate of78.3%.Compared with the oil extracted by solvent at low temperture, the oil produced by enzymatic hydrolysis method get higher L*, a*and b*, lower acid value and peroxide value. The saponification value of the oil produced by enzymatic hydrolysis method is higher. Other all the indexes have no obvious difference, the overall quality is good.Finally, protein hydrolysate was processed into the protein powder by the spray drying technology, the oxidation resistance and functional properties of which was studied. The results reveal that antioxidative activity and functionalities of protein hydrolysates from seed-watermelon seed were determined by the DH and by the enzyme ype employed.the antioxidative activity was determined when the concentration of1-40mg/mL range. The protein powder’s DPPH,·OH, O2·-radical-scavenging activity and reducing power were better with high concentration of protein. With DH rising, NSI, Emulsifying activity index, Emulsion stability index, Foaming capacity and Foaming stability decrease. Water-holding capacity and oil-holding capacity increase with DH rising. The protein power had good solubility. The lowest solubility appeared in isoelectric point, alkali protease hydrolysis product solubility better. The protein Hydrolysates with alkaline protease had the high temperature of degeneration, the stability is good.