Research And Development On The Solid Beverage Of Selenium-enriched Oyster Protein

The main purpose of this research is to develop one kind of solid beverage of selenium-enriched oyster protein. The beverage is rich in organic selenium and free amino acid. It also includes some active substance such as taurine, glycogen, Zn and so on. Meanwhile beacause of less fishy smell it is well accepted by consumers. The main content of this research is as follows:1. The effect of hydrolyzing pacific oyster (Crassostrea gigas) using four kinds of proteinase and the change of active substance content in enzymatic hydrolysate during hydrolysis are studied. The potimum parameters of hydrolyzing pacific oyster are founded. The result indicates that the degree of hydrolysis of Neutral proteinase is the highest, then the Flavor proteinase. The degree of hydrolysis of Papain and Bromelain is the lowest. Protein returns-ratios of four kinds of proteinase are 79.9% (Neutral proteinase), 53.7% (Flavor proteinase), 52.0% (Papain) and 46.9% (Bromelain). Result of the sensory evaluation indicates that flavor of Papain enzymatic hydrolysate is better than the others. And the flavor of Neutral proteinase is the worst. The change of active substance contents in enzymatic hydrolysate during hydrolysis is studied. The result shows that the contents of glycogen and taurine are maximum in Papain enzymatic hydrolysate and the contents of Zn, Cu, Se are maximum in Flavor proteinase enzymatic hydrolysate. The conditions of enzymatic hydrolysis are optimized by factorial experiment and step climbing experiment. The result of factorial experiment demonstrates that the effect on response value from two factors (pH, enzyme dosage) was prominent. The optimum conditions on enzymatic hydrolysis obtained by step climbing experiment are as follows, initial pH (5.8~6.2), enzyme dosage (1.5~1.7%), enzymolysis temperature (55oC), enzymolysis time (4 hours). Under this condition, the content of soluble protein in the enzymatic hydrolysate is 2.93g/100ml while amino nitrogen (0.33g/100ml), glycogen (2.52g/100ml), taurine (8.38mg/ml), Zn (63.55μg/ml), Cu (23.43μg/ml), organic Se (101.66μg/L). Enzymatic hydrolysate is light yellow, lauter, less bitter and fishy smell.2. Deodorization of oyster enzymatic hydrolysate is researched. The optimum condition of deodorization is founded. The result indicates that NaCl, tea, sugar, acid, lactobacillus andβ-CD make little effect on deodorization of oyster enzymatic hydrolysate. The effect of charcoal, activated charcoal and yeast is obvious. Result of orthogonal experiment showed that the optimum conditions of charcoal are: concentration (2%), temperature (20oC) and time (60 minutes). The optimum conditions of activated charcoal are: concentration (1.5%), temperature (40oC) and time (40 minutes). The optimum conditions of yeast are: concentration (1.5%), temperature (30oC), time (20 minutes). According to the results, charcoal and yeast are combined to remove the fishy smell. The reaction first occurs at 40oC for 40 minutes with 1.5% activated charcoal, and second at 30oC for 20 minutes with 1.5% yeast. The fishy smell is deodorized mostly through the above mentioned conditions. The hydrolysate is clear and light fragrant. The volatile flavor compounds were extracted by SPME and were detected by GC-MS in oyster hydrolysate. The detection results demonstrat that after deodorization the comparative content of aldehyde, ketones, ester,organic acids, sulfur-containing compounds and furan increase while hydrocarbon and alcohol decrease. The change of the volatile components causes the flavor of oyster hydrolysate more acceptable by consumers.3. The process about accumulations of selenium in pacific oyster is studied by the measure of temporary rearing of oyster in inorganic selenium added sea water. Result of singal factor experiment shows that the total selenium content in oyster increases along with the increasing Na2SeO3 content of sea water and the time of accumulation. And the increasing rate of organic selenium is observably more rapid than inorganic selenium. All the three parts (mantle and cheek, adductor, visceral mass) of oyster have the ability of accumulating selenium. But the selenium increasing ratio of the three parts is different. Besides the adductor part, the selenium increasing ratio of other two parts is more rapid during 2-3d than 1-2d. The selenium content of adductor is nearly invariable during 2-3d. After concentrating 3d, contents of selenium in different parts are 5.832μg/g (mantle and cheek), 3.465μg/g (visceral mass) and 1.971μg/g (adductor). The optimum conditions of accumulation are: concentration of Na2SeO3 (12-16 mg/L), time (2-3d). Under this condition the total selenium content in oyster is 3.926μg/g while the organic selenium content is 3.222μg/g.4. Processing craft about the solid beverage of selenium-enriched oyster protein is investigated. The result indicated that the content of organic selenium in selenium-enriched oyster protein enzymatic hydrolysate is 913.8μg/L which is 9 times of the usual. The ratio of essential amino acids is 49.56%. And the ratio of taurine content achieves 14.29% of total amino acids. The enzymatic hydrolysate also contains massive active substance such as glycogen, Zn and so on. Simultaneously beacause of less fishy smell and great flavor it is well accepted by consumers. The enzymatic hydrolysate is concocted with orange juice, sweetener and so on to produce a kind of solid baverage which contains the nutrient substance of oyster and orange.