| Fish protein powder is a kind of light yellow powder which has high protein, low fat, richamino acids and high nutrition value and is characterized by low moisture content and easy tostorage. At present, there is still problems of low solubility, poor dispersibility and fishy smell in thefish protein powder. Therefore, this research aims to get a kind of fish protein powder which has nofishy smell, better solubility and better dispersibility by focusing on the key process in theproduction of fish protein powder including enzymatic hydrolysis process, flavoring process anddrying process. It is not only impotant to expand the range of applications of fish protein powderbut also significant to promote the development of further processing of bulk freshwater fish.The optimum conditions of enzymatic hydrolysis of silver carp protein with papain weredetermined by studying the effects of papain dosage, temperature, time, substrate concentration, pHon the degree of hydrolysis (DH) and protein recovery (PR),which were: temperature50oC,enzyme dosages4000U/g protein, pH6.5, time4h. Under this condition, the DH of hydrolysatewas29.82%and the PR was as high as90.29%.The effects of the conditions of spray drying on the physical properties and the water solubilitywere studied by using the moisture content, bulk densiity, dispersibility, flowability, wettability andwhiteness as the index. The optimum conditions of spray drying were determined: feedconcentration25~30%, inlet air temperature170~180oC, feed rate10~12mL/min, feedtemperature50oC, outlet air temperature80~90oC. Under this condition, the solubility of the fishprotein powder was98.52%of which the dispersibility and the fluidity became better. Its essentialamino acid content was more than40%which are rich in lysine. It is a kind of quality protein withhigh nutritional value and can be used as the functional food ingredients.The qualities of the fish protein powder were analyzed through measuring the basiccomponents, the total free amino acids, the amino acid composition, the molecular weightdistribution, the mineral elements and trace elements as well as composition with otherproducts.The results showed that: the fish protein powder was a convenience foods of high-protein,and low-fat. It was also rich in mineral elements and trace elements. The sulfur-containing aminoacids were the first limiting acid.Lysine content was significantly higher than the FAO/WHOrecommended values which can be used as an excellent protein supplements.The effects of the sugar types and concentrations, temperature, time, pH and the DH of proteinon the flavor and color of the products of the Maillard reaction(MRPs) and the effects of theMaillard reaction condition on the antioxidant activity were studied by using browning intensity，theamount of flavor intermediates,DPPH·scavenging rate and the reducing power as the index. Theconditions of the Maillard reaction were determined together with sensory evaluation. The resultsshowed that: choose the5mg/mL glucose as the reaction sugar, temperature115oC, reaction30min. The product was light yellow, transparent, barbecue flavor and sweetness. DPPH·scavengingrate was as high as90.20%.The analysis of the volatile flavor compounds in the MRPs showed that E,E-2,4-heptadienal,E,E-2,4-decadienal and E-2-decylenal which expressed as fishy smell were not detected. This isconsistent with the result of sensory evaluation. Fufural has the smell of almond banana. And nonanal expressed as the fat flavor. The heterocyclic substances perform as barbecue flavor or cokesmell. There are also some substances which expressed as ester flavor including octanoate,diisobutyl phthalate,2,5-18-alkynyl, methyl ethyl linoleate. All this can prove that the Maillardreaction achieve the purpose of increasing the flavor. |
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