Study On The Protein Powder Preparation Of Freshwater Mussel Meat And Its Antioxidant Activity

Freshwater mussel is an important freshwater resource in China, and because of itsmedicinal function and the promising market of the pearls, it has been great breeding for along history. However, due to the properties of seasonal breeding, large quantity, bad fishysmell and perishable properties, the freshwater mussel meat after the pearls harvested wereusually discarded as waste or dried directly to be smashed as animals’ food, which caused agreat waste of resource. The protein powder is a kind of light yellow powder which has richprotein, poor fat, abundant amino acids and high nutrition value and is characterized by lowmoisture content and easy to be stored. At present, there isn’t the report about protein powderof freshwater mussel meat. Therefore, the main aim of this paper is to take advantage ofenzymatic technology, Maillard reaction and spray-drying for processing the freshwatermussel meat to prepare the protein powder which could be easily dispersed and soluble. It notonly provides the theory of comprehensive utilization of freshwater mussel, but also has thegreat significance for improving the adding-value of freshwater mussel products.Research on the isolation and determination of freshwater mussel meat proteincomposition was done, results showed that contents of non-protein nitrogen, myogen,myofibrillar protein and salt insoluble protein were28.01%,17.80%,14.83%and39.37%,respectively. The content of water insoluble protein was more than54%. Therefore, in orderto improve the solubility of the protein of freshwater mussel meat, the hydrolysising offreshwater mussel protein was needed.The optimum conditions of enzymatic hydrolysis of freshwater mussel meat with papainand flavorenzyme were determined by the research on the effects of double enzymes dosage,temperature, time, ratio of substrate/water, pH and the adding mode of flavorenzyme for thedegree of hydrolysis (DH) and the protein recovery (PR). Results showed the optimumconditions were temperature50℃, pH6.5, time5h, ratio of substrate/water1:2, papaindosage0.8%, flavorenzyme dosage1.2%, adding mode of flavorenzyme “2+3”. Under theseconditions, DH and PR of protein of freshwater mussel meat was19.22%and79.32%,respectively. The content of protein molecular weight below5kDa was more than95%, whichcould indicate that molecular weight of protein was reduced markedly and the solubility ofprotein was improved effectively.The optimum conditions of Maillard reaction about ratio of glucose/xylose, dosage ofsugar, ratio of glycine/L-glutamic acid, dosage of amino acids, temperature, time and pH werestudied with the index of amount of flavor intermediates, browning intensity and sensoryscore. And the study on the effects of these factors on DPPH·scavenging rate was also done.The results suggested the optimum conditions of Maillard reaction were amino acids dosage2%, m(glycine):m(L-glutamic acid)=1:3, sugar dosage1.5%, m(glucose):m(xylose)=1:2,temperature115℃, pH6and reaction time30min. In the combination of sensory score andanalysising of the volatile flavor compounds, better improving in the flavor by Maillardreaction was found. At the same time, DPPH radical scavenging activity (RSA) of Marllaidreaction products (MRPs) was90.28%. It indicated that MRPs was a good antioxidant. Finally, the effects of parameters of spray-drying on the powder quality were studied,and the final product’s composition was analyzed. The optimum parameters of spray-dryingwere as follows: the inlet air temperature was180℃, feed rate was10-12mL/min and feedtemperature was40℃. At last, the light yellow, easily wetted and good flowing powder wasobtained with the content of protein, fat and moisture were70.25%,3.84%and4.36%,respectively. It indicated that powder was a kind of products which had rich protein, low fatand could be stored for a long time and could be used as the functional food ingredients.