Improvement Of Drying Process Of Chlamys Nobilis Scallop And Formation Mechanism Of Its Flavor Components

The flavour formation of dried scallops was the results of a series of complex biochemical reactions,and the mechanism was not yet clear,protein and lipid oxidation degradation were two important biochemical changes of dried scallops during the processing.In this paper,the flavour formation of dried scallops and the effects of protein and lipid oxidizing products on the formation of dried scallops flavour were analyzed,the correlation of protein,lipid oxidation with flavor and quality formation of the dried scallops were explored.The main results were as the following:1.The protein composition of Chlamys nobilis scallop was isolated and the amino acid composition,free amino acid,molecular weight distribution,thermal stability and flavor of the adductor muscle were detected and analyzed.The results demonstrated that the contents of moisture,protein were 78.12 % and 18.19 %,respectively.Three protein components were isolated from adductor muscle including myofibril protein,myostromin and myosinogen representing 46.80 %,32.70 % and 20.5 % of the total proteins,respectively.The analysis of amino acids composition indicated that a wide variety of amino acids were found in adductor muscle,the concentrations of free amino was 90.31mg/100 g.SDS-PAGE analysis showed that the subunit molecular weights of myosinogen were in the range of 16¹05 kD,those of myofibril protein mostly ranged from 35⁵0 kD and nearby 105 kD,and myostromin had two obvious bands between 35 and 50 kD and one band near 71 kD.Thermal stability analysis indicated that the denaturation temperature of myosinogen,myofibril protein,mystromin was 65.8,50.5 and 59.6 ?,respectively;and there were abundant of flavor substances in adductor muscle.2.The adductor muscle of Chlamys nobilis was rich in protein and it was delicious.In order to further improve its value,orthogonal experiments were carried out to optimize the traditional dry process technology,the best dry process parameters were determined,and the basic component,free amino acids,flavor nucleotides and betain of the self-made dried scallop were detected and analyzed.The flavor properties were compared with a dried scallop from the local market.The results indicated that the optimum processing technology of the dried scallop of Chlamys nobilis: the addition of salt was 8 %,rinse time was 40?min,bakig temperature was 110 ?,baking time was 40 min and sun-curing timewas 6?h.The protein content of dried scallops as high as 69.28 %,and the fat content about2.36 %,it was a kind of high-protein and low-fat product.Seventeen types of free amino acids were detected in scallops,the total content was up to 1037.4?mg/100?g,and the taste active values of Glutamic acid,Glycine and Arginase were 1.57,4.54 and 6.40,respectively,these data indicated that the three kinds of amino acids had significant contribution to the flavor of the product.The content of betain in the self-made scallop?14.23?mg/g?was slightly higher than that in the dried scallop from the local market?12.71?mg/g?,and the total contents of nucleotides in the self-made scallop were more than that in market scallops also,the self-made scallop contained a higher content of AMP,which was 96.74??mg/g,and the content of TAV was 193.48 mg/g;The equivalent umami concentration of flavor amino acids and flavor nucleotides was 103.58?gMSG/100?g.Therefore,fresh,tender and delicious dried scallop could be made from the adductor muscle of Chlamys nobilis.3.Using high performance liquid chromatography and headspace solid phase micro extraction GC-MS?HS-SPME-GC-MS?,on the basis of identification of the characteristics of different samples flavor components,fresh and vacuum freeze-drying treatment Chlamys nobilis adductor muscle for control,the study explored the effects of hot-working treatment on the formation of characteristic flavour components of Chlamys nobilis adductor muscle.The results showed that the contents of crude protein and crude fat of scallops by different drying methods changed slightly.Compared with fresh Chlamys nobilis adductor muscle,hot-working made the contents of AMP,betain,Na⁺ and Clincreased significantly?p<0.05?,the amount of free amino acids,nucleotides and related compounds?except AMP?,succinic acid,K⁺ and PO₄^3- decreased significantly?p<0.05?,changes in hot-working treatment was more obvious than changes in vacuum freeze-drying treatment.There were 34,64 and 63 kinds of volatile compounds isolated and identified from different treatment scallops,respectively.The major volatile compounds in three kinds of scallops were alcohols,acids and hydrocarbons,aldehyde,which accounted for26.20 %,60.44 % and 16.78 % of the total volatile compounds of the three kinds of scallops,respectively.The major odors of hot-working treatment scallops were confirmed as fishy,honey aroma,fruity,fatty and grease,trimethyl amine,1-octen-3-ol,?2z?-2-penten-1-ol,1-penten-3-ol,1-pentanol,nonanal,undecanal,hexanal,heptaldehyde,benzaldehyde,octanal,decanal and 3-octanone were found to be involved in the formation of characteristic flavor components.4.The flavor contents change of the dried scallop of Chlamys nobilis were detected during the processing.The relationship between flavor,quality of dried scallops andprotein and lipid oxidation were discussed in combination with product color change and sensory score and protein,lipid oxidation indexes.The results showed that the contents of glutamic acid,glycine and arginine,IMP,succinic acid and betaine of scallops were decreased before baking,and the contents increased continued at 3 h to the end of drying.34,63,34,35,57,56,63,76 kinds of volatile components were identified from the samples during the processing,which were mainly alcohols,aldehydes,esters,ketones,acids and hydrocarbons,respectively.The type and content of carbonyl compounds were similar to the variation trend of protein carbonyl values,and their sources may be produced by protein oxidation.The color and sensory scoring data showed that there were no significant differences?p?0.05?in color,taste and flavor of scollops sun-curing 6 h and sun-curing 12 h.