Study On Flavor Of Crab Meat

Crab is a traditional savory food in China with delicious taste and rich nutrition. Mud crab (Scyller Serrata), Swimming crab and Chinese mitten crab are very popular in people's daily life. Due to the factors of price and season, it is impossible for people to eat crabs at a low price all year around. If we develop crab flavoring which is added to food, it will be favored by consumers and have broad market. In this paper, the flavor components of the above three crabs were studied, which provided corresponding experimental data for development the crab flavoring in order to meet consumer demand. The main contents were as follows:First of all, a total of six samples (each of the three crab including male and female) were analyzed for basic components, amino acids composition, and also evaluated for the nutritional quality. Second, the taste active compounds were analyzed in order to clarify the reasons why crab meat had a strong flavor. Then, the aroma components in female Mud crab meat which was extracted by simultaneous distillation extraction (SDE) and headspace-solid phase microextraction (HS-SPME) respectively were analyzed and an optimal extraction method was chosen to extract aroma components of the six samples. Finally aroma components of the six samples were analyzed by HS-SPME with gas chromatography-mass spectrometry. The characteristic aroma components were analyzed by relative odor activity value. The main results were as follows:(1) Crab meat was rich in protein and low in fat. The protein of crab meat contained many kinds of amino acids. The essential amino acids proportions complied with FAO/WHO standards. Crab meat was rich in umami amino acids such as glutamic acid, glycine, alanine, aspartic acid and so on. Therefore crab meat was an excellent source of protein and the ideal animal food for human.(2) Compositions of nucleosides:the high concentration of AMP was detected in the six samples. AMP detected in the female Chinese mitten crab was the highest. AMP was an important taste active component according to TAV values. IMP was detected in the Mud crab, the female Swimming crab and the female Chinese mitten crab. Hx was detected in the male Mud crab and the female Swimming crab. GMP was not detected in the six samples.(3) Compositions of organic acid:the high concentration of lactic acid was detected in the six samples. Lactic acid detected in the Chinese mitten female crab was the highest. Lactic acid was an important taste active component according to TAV values. Citric acid was detected in the Swimming crab and it was an important taste active component of the Swimming crab according to TAV values. Succinic acid was detected in the female Mud crab. Malic acid and acetic acid was detected in the male Chinese mitten crab. Tartaric acid and propionic acid was not detected in the six samples.(4) Composition of betaine:the difference of betaine concentration between the male and female crab meat was small. But the concentration of betaine in the Mud crab, the Swimming crab was much more than in the Chinese mitten crab.(5) Compared the extraction efficiency of aroma components in the female Mud crab meat by SDE and HS-SPME and the results showed that:more kinds of aroma compounds were detected by SDE, but due to the high extraction temperature and long extraction time some low boiling point compounds were easy to loss. Few kinds of aroma compounds were detected by HS-SPME, but the low boiling point compounds and some aroma compounds which were important to crab such as raldehydes, trimethylamine, and sulfur were easy to extract by HS-SPME. Meanwhile HS-SPME had the advantage of convenience, etc. After comprehensive consideration, HS-SPME was selected as the method of extraction of aroma components of crab meat. (6) The aroma components of the six samples were analyzed by HS-SPME-GC-MS.70 aroma compounds were detected in the six samples, including 11 hydrocarbons,15 alcohols,9 aldehydes,13 ketones,1 ester,5 phenols, 2 furans,3 pyrazine,3 kinds of other nitrogen heterocycles,3 thiazoles and 5 other compounds.During the high content aroma components, the six samples contained 5 common components such as pentanol, pentanal, hexanal, nonanal, and trimethylamine. The differences of the aroma compositions between different samples were large. The Mud crab contained more aroma components than the other two kinds.The female kinds of the Swimming crab and the Chinese mitten crab contained more aroma components than the male kinds.(7) ROAV method was applied in evaluating the contributions to global odor perception of crab meat. Trimethylamine, nonanal, pentanal,1-octene-3-ol and 3-methylbutanal were the key odor compounds of the male Mud crab. Trimethylamine, octanal, nonanal, heptanal,1-octene-3-ol, decanal and pentanal were the key odor compounds of the female Mud crab. Trimethylamine, nonanal and pentanal were the key odor compounds of the male Swimming crab. Dimethyl trisulfide, trimethylamine, nonanal, pentanal,3-methylbutanal and 1-octene-3-ol were the key odor compounds of the female Swimming crab. Trimethylamine, nonanal and octanal were the key odor compounds of the male Chinese mitten crab. Trimethylamine, nonanal, 1-octene-3-ol and pentanal were the key odor compounds of the female Chinese mitten crab.Trimethylamine and nonanal which had a great contribution to the six samples could be considered the essential compounds of the crab flavor. The other aroma compounds might be important to distinguish the difference of aroma components between different kinds of crabs. More key odor flavor components were found in the female crab meat than in the male. This might be one of the reasons that more people liked to eat female crab.