Post-harvest Metabolism And Quality Evaluation Of Live Ruditapes Philippinarum

Based on the field research,live Ruditapes philippinarum were selected to explore the post-harvest metabolism and quality evaluation of live shellfish.The changes and storage properties of live Ruditapes philippinarum along live trade chain were explored through physicochemical analysis and sensory assessment after a sensory evaluation system for live clams was established.The main findings are as follows:(1)Field research:According to investigation,post harvest Ruditapes philippinarum trade chains includes domestic marketing and export.The export chain includes raw materials and blanching products processed and depurated by the factory.And the physicochemical indicators(ATP,glycogen,pH and moisure)of Ruditapes philippinarum in each processing of the export trade chain showed no difference indicating that this pattern can better maintain the physiological state of the post harvest Ruditapes philippinarum.By contrast,domestic marketing is treated by retailers without large-scale depuration,which is completed only by their previous experience.And the depuration effect was evaluated only by sandy and survival,during which the impairment of flavor has been neglected,and there is a lack of assessment system of quality changes in Ruditapes philippinarum.(2)Established of live Ruditapes philippinarum sensory assessment system:9 elected assessors were selected to establish sensory panel from 109 volunteers.Sensory panel of live Ruditapes philippinarum was established and 30 descriptive words were determined by generating and screening from the panel including: Appearance(colour and gloss),Odors(umami,aroma,sweetness,boiled potatoes,boiled chestnuts,saltiness,earthy,fishy,smelly),taste(umami,aroma,sweetness,saltiness,earthy,fishy,bitter,smelly),texture(springiness,chewiness,hard,adhesiveness),aftertaste(sweetness,umami,saltiness,aroma,fishy,earthy,bitter).Based on this,scientific sensory evaluation of the Ruditapes philippinarum can be conducted.(3)Effects of post-harvest handling on storage properties of live Ruditapes philippinarum: The effects of emersion(0d,1d,3d,4d)on depuration and storage properties of live Ruditapes philippinarum were studied through physicochemical analysis and sensory assessment,E0,E1,E3 and E4 as 0,1,3 and 4 day-emersion,respectively.Results showed that,first,nearly 100% survival presented in 3 day-emersion,and the survival of E4 maintained about 90%;recovery of raw clams were observed,E1,E3 and E4 had the same ATP,AEC and K value levels higher than the raw,and the raw material presented unpleasant descriptors(bitter,fishy,earthy).After 1-3 day-standing in the air,however,the pleasant descriptors(sweet,fresh,salty and aroma)dominated the flavor profiles,and spoilage odors appeared in E4.Second,the survival of depurated clams in 1,3,4 day-emersion was 100%,91% and 85%,respectively.ATP depletion during depuration was found with the increase of emersion time,K value indicated that E4 depurated clams was different from other treatments,and there were no obvious AEC differences among the treatments.Sensory evaluation results showed that depurated clams in 2 day-emersion present favorite flavor.Umami,sweet,pleasant odor and other pleasant descriptors appeared in E0,E1 group,and the flavor tended to decline in ?3 day-emersion,unpleasant descriptors appeared in E3,and E4 group presented spoilage odors.Third,for 7-day live wet storage,the survival of E0 and E1 group maintained around 90%,the E3 reached up to 70%,and the E4 dropped to 0.As for the 7-day live dry storage,90% survival for the E0 and E1,and 80% for the E3 and E4 could be inferred.K value of E3 and E4 was significantly higher than that in E0 and E1 during all live storage groups.All treatments showed the same level of ATP and AEC values with exception of E4,while the E4 wet storage decreased distinguishably.Finally,E0,E1 and E3 presented pleasant descriptors in the 2-day wet storage;However,for the dry storage,E0 and E1 hold pleasant flavor;off flavor appeared in the E3,and which was worse for the E4 with spoilage odors.In summary,the recovery of the clams occurred during the crucial perishable period,the tolerable emersion time of raw material is around 2 days under the cooling conditions,in which time,handling,landing and transit under air exposure condition will not compromise the shelf-life of the live products.