Changes In Structure And Rheological Properties Of Abalone During Drying And Storage Process

Abalones are regarded as member of a large class, Gastropoda, of mollusks,which contains various nutritional ingredients. It is famous for its nice flavor andtender texture, and also has very high dietary therapy and medicinal values.Recently, more and more consumers enjoy abalone since its traditional culture historyand special flavor. In this paper, the Haliotis discus hannai Ino was chosen and thefollowing researches were carried out.Firstly, the changes of quality, tissue structure and rheological properties ofabalone samples by different drying methods were studied. Abalone samples weredried with cold air drying and natural drying respectively after heated. The dryingrate, content of main composition, tissue structure and rheological properties (E, η, τ,RS) were determined to study the influences on quality of abalone samples. Theresults showed that, both the two drying methods were undergoing a short ratesincreasing stage and a long rates decreasing stage, the natural drying cost168h, thecold air drying cost120h, which was71%of natural drying. With the increasing ofdrying time, the content of main compositions in abalone samples were decreased; thetissue structure shrank, the muscle fibers became thicker, holes among fibers tendedto be expanded and the muscle structure became tougher; the elasticity modulus E,viscosity η and RS tended to be increasing, while the relaxation time τ had nosignificant changes. Compared with natural drying, the cold air drying cost shortertime, the samples had less nutrient loss, the muscle fibers were shrank evenly and hadno rupture, the color and light permeability and rheological properties were better.In a word, the cold air drying had more advantage.Secondly, changes in main compositions, tissue structure and rheologicalproperties of reconstituted abalone samples by different drying methods wereinvestigated. The results showed that the optimum reconstituted condition was:firstly, immersed in water for24h, then heated for20min, and lastly, water reconstituted for48h. Compared with raw sample, the actual content of maincompositions in reconstituted abalone samples were decreased significantly; themuscle fibers nearly parallel ordered with each other, the voids in muscle tissue waslarger and the tissue structure was looser as a whole; the elasticity modulus E,viscosity η and RS were decreased, the relaxation time τ was increased. It indicatedthat the reconstituted abalone samples were more tender and flexible while lesshardness than that of raw abalone sample. Compared with natural drying abalonesample, the contents of main compositions in cold air drying sample were higher; thetissue structure was more approximate to the raw abalone sample. Thus, it statedthat reconstituted sample by cold air drying had better quality.Thirdly, the changes in quality and rheological properties of abalone meat duringstorage process were studied. The results showed that, with the extension of storagetime, the content of water and crude protein were decreased, and the content ofpolysaccharide was increased; the rehydration rate was gradually increased; thecollagen fibers in the muscle tissue were coagulated and the aperture amongmyofibrils expanded gradually; the elasticity modulus E, RS and TPA were tended tobe decreased, the viscosity η and relaxation time τ were increased. Compared withraw sample, the voids among muscle fibers in reconstituted sample became bigger,and it had a more distinct net structure; the elasticity modulus E and RS wasdecreased obviously and the viscosity η and relaxation time τ were increasedobviously. Compared with natural drying sample, the changed speed of eachindicator of cold air drying sample was declined obviously. It indicated that the coldair drying abalone sample could ensure the quality best during storage process.