Study On Processing And Storage Of Re-structured Fish Crisp Granule Using Low-value Small Hairtail As Materiai

Hairtail is one of marine fishes with large amount of fishing in our country, which isdelicious and nutrient-rich. However, a large number of cheap small hairtails （25cm³4cm）are often entrained during fishing, whose amount accounts for about20%³0%of the totalamount of fishing of hairtail. How to use the resource reasonably is increasingly becoming atopic of concern for coastal fisheries sector. Now small hairtails are mainly processed intofishmeal and feed with low additional value, which does not make full use of resources.Therefore, this research adopted the new idea that low-value small hairtails were seasoned,reorganized and microwave puffed to produce re-structured fish crisp granule with highadditional value, which not only increased the content of nutriment in the products, but alsotook full advantage of leftovers. The study further improved the additional value of low-valuefish products and promoted the deep-processing technology of marine products.In order to get the optimal formula and technological parameter of re-structured fishcrisp granule, taking color, expansion ratio, breaking force and the value of sensoryevaluation as indexes, single factor and orthogonal test on seasoning, restructuring andchopping process of low-value small hairtail were conducted. The result showed that theoptimal formula and technological parameter of crisp granule were as follow: carrot15%, thechives, ginger and garlic seasoning0.9%, starch8%, white sugar8%, salt2.0%and choppingtime16min.In order to investigate a suitable drying method for re-structured fish crisp granule, theeffects of vacuum drying（VD）, vacuum microwave drying（VMD） and pulse spouted vacuummicrowave drying （PSVMD） on the drying characteristic, expansion ratio, breaking force,color, the value of sensory evaluation and microstructure of crisp granules were investigatedcomparatively. The results showed that drying time of VMD was the shortest which only need18min, the second was PSVMD, while drying time of VD was210min. PSVMD crispgranules exhibited the best texture and color properties, and the sensory quality and expansionratio were also relatively desirable. Crisp granules processed by VMD and PSVMD haveobvious porous honeycomb network structure and big pore size on the section, while VDsamples did not. What’s more, the pore size and its distribution of the PSVMD crisp granuleswere more uniform.In order to get the optimal technological parameter combination of PSVMD, thequadratic regression orthogonal rotatable central composite design was used. Combining theanalysis of response surface and contour line, the effects of microwave power density, initialmoisture content, spouted time and their interaction on breaking force and expansion ratiowere investigated. The optimal technological conditions were gotten: microwave powerdensity6.4W/g, per minute spouted time7.0, initial moisture content59.4%. Meanwhile, in order to further verify drying uniformity of PSVMD, under the optimal technologicalconditions, moisture content, temperature distribution of crisp granules at different stages ofdrying and the color of final products were measured. It showed that it didn’t have significantdifference（p>0.05）between moisture contents of crisp granules at each drying time points,surface temperature distribution of crisp granules were uniform and it didn’t have significantdifference（p>0.05）between color of crisp granules, therefore PSVMD could achieve thepurpose of uniform drying.In order to predict the shelf life of re-structured fish crisp granule, acceleration test wasutilized, and kinetics model equations using peroxide value （POV） and acid value （AV） asindexes were established respectively: A=A0exp (534.5899e^-29450/RTt) and A=A0exp(3.766×10⁵e^-47202/RTt), and the predictions of the shelf life of crisp granules stored at37℃high temperature,25℃room temperature and22℃supermarket summer air conditionercondition were182days,289days,326days respectively by these equations.