Studies On Processing Techniques And Storage Stability For Fish Biscuit

The by-products from processing of aquatic products are rich in protein,fat,minerals and other bioactive components.However,the utilization of these by-products in food processing is very low.It is important for aquatic products processing to improve the economic value and the comprehensive utilization of them.Therefore,this thesis used the by-product of minced fish and the surimi to develop a new high-value product of fish biscuit.The processing technologies of fish biscuit and the effect of drying,packaging,and other storage conditions on the quality of fish biscuit were studied,and the results were showed as follows.1)Two different dehydration methods for minced fish on the quality of the fish biscuit were studied.The results showed that to achieve the same moisture content,the products with drying dehydration had the least hardness,springiness,cohesiveness and chewiness and highest TBA and POV.Products made from frying dehydration had the least AV,free fatty acids and POV.Both frying and drying can improve digestibility of protein.The protein digestibility of biscuit made from the frying was the highest.Therefore,frying dehydration can be choosed as the most optimal way for dehydration of minced fish.In addition,scanning electron micrographs showed the products made from frying wrapped a layer of oil.The FTIR analysis found that there was a new carboxyl bond esters that could produce the flavor compounds formed in the frying products.2)The influence of different oils of butter,soybean oil,peanut oil,lard oil,shortening oil and palm oil used on the fried of minced fish on the quality of the fish biscuit were studied.The results showed that the brightness,hardness,TBA content,POV of lard products were the highest.The palm oil products' red was the maximum and TBA and POV values were minimum.The products fried with butter had the highest AV and soybean fried products had lowest AV.The protein digestibility of products fried with lard oil was the highest,followed by palm oil,and the lowest is product fried with shortening oil.Palm oil was choosed as the most suitable oil for frying due to the better smell and strong antioxidant capacity.3)The amounts of palm oil for frying fish on the quality of biscuits were studied.The palm oil to minced fish ratios were 1-11%.The results showed that with the increase of the palm oil,L*,b*,TBA,AV and POV decreased,but springiness,cohesiveness and chewiness increased gradually,and a* values and in vitro digestion of proteins decreasd after the first increase.The hardness first increased,and finally stabilized with the increase of the palm oil.Combined with products' formability and appearance,we selected the 5% of palm oil adding to minced fish for frying.4)The amounts of surimi on the quality of fish biscuit were studied.The ratios of surimi to minced fish were 1:2-1:4.5.The results showed that with the increase of surimi content,the biscuits' hardness,springiness,cohesiveness and chewiness were gradually increased,but the protein digestibility and L*,a*,b* value decreased.The electron micrographs showed that the more amount of surimi,the weaker activity of oil wrapped materials and the harder biscuits' organizational texture.It is recommended that the best ratio of surimi to minced fish is 1:4.5)The influence of different drying temperature(40?-90?)on the quality of the fish biscuits were studied.The results showed that when achieved the same moisture content of biscuits,with the drying temperature increased,the hardness and chewiness of biscuits reduced,springness basically unchanged,cohesiveness reduced after the first increase and chroma changed slightly.The effect of different drying temperature on the chemical index was as follows.TVB-N values increased and TBA content basically unchanged,but AV and POV increased firstly and then declined with the increased of drying temperature.Considering with degree of fat lipid oxidation and drying time needed,the optimal drying temperature is 60 ?.6)The texture,chroma and sensory characteristics of the fish biscuits with different moisture content(14-20%)were observed,and the relationship of instrumental measure indices of texture and chroma with sensory score was analyzed to evaluate the role of instrumental measures for texture and chroma on the quality of restructured fish product.With the moisture content decrease,the texture indices of gel strength,gumminess,hardness,share forece,chewiness and the chroma of a* and b* value of the fish biscuits increased,but L* value and ?E decreased.Sensory score of the slices with moisture contents of 16% was highest compared to the others.Gel strength can distinguish the four kinds of the fish biscuits with different moisture content totally(4/4),followed by ?E(3/4).As compared with principal component analysis,linear discriminant analysis can distinguish different moisture content products more efficiently,mainly though the first linear discriminant of gel strength in texture indices and ?E in chroma indices.6)The texture,chroma and sensory characteristics of the fish biscuits with different moisture content(14-20%)were observed,and the relationship of instrumental measure indices of texture and chroma with sensory score was analyzed to evaluate the role of instrumental measures for texture and chroma on the quality of restructured fish product.With the moisture content decrease,the texture indices of gel strength,gumminess,hardness,share forece,chewiness and the chroma of a* and b* value of the fish biscuits increased,but L* value and ?E decreased.Sensory score of the slices with moisture contents of 16% was highest compared to the others.Gel strength can distinguish the four kinds of the fish biscuits with different moisture content totally(4/4),followed by ?E(3/4).As compared with principal component analysis,linear discriminant analysis can distinguish different moisture content products more efficiently,mainly though the first linear discriminant of gel strength in texture indices and ?E in chroma indices.