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Research And Development Of The Key Techniques Of Grass Carp (Ctenopharyngodon Idellus) Processing

Posted on:2009-02-02Degree:DoctorType:Dissertation
Country:ChinaCandidate:T WuFull Text:PDF
GTID:1101360302981925Subject:Food Science and Engineering
Abstract/Summary:PDF Full Text Request
In China, the gross product of low value freshwater fishes, such as grass carp (Ctenopharyngodon idellus), silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis), exceeds 60% of the total freshwater fishery yield. But the potential of these fishes as a source of low fat, high protein food has not yet been fully utilized, due to the limited storage period and, sometimes, their strong fishy odour. Fresh fish contains up to 80% of water and is highly perishable, with a short storage life. The appearance of earthy and musty odour or taste in fish may cause a major reduction in the consumption of the products, or make them unsuitable for sale. To improve their preservation quality and acceptance by consumers, more innovative processing techniques need to be applied. The surimi-based product is a very important part of freshwater fish products in China, including a variety of formulated seafood analogues. In China, surimi-based product is the traditional way to utilize freshwater fish with low commercial value, such as grass carp (Ctenopharyngodon idellus), silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). The freshwater fish resources were extensive used as the material of surimi-based products, however, the thermal gelling properties of freshwater fish surimi is not as good as that from seawater fish, it is necessary to improve thermal gelling properties of freshwater fish surimi by correlative research. For that, a series of exploratory work for the key techniques of a typical freshwater fish, grass carp processing such as deodorization, preservation, drying and surimi-based products have been researched in this study.Earthy-musty odours in freshwater-farmed fish represent one of the most significant economic problems encountered in aquaculture. Deodorant effect of yellow wine; aqueous extraction of ginger, onion and garlic; yellow wine extraction of ginger, onion and garlic use to fresh grass carp deodorization were compared, and the most effective deodorant, yellow wine extraction of ginger, onion and garlic was used to keep the preservation quality of grass carp fillets. The effects on preservation quality were determined by biochemical (pH, total volatile basic nitrogen, thiobarbituric acid), microbiological (total bacterial count) and sensory determinations during storage at 4℃. The extraction exhibited a beneficial effect on inhibiting lipid oxidation and bacterial growth in the fillets. Increases of pH, total volatile basic nitrogen, thiobarbituric acid and total bacterial count in fillets during storage were significantly reduced by the extraction. The present study provides a possible application of the yellow wine extraction of ginger, onion and garlic as an inartificial deodorant and preservative for freshwater fish.Surimi is a high quality myofibrillar protein concentrate that obtained from fish muscle, with high commercial value and extensive application in seafood production. Corn starch and calcium chloride were added to kamaboko gels made from grass carp surimi, and the correlative influences on gelling quality was evaluated by pH, color, texture and expressible water. Calcium chloride increase the whiteness, springiness, cohesiveness, but decrease the pH value and water holding capacity of the gels, while expressible water decreased when corn starch was added in gels. Addition with corn starch and 0.2% calcium chloride was considered as a promising approach in the processing of grass carp gels to improve thermal gelling properties.Chitosan was applied to kamaboko gels made from grass carp, and the correlative influences on gelling quality and lipid oxidation were evaluated by color, texture, expressible water, TBA (2-thiobarbituric acid) and peroxide values. Whiteness, hardness, springiness, cohesiveness, chewiness, adhesiveness, TBA value increased, while expressible water and peroxide value decreased when 1% chitosan was added in gels. Addition with 1% chitosan was considered as a promising approach in the processing of grass carp gels to improve thermal gelling properties and delay lipid oxidation.Chitosan was added to kamaboko gels made from grass carp, and the effects on preservation quality were determined by biochemical (pH, total volatile basic nitrogen, thiobarbituric acid, peroxide value) and microbiological (total bacterial count) determinations during storage at 4℃. Application of chitosan, at a level of 1% (w/w), exhibited a beneficial effect on inhibiting lipid oxidation and bacterial growth in the gels. The preservative function was related to the molecular weight of chitosans. Relative low molecular weight chitosan showed a higher antioxdant capacity than high molecular weight chitosan. However, mixture of 300 kDa and 10 kDa chitosans exhibited the highest antibacterial activity. Increases of pH, total volatile basic nitrogen, thiobarbituric acid and peroxide values in gels during storage were significantly reduced when chitosan was applied. The present study provides a possible application of chitosan as a food additive for surimi-based food.Hot air drying and microwave drying were applied to dry fish fillets made of grass carp, and the correlative influences on nutritional and odorous properties were evaluated by proximate composition, protein solubility, amino acid composition, fatty acid composition, peroxide value, anisidine value, and odour evaluation. Drying resulted in a significant increase of protein but reduced fat content. There was lack of negative influence of the drying process on the amino acid composition of grass carp fillets. Both saturated and monounsaturated fatty acid contents decreased, while polyunsaturated fatty acids increased by an average of 23.8% after drying. Microwave-dried samples showed lower fat loss, higher protein solubility, and lower anisidine values did hot air-dried samples. There was no significant difference in odour quality between hot air-dried and microwave-dried samples. The present study provides a possible application of microwave drying as an efficient drying process for fish fillets.
Keywords/Search Tags:Grass carp, Processing techniques, Deodorization, Preservation quality, Surimi-based food, Gelling quality, Corn starch, Calcium chloride, Chitosan, Hot-air drying, Microwave drying, Nutritional properties
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