Tudy On Drying-Reping Process Of Perchs,Lipolysis-Lipid Oxidation And Fleavour Character During Processing

Perch is one of the up scale fresh water fish specieses in our country, its can be used for deeply processing because of its meat quality is delicate, have suitably fat content, and bone sting less. The traditional drying fish is subjected to large consumer’s favor bedeeply because of special taste quality; change of proteolysis and sensory quality in perch during dry curing processing have been researched, lipolysis and oxidation is main bio-chemical reaction and have important impact on quality and flavor character of perch during processing, but few research to report. However, up to now, studies on the regulation of lipid oxidation in dry-cured perch products during processing have just started. The main aim of this topic is to make clear the lipid oxidation regulation and flavor of dry-cured perch and to optimize drying-ripening Process of Perch,provide experiment foundation and theoretics there under, The main results were summarized as follows:1.Research on Air-drying Ripening Processing of Dry-cured PerchThe lipolysis-oxidation and Sensory evaluation correlations with Marinating salt,drying temperature and drying duration were investigated by response Surface experimental design of drying-ripening Process of Perch.The results show:drying temperature have a significant impact on Sensory evaluation in3factor, The optimum process obtained by regression optimizing using Sensory evaluation as response were:Marinating with2.5%salt,drying temperature14℃and drying of3.5days. Sensory evaluation anlarge first and decrease later when increase NaCl content during curing and drying time at the same time,NaCl content during curing had significant interactions (P<0.05) with drying time.The drying time critical value decreased linearly with NaCl content increasing (y=-0.6712x+5.5553, R2=1), All these results indicated that Sensory evaluation in dry-cured perch could be regulated by controlling process factors during the processing.2. Lipolysis and lipid oxidation in perchs during curing and drying-ripingDry-cured perchs were processed using perchs as material by dry-salting and drying-ripening. The change of lipid composition, lipase, lipoxygenase (LOX), thiobarbituric acid reactive substance value (TBARs) and peroxide value (POV) in perchs sample muscles were tracked and measured during processing in order to investigate the rule of lipolysis and lipid oxidation. The results showed that lipid content showed a significant decrease (P<0.05), neutral lipid and phospholipids decrease and FFA increased significantly (P<0.05) during process. Palmitoleic acid(23.95%), stearic acid(14.69%), oleic acid(17.01%), eicosapentaenoic acid(15.42%) and docosahexaenoic acid(21.22%) were the main fatty acid. Three lipase activities decreased significantly during processing (P<0.05), Neutral lipase is mainly lipase because showed higher activity than acid lipase and phospholipase (P<0.05). LOX activity gradually decreased during drying-ripening period, POV and TBARs value increased initially then decreased in the whole processing,suppose non-enzymatic oxidation have important Contribution on lipid oxidation especially polyunsaturated fatty acids oxidation likeEPA and DHA.3. Effect of drying ripening maturation on quality and flavor of perchsThe volatile components in dry-cured perch during processing were analyzed by headspace-solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), the extraction of volatile flavor compounds were identified and Change of relative content of volatile compound in dry-cured perch during processing have been compared. The results show:64volatile compounds were isolated and identified, which included15aldehydes,20alcohols,7ketones,7esters and15hydrocarbons; aldehyde,unsaturated alcohol, unsaturated ketone are main compound during process, explain lipid are significant precursor of volatile components, These results appear to be accelerating flavour development through controlling lipid oxidation during dry-cured perch processing; Through to the main volatile compounds threshold value analysis about volatile components to product whole flavor contribution, Hexanal,2-methyl-4-Pentenal,2-aldehyde,2-octene aldehyde, benzaldehyde,1-octen-3-ethanol,2-heptanone,(E, E)-3,5-octadiene-2-ketone May the characteristic flavor substances of product.