Effect Of Chitosan Plus Other Thickener On Gelling Properties Of Fish Sausage

Chitosan could enhance textural quality of surimi. However, due to high price and largeamount to achieve the desired results, the application of chitosan as food thickener is largelylimited. Synergistic effect research among different additives and its application are popularnow. Yet there were few studies refer to synergistic effects among chitosan and otherthickener, as well as its application to improve the quality of surimi products. Therefore,effect of chitosan plus other additives on physic-chemical properties of fresh water fish surimias well as the thickening mechanism were studied.When chitosan was mixed with anionic polysaccharide in low concentration precipitationwill emerged while in high concentration gel was formed. No synergistic effects weredetectable among chitosan and non-ionic polysaccharide. However, when chitosan was mixedwith sodium caseinate, synergistic effect was detectable.Mixtures of chitosan plus other additives (carrageenan, sodium caseinate, CaCl2) wereexamined for their synergistic effects when added to surimi together. Synergistic effects weredetectable between chitosan and carrageenan or sodium caseinate when added to fish surimitogether. Addition of0.5%chitosan plus carrageenan or1%chitosan plus sodium caseinatewith complex ratio of1:1could make the surimi gel strength increased approximately by50%while the water loss rate decreased by19%and28%respectively. And no opposite effect wasdetectable to surimi color. However, no synergistic effect was detectable between chitosanand CaCl2when they were added to fish surimi together. The optimization experiment ofchitosan plus carrageenan and sodium caseinate was carried to examine their effect onphysic-chemical properties of silver carp surimi. The surimi products exhibited the highest gelstrength when addition of chitosan, carrageenan and sodium caseinate was0.5%,0.3%and0.5%respectively. Gel strength increased by approximately57%while water loss ratedecreased by25%.The mixed gums were added to surimi to examine their effects compared with thecommonly used thickener available in the market. Results showed that0.5%chitosan pluscarrageenan or1%chitosan plus sodium caseinate with complex ratio of1:1had similareffects with adding6%or8%starch respectively. It can make surimi products with low levelsof starch and even no starch addition. Besides, addition of chitosan plus carrageenan orsodium caseinate could make gel strength and other quality indexes significantly superior tothat of adding CMC. Besides, the mixed gums could also improve the quality of grass carpsurimi-based products.Rheological properties, selective protein solubility and microstructure of surimi geladded with mixed thickener were also studied to reveal the thickening mechanism. Resultsshowed that storage modulus of salt-soluble meat proteins increased greatly after mixing withchitosan plus sodium caseinate, indicating that chitosan and sodium caseinate participated inthe development of salt-soluble meat proteins gel networks. Electrostatic interactions andhydrogen bonds in surimi gels were significantly increased after two stage heating procedurewhen chitosan plus carrageenan were added. Hydrogen bonds content was four times higher than that in control samples, while hydrophobic interaction in surimi gels was significantlyincreased when chitosan plus sodium caseinate were added. A compact and homogeneousstructure was observed on the gel surface with mixed gums addition through SEM comparedto control samples.The present study provides a solid theoretical basis for chitosan to develop functionalfood assistive and ingredient, and is also of great importance for producing high qualitysurimi products.