Chitosan Coating Materials And Application In Food Preservation

Chitosan is a natural macromolecule of polysaccharide which has many characteristics,for example,non-toxic,tasteless,antibacterial and biodegradable.It has been adapted for preservation on fruits and vegetables.Due to its defect of obdurability and ability of water holding,its application is limited.In this research,SiOx nanoparticals and glyeml monstearate single stearic acid glycerine ester were added to the solution of chitosan to modify the chitosan. Because SiOx nanoparticals is very tiny,it has high surface energy.It is disadvantageous to dispersibility of SiOx nanoparticals in organism.So a hydrophobization method was used on SiOx nanoparticals by anion surfactant(SDS). It was proved that the dispersion degree is good by IR spectroscopy and TEM.Four equations were gotten by Response Surface Methodology analysis.The four factors which were water permeability,tensile strength,elongation-at-break,and orthogonal avulsion strength were selected to measure the result of experiment.The equation of water permeability as follows:Y₁=0.0401-0.0323X₁-0.7156X₂-0.2736X₃+0.0081X₁²+0.1637X₂X₁+8.2157X₂²+0 .1640X₃X₁+0.4751X₃X₂+0.2157X₃²;The equation of tensile strength as follows:Y₂=-141.5286+144.3922X₁+3228.5101X₂+1325.5599X₃-29.3930X₁²-932.4708X ₂X₁-30672X₂²-306.1149X₃X₁-8434.4458X₃X₂-7484.4735X₃²;The equation of elongation-at-break as follows:Y₃=-26.2514+37.127611X₁+1157.0840X₂-564.1410X₃-17.4240X₁²-367.4702X₂ X₁-10894X₂²+781.4476X₃X₁-3447.0005X₃X₂-3394.1620X₃²;The equation of orthogonal avulsion strength as follows:Y₄=-93.8236+256.5707X₁-1835.5433X₂-1074.6392X₃-61.8828X₁²+229.3352X₂ X₁-39254X₂²-1375.2567X₃X₁+90138X₃X₂-566.0050X₃²;In this paper,water permeability was selected as the most important factor. According to the result of experiment and RSM analysis,the optimum process conditions were obtained,as follows:chitosan of 1.547g,SiOx nanoparticals of 0.028g,glyeml monstearate single stearic acid glycerine ester of 0.04g.The optimum process conditions were applied for preserving Jinqiu pear,fish and meat in room temperature.This study compared the preserving effects of chitosan(CTS),chitosan/ SiOx nanoparticals(CTS-SiOx),chitosan/SiOx nanoparticals/ glyeml monstearate (CTS-Compound) with the blank sample through the keeping fresh experiments on Jinqiu pear in room temperature.The results indicated that:for preserving Jinqiu pear, the effect of CTS-Compound was the best,and the shelf life of Jinqiu pear could be extended from 20 days to 40 days and there was no decay phenomenon.After 30 days,the water content of Jinqiu pear was 87.1%,the content of vitamin C was 5.8%, and the hardness of Jinqiu pear was 8.67×10⁵ Pa which was higher than the other three groups obviously.The total sugar was 8%which approached to the fresh pear. And the change of total acids was steady.For preserving the fish and meat,the effect of CTS-SiOx was the best.After being stored 2 days,the TVB-N content of the fish treated with CTS-SiOx was 28.65mg/100g,and the blank group was 279.77mg/100g.The antibacterial rate of CTS-SiOx was 75.36%,which was 25.72%higher than CTS.It also had a good effect on meat.After being stored 1 day,the TVB-N content of CTS-SiOx was 50.85mg/100g,and the blank sample was 127.89 mg/100g.The TVB-N content of CTS-SiOx was 39.76%of the blank sample.After being stored 2 days,the TVB-N content of CTS-SiOx was 75.62mg/100g,and the blank sample was 419.34 mg/100g.The TVB-N content of CTS-SiOx was 18.03%of the blank sample.The antibacterial rate of CTS-SiOx was 75.36%after 1 day,which was 48.87%higher than CTS.The antibacterial rate of CTS-SiOx was 64.85%after 2 days,which was 60.72%higher than CTS.