不同相对分子质量的壳聚糖在草莓保鲜中的作用

Effect of Chitosan Coating on Strawberry Preservation

采用平板法实验7种不同相对分子质量壳聚糖的系列样品对草莓灰霉病病原真菌的抗菌性能,结果表明6种水不溶性壳聚糖的乙酸溶液表现出抑菌活性,特别是中等相对分子质量(Mw7.8×104、4.8×104)壳聚糖的抑菌活性明显优于更高相对分子质量的壳聚糖或低相对分子质量壳聚糖,而壳寡糖的抑菌活性则很弱。水不溶性壳聚糖的乙酸溶液浸泡采后草莓30s后,草莓受灰霉病菌的侵染和软化被显著抑制,果实含糖量和VC含量的下降趋势也得到了延缓,提高了保鲜效果,但是壳寡糖无明显该作用。根据实验结果,相对分子质量在5×104～20×104的壳聚糖在5～10g/L质量浓度处理的草莓保鲜效果较好。

Seven different molecular weight chitosans were tested for antimicrobial effect against Botrytis cinerea by spread plate method. Along with this, the effect of chitosan coating on hardness and soluble solids, VC and reducing sugar contents of strawberry stored at ambient temperature was investigated. Results showed that of the 7 chitosans, 6 water insoluble ones dissolved in acetic acid exhibited a higher inhibitory effect against B. cinerea, especially medium weight molecular chitosans （7.8 × 10^4, 4.8 ×10^4）, whereas chitooligomer exhibited a poorer inhibitory effect. Exposure to water insoluble chitosans dissolved in acetic acid for 30 d significantly protected strawberry from Botrytis cinerea invasion, inhibited fruit softening and delayed the decreases in contents of reducing sugar and VC, thereby providing a good preservation effect. However, no significant preserva- tion effect of chitooligomer was observed. According to experiments, within the concentration range of 5-10 g/L, chitosans with molecular weight between 5 ×10^4 and 20 × 10^4 demonstrated a better oreservation effect on strawberrv.