银耳多糖的提取及其对鲜切果蔬褐变的抑制作用研究

为探究银耳多糖对鲜切果蔬褐变的抑制作用，以古田银耳为原料，采用超声辅助法提取银耳多糖，并对提取工艺进行优化；以果蔬褐变度、多酚氧化酶活性、可溶性固形物含量、果蔬硬度为指标研究银耳多糖对鲜切苹果和鲜切土豆褐变的抑制作用。结果表明，银耳多糖提取最佳工艺条件为：料液比1∶60（g/mL），浸提温度80 ℃，预浸提时间60 min，超声时间40 min，在此条件下多糖得率为26.83%；与空白组（以蒸馏水代替银耳多糖）相比，冷藏3 d时，采用质量浓度为4.0 mg/mL的银耳多糖处理的鲜切苹果和鲜切土豆的多酚氧化酶活性分别是空白组的0.44倍和0.66倍，硬度是空白组的16.00倍和3.20倍，可溶性固形物含量是空白组的1.81倍和1.76倍，褐变度是空白组的0.27倍和0.64倍。银耳多糖具有较好的抑制鲜切果蔬褐变的能力，可以降低鲜切果蔬多酚氧化酶的活性和褐变度，提高果蔬的可溶性固形物含量及硬度，且与其浓度呈正相关。研究结果可为果蔬保鲜提供一定的理论借鉴。

Study on the Extraction of Tremella fuciformis Polysaccharide and the Inhibitory Effects on Fresh-Cut Fruits and Vegetables Browning

The present study aimed to investigate the inhibitory effects of Tremella fuciformis polysaccharide on freshcut fruits and vegetables browning. The Tremella fuciformis polysaccharide was prepared via ultrasound-assisted extraction method after optimization, and the inhibiting effects of polysaccharide on the browning of fresh-cut apples and potatoes were investigated using browning degree, polyphenol oxidase activity, soluble solid content and hardness as indicators. The results showed that the optimal extraction conditions were determined as follows: solid-liquid ratio of 1∶60（g/mL）, preextraction temperature of 80 ℃, extraction time of 60 min and ultrasonic time of 40 min. Under these conditions, the extraction yield of polysaccharide was 26.83%. Compared with the blank group (with distilled water instead of Tremella fuciformis polysaccharide), the activities of polyphenol oxidase in apples and potatoes treated with 4.0 mg/mL Tremella fuciformis polysaccharide after 3 days refrigeration were 0.44 times and 0.66 times of the blank group, respectively, hardness was 16.00 times and 3.20 times of the blank group, soluble solid contents were 1.81 times and 1.76 times of the blank group, and the browning degrees were 0.27 and 0.64 times of the blank group. Tremella fuciformis polysac?charide presented superior inhibitory effects on the browning of fresh-cut fruits and vegetables, which could reduce the activities of polyphenol oxidase and the browning degrees of fresh-cut fruits and vegetables, and improve the contents of soluble solids and hardness, and it is positively correlated with the concentrations. The results can provide certain theoretical references for fruits and vegetables preservation.