整果荔枝干护色研究

Studies on the Color Retention of Dried Litchi Fruit

新鲜荔枝果实应用A(连二亚硫酸钠)、B(亚硫酸氢钠)、C(熏硫)三种方法作退色处理，以HCl、H2SO4、植酸作复色处理，每种酸采用pH为0.5、1和3，浸泡时间为5、10和15min，处理后的果实置于50～60℃下进行间歇干燥，最后以果肉含水量29％～32％为成品，此时产品得率为25％～28％。结果表明：护色效果及感官因酸的种类、pH值和浸泡时间而稍有差异其中以A、B处理后再用pH=3的H2SO4浸泡5min，烘干后果实护色效果及口感最好，色泽接近原色具荔枝干特有的香味，无SO2残留味。对总酸、VC、还原糖、SO2等的测定结果表明：与对照组相比，总酸升高，总糖和还原糖有降低，SO2含量微量。对成品的贮运试验证实，成品密封于保鲜袋中，常温下保存一年以上果皮仍为自然的红色，果肉不发霉，无异味。

This study was conducted on the color retention of dried Litchi fruit.The treatments were as follows:fresh litchi fruit was bleached by dipping in three different solutions(Sldium dithionite,Sodium bisulfite and Sulfurizafion)firstly;then dipped in three different acid solutions(HCL,H2SO4 and Phytic acid)at different pH value(0.5,1.0 and 3.0)for different time(5,10 and 15 min)respectively Then after it was dried only in the daytime at 50～60℃.When water content in the pulp reached 29％～32％,the product yidld was 25％～28％. The results showed that the kinds of acid,pH and the dipping time made a little different effect on skin color retention and sensory of fruit.The opfimal effect was obtained by smoking first,then soaking in H2SO4 solution at pH3 for 5 min.After drying the skin color almost kept the initial color and the pulp had the characteristic favor of litchi without residual taste of sulphiteAffer assoy,the total acidity rose,total sugar and redued sugar changed a little,Vc decreased greatly and the residul guiphite was in trace amount compared with the control. The results of storage experiment of products showed that the skin color kept a natural redness,and the pulps did not mildew and had no monstrous flavor after more than one year storage at room temperature sealed in freshing package.