新鲜与干制柑橘皮果胶物化特性比较分析

以柑橘皮为原料,分析、比较新鲜柑橘皮果胶(fresh citrus pectin,FCP)与干制柑橘皮果胶(dried citrus pectin,DCP)的物化特性差异。采用传统酸法结合金属螯合剂(六偏磷酸钠)分别从新鲜、干制柑橘皮中提取得到果胶FCP、DCP,测定FCP和DCP的物化特性参数,包括水分、灰分、酸不溶灰分和蛋白含量等基本理化指标,以及半乳糖醛酸含量、酯化度、胶凝度、分子质量和表观黏度等果胶品质评价指标。结果表明:FCP与DCP的基本理化性质相差不大,FCP半乳糖醛酸含量、酯化度、胶凝度和分子质量分别为77.29%、67.5%、179.8和158.8 kD,而DCP对应的值依次为74.98%、66.7%、153和109.1 kD,FCP表观黏度值高于DCP。新鲜和干制柑橘皮果胶品质存在一定差异,特别是作为果胶品质重要参考指标的胶凝度,FCP要高于DCP,而这可能与FCP的分子质量较高有关,但两者的半乳糖醛酸含量和酯化度均符合果胶品质的国家标准GB25533—2010《食品安全国家标准食品添加剂》要求。

超声波协同护色剂浸渍工艺对橘瓣干制品色泽的影响

柑橘片在干制过程中极易发生褐变,为了更好地保持柑橘片加工过程中的色泽,从柑橘汁、柑橘渣2个角度比较了5种不同护色剂(抗坏血酸、柠檬酸、L-半胱氨酸、亚硫酸钠和β-环状糊精)对其褐变的影响,并采用不同超声功率(300、400、500 W)预处理后协同护色剂处理,在70℃下烘制8 h,每隔1 h测定其色泽,探索最佳的抗褐变处理条件。结果显示,护色剂单独处理时,0.20%的亚硫酸钠溶液处理抗褐变效果最佳;结合超声波预处理发现,在橘汁和橘渣中具有最好抗褐变效果的处理条件为超声功率400 W结合0.20%的亚硫酸钠溶液,并在橘瓣上验证此处理组具有最明显的抗褐变效果。

Effects of Drought Stress on Antioxidant System of Leaves from Different Citrus Rootstocks

[Objective] The paper aims to study the effects of drought stress on antioxidation system of different Citrus rootstock leaves. [Method] Potted plant experiments were carried out to control the water content of soil in pots,in order to investigate the effects of drought stress on antioxidation system activity （SOD,POD and CAT） and the content of protein,GSH,MDA and O-·2 from the leaves of Shandong Zhike,Ningminju,Yangshuojinbaosuanju,Huapijinju and Guizhi No.1. [Result] The content of chlorophyll a,chlorophyll b and chlorophyll （a＋b） from the test 5 breeds decreased with the enhancement of drought stress,and there were significant differences between them and the control under the severe stress; the activities of SOD,POD and CAT from the 5 breeds increased as the drought stress strengthened; the content of soluble protein declined while that of GSH,MDA and O-·2 rose because of the drought stress. [Conclusion] This research provided a good reference to choose the breeds of citrus rootstocks in arid and semi-arid areas.