【作者】 陈荔红；

【导师】 郑宝东；

【作者基本信息】 福建农林大学 ， 农产品加工及贮藏工程， 2010， 硕士

【摘要】 仙草(Mesona procumbens Hemsl.),又名仙人草或凉粉草,为唇形科一年生草本植物,仙草胶系以仙草茎叶为原料,采用浸提技术获得的仙草提取液,具有良好的天然水溶胶性能。本项目通过研究仙草胶提取液不同脱色工艺及技术,在此基础上,研究仙草胶—卡拉胶复合膜的制备及性能研究,并进行抑菌试验,将其应用于枇杷保鲜。研究成果将进一步拓展仙草利用途径,同时对天然水溶胶在食品领域的应用提供一定的理论依据。1、通过对仙草胶提取液不同脱色工艺的研究,比较活性炭、树脂、超滤三种不同方法的脱色性能,获得最佳脱色方法及工艺参数。结果表明,以粉末活性炭作脱色剂,仙草胶提取液脱色最佳工艺参数为:活性炭用量2.5%,温度60℃,时间50min,脱色率达92.3%,此条件下多糖损失率为20.5%;从5种离子交换树脂和大孔吸附树脂中筛选出脱色效果好的树脂D301,最佳工艺参数为:树脂用量3%,时间3h(130r/min),温度50℃,pH 5.0,在此条件下脱色率达95.5%,多糖损失率为15.5%;截留分子量为10000Da PES膜能够有效地脱除仙草胶提取液中的色素,脱色率达85.4%,多糖损失率为20.4%。综合研究结果表明,树脂D301对仙草胶提取液脱色率最大,而多糖损失率最小,因此,选择树脂D301作为仙草胶提取液的脱色剂。2、以脱色仙草胶、卡拉胶为基质,研究不同因素对复合膜性能的影响;在此基础上,选取总固形物、配比、蔗糖酯以及干燥温度为参试因子,以穿刺强度、拉伸强度以及断裂伸长率、水蒸气透过系数为指标,进行均匀正交试验,并采用主成分几何平均分析法对影响复合膜性能的因素和水平进行多指标综合分析。结果表明,总固形物1.6%,仙草胶/卡拉胶配比20/80,蔗糖酯0.1%,干燥温度52℃的条件下,控制甘油含量1.5%,pH为7,可以获得综合性能优良的仙草胶—卡拉胶复合膜。3、研究了尼辛和纳他霉素对脱色仙草胶—卡拉胶复合膜液抑菌效果的影响,并将其应用于枇杷保鲜,结果表明,仙草胶—卡拉胶涂膜液中加入200mg/L尼辛、20mg/L纳他霉素对金黄色葡萄球菌、李斯特菌等细菌及青霉菌、根霉菌等霉菌均有明显的抑制作用。保鲜试验显示,仙草胶—卡拉胶复合抑菌涂膜液可以显著抑制枇杷的生理代谢,减少营养物质的损失,对枇杷的室温贮藏有很好的保鲜效果。更多还原

【Abstract】 Hsian-tsao(Mesona procumbens Hemsl.), called Eone Chinensis or Mesona Blumes, is an annual herbaceous plant of Labiatae. Hsian-tsao gum extracted from the Stem and leaf of Hsian-tsao have good performance of natural hydrocolloids. Different decoloring methods was applied to hsian-tsao gum extraction, and preparation and characterization of hsian-taso gum/carrageenan film was analyzed. Futhermore, the antimicrobial activity was experimented, and effect of edible hsian-taso gum/carrageenan coating as carrier of nisin and natamycin on shelf life of loquat was also investigated. Therefore an effective utilization way for the use of Hsian-tsao was offered, a theoretical basis for the applications of natural hydrocolloids in food field was also provided.1. Three different decoloring methods, including activated carbon, resin and ultrafiltration, were compared to determine the most optimum method and condition. The best result was obtained when activated carbon dosage was 2.5%, decolorization temperature was 60℃and decolorization time was 50min, under which the decolorizing rate reached 92.3% and polysaccharide loss rate was 20.5%; The D301 resin used to decolorize hsian-tsao gum was selected from five types of ion exchange resins and macroporous absorption resin. The best result for decolorizing hsian-tsao gum was determined as follows: the volumn of resin was 3%, decolorization time was 3h(130r/min), decolorization temperature was 50℃and pH was 5.0, under which the decolorizing rate reached 95.5% and polysaccharide loss rate was 15.5%; the pigment substance would remove efficiently from hsian-tsao gum by 10000Da molecular weight cut-off PES, under which the decolorizing rate reached 85.4% and polysaccharide loss rate was 20.4%. Through the research of the process conditions on decolorizing, the D301 resin possessed higher decolorizing rate and lower polysaccharide loss rate. It was indicated that the D301 resin was the best technology for the decoloration of hsian-tsao gum.2. Effects of different factors on the properties of hsian-tsao gum/carrageenan film were studied. Based on the indices of puncture strength, tensile strength, elongation at break and water vapour permeability, the uniform orthogonal designs method was conducted by selecting four factors such as total solid(1.5%, 2.0%, 2.5%), different ratio(10/90, 20/80, 30/70), sucrose ester(0.1%, 0.2%, 0.3%) and drying temperature(40℃, 50℃, 60℃), and the principal component geometric mean analysis method was adopted to carry out multi-index analysis of the edible film according to the factors and levels. The best result was obtained when total solid was 1.6%, ratio of hsian-tsao gum and carrageenan was 20/80, sucrose ester was 0.1%, drying temperature was 52℃, glycerol content was 1.5% and pH was 7, under which hsian-tsao gum/carrageenan film is of good comprehensive property.3. The antimicrobial properties of nisin and natamycin supported in decolorized hsian-tsao gum/carrageenan film was tested, and then applied to loquat storeage. The results showed that edible coating made by mixture of hsian-taso gum and carrageenan had significant inhibitory effects on bacteria such as Staphylococcus aureus, Listeria monocytogenes and mould such as Penicillium, Rhizopus when the addition of Nisin was 200mg/L, natamycin was 20mg/L. The results showed that edible coating with antimicrobial agents could significantly inhibit the physiological metabolism of loquat, and decrease nutrient loss. Thus, edible coating made by mixture of hsian-tsao gum/carrageenan could get the best performance for room temperature preservation of loquat.更多还原