【作者】 于东；

【导师】 叶兴乾；

【作者基本信息】 浙江大学 ， 食品科学， 2011， 硕士

【摘要】 山药是一种药食兼用的蔬菜,营养丰富并且具有潜在保健功效,深受消费者青睐。本论文以产自浙江省台州市黄岩区的紫山药为研究材料,对其常量营养成分和微量功能成分进行了分析,优化了总酚的提取工艺,研究了紫山药真空微波干燥干燥特性及其干燥数学模型,在此基础上优化了紫山药真空微波干燥工艺参数。试验结果如下：1、分析表明,每100g新鲜紫山药中,含水分78.5g,蛋白质1.91g,脂肪0.78g,总糖2.26g,灰分0.75g,花色苷2.88mg,总酚50.75mg,没有检测到抗坏血酸。紫山药中总氨基酸含量达1595.69mg,含有构成生物体的全部18种氨基酸,必需氨基酸含量占总氨基酸含量的38.03%。紫山药中必需微量元素锌、铁、镁、锰等含量丰富,其中钾含量可高达185.38mg/100g。结果表明紫山药是一种营养丰富并极具开发和利用价值的食品。2、采用大孔树酯对紫山药中的花色苷进行了分离,并用高压液相色谱-二极管阵列检测-质谱检测技术对其中的主要花色苷进行了结构鉴定。紫山药中的四种主要花色苷可能是：矢车菊素-3-葡萄糖苷或半乳糖苷的双咖啡酸酰化物,矢车菊素-3-二糖苷的芥子酸酰化物,矢车菊素-3-二糖苷阿魏酸的酰化物,芍药色素-3-二糖苷的芥子酸酰化物。3、采用高压液相色谱-二极管阵列技术,对紫山药中的酚酸类化合物进行鉴定,并对其含量进行测定。分析结果表明,酚酸在紫山药中主要以可溶态酚酸形式存在。紫山药中可溶态酚酸类和不可溶态酚酸类均主要为芥子酸和阿魏酸,且芥子酸含量均高于阿魏酸含量。紫山药中可溶态酚酸含量为356.71μg/gDW;不溶态酚酸含量为26.92μg/g DW。4、在单因素试验的基础上,采用响应面法研究了乙醇浓度、提取时间、提取温度、液料比等因素对紫山药总酚得率的影响,建立了紫山药总多酚的提取方法二次多项数学模型,优化了紫山药总多酚提取的工艺参数。结果表明：在乙醇体积分数45.33%,提取时间45.76min,提取温度70℃,液料比值29.63时得率最高,总酚得率为7.335mg/g,与实测值相符。5、研究了在不同真空度、微波强度、切片厚度等参数条件下,该紫山药的干燥特性。利用指数模型、Page方程和单扩散模型常用的三种扩散干燥模型对紫山药的真空微波干燥进行了拟合,结果表明,Page方程拟合效果最好。采用均匀设计试验,进一步确定了紫山药真空微波干燥条件下的干燥常数模型和有效扩散系数模型,经统计检验,各模型拟合效果良好。6、采用正交试验设计和多指标综合评分法,以干燥速率、感官品质、总酚含量为指标,优化了真空度、微波强度、切片厚度、干燥时间四个主要因素对真空微波干燥产品品质的影响。试验结果表明：在真空度-90kPa,微波强度18w/g,切片厚度2mm,干燥时间30min条件下干燥的紫山药产品综合品质最好。真空微波干燥是适合紫山药脱水的有潜力的干燥技术。更多还原

【Abstract】 As a kind of medicinal and edible vegetable, yam has abundant nutrition and potential healthcare functions and wins warm praise from customers. The common nutrients and trace functional components of purple yam produced from Huangyan district, Taizhou city, Zhejiang province were analyzed, the extraction processing parameters of total phenolic compounds were optimized, vacuum microwave drying characteristics and mathematical models of purple Yam were studied and technical parameters for vacuum microwave were optimized. The main results were presented as follows:1. The results showed that the contents of water, protein, fat, total sugar, ash, anthocyanidin and total polyphenol in 100g of fresh purple yam were 78.5g,1.91g,0.78g,2.26g,0.75g, 2.88mg and 50.75mg, respectively. The ascorbic acid was not detected in the yam. The total amino acid was 1595.69mg, and the essential amino acid accounted for 38.03% of the total amino acid. Furthermore, the content of trace elements was also rich, and K was up to 185.38mg/100g fresh weight. This research indicated that purple yam was a kind of food with rich nutrients and worthy of development and utilization.2. Anthocyanins extracted from purple yam were isolated by macroporous resin and the major 4 types of them were tentatively identified by the method of HPLC-DAD-ESIMS. The 4 major anthocyanins may be cyanidin-3-glucoside (galactoside) acylated with two caffeic acids, cyanidin-3-diglucoside acylated with sinapic acid, cyanidin-3-diglucoside acylated with ferlulic acid and peonidin-3-diglucoside acylated with sinapic acid.3. Phenolic acids in the purple yam were identified and determined by the method of high performance liquid chromatography (HPLC), photodiode array detection (PAD). The phenolic acids were mainly present in soluble form. Sinapic acid and ferulic acid dominated in both soluble and insolulble fraction and the content of sinapic acid were higher than that of ferulic acid. The total content of soluble phenolic acid was 356.71μg/g DW and that of insoluble phenolic acid was 26.92μg/g DW. HPLC-PAD-MS is a fast and effective method to analyze phenolic acids in purple yam.4. On the basis of single-factor experiments, the response surface method (RSM) was taken to evaluate the effects of the four factors, including ethanol concentration, extraction time, extraction temperature and ratio of solution to material. A quadratic polynomial regression equation of forecasting model was set up by using Box-Behnken design in order to optimize processing parameters. The result showed that the optimal parameters were ethanol concentration 45.33%, extraction time 45.76min, extraction temperature 70℃and the ratio of solution to material 29.63. Under these conditions, the predicted value of polyphenols extraction yield from purple yam was 7.335mg/g, which was in consistent with the measured value.5. The drying characteristics of purple yam were studied under the conditions of different vacuums, microwave power density, section thickness. In addition, exponential model, Page equation and monomial proliferation model were used to describe the vacuum microwave drying purple yam and the results showed Page equation was the best mathematical model. Uniform design was used to determine the drying constants model of Page equation and effective diffusion coefficient model. The statistical testing results indicated that the fitting effects of these models were satisfactory.6. The orthogonal test design and grading method for multi-index on the parameters of drying rate, sensory quality, and total phenolic content were carried out to optimize the four main factors (vacuums, microwave power density, section thickness and drying time) which can affect the products quality via vacuum microwave drying technology. The optimum processing parameters determined were listed as follows:the vacuum was-90kPa, the microwave power density was 18w/g, the section thickness was 2mm and the drying time was 30min. Therefore, vacuum microwave drying technology is suitable for drying purple yam.更多还原