超声预处理大米蛋白制备抗氧化肽

为优化中性蛋白酶酶解大米蛋白制备抗氧化肽的工艺条件,采用超声波预处理大米蛋白.以1,1-二苯基-2-苦基苯肼(DPPH)清除率为响应值,用响应面分析法研究超声功率、超声处理时间和超声处理初始温度对制备抗氧化肽工艺的影响.同时研究了其抗氧化肽清除超氧自由基、DPPH、羟自由基能力及螯合Fe2 和还原能力.结果表明:最佳超声预处理大米蛋白的工艺为:超声功率1500 W、超声处理时间20 min、超声处理初始温度40℃,该条件下的抗氧化肽(2.2057 g/L)清除DPPH可达到74.8%,抗氧化肽得率为33.2%.与未经超声预处理比较,抗氧化肽得率提高了43.7%,DPPH的半抑制率(IC50)降低了17.7%.抗氧化试验表明,大米蛋白抗氧化肽清除超氧自由基、DPPH和羟自由基的IC50值分别为0.0678、0.9315和0.1173 g/L,分别是维生素C的IC50值的1.8、175.8和1.4倍;其螯合Fe2 的IC50值是乙二胺四乙酸的42.2倍,还原能力是维生素C的0.7倍.     

黑大豆种皮花色苷的提取及其抗氧化作用研究

以黑大豆皮为材料,采用二次回归正交旋转组合设计对其花色苷的提取工艺进行了优化研究。结果表明,最佳提取参数为温度60℃、时间1 h、乙醇浓度60％、料液比1∶40。对黑大豆种皮花色苷含量与总抗氧化能力之间的相关性分析表明,二者之间存在极显著的线性关系(P<0.01),且黑大豆种皮花色苷提取物表现出较强的清除OH·、O^{-₂·及有机自由基DPPH·的体外抗氧化作用,其清除能力是维生素C的1.6倍、2.2倍、1.4倍。}     

麦麸中低聚木糖的制备及抗氧化活性研究

以麦麸木聚糖为原料,采用酶法水解制备低聚木糖,研究其抗氧化活性。在单因素基础上,采用正交试验设计,考察酶解时间、酶解温度、pH值、加酶量对低聚木糖含量影响以及酶解的最佳工艺。通过对DPPH自由基,羟自由基和超氧阴离子自由基清除率的测定,研究了麦麸制备的低聚木糖抗氧化作用。研究表明,酶法制备麦麸低聚木糖的最佳工艺条件为:加酶量600U·g-1,pH值为6,酶解时间90min,酶解温度60℃,在最优条件下的验证试验得到低聚木糖含量为5.09mg·mL-1。对低聚木糖的抗氧化研究表明,1mg·mL-1低聚木糖对DPPH自由基和羟自由基的清除率分别达到76.55%和80.30%,对超氧阴离子自由基的抑制效果较弱,最大清除率为41.12%,低聚木糖能有效清除自由基,表现出良好的体外抗氧化活性。     

黑水虻幼虫蛋白质的制备及体外抗氧化活性

本文主要研究黑水虻幼虫蛋白质的制备及其体外抗氧化活性。以黑水虻幼虫为原料,采用碱提酸沉法提取黑水虻幼虫蛋白质,并于等电点沉淀,沉淀复溶后再浓缩、透析、冻干。分别测定了其总还原力,超氧阴离子自由基清除活性、羟基自由基清除活性、DPPH自由基清除活性、ABTS自由基清除活性、金属离子螯合能力及脂质体系中抗氧化能力,并将其体外抗氧化能力与维生素C(测定金属离子螯合能力时与EDTA)和卵清白蛋白进行比较。结果显示:BSFLP的等电点在4.8左右,并且该法所提蛋白纯度较高,表明利用碱提酸沉法对黑水虻幼虫进行蛋白的提取的方法可行。BSFLP的总还原力约是VC的0.013倍,是OVA的1.319倍;BSFLP的超氧阴离子自由基清除活性强于OVA,而弱于VC;其清除羟基自由基、清除DPPH自由基、清除ABTS自由基、螯合亚铁离子、亚油酸体系中抑制过氧化的IC50分别为2.577、3.965、0.228、0.876、5.050 mg·m L-1,也均介于VC(或EDTA)和OVA之间,说明BSFLP具有较高的体外抗氧化活性。本文为黑水虻的进一步研究与综合利用及抗氧化功能蛋白食品的研发提供了一定的依据。     

茶花粉酶法破壁工艺提高提取物抗氧化活性及多酚含量

为了建立蜂花粉抗氧化活性物质的提取工艺并探索其抗氧化活性与多酚含量的关系,该文研究了破壁用酶、提取溶剂、超声波处理对茶花粉提取液多酚含量及其抗氧化活性的影响。结果表明,茶花粉经纤维素酶破壁后其上清液具有较高的还原力和DPPH自由基清除能力;与温水和酸处理相比,纤维素酶破壁沉淀物经乙醇提取后,溶液多酚含量较高、抗氧化活性较强;茶花粉不同提取方式多酚含量与2种抗氧化活性指标具有一定的相关性（r=0.8685及r=0.7600）（p＞0.05）;与乙醇提取和水提取相比,纤维素酶破壁处理结合乙醇提取将茶花粉的多酚含量、还原力及DPPH自由基清除能力分别提高1.82倍、2.17倍、1.4倍和1.56倍、1.38倍、11倍,且二者对混合物还原力、DPPH自由基清除能力及多酚含量的贡献比例分别为1.6：1、3：1、1.08：1。该研究结果可为花粉资源的开发利用提供参考。     

马面鱼皮胶原抗氧化肽的分离制备及稳定性研究

为促进对马面鱼皮资源的综合利用,开发高附加值产品,本试验以DPPH自由基清除率和水解度(DH)为评价指标,探讨马面鱼皮胶原蛋白的最佳酶解工艺,并采用超滤和凝胶柱层析法分离制备抗氧化肽,通过超高效液相色谱-质谱联用(UPLC-MS)法对其进行结构解析。此外,还探讨了pH值、温度及体外模拟消化对多肽抗氧化活性的影响。结果表明,利用双酶分步酶解法可制备高活性抗氧化多肽,即在底物浓度3%,加酶量3 600 U·g^-1以及温度50℃的条件下先用Proteasea A ‘Amano’2G酶解3 h,再用酸性蛋白酶酶解2 h,清除DPPH自由基的IC₅₀值为13.03 mg·mL ^-1。经超滤及柱层析分离后,可得到抗氧化活性较高的A₁组分,其清除DPPH自由基的 IC₅₀值为1.80 mg·mL^-1。稳定性研究结果表明,所制备的胶原蛋白抗氧化肽热稳定性好,在偏酸性条件下能保持较高的活性,经体外模拟胃肠消化后仍能保持较高的抗氧化活性。根据UPLC-MS分析推测A₁的氨基酸序列可能为Gly-Glu-Gly-Ala-Cys-Asn或Asn-Glu-Gly-Ala-Cys-Gly。本研究结果为马面鱼皮的高值化利用及高活性抗氧化肽的筛选提供了一定的理论依据。     

铜藻多糖微波辅提工艺优化及其抗氧化活性研究

运用响应曲面法优化铜藻多糖(tong zao polysaccharide,TZP)微波辅助提取的工艺条件,利用分级醇沉法得到TZP30%、TZP60%和TZP80%3个多糖组分。并对其DPPH自由基、ABTS自由基、OH自由基和O2-自由基的清除能力及其还原力进行了研究。结果表明:铜藻多糖微波辅助提取的最佳条件为料液比1:65,提取温度72℃,提取时间39min,多糖提取率为12.02%(n=3);在试验浓度范围内,TZP30%组分对羟基自由基的清除能力最高达98.07%;TZP60%组分对DPPH自由基清除能力最高达85.01%;TZP80%组分对ABTS自由基清除能力较强,还原力较大。铜藻多糖具有较高的抗氧化活性,具有作为天然抗氧化剂的应用前景。     

中性蛋白酶水解鸡骨泥制备短肽工艺优化

为了探究酶法制备鸡骨泥短肽的最佳工艺,该文研究了以中性蛋白酶酶解鸡骨泥时各因素对短肽得率和羟自由基清除率的影响,以及鸡骨泥肽清除超氧阴离子自由基和1,1-二苯基-2-三硝基苯肼自由基(2,2-diphenyl-1-picrylhydrazyl)的能力。试验探究了酶解过程中不同底物浓度、酶浓度、反应温度和反应时间对短肽得率和羟自由基清除率的影响,采用响应曲面优化得到了以短肽得率为目标的中性蛋白酶酶解鸡骨泥的最优工艺,当反应液p H值为7.2,反应温度42℃,反应时间2 h,底物质量分数5%,酶添加量200 mg/g,该条件下制备鸡骨泥肽,测得其短肽得率为56.16%,羟自由基清除率为54.12%。采用该酶解工艺制备鸡骨泥肽,测得其对超氧阴离子自由基最高清除率为56.01%,对DPPH自由基最高清除率为81.57%,说明鸡骨泥肽具有一定的抗氧化活性,研究结果为酶法制备鸡骨泥肽提供参考。     

燕麦生物碱的提取及其抗氧化活性研究

采用正交试验设计对麸皮中燕麦生物碱（AV）的提取条件进行优化,提取物经大孔吸附树脂纯化,并利用活性氧和DPPH自由基的清除率研究其抗氧化活性。结果表明：最佳提取参数为温度60℃,提取时间2h,溶剂为乙醇/水/冰醋酸（80/19.9/0.1）,料液比1︰8,此条件下得率为5.29%,经树脂纯化后粗提物中生物碱纯度达19.2%,且纯化后的燕麦生物碱表现出较强的清除OH·,O2-·和有机自由基DPPH的体外抗氧化活性,其清除能力分别是α-生育酚的79.4%、82.2%和78.0%。     

费菜总黄酮碱法提取工艺及抗氧化活性

为了研究费菜中总黄酮的碱法提取工艺及其抗氧化活性,该文以总黄酮得率为试验指标,考察了料液比、溶液pH值、提取温度及提取时间等因素对提取效果的影响,并通过正交试验优化了提取工艺参数。结果表明,碱法提取最适宜的工艺条件为：料液比1:10,溶液pH值9,提取温度100℃,提取时间6?h,在该条件下,总黄酮的得率为5.37%。所得的费菜总黄酮对DPPH、羟基自由基及超氧阴离子自由基具有较强的清除作用,半抑制浓度（IC50）分别为0.013、0.109和0.996?mg/mL,表明费菜总黄酮具有一定的抗氧化活性。该试验结果为费菜的进一步开发利用提供了科学依据。     

适宜干燥方法提高干制枸杞品质

为缩短鲜枸杞的干制时间,获得高品质的干制枸杞,该文通过比较自然晾晒、燃煤烘干房以及太阳能干燥设备对枸杞的干燥效率的差异以及测定并分析3种干燥方式获得干果的主要功能性成分（总糖、总黄酮、多糖、甜菜碱,类胡萝卜素）含量及外观品质和出糖率的差异。试验结果表明,采用太阳能干燥设备干燥枸杞的时间最少约为26 h,功能性成分总质量分数约71.71 g/(100 g),与其他2种干燥方式相比功能性成分损失降低,干枸杞色泽更接近鲜枸杞的色泽,出糖率约为1.53%,低于其他2种干燥方式。太阳能干燥设备对于枸杞干燥具有显著的优势,应用前景广阔。     

枸杞真空冷冻干燥动力学的数值模拟及分析

为探究枸杞真空冷冻干燥过程中的热质迁移,克服应力应变现象不能直观获取的问题。该研究通过对鲜枸杞切片试验图像二值化处理,建立了鲜枸杞真空冷冻干燥的热-质-结构耦合的物理模型,对真空冷冻干燥过程中枸杞温度变化、水分变化以及其内部的应力应变进行了热-质-力耦合分析,并对分析结果进行试验验证。模拟分析结果表明,预冻结过程中,细胞始终在膨胀,当细胞完全冻结时细胞所受应力达到最大,而干燥阶段热质传递对应力影响较小。提高真空冷冻干燥过程中的升温速率,在一定程度上能够缩短冻干所需时间,并且真空冷冻干燥过程中的枸杞样本的含水率下降速率随干燥时间的增大而减小,该变化趋势与Wang and Singh模型更加贴合（R2为0.983）。同时试验验证结果表明,该研究建立的模型能够较好反映并预测真空冷冻干燥过程枸杞样本的温度及应力应变的变化趋势（R2为0.857）。研究结果可为真空冷冻干燥系统优化和工艺参数的科学制定提供参考。     

Effects of Drying Processing Conditions on the Quality of Uncooked and Cooked Pasta Made Up of Nonconventional Raw Material

Drying process plays a fundamental role in pasta making. The greatest number of studies have been focused on the optimization of drying conditions for semolina pasta, and the obtained results have been applied in a similar way on pasta made up of nonconventional raw materials without considering a processing optimization. The aim of this research was to evaluate the influence of different drying treatments (low, medium, and high temperature) on the quality of uncooked and cooked soft wheat pasta enriched with oat flour. Results of total organic matter and dried residue showed no significant difference between samples dried by medium and high temperature treatments. Moreover, these last samples showed a slight improvement in cooking quality over samples dried at low temperature (total organic matter results were 1.31 versus 1.66 g/100 g of dried pasta). This study revealed that the improvement of cooking quality of pasta enriched with oat flour did not require the application of high drying temperature (>80°C) that involves a considerable consumption of energy and could favor the development of a Maillard reaction, decreasing quality characteristics of this kind of product.     

姜浆物料折射窗薄层干燥特性

为探索一种不宜进行喷雾干燥的热敏性浆料物质的干燥方式,利用折射窗（Refractance window）干燥对姜浆物料的干燥特性进行研究。结果表明,在75～95℃下干燥,物料温度变化曲线显示其在干燥开始时迅速上升至60～75℃,之后随干燥时间渐趋平缓。物料温度始终比干燥热源温度低,温差在15～25℃之间。在相同的干燥温度和风速下,不同薄层厚度物料的温度差异不明显。提高风速可以降低物料的温度。在较高干燥温度下没有观察到典型的恒速干燥阶段。干燥强度和样品最终含水率分别随着物料薄层厚度的减小,干燥温度提高和风速的增大而增大和降低。该研究为Refractance window干燥技术应用于浆液状物料的薄层干燥作出了探索。     

枸杞黑果病与气象条件关系初探

根据2000年、2001年和2003年5-10月田间试验和相应的气象观测资料,利用相关普查和回归分析方法分析了果实形成期枸杞黑果病与气象因子的关系。结果表明,枸杞黑果病病情指数与果实形成期的降水量、降水日数、平均相对湿度、平均日照时数和平均风速间均具有极显著相关关系。其中降水量、降水日数和平均相对湿度是枸杞黑果病暴发流行的主要原因。     

热泵干燥槟榔中试工艺参数优化

为了探索新型节能、低碳排放的槟榔干燥技术,应用热泵干燥设备对槟榔进行干燥研究,获得槟榔热泵干燥中试工艺参数。单因素试验分析了煮沸时间对槟榔硬度的影响,干燥温度和装载量对槟榔水分的影响;采用正交试验,通过加权评分值计算方法评价干果品质,优化热泵干燥工艺参数;测定储藏30 d后的干果进行理化和微生物指标;比较热泵干燥、蒸汽干燥和传统干燥槟榔的成本及品质。结果表明,新鲜槟榔经过沸水煮沸15 min,前12 h内干燥温度为50℃、12 h后干燥温度为65℃、装料量为3.5 t、烘房空气相对湿度为25%时,槟榔含水率为16.8%,好果率为96.0%,均匀度为91%,单位质量干果耗电量为0.92(k W·h)/kg,所干燥的槟榔干果综合评分为90.1分,呈橄榄黄或褐色。25℃储藏30 d无霉腐现象,检测结果显示含水率为17.8%,未检测出汞和苯并芘,铅和砷质量分数分别为0.02和0.1 mg/kg,致病菌未检出,大肠菌群数30 cfu/g,霉菌计数为30 cfu/g。经比较,热泵干燥槟榔比蒸汽干燥成本低11%,比传统土炉干燥成本低50%,零排放、无污染、操作智能化。研究结果为槟榔热泵干燥的标准化生产提供技术参考。     

2-O-(beta-D-Glucopyranosyl)ascorbic acid, a novel ascorbic acid analogue isolated from Lycium fruit

A novel stable precursor of ascorbic acid (vitamin C), 2-O-(beta-D-glucopyranosyl)ascorbic acid, was isolated from both the ripe fresh fruit and dried fruit of Lycium barbarum L., a plant of the Solanaceae family. The chemical structure was inferred by instrumental analyses and confirmed by chemical synthesis. The dried fruit of Lycium barbarum L. contained ca. 0.5% of it, which is comparable to the ascorbic acid content of fresh lemons. It increased the blood ascorbic acid by oral administration to rats, and it was also detected in blood from the portal vein.     

Influence of High‐Temperature Drying on Structural and Textural Properties of Durum Wheat Pasta

Starch and protein are the main polymeric ingredients of pasta and they determine the structural and textural properties of cooked pasta. The present investigation sought better understanding of the impact of high‐temperature (HT) drying on the starch and the protein fraction, and their role in structure and texture of pasta. Durum wheat spaghetti was prepared in a pilot‐plant installation. The drying conditions were selected for the HT phase at 80 or 100°C applied at high, intermediate, or low product moisture content. Spaghetti dried at 55°C served as a reference sample. The color of dry pasta was measured and the changes in the starch and protein fractions were determined by protein solubility, light microscopy, confocal scanning laser microscopy (CSLM), cooking tests, and texture measurements. HT drying at 100°C and low product moisture promoted browning of pasta. At the molecular level, HT drying promoted protein denaturation. At the microscopic level, HT drying contributed to a better preservation of the protein network and reduced swelling of starch and disintegration of granules. At the macroscopic level, HT drying enhanced the firmness of cooked pasta and reduced surface stickiness. In general, the changes were more pronounced by increasing the drying temperature from 80 to 100°C and by shifting the HT phase from an early to a late stage of the drying process. The drying conditions are determinant for the phase morphology of protein and starch in cooked pasta which, in turn, govern the textural properties of pasta.     

Physical and Cooking Quality of Spaghetti Made from Whole Wheat Durum

The effects of cultivar on dough properties of ground whole wheat durum, and the effects of cultivar and drying temperature on the physical and cooking quality of spaghetti made from semolina and whole wheat were evaluated. Rankings of cultivars based on dough properties were similar for whole wheat and semolina. Dough made from whole wheat was weak and had poor stability. Whole wheat spaghetti had a rough reddish brown surface compared with the very smooth, translucent yellow color of spaghetti made from semolina. The reddish brown color of whole wheat spaghetti was enhanced by high‐temperature drying (70°C). Mechanical strength and cooking quality of spaghetti made from ground whole wheat or semolina varied with cultivar and with drying temperature. Compared with spaghetti made from semolina, whole wheat spaghetti had lower mechanical strength and cooked firmness and had greater cooking loss. Mechanical strength of whole wheat spaghetti was lower when dried at high temperature (70°C) than at low temperature (40°C). Conversely, the mechanical strength of spaghetti made from semolina was greater when dried at high temperature than at low temperature. Whole wheat and traditional spaghetti dried at high temperature had lower cooking losses than spaghetti dried at low temperature. When overcooked 6 min, firmness of spaghetti made from semolina or whole wheat was greater when dried at high temperature than at low temperature.     

Processing and cooking effects on lipid content and stability of alpha-linolenic acid in spaghetti containing ground flaxseed

Research was conducted to determine the effect of processing and cooking on the content of hexane-extractable lipid and the stability of alpha-linolenic acid (ALA) in spaghetti fortified with ground flaxseed. Lipid content, ALA, and free fatty acids (FFA) were lower in dried spaghetti samples than in the original semolina-flaxseed mixture. The data indicate that the decline in lipid, ALA, and FFA contents occurred during the extrusion process. In contrast, conjugated diene levels were greater in dried spaghetti than in the corresponding premix. Conjugated diene level was similar for spaghetti samples dried using low- or high-temperature drying cycles, and was lower in cooked than in uncooked spaghetti. The low levels of FFA and conjugated diene indicate that ALA remained stable during processing and cooking of spaghetti fortified with ground flaxseed.