不同叶幕机械修剪方式下赤霞珠葡萄所酿酒的酚类物质研究

以赤霞珠葡萄为试材,研究机械修剪叶幕厚度对葡萄酒酚类物质的影响,为试验地葡萄管理提供理论基础。通过叶幕修剪机设置4种叶幕厚度（机械+人工、机械70 cm、85 cm、100 cm）,果实成熟后采收并采用传统工艺酿造干红葡萄酒,检测花色苷及非花色苷酚类物质组成及含量。结果表明,机械+人工及机械70 cm处理方式能够有效增加基本花色苷、乙酰化花色苷、香豆酰化花色苷及咖啡酰化花色苷含量,并丰富其组成;机械70 cm处理能促进黄酮醇及非类黄酮物质的积累,并增加其组成;而机械+人工处理降低了黄烷醇及羟基肉桂酸酚类物质含量。因此,在选择叶幕管理方式时,机械+人工及机械70 cm这两种处理具有现实的参考意义。     

真空耦合超声波提取苹果渣多酚的工艺优化

在单因素试验基础上,采用响应面优化法建立基于真空耦合超声波提取苹果渣中多酚类物质的工艺条件优化,并通过高效液相色谱检测多酚组成且对抗氧化活性进行分析。结果表明,最佳提取工艺条件为乙醇溶液体积分数50%、提取温度50℃、真空度0.08 MPa、超声功率420 W、提取时间13 min、料液比1∶30(g/mL),在此条件下,苹果渣中多酚提取得率为6.46 mg/g。与超声波提取法相比,该方法可以明显缩短提取时间,获得多酚中表儿茶素及芦丁含量较高,并且具有较强的抗氧化活性。     

Impact of cover crops in vineyard on the aroma compounds of Vitis vinifera L. cv Cabernet Sauvignon wine

This study compared the influence of different cover crops with clean tillage on wine aroma compounds of 5-year-old Cabernet Sauvignon vines. White clover, alfalfa, and tall fescue were used in the vineyard and compared with clean tillage. Aroma compounds of wine were analysed by solid-phase microextraction gas chromatography–mass spectrometry (SPME-GC/MS). Forty-seven volatile compounds were identified and quantified. Wines made from grapes grown with various cover crops had higher levels of aroma compounds. Ethyl acetate, isoamyl acetate, ethyl octanoate, ethyl hexanoate, phenylethyl acetate, isoamyl alcohol, linalool, citronellol, β-damascenone, α-ionone, and 5-amyl-dihydro-2(3H)-furan were the impact odorants of sample wines. Wines from cover crop also had higher contents of these impact odorants than the control. For different cover crops, alfalfa sward yielded the highest levels, followed by the tall fescue treatment. According to the data analysis of aroma compounds and sensory assess, permanent cover crop may have the potential to improve wine quality.     

乙醇利用菌株的分离鉴定及在低醇苹果酒中的应用

随着人们对自身健康的关注,低醇酒越来越受到人们的欢迎。为获得利用乙醇的菌株,利用YPD以及乙醇唯一碳源的培养基,经过多次分离与筛选,得到3株乙醇利用菌株SJ01、SJ02、SJ03,并对筛选菌株进行乙醇耐受特性的测定及乙醇利用曲线的绘制。同时,通过菌株菌落形态,细胞形态特征,结合26S rDNA序列分析和系统发育树的构建,确定了3株分离菌的遗传学位置。结果表明:SJ01、SJ02、SJ03三株菌株的乙醇耐受浓度分别为10%、8%、9%。在唯一碳源培养基中培养20 d后,其乙醇利用率分别为39.9%、35.7%、31.8%。菌株SJ01和SJ02为Pichia kudriavzevii,菌株SJ03为Candida ethanolica。最后根据菌株能够利用乙醇作为唯一碳源生长的特性,将菌株SJ01和SJ03加入至苹果酒中进行低醇苹果酒的酿造,苹果酒的酒精度分别降低了17.5%和27.8%,且苹果酒品质得到了改善。     

采后猕猴桃可溶性固形物含量的高光谱无损检测

为探讨基于高光谱成像技术无损检测采后猕猴桃可溶性固形物含量（soluble solids content,SSC）的可行性,基于猕猴桃900～1 700 nm波长范围的反射高光谱,建立了预测SSC的偏最小二乘、支持向量机及误差反向传播 （error back propagation,BP）网络模型,并综合比较了分别以全光谱的226 个波长,利用连续投影算法提取的12 个有效波长和采用无信息变量消除法提取的128 个有效波长作为模型的输入变量对各模型预测效果的影响。结果表明,连续投影算法能有效地提取有效波长,其在简化模型方面优势明显;BP网络与连续投影算法相结合具有最好的预测性能（预测相关系数为0.924,预测均方根误差为0.766）。研究表明,高光谱成像技术可无损检测猕猴桃的SSC,该技术将使猕猴桃内部品质的工业化分级成为可能。     

不同成熟期灵武长枣酚类组分及抗氧化活性差异分析

对不同成熟期（白绿、微红、大半红、全红）灵武长枣酚类成分组成、含量及其活性的差异进行研究,以期发现不同成熟期灵武长枣抗氧化功能品质的变化规律。以宁夏不同成熟期的灵武长枣为研究材料,比较总酚、总黄酮及酚类物质的组成及抗氧化能力（DPPH自由基清除率、抗亚油酸过氧化能力和总还原力）的差异性。结果表明：1）4 个成熟期的灵武长枣总酚含量变化范围为2 996.60～5 801.84 μg/g（以没食子酸计）,总黄酮含量变化范围为33.12～122.12 μg/g（以芦丁计）,白绿期总酚和总黄酮含量最高,两者随着果实的成熟逐渐下降。2）灵武长枣中检出的酚类物质主要有根皮苷、阿魏酸、肉桂酸、柚皮素和根皮素,各含量均呈现先上升后下降趋势,微红期含量最高。3）灵武长枣抗氧化活性表现为白绿＞微红＞大半红＞全红。抗氧化能力与总黄酮、总酚含量呈显著相关性（P＜0.05）,与检测出的5 种酚类物质相关性较弱（P＞0.05）,决定其抗氧化能力的酚类物质仍有待进一步确定。白绿期灵武长枣的抗氧化活性均比其他成熟期高,因此从该时期获取天然抗氧化活性物质更为合适。     

食源性鲜味肽和浓厚感肽的研究进展

鲜味肽和浓厚感肽影响食品的风味质量,从而影响消费者对食品的接受度。食源性鲜味肽和浓厚感肽来源广泛,在许多动物、植物或发酵食品中都含有鲜味肽和浓厚感肽。本文对鲜味肽和浓厚感肽的来源、种类、含量、作用、构效关系和分子基础等研究进展进行综述,并对鲜味肽和浓厚感肽研究中存在的问题进行分析,提出未来研究的方向,为味感肽的深入研究提供参考和指导。     

基于介质损耗因数的红小豆含水率测量方法研究

以红小豆为对象,研究测量信号频率(1kHz～1MHz)、含水率(13.8%～21.8%)、容积密度(747～851kg/m3)和温度(5～40℃)对介质损耗因数的影响规律,从理论上分析介质损耗因数的变化原因,建立500kHz条件下红小豆的介质损耗因数、容积密度和温度与含水率的数学模型,并验证模型的正确性。结果表明：在1kHz～1MHz频段内,红小豆的介质损耗因数随测量信号频率的增大而减小,却随含水率、容积密度和温度的增大而增大;可用三元二次方程表征含水率与介质损耗因数、容积密度和温度之间的关系,模型的决定系数为0.9882。     

超声波辅助酸性缓冲液浸提木枣多糖的工艺优化

以木枣多糖的提取率为响应值,柠檬酸盐缓冲溶液作为溶剂,利用单因素试验和响应面设计对超声波辅助提取木枣多糖工艺进行优化。结果表明:木枣多糖的最佳提取条件为以pH为5.6的柠檬酸盐缓冲溶液为提取剂,液料比23.1︰1(V︰m),提取温度68℃,超声波功率420 W,提取时间30 min。该条件验证多糖提取率达到(67.38±0.16)%,接近于预测值67.63%。说明该优化方法可行,可为木枣多糖的提取提供参考数据。     

Liver fibrosis is a common pathological change in the liver of dairy cows with fatty liver

Fatty liver (i.e., hepatic lipidosis) is a prevalent metabolic disorder in dairy cows during the transition period, characterized by excess hepatic accumulation of triglyceride (TG), tissue dysfunction, and cell death. Detailed pathological changes, particularly hepatic fibrosis, during fatty liver remain to be determined. Liver fibrosis occurs as a consequence of liver damage, resulting from the excessive accumulation of extracellular matrix, which distorts the architecture of the normal liver, compromising its normal synthetic and metabolic functions. Thus, we aimed to investigate liver fibrosis status and its potential causal factors including oxidative stress, hepatocyte apoptosis, and production of inflammatory cytokines in the liver of cows with fatty liver. Forty-five dairy cows (parity, 3–5) were selected, and liver biopsy and blood were collected on the second week postpartum (days in milk, 10–14 d). On the basis of the degree of lipid accumulation in liver, selected cows were categorized into normal (n = 25; TG <1% wet wt), mild fatty liver (n = 15; 1% ≤ TG <5% wet wt), and moderate fatty liver (n = 5; 5% ≤ TG <10% wet wt). Compared with normal cows, blood concentrations of nonesterified fatty acids and β-hydroxybutyrate, along with alanine aminotransferase and aspartate aminotransferase activities, were greater in the cows with fatty liver (mild and moderate). Hepatic extracellular matrix deposition, as indicated by Picrosirius red staining, was greater in cows with fatty liver than those with normal ones. In addition, we observed an increased proportion of collagen type I fiber in extracellular matrix with increased lipid accumulation in the liver. Compared with normal cows, the area of α-smooth muscle actin (α-SMA)-positive staining along with the mRNA abundance of collagen type I α 1 (COL1A1), ACTA2 (gene encoding α-SMA), and transforming growth factor-β (TGFB) were greater in cows with fatty liver. Compared with normal cows, hepatic contents of malondialdehyde, glutathione disulfide, and 8-isoprostane were greater, whereas total antioxidant capacity, the hepatic content of glutathione, and activities of antioxidant indicators, including superoxide dismutase, glutathione peroxidase, and catalase, were lower in cows with fatty liver. The number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells and abundance of apoptosis-related molecules BAX, CASP3, CASP8, and CASP9 were greater in cows with fatty liver. However, mRNA abundance of the anti-apoptotic gene BCL2 did not differ. The mRNA abundance of pro-inflammatory cytokines including tumor necrosis factor-α (TNFA), interleukin-1β (IL1B), and interleukin-6 (IL6) was greater in the liver of cows with fatty liver. Overall, the present study indicated that fibrosis is a common pathological response to liver damage and is associated with oxidative stress, hepatocyte death, and inflammation.