啤酒生产用玉米淀粉指标体系的探讨

近年来,玉米淀粉作为辅料在我国啤酒行业的应用越来越广泛。但目前没有专门针对啤酒生产用玉米淀粉的质量标准。大多数啤酒企业都参照国家标准GB/T8885-2008食用玉米淀粉的规定执行。对该标准中对啤酒生产影响较大的指标如二氧化硫、酸度、脂肪、细度等;以及该标准中没有做规定,但啤酒酿造又有特殊要求的指标如气味、pH、脂肪酸值、浸出率等进行了探讨。阐述了上述指标的检测对啤酒生产的指导意义,指出了该标准应用于啤酒行业的不足。最后对今后啤酒生产用玉米淀粉的发展作了展望。     

Antioxidant capacities and total phenolic contents of 62 fruits

In order to supply new information on the antioxidant function of selected fruits for nutritionists and the general public, antioxidant activities and total phenolic contents of 62 fruits were evaluated using ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays as well as the Folin–Ciocalteu method, respectively. The correlations between the FRAP value and the TEAC value as well as total phenolic content were also assessed. The results showed that different fruits had diverse antioxidant capacities and the variation was very large, and seven fruits, Chinese date, pomegranate, guava, sweetsop, persimmon, Chinese wampee and plum, possessed the highest antioxidant capacities and total phenolic contents among tested fruits, and could be important dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress.     

小尾寒羊不同部位羊肉理化特性及肉用品质的比较

以我国著名的优良品种小尾寒羊为研究对象,对其不同分割部位(脊背、腰窝、肋条、前腿、后腿、腱子)羊肉的理化特性进行测定,并对其熟制品(牙签肉)食用品质进行比较.结果表明,根据理化性质不同可将不同分割部位分成臀腿部和躯干部两部分,肉品的脂肪含量、颜色、失水率、剪切力、肌纤维直径和密度有显著差异(p<0.05).肌肉脂肪含量明显影响羊肉产品风味,可作为羊肉风味的评价指标.肌纤维的组织学特性和剪切力都可作为嫩度的评价指标.肋条和腰窝部位肌肉脂肪含量较高,肌肉肌纤维直径细、密度大,系水力较强,剪切力小,肉质较嫩,香气浓郁,因此具有较好的食用品质,是制作烧烤涮羊肉制品的最佳原料.     

Optimisation of puffing naked barley

The expansion of volume (the puffing index) of naked barley was investigated at various operating conditions of the puffing process. The purpose was to optimise the manufacture of expanded grains of the naked barley cultivars that have exceptional nutritional value for humans. The influence of the following parameters on the puffing index was investigated: the mass and the moisture content of the charge of the puffing barrel, pressure and temperature during the puffing process, the cultivar of barley, pre-processing of the grain (grinding and polishing), adding water into the barrel and the sensory quality of the product.

A regression equation was established for the calculation of the puffing index as a function of the operating parameters. The puffing index is influenced especially by the operating temperature and pressure. There was no influence found of mass of the charge, the cultivar of barley, the degree of grinding of barley, washing of the grains and adding water on the puffing index. The puffing index is not the sole indicator of the quality of the expanded product. It is necessary to take into account the sensory evaluation. A quality expanded naked barley was obtained at the operating temperature of 550 °C and pressure from 0.9 to 1.0 MPa with the moisture content of the charge around 16.5%.     

Genetics of grass dry matter intake, energy balance, and digestibility in grazing irish dairy cows

The objective of this study was to estimate genetic parameters for grass dry matter intake (DMI), energy balance (EB), and cow internal digestibility (IDG) in grazing Holstein-Friesian dairy cows. Grass DMI was estimated up to 4 times per lactation on 1,588 lactations from 755 cows on 2 research farms in southern Ireland. Simultaneously measured milk production and BW records were used to calculate EB. Cow IDG, measured as the ratio of feed and fecal concentrations of the natural odd carbon-chain n-alkane pentatriacontane, was available on 583 lactations from 238 cows. Random regression and multitrait animal models were used to estimate residual, additive genetic and permanent environmental (co)variances across lactations. Results were similar for both models. Heritability for DMI, EB, and IDG across lactation varied from 0.10 [8 days in milk (DIM)] to 0.30 (169 DIM), from 0.06 (29 DIM) to 0.29 (305 DIM), and from 0.08 (50 DIM) to 0.45 (305 DIM), respectively, when estimated using the random regression model. Genetic correlations within each trait tended to decrease as the interval between periods compared increased for DMI and EB, whereas the correlations with IDG in early lactation were weakest when measured midlactation. The lowest correlation between any 2 periods was 0.10, −0.36, and −0.04 for DMI, EB, and IDG, respectively, suggesting the effect of different genes at different stages of lactations. Eigenvalues and associated eigenfunctions of the additive genetic covariance matrix revealed considerable genetic variation among animals in the shape of the lactation profiles for DMI, EB, and IDG. Genetic parameters presented are the first estimates from dairy cows fed predominantly grazed grass and imply that genetic improvement in DMI, EB, and IDG in Holstein-Friesian cows fed predominantly grazed grass is possible.     

基于高压脉冲电场技术提高松子肽的抗氧化活性研究

目的为了初步揭示高压脉冲电场(PEF)技术提高分子量小于1 kDa松子肽的抗氧化活性的作用机制。方法以DPPH自由基清除能力为衡量指标,利用单因素和响应面试验设计研究方法,构建出基于PEF技术提高分子量小于1 kDa松子肽的抗氧化活性回归模型,优化出最佳技术参数,并借助傅立叶红外光谱技术分析其官能团变化情况。结果回归模型为:Y=84.4+0.31X_1+0.6X_2+1.13X_3-0.26X_1X_2-0.062X_1X_3-0.79X_2X_3-3.32X_1~2-5.21X_2~2-3.37X_3~2,最佳技术参数为电场场强12.6 kV/cm、电场频率1616 Hz、物料流速3.456 mL/min,其DPPH自由基清除能力为83.5 1%±0.61%,与未经高压脉冲电场处理松子肽相比,增加了26.69%;借助傅立叶红外光谱技术分析发现,分子量小于1 kDa松子肽经PEF处理后的-C≡N键发生变化。结论高压脉冲电场技术可以提高松子肽的抗氧化活性,通过傅立叶红外光谱技术可知抗氧化活性的提高可能是由于松子肽的-C≡N键发生变化。     

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。     

SDE-GC-MS结合保留指数分析不同预处理的豆浆风味

采用同时蒸馏-气相色谱-质谱联用技术分别对未处理、微波处理、冷冻处理和超声处理后豆浆的挥发性物质进行分析,在利用NIST质谱检索库检索的基础上,结合保留指数进行定性,同时运用峰面积归一化法加苯甲醇作内标定量。结果表明：共鉴定出48 种挥发性成分,4 种预处理后的样品挥发性成分分别为28、26、30 种和33 种。不同预处理后的风味物质均以醛类、醇类、酮类、呋喃为主,醛类含量最多。结合感官评价得出冷冻处理后豆浆风味最佳。     

界面组成对乳化颗粒填充乳清蛋白凝胶强度及持水性的影响

考察了p H（3、7）、氯化钠浓度（50、200mmol/L）以及热处理（90℃、30min）对不同乳化剂（乳清分离蛋白、Tween20、Tween20+马铃薯蛋白水解物）制备O/W乳状液分层稳定性的影响。并以凝胶持水性和凝胶强度为指标,考察了p H和氯化钠浓度对上述不同界面组成的乳化颗粒填充乳清蛋白热诱导凝胶性质的影响。结果表明,以乳状液为溶剂制备的凝胶持水性与凝胶强度高于以水为溶剂制备的凝胶。加入一定量的氯化钠有助于乳状液凝胶持水性与凝胶强度的增加。研究表明,p H和盐浓度对乳状液填充凝胶强度均有影响,乳状液性质对乳状液填充凝胶强度和持水性有一定影响。      

基于格矢量量化和倒排文件的快速图像检索方法

本文提出一种新的快速图像检索方法,它用格矢量量化器对特征矢量进行量化和描述,用倒排文件和Hash表存储和索引量化后的特征矢量,利用代数格良好的几何和代数性质实现快速检索.最后,本文分析了新方法的检索性能,并给出实验结果.