玉米直链淀粉含量遗传研究进展

高直链淀粉在食品、包装、造纸和生物降解材料等产业中占据着越来越重要的地位。本文在介绍高直链淀粉用途的基础上,综述了玉米直链淀粉含量变异、生态环境影响、直链淀粉含量遗传、生物合成、玉米直链淀粉含量的分子生物学研究以及高直链淀粉玉米种质创新,展望了今后高直链淀粉玉米育种的发展方向。     

羟丙基氧化高直链玉米淀粉的制备、表征及性能研究

以高直链玉米淀粉为原料,次氯酸钠为氧化剂,环氧丙烷为醚化剂,氢氧化钠为催化剂,对羟丙基氧化高直链玉米淀粉的制备、表征及性能进行了研究。考察了环氧丙烷用量、羟丙基化时间、羟丙基化温度、氢氧化钠用量和无水硫酸钠用量对羟丙基氧化高直链玉米淀粉取代度的影响。结果表明,制备氧化高直链玉米淀粉的较佳工艺条件为:羟丙基化时间18h、羟丙基化温度40℃、无水硫酸钠用量10%、氢氧化钠用量1.2%。高直链玉米淀粉经氧化后,在波数1 735cm-1处出现CO的伸缩振动峰;羟丙基化、氧化改变了高直链玉米淀粉热稳定性。氧化、羟丙基化能提高高直链玉米淀粉的冻融稳定性和膨胀能力,氧化使高直链玉米淀粉蓝值降低,羟丙基化基本不改变高直链玉米淀粉的蓝值。     

海藻酸钠对不同直链淀粉含量的玉米淀粉物化性质的影响

采用快速黏度分析仪、差示扫描量热仪、动态流变仪、物性测试仪等,研究了海藻酸钠对3种不同直链淀粉含量的玉米淀粉糊化、凝胶及老化性质的影响。结果表明:海藻酸钠显著影响高直链玉米淀粉、普通玉米淀粉及蜡质玉米淀粉的物化性质,且对不同直链淀粉含量的玉米淀粉物化性质的影响不同。海藻酸钠使3种玉米淀粉的糊化难度增大,起始糊化温度、峰值糊化温度、终止糊化温度升高,糊化焓增加。海藻酸钠提高3种玉米淀粉的峰值黏度、末值黏度、表观黏度及损耗模量。海藻酸钠提高高直链玉米淀粉的热稳定性和抗老化性,使高直链玉米淀粉的衰减值、老化率降低。海藻酸钠阻碍高直链玉米淀粉形成凝胶,使高直链玉米淀粉的损耗角正切值升高、凝胶硬度降低。     

3种玉米淀粉的性质比较

研究了高直链玉米淀粉、糯玉米淀粉、普通玉米淀粉的粒度分布、糊流变、质构、冻融稳定性等物理化学性质,结果表明:3种玉米淀粉的颗粒形状差异不大。高直链玉米淀粉的粒度分布一致性较高,同样条件下糯玉米淀粉糊粘度大于其他2种淀粉,糯玉米淀粉的冻融稳定性大于普通玉米淀粉和高直链玉米淀粉,为玉米淀粉在食品中的应用奠定了基础。     

3种玉米淀粉的羧甲基改性产物浆料性能对比

以高直链玉米、蜡质玉米和普通玉米淀粉为原料,分别制备了各自的羧甲基淀粉浆料,并对其浆液黏度、浆膜和浆纱性能进行对比研究。结果表明：相近取代度的3种羧甲基改性玉米淀粉中,羧甲基高直链玉米淀粉的浆液黏度最小,黏度热稳定性最好;羧甲基高直链玉米淀粉的浆膜断裂强力和断裂伸长率最好,而羧甲基蜡质玉米淀粉的浆膜性能较差;羧甲基蜡质玉米淀粉浆料的黏附力最大,羧甲基高直链淀粉的黏附力最小。浆纱结果表明：羧甲基高直链玉米淀粉浆纱的力学性能显著提高,其浆纱的断裂增强率、耐磨增强率和伸长减少率均好于羧甲基蜡质玉米淀粉和羧甲基普通玉米淀粉。认为：在相近取代度的3种玉米淀粉羧甲基改性产物中,羧甲基高直链玉米淀粉的浆纱性能最优。     

高直链玉米淀粉性质的研究

以选育的高直链玉米为试材,在实验室条件下提取高直链玉米淀粉,并对其表面结构、直链淀粉含量、热焓特性、淀粉的黏度、糊化温度及淀粉糊性质等方面进行了比较系统的研究,为今后高直链玉米淀粉的应用提供理论依据。     

高直链玉米淀粉的糊化特性研究

目的研究水浴加热、微波加热和高压加热方法对高直链玉米淀粉糊化性能的影响,为高直链淀粉的进一步开发和应用提供理论基础。方法以高直链玉米淀粉为原料,在过量水分存在条件下,分别采用水浴加热、微波加热和高压加热制备高直链玉米淀粉糊,分别研究不同温度和微波功率下,高直链玉米淀粉糊碘兰值和酶解力随糊化时间增加的变化规律。结果水浴加热、微波加热和高压加热糊化过程中高直链玉米淀粉的碘兰值和酶解力均随时间的延长呈上升趋势,微波加热高直链玉米淀粉糊的碘兰值和酶解力低于高压加热但高于水浴加热,微波加热淀粉的糊化速度大于水浴加热和高压加热。结论高压加热淀粉糊化效果好,淀粉的糊化程度高,是使高直链淀粉完全糊化的较好方法。     

脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物结构和热性能的影响

本文研究了脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物热性能、微观结构、粒径分布及Zeta电位的影响。结果表明,高直链玉米淀粉与脂肪酸形成复合物后热稳定性降低,且复合物的热稳定性随脂肪酸不饱和度的增加而降低;高直链玉米淀粉与脂肪酸形成复合物的结晶结构为V型,结晶度随着不饱和度的增加而减小;高直链玉米淀粉-脂肪酸复合物有两种存在形式,分别为颗粒表面凸起的球晶和嵌在颗粒表面的层状或絮状结构,后者存在形式随脂肪酸中双键个数的增加而减少;高直链玉米淀粉与脂肪酸形成复合物后淀粉颗粒变小,分散液稳定性增加。总之,脂肪酸不饱和度对高直链玉米淀粉-脂肪酸复合物的结构和热性能具有明显影响。     

淀粉种类与结构对其上浆性能的影响

概述淀粉种类与结构对其上浆性能的影响。研究了直链淀粉的糊化性能,分析了不同直链淀粉和支链淀粉比例的淀粉浆液凝沉性能,探讨了马铃薯淀粉、木薯淀粉、玉米淀粉、高直链玉米淀粉及蜡质玉米淀粉黏度随浓度变化的情况,测试了各种淀粉对纯棉和涤棉粗纱的黏附力及浆膜性能。研究表明:高直链玉米淀粉起始糊化温度130℃,温度对淀粉糊化影响较大;随着淀粉中直链淀粉含量的增加,淀粉浆液凝沉作用增强,容易老化;5种淀粉中,高直链玉米淀粉随浆液浓度增大,黏度变化最小,对棉和涤棉粗纱的黏附力最低,蜡质玉米淀粉的浆膜性能较差。认为:淀粉种类不同,其分子量大小、分子链形状、直链淀粉与支链淀粉比例以及淀粉中所含的微量成分不同,对淀粉浆料的浆液、浆膜性能会造成显著影响。     

淀粉结构对浆料性能的影响

研究直链淀粉和支链淀粉比例对浆料性能的影响。以高直链玉米淀粉和蜡质(支链)玉米淀粉为原料,运用光学显微镜、差示扫描量热仪研究了高直链玉米淀粉糊化所需要的条件;测试比较了不同比例的直链淀粉和支链淀粉混合浆液黏度、浆液黏附性能、浆膜性能等指标。结果表明:高直链玉米淀粉在130℃下糊化15min才能完全糊化;随着直链淀粉含量的增加,浆液的黏度下降,黏度热稳定性提高;浆膜的断裂强度、断裂伸长、耐屈曲性及磨耗增加,但对棉、涤棉粗纱的黏附力降低。认为浆料中直链淀粉和支链淀粉比例对其上浆性能有明显影响。     

储藏期与储藏压力对稻谷籽粒压缩特性的影响研究

利用质构仪压缩稻谷籽粒的短轴来测定稻谷籽粒的压缩特性。测定的稻谷储藏在不同的时间与压力下。实验结果表明:当储藏时间为60 d且储藏压力由0 kPa增加到300 kPa,稻谷籽粒的破坏力由81.6 N减小到73.8 N,破坏能由8.10 mJ减小到6.27 mJ,破坏应变由0.139减小到0.117,表观接触弹性模量由171.3 MPa减小到57.7 MPa,最大接触应力由40.8 MPa减小到19.1 MPa。当稻谷储藏压力为77、100、139、200 kPa且储藏时间由0～60 d,稻谷籽粒的破坏力由81.6 N分别减小到79.6、79.1、78.2、77.0 N;破坏能由8.10 mJ分别减小到7.55、7.35、7.08、6.85 mJ;破坏应变由0.139分别减小到0.131、0.128、0.126、0.121;表观接触弹性模量由171.3 MPa分别减小到136.0、121.8、110.6、83.3 MPa;最大接触应力由41.2 MPa分别减小到35.0、32.5、30.3、15.0 MPa。结果表明储藏压力与储藏时间对稻谷籽粒的压缩特性有重要的影响。     

国内外大豆加工业生产现状与发展趋势

结合工作与生产实际，在查阅和调研了国内外大豆加工业相关资料和项目之后，对生产现状进行了简要表述，对发展趋势进行了粗浅分析。明确指出：国外大豆加工业的发展趋势是原料生产与产品研发同步进行，努力抢占国内外市场，开发传统品牌产品，加强宣传工作力度，瞄准“三高”产品，增加社会经济效益，组建发挥社会团体作用，推动大豆产业发展。国内发展趋势是注重快餐型大豆食品生产，适应消费人群生活特点，注重大豆蛋白功能性的研发，满足国内市场需要，注重油脂加工业合理布局，扩大相关产业向前发展，以此发挥优势和强项，打造具有中国特色的与世界同步发展的大豆加工产业。     

The effect of storage pressure on the mechanical properties of paddy grains

To investigate the effect of storage pressure and storage time on the mechanical properties of paddy grains, an experimental study was carried out to determine the mechanical properties of paddy grains compressed at minor axis orientation using the Texture Analyzer. The paddy grains were stored under different pressures and for different time. The results showed that as the storage pressure increased from 0 to 300 kPa, the rupture force of paddy grains stored for 60 days decreased from 81.58 to 73.78 N, the rupture energy from 8.10 to 6.27 mJ, the rupture strain from 0.1392 to 0.1168, the apparent contact modulus of elasticity from 171.32 to 57.68 MPa and the maximum contact stress from 40.84 to 19.11 MPa. All of the mechanical properties of the paddy grains exhibited a linear relationship with storage pressure. As for the paddy grains stored under the pressures of 77, 100, 139, 200 kPa, as the storage time increased from 0 to 60 days, the rupture force of the paddy grains decreased from 81.58 to 79.58 N, 81.58 to 79.12 N, 81.58 to 78.21 N and 81.58 to 76.96 N; the rupture energy decreased from 8.10 to 7.55 mJ, 8.10 to 7.35 mJ, 8.10 to 7.08 mJ and 8.10 to 6.85 mJ; the rupture strain decreased from 0.1392 to 0.1309, 0.1392 to 0.1283, 0.1392 to 0.1257 and 0.1392 to 0.1213. The apparent contact modulus of elasticity decreased from 171.32 to 135.97 MPa, 171.32 to 121.77 MPa, 171.32 to 110.59 MPa and 171.32 to 83.32 MPa; the maximum contact stress decreased from 41.16 to 35.00 MPa, 41.16 to 32.45 MPa, 41.16 to 30.32 MPa and 41.16 to 14.97 MPa, respectively. The results revealed that both storage pressure and storage time have a significant effect on the mechanical properties of paddy grains.     

Challenges ahead for food science

Over the last decades, market forces have pushed many food companies into a process of continuous cost cutting and rationalization. The only way to escape this 'spiral of death' is to innovate.
  This presents new challenges to food technologists: they have to connect the right functional benefits to the emotional benefits to support brand strengths. To achieve the desired speed to market, companies should build skills to utilize the latest technology and learn to work in an open innovation environment.     

小米馒头工艺与品质研究

通过对小米馒头的工艺与品质进行研究,可知随着小米粉添加量的增加,加水量逐渐降低,发酵体积逐渐减小,通过正交实验可以得出在小米粉添加量为45%、加水量为45%、发酵时间为3h、醒发时间为40min时,可以得到品质良好的小米面馒头。     

The influence of attachment to beef surfaces on the survival of cells of Salmonella enterica serovar Typhimurium DT104, at different a(w) values and at low storage temperatures

This study investigated the influence of attachment to beef surfaces on the survival, injury and death of stationary phase cells of Salmonella enterica serovar Typhimurium DT104, compared to cells free in solution. The effects on cells are considered at different a(w) values and low temperatures in relation to osmotic and cold temperature shock effects. Attachment of cells to meat surfaces prevented cell injury and death from hyperosmosis and low temperatures, compared to meat solutions. Storage of cells for 72h resulted in higher levels of cell death on cells attached to meat surfaces. The improved survival of cells in solutions was considered to be related to adaptation to osmotic stress as a result of exposure to a previous hyperosmotic shock and the ability of the cells to produce cold shock proteins. Pathogen cell growth at low temperatures is discussed in relation to the presence of low levels of NaCl. Finally the data is discussed in relation to pathogen survival on beef carcass surfaces during refrigeration.     

钢丝绳质检员的职责与业务拓展

介绍全面质量管理的关键点及在钢丝绳制造中的应用。对照相应标准列举钢丝绳的捻制缺陷。根据工作实践与体会,表述钢丝绳质检员的职责:严格执行钢丝绳产品标准,验证技术工艺规程对钢丝绳质量保证程度,及时发现钢丝绳的捻制缺陷,判定与标准的符合程度,尽力提出对缺陷的纠正措施或参考建议,不断拓展参与新产品试制的能力,为新产品有别于常规产品的性能和良好使用性能恪尽职守。     

Moisture Dependent Physical Properties of Dry Sweet Corn Kernels

Physical properties of sweet corn kernels have been evaluated as a function of kernel moisture content, varying from 9.12 to 17.06% (db). In the moisture range, kernel length, width, thickness, and geometric mean diameter increased linearly from 9.87 to11.09 mm, 7.41 to 9.25 mm, 3.25 to 4.37 mm, and 6.18 to 7.62 mm, respectively, with increase in moisture content from 9.12–17.06%. The sphericity index, kernel volume, kernel surface area, and thousand seed weight increased linearly from 62.6 to 68.8, 93.8 to 194.3 mm³, 120.1 to 182.9 mm², and 220 to 268 gr, respectively. Apparent density and bulk density decreased linearly from 1.315 to 1.232 g/cm³ and 0.765 to 0.698 g/cm³, respectively, while bulk porosity increased from 41.8 to 43.3%. The highest static coefficient of friction was found on the plywood surface. The static coefficient of friction increased from 0.680 to 0.891, 0.605 to 0.741, and 0.530 to 0.644 for plywood, galvanized iron, and aluminum surfaces, respectively. The angle of repose increased linearly from 30.2 to 35.2° with the increase of moisture content.     

Analysis of factors related to illegal tobacco sales to young people in Ontario

OBJECTIVE: To identify and to discuss factors influencing illegal merchant sales of tobacco to underage people in Ontario, Canada. DESIGN: Results were obtained through random retail compliance checks of tobacco merchants. A multivariate analysis specified the relationship between selected independent variables and the willingness of tobacco merchants to sell to minors. The selected independent variables included retail operation type, community population size, the presence of tobacco production, signage, sex and age of volunteers, smoking prevalence rates, and enforcement rates. PARTICIPANTS: A random, stratified sample of 438 tobacco retailers in 186 communities in Ontario. MAIN OUTCOME MEASURE: Willingness of merchants to sell tobacco to minors. RESULTS: Older youths and girls were more likely to be sold tobacco products. Purchase attempts carried out in tobacco-producing regions were also statistically related to illegal sales. CONCLUSIONS: Policy efforts to control youth access to tobacco in Canada may need to invoke legislation requiring merchants to request proper identification from customers who appear to be under the age of 25, and who seek to purchase tobacco products. Further attention could also be directed at tobacco control policies and enforcement strategies that need to consider the unique challenges faced by jurisdictions where the tobacco industry is a powerful presence.     

谈面粉企业的标准化体系

面粉企业的标准化是企业推行ISO9001质量认证的基础，其标准化工作要以满足市场需要的、质量稳定的小麦粉生产为重点；以小麦粉质量标准为工作核心、健全面粉企业的标准化体系。通过完善关键技术标准，加强标准化工作的实施，以规范企业小麦粉生产技术行为，推动小麦粉生产健康发展，迎接“入世”挑战。