DETERMINATION OF THE MOISTURE AND NITROGEN CONTENTS OF BARLEY AND MALT BY NEAR INFRARED SPECTROSCOPY (NIRS)

The determination of the moisture and nitrogen contents of barley and malt by near infrared spectroscopy (NIRS) has been tested by the Analysis Committee of the European Brewery Convention. In the collaborative trial four samples of barley and malt were analysed by 17 laboratories. Repeatability (r₉₅) and reproducibility (R₉₅) values of 0.3 and 1.5% m/m respectively were obtained for barley moisture over the range 12.7 to 15.8% m/m. For malt moisture these values were 0.2 and 1.3% m/m over the range 4.0 to 4.3% m/m, for barley nitrogen 0.1 and 0.3% m/m on dry matter over the range 1.57 to 2.14% m/m, and for malt nitrogen 0.1 and 0.2% m/m on dry matter over the range 1.58 to 1.82% m/m, respectively.     

冷冻对纸张耐久性影响的研究

低温冷冻杀虫和低温冷冻干燥是备受推崇的纸质藏品保护技术,但是冷冻对纸张耐久性的影响研究尚不充分。为了避免对纸质藏品造成保护性伤害,本文考察了冷冻对不同含水量的酸性纸和中碱性纸耐久性的影响。研究发现,冷冻对纸张耐久性的影响与其含水量和纸张类型相关。冷冻对于干燥中碱性纸耐久性无影响,会降低潮湿和浸湿中碱性纸耐久性,对不同含水量酸性纸耐久性均存在劣化作用。因此,低温冷冻杀虫处理适用于干燥的中碱性纸质藏品,低温冷冻干燥需进一步改善工艺提高其安全性。     

Moisture Sorption Characteristics of Freeze Dried Blueberries

Moisture sorption isotherms of freeze dried lowbush blueberries at 4, 16, 25, 35, and 45°C were determined using indirect gravimetric method. Moisture sorption kinetics at these temperatures and 75% RH were also investigated. The isotherms followed a type III shape with a temperature inversion effect at 0.9 water activity. They were best described by the GAB equation. Net isosteric heat of moisture sorption in freeze dried blueberries, determined using the Clausius Clapeyron equation, varied from 5.5 to 0.25 kJ/mol as moisture content changed from 8 to 36% (dry basis). Moisture adsorption kinetics in freeze dried blueberries were well described by the first order kinetics equation. The rate constant followed the Arrhenius relationship with an activation energy of 38.6 kJ/mol.     

吸湿快干机织物制备方法进展

文章对吸湿快干机织物的制备方法进行了分析及总结,着重从差别化纤维法、结构设计、后整理及纳米技术4个方面总结论述了各方法的影响因素和优缺点。通过某一种方式来实现机织物的吸湿快干性能已不能满足制备吸湿快干机织物的要求,将几种方法相结合可获得更优良的吸湿快干性能,最后展望了吸湿快干机织物的发展前景。     

箱纸板爆线的防控措施

瓦楞纸箱折痕线部位在加工、折叠、装箱及堆垛时出现的面、里纸爆裂现象称为爆线。爆线不仅严重影响到纸箱品质,造成废品率急剧攀升,而且还会延迟交货期,使企业蒙受经济损失,是纸板的重大质量缺陷之一。纸板爆线问题严重困扰着纸板生产和纸箱加工企业,目前尚无可靠试验显示箱纸板可以完全避免。     

微冻贮藏对牛肉保水性的影响

本实验以冷藏（2 ℃）和冷冻（－18 ℃）作为对照组,从肌原纤维蛋白结构和水分迁移等方面分析了微冻（－4 ℃）贮藏条件下牛肉保水性变化的机制。结果表明：微冻贮藏牛肉的汁液损失率和蒸煮损失率显著高于冷藏和冷冻处理组（P＜0.05）,保水性最差。微冻贮藏过程中,牛肉中的水分弛豫时间逐渐变长,结合水相对含量无明显变化,不易流动水相对含量显著下降,自由水相对含量显著上升（P＜0.05）。随着贮藏时间的延长,3 种贮藏方式下牛肉的总巯基含量和活性巯基含量均显著下降,蛋白质表面疏水性显著上升（P＜0.05）,且贮藏温度越低,变化速率越慢。微冻贮藏过程中,牛肉肌原纤维蛋白降解程度较低,贮藏后期蛋白质变性程度较高,提升了肌原纤维蛋白网络中不易流动水的自由度,使得部分不易流动水转化为自由水,导致了微冻牛肉较差的保水性。     

木浆中水分测量结果不确定度的评定

根据FZ/T 50010.2—1998对漂白阔叶木浆进行水分测量,并根据标准JJF1059—1999对其进行不确定度评估。不确定度主要来源：重复性测量、试样质量、干燥前后试样及称量瓶质量。这批漂白阔叶木浆水分测量结果的扩展不确定度为0.06%。     

食品添加剂在蛋黄派生产中的应用

本文简要介绍了新型休闲食品——蛋黄派的由来、特点、生产配方和制作工艺以及在蛋黄派生产中乳化剂、防腐剂、保湿剂和疏松剂等各类食品添加剂的功能、选择和应用。指出：在蛋黄派的生产过程中，应该根据不同生产阶段的不同需要，结合实际的蛋黄派生产配方和工艺，选择使用不同的食品添加剂，以保证生产的顺利进行和产品质量的稳定；同时在选用添加剂时必须考虑到不同原材料之间的相互作用与在不同的加工过程中物料本身和物料之间可能发生的变化以及食品的安全性。     

Farm‐Scale Experiments to Compare Infestation and Quality Changes in Malting Barley Stored at Three Moisture Contents

Comparison of changes in temperature, moisture content, infestation and germination were made in six aerated 20 t bins of malting barley. Two were at about 13.5% moisture content, three at about 15.5% moisture content, and one at about 16.5% moisture content. The grain started at between 20–25°C and, during aeration, fell at a rate dependent on the moisture content, damper grain being cooler, presumably due to evaporative cooling. The ‘high’ moisture content grain was often over 5°C cooler at 1m and 2m than the ‘low’ moisture content bins. Moisture uptake at the surface was related to bulk moisture content and trends in mite population changes were related to moisture content. Mite population achieved highest numbers at the grain surface but usually before the moisture content absorption was at its peak. They were commonest in the ‘high’ moisture content bin and least numerous in the ‘low’ moisture content bins. There were no apparent differences between bins in the numbers of insects trapped, for instance they were not less numerous in the coolest ‘high’ moisture content bin. However, the trends of numbers trapped followed a similar pattern in all bins; normally O. surinamensis and S. granarius only began to decline after nine weeks storage in December when temperatures fell below 10°C. Germination loss at the surface of the dampest bin was sufficient to cause rejection of the entire bulk for malting. Micromalting indicated that yield of extract and friability were particularly affected by the changes at the surface of the dampest barley.     

玉米储藏中霉菌类群及玉米赤霉烯酮毒素含量的研究

研究玉米储藏过程中霉菌类群与玉米赤霉烯酮毒素(ZEA)的关系,确定不同储藏环境下,优势霉菌数量、ZEA含量差异性及二者相关性。将初始水分含量12.41%、14.30%、15.89%、17.62%、19.88%的玉米在30 ℃,相对湿度(RH)为75%、84%和92%的模拟环境中储藏28 d,测定霉菌、串珠镰刀菌、木霉数量及玉米赤霉烯酮含量及相关性。结果表明：在低湿度环境下,初始水分对木霉抑制ZEA随初始水分升高而迅速增强;在中高湿度环境下,木霉对ZEA的抑制效果增强,受初始水分影响较小。RH为92％环境下,玉米初始水分含量12.41%、14.30％时霉菌丰富度较高,19.88%时菌源丰富度低;经相关性分析,不同含水量的玉米在30 ℃储藏28天后,在RH75%的环境下,玉米中的霉菌、木霉、串珠镰刀菌数量和水分含量均与ZEA的积累量呈负相关;在RH92%的环境下,均呈正相关;在RH84%的环境下,木霉量和水分含量与ZEA积累量呈显著正相关(P<0.05),镰刀菌和霉菌总量与ZEA积累量呈负相关;在三种储藏环境下,储藏玉米霉菌的Shannon多样性指数(H)和margalef丰富度指数(D)均与ZEA积累量呈显著性负相关(P＜0.05)。结果表明,在中低湿度环境下,ZEA的含量受生物因素和环境因素的影响较大;在高湿度环境下, ZEA含量主要由镰刀菌控制。