十三香调味料精油的抑菌作用研究

采用水蒸气蒸馏法提取十三香调味料的精油,测定十三香调味料精油对常见细菌、霉菌和酵母菌的抑菌圈、最低抑菌浓度及气态防腐作用。结果表明:十三香调味料精油对受试微生物抑菌作用程度依次为:霉菌>细菌>酵母菌。十三香调味料精油具有气态防腐性,具有实际应用于食品防腐保鲜的潜力。     

大豆磷脂水分快速测定法

大豆磷脂生产过程中需控制水分。现有的测定大豆磷脂中水分的方法都耗时较长 ,不适用于生产的中间控制。比如蒸馏法[1] ,它是在一个特定的装置中 ,用一种与水不相溶的有机溶剂 (如甲苯 )与磷脂共沸蒸馏 ,将水分蒸馏出来。该法完成一次测试需 3ｈ - 4ｈ ,且不易操作 ;再一种方法     

猪肉水分含量测定方法的优化及比较

利用GB 5009.3-2016《食品中水分的测定》中的第一法直接干燥法进行了猪肉中水分的检测与方法优化,并与第三法蒸馏法进行了方法比较,为直接干燥法适用于猪肉中水分含量测定提供了数据支撑。直接干燥法通过高温挥发水分干燥样品,根据前后重量差值计算水分含量,本试验得出最优化方案参数为105℃加热温度下,准确称量样品5g,加入5mL无水乙醇,10g海砂,先经4h烘干后冷却称重后再次烘干至恒重,其检测结果显示与蒸馏法结果无显著差异,且直接干燥法较蒸馏法设备简单操作方便,稳定性好,适宜进行大批量检测。     

枸杞水分测定中减压干燥法与蒸馏法的比较

本文分别按照两种方法对五组枸杞样品进行水分测定,并比较其在实际应用中的利弊。减压干燥法应用广泛,且无毒易操作,而蒸馏法更高效,具有检验周期短、精密度高、操作简单等优势,按照食品安全国家标准方法中的蒸馏法测定枸杞水分含量,更易于推广。     

化学计量学与保留指数辅助十三香挥发成分的GC-MS分析

采用水蒸气蒸馏法从十三香调味品中提取挥发油,使用气相色谱-质谱法分离测定十三香调味品的挥发油化学组成,通过质谱库的标准图比对,并利用化学计量学方法与色谱保留指数辅助定性分析。在十三香挥发油中鉴定了77种组分,占挥发油98%以上。含量最多的5种化学成分分别为茴香脑(48%)、柠檬烯(10%)、对-丙烯基苯基异戊烯醚(5.4%)、花椒素(3.4%)和草蒿脑(3.3%)。化学计量学与保留指数的辅助定性方法可增加气相色谱-质谱分析的能力。     

蒸馏法提取香根油成分的GC-MS分析

为研究蒸馏法香根油化学成分,以气相色谱-质谱联用仪检测水蒸馏法香根油,在香根油中鉴定发现异丁香酚等21种化学成分的化学结构,其中有5-甲基糠醛等12种化合物是香根油中首次发现的天然化合物,该发现对以香根油为原料的新食品添加剂研发及应用具有重要意义。     

川法小曲白酒生产技术(七)

川法糯高梁小曲酒操作法的蒸馏工序操作包括放黄水、装甑、蒸酒、配糟管理；工艺操作控制参数：泡粮、初蒸复蒸时间，出甑粮醅水分，用曲量，配糟比例。川法包谷小曲酒操作工序包括：蒸粮、培菌、配糟入窖发酵和蒸馏。川法薯干小曲酒操作法工序有：泡粮、蒸粮、培菌、发酵、蒸馏等。（孙悟）     

浓香型大曲酒丢糟综合利用的研究第一报：丢糟谷壳在串香酒生产中的应用

通过用不同水平丢糟壳的水分和数量,替换串香酒香糟的新鲜谷壳的试验,发现水分20％左右,用量20kg/甑的丢糟谷壳的使用,能改变蒸馏桶中串香糟内化学成分和物理性能,进而使串香酒质量得到比较明显的提高,体现出很好的社会经济效益。     

浆纱油剂的水分定量和石蜡检测分析

运用烘燥失重法和恒沸蒸馏法定量测定了浆纱油剂中的水分含量 ,烘燥法水分直接在 10 5℃下除去 ,恒沸蒸馏法水分与甲苯一起馏出分离 ,比较而言 ,烘燥失重法测定方便。用皂化分解法建立了浆纱油剂中石蜡成分的检测方法 ,并用红外光谱分析验证了该方法的可靠性。     

三种方法检测猪肉中水分含量

采用直接干燥法、蒸馏法及卤素水分测定仪检测猪肉中水分含量。直接干燥法是利用猪肉中水分的物理性质,在温度101~105℃下采用挥发方法测定样品中干燥减失重量,在通过干燥前后的称量数值计算出水分的含量。该方法平行性良好,相对标准偏差(RSD)0.24%。蒸馏法是利用水分的物理化学性质,使用水分测定器将肉中的水分与甲苯或者二甲苯共同蒸出,根据接收水体积计算出试样中水分的含量。该方法平行性良好,相对标准偏差(RSD)0.44%。卤素水分测定仪通过仪器系统自动检测水分含量。该方法平行性良好,相对标准偏差(RSD)0.37%。结果进一步证明干燥法测量结果略高,精密度良好。     

热辐气动干燥法快速测定牛奶中总固体和水分

利用圆盘自动进样热辐箱式胶乳样品干燥仪研究快速测定牛奶中总固体和水分含量的方法。分别对加热温度、加热时间及温度平衡时间进行实验,以烘箱法（标准法）为对照,不断优化实验条件,并测定了多份牛奶样品中总固体和水分的含量。结果表明：用本方法和烘箱法测定相同样品中总固体和水分含量的准确度和精确度结果一致,而烘箱法需耗时约3.5 h,本方法只需2.0 min完成,大大提高了分析效率。     

Proposal of a new reference method to determine the water content of dried dairy products

The water content of milk powders is “officially” determined by drying. The result of drying techniques is, however, the mass loss the sample undergoes under the conditions applied. No differentiation between water and other volatile substances is made. A particular problem is the lactose that is present in all dried dairy products. The α-form contains one mole of water of crystallisation per mole. This water fraction is not determined completely by ordinary drying methods. How much of the crystallised water is detected depends very much on the conditions applied. The entity determined by drying is not defined. It is only a tradition to regard the mass loss thus detected as water content. More and more, however, the expression moisture content is used for the result of drying techniques, although this term is also unsatisfactory and misleading. The discrepancy between mass loss on drying and water content becomes more pronounced when the product has high crystalline lactose content, such as whey powders or lactose itself. In these cases the difference between mass loss and water content can be quite significant. The existing reference method for moisture determination in dried milk is therefore not reasonably applicable on dairy products with high crystalline lactose content. It could be shown that the water content of dried dairy products can be determined using the Karl Fischer titration independently of the level of crystallisation water. The results are not only more accurate but also more precise than those obtained by the reference drying method. It is therefore proposed to introduce the Karl Fischer titration as reference method for dried dairy products.     

红薯叶复合面条热泵-热风联合干燥特性及干燥模型建立

将红薯叶粉添加到复合面条中,基于响应面法对红薯叶复合面条的热泵-热风联合干燥特性进行探究,运用低场核磁技术分析干燥过程复合面条内部水分迁移的质热传递规律,建立红薯叶复合面条联合干燥过程的数学模型.结果表明:随着热泵干燥温度的升高、转换点含水量的增大、热风干燥温度的升高,干燥所需能耗降低,有效水分扩散系数增大,煮制吸水率...     

Can the water content of dairy products be determined accurately by microwave drying?

 Oven drying is the most frequently used moisture determination method. To obtain results faster than heating by convection in classic drying ovens, more rapid heating techniques are used. One of these is drying by microwaves. The result of all drying methods is mass loss under the conditions applied. Only in a few cases does the mass lost correspond exactly to the water content. Mass loss is caused by the evaporation of all volatile matter during the drying process, i.e. not only by the loss of water. Foodstuffs in particular risk decomposition reactions and the formation of volatile substances at higher temperatures. The results of drying processes depend on the drying parameters and are variable, whereas the water content is a specific property of the sample. If the water content is to be determined accurately by a drying process, the drying parameters must be adjusted in a way that the results equal those obtained by a specific method, e.g. the Karl Fischer titration. The dependence on the drying parameters varies for different products. In many cases the levels of a set of parameters can be determined so that the mass lost equals the analysed water content; in other situations a differing but reproducible result can be multiplied by a constant factor to give the reference value. This study shows that, for some dairy products, the water contents found by microwave drying are very close to those determined by Karl Fischer titration. Received: 26 May 1998     

Can the water content of dairy products be determined accurately by microwave drying?

 Oven drying is the most frequently used moisture determination method. To obtain results faster than heating by convection in classic drying ovens, more rapid heating techniques are used. One of these is drying by microwaves. The result of all drying methods is mass loss under the conditions applied. Only in a few cases does the mass lost correspond exactly to the water content. Mass loss is caused by the evaporation of all volatile matter during the drying process, i.e. not only by the loss of water. Foodstuffs in particular risk decomposition reactions and the formation of volatile substances at higher temperatures. The results of drying processes depend on the drying parameters and are variable, whereas the water content is a specific property of the sample. If the water content is to be determined accurately by a drying process, the drying parameters must be adjusted in a way that the results equal those obtained by a specific method, e.g. the Karl Fischer titration. The dependence on the drying parameters varies for different products. In many cases the levels of a set of parameters can be determined so that the mass lost equals the analysed water content; in other situations a differing but reproducible result can be multiplied by a constant factor to give the reference value. This study shows that, for some dairy products, the water contents found by microwave drying are very close to those determined by Karl Fischer titration. Received: 26 May 1998     

核桃干燥过程的低场核磁共振横向驰豫分析

为了快速监测干燥过程中水分和油脂的变化,采用低场核磁共振(LF-NMR)技术对恒温和变温滚筒催化红外-热风干燥过程中核桃自由水、弱和强结合水及油脂进行测定,并与单一热风干燥相比较,同时建立水分横向弛豫峰面积占比与含水率之间的数学模型。结果表明,三种干燥方式下的干燥曲线变化趋势一致,与单一热风干燥相比[时长20 h,最大干燥速率0.11 g/(g·min)],变温和恒温红外-热风干燥效率[时长14.38 h和16.16 h,最大干燥速率0.28 g/(g·min)和0.48 g/(g·min)]显著提高,干燥时间分别缩短了28.10%和19.20%,最大干燥速率分别提升了2.55和4.36倍,表明红外干燥处理显著提升了干燥效率。LF-NMR横向弛豫图谱显示干燥过程中自由水峰面积显著下降直至消失,弱结合水峰面积显著降低,强结合水和油脂峰面积基本不变,表明干燥处理去除了几乎全部的自由水和大部分的弱结合水,对强结合水和油脂含量无明显影响。建立了水分弛豫峰面积占比与实际含水率之间的数学模型,R2均大于0.90,预测效果良好。总之,与国标法相比,LF-NMR能够很好地对干燥过程中水分和油脂变化进行检测,是一种高效快速检测含水率的新型方法。     

近红外光谱结合偏最小二乘法快速测定糖果中水分含量

采用近红外光谱(NIR)结合偏最小二乘法(PLS)建立了一种糖果中水分含量快速准确的测定方法。在12500~3600 cm-1光谱范围内采集116批糖果的近红外漫反射光谱,并用减压干燥失重法测定其水分含量。通过比较不同参数对建模的影响,发现用多元散射校正法进行预处理,在11682.2~9826.1、8939.0~6267.9、5378.8~4487.8 cm-1光谱范围内,主成分数为15时,应用PLS方法建立的糖果水分的定量分析模型效果最佳。所建立模型的相关系数为0.9716,校正均方根误差和验证均方根误差分别为0.97%和1.03%。该方法结果准确可靠、操作简便,可用于糖果中水分含量的快速检测。     

制革污泥干化过程研究

通过制革污泥自然干化过程、传统热干化过程和微波干化过程的研究,了解各种干化方法的干化速度,找出影响污泥干化的主要因素,研发适合温州当地实际的制革污泥干化设备.研究表明,214 g含水率为73.34%的制革污泥用自然干化方法至恒重需18 d,含水率5.36%;165 ℃热干化至恒重需7 h,含水率3.31%;900 W微波干化至恒重需14 min,含水率3.28%,可以给制革污泥微波干化专用设备研发提供参考.     

锅巴中水分测量结果的不确定度评定

目的 对锅巴中水分测量结果进行不确定度评定。方法 依据GB 5009.3-2016《食品安全国家标准 食品中水分的测定》第一法直接干燥法对锅巴中的水分进行测定,建立数学模型,分析检验结果的影响因素。结果 通过分析3种不确定的影响因子,得出不确定度分别为：3.30×10-3、2.75×10-4、2.92×10-3。结论 通过对各不确定度分量进行计算和分析表明, 锅巴水分检验中重复性测量对不确定度影响最大,天平称量的影响最小。     

黄花梨减压贮藏保鲜技术研究

本文研究了黄花梨在0±0.5℃,减压条件下的生理生化变化。结果表明,减压贮藏可以显著降低黄花梨贮藏期的呼吸强度,减少VC的损失,有利于保持果实含水量、硬度和可溶性总糖;能够有效保持超氧化物歧化酶(SOD)活性,并抑制过氧化氢酶(CAT)活性的上升。