Sensory and oxidative quality of screw-pressed flaxseed oil

Cold-pressed flaxseed oil is an excellent source of dietary α-linolenic acid (ALA). However, breakdown of ALA in the oil, either in the seed before or during storage, or as a result of processing, may result in unacceptable flavors. Screw-pressed flaxseed oil from four seed lots and a commercial sample were analyzed for headspace volatiles (HV) by solid-phase microextraction; for nutty, painty, and bitter flavors; and for overall quality. HV and sensory analyses were performed after storage for 7 d at room temperature and again after 15 wk at 4°C. Marked, significant differences were observed between samples for painty and bitter flavors and overall quality, but only slight differences for nutty flavor (P<0.05). Samples remained stable between the two storage periods. HV traces showed distinct differences between samples in number of peaks and in peak heights. Areas under peaks corresponding to select retention times were positively correlated (P<0.01) with nutty, painty, and bitter flavors. Therefore, the HV analysis by solid-phase microextraction may be a useful tool for screening flaxseed lots to be used for the production of screw-pressed oil.     

翡翠的品质评价

近年来,翡翠越来越被人们所熟知,所喜爱,翡翠的价格也是“突飞猛进”.那么,在这样一个买玉成风的年代,如何在市场上选购一件称心如意的翡翠制品显得尤为重要.当你面对琳琅满目的翡翠饰品时,又该从哪些方面进行考量、进行选择呢？文章主要阐述翡翠品质评价的几个重要方面.     

防晒剂的性能及质量评价

随着臭氧层的日益变薄,到达地面的紫外线不断增多,防晒变得越来越重要,人们对紫外线的防护意识也日益增强。介绍了防晒剂的种类、特点及性能,防晒剂的评价指标及安全性,以及天然防晒剂的发展趋势。     

Sensory and chemical evaluation of stored oil-roasted,high oleic nonoil sunflower kernels

High oleic acid (HOA) and high linoleic acid (HLA) nonoil (confectionery) sunflower kernels were oil-roasted at 180 C and then stored at 27 C for up to 26 weeks (wk). At two- and/or four-wk intervals, samples were removed for chemical and sensory analyses. Fatty acid composition of the oils extracted from the roasted kernels were as follows: HOA — 16:0, 3.6%; 18:0, 3.3%; 18:1, 68.3%, and 18:2, 23.7%; regular HLA — 16:0, 5.0%; 18:0, 3.5%; 18:1, 29.0%, and 18:2, 62.6%. Hunter L and a values and hue angle for HOA and HLA kernels changed significantly (P<0.01) during 26 wk storage. Hunter a values for HLA did not change significantly but Hunter a values for HOA decreased significantly (P<0.01) during storage. Free fatty acids (FFA) of both the HLA and the HOA kernels increased significantly (P<0.01) beginning at 16 wk storage. In addition, the FFA from HLA kernels were significantly higher (P<0.01) than those from HOA kernels. Both types of stored, roasted kernels showed significant differences in sensory scores from the control samples (regular HLA type held at −35 C) beginning at four wk but rate of change throughout storage was similar for both kernel types. Sensory data were combined with objective parameters to analyze the multivariate data set by VARCLUS. Four clusters of attributes were extracted that explained 71.9% of the variation in the data. The data show there was a significant increase in off-flavor for both HLA and HOA kernels but no significant difference between the two types of kernels. Changes in the color of the sunflower kernels during storage evidently were not related to flavor quality.     

Rat models in protein quality evaluation

The ideal methodology for establishing protein quality has not yet been elaborated. On the other hand, the proposed introduction on the market of novel protein sources urges the industry to ask for an in vitro test, characterized for being inexpensive fast, reliable, and acceptable at an official level. Obviously, the in vitro test must be confirmed by an appropriate in vivo test. In this connection the problems relative to the species on which to experiment if it should or should not be the one to whom the protein food is directed—and the characteristics of the in vivo test are discyssed. Although the rational appears to be to assay on man protein directed to him, the cumbersomeness of the procedure, technical difficulties, uncertainties in the interpretation of the results as wel as ethical considerations for what children are concerned, don’t favor experimentation on man. An extensive experimental study, aimed at testing various conventional and novel proteins, confirmed that the multiple doses test, as proposed by Samonds and Hegsted (RPV), has the highest discriminating capacity and is scientificically the most reliable. A research project to verify the correlation between the two methods for evaluating biological quality, namely PRV and the method of the in vitro ultrafiltered digest (EUD), is under investigation.     

Judd's contributions to color metrics and evaluation of color differences

The contributions of Dr. Deane Brewster Judd to colorimetry extended over five decades. Among the most crucial contributions to the development of modern colorimetry were his studies of colorimetric purity, relations among color-mixture and luminosity data, visual sensibility to color differences, uniform chromaticity diagrams, Munsell notation and renotation, color names, color blindness and anomalies, color-vision theory, and uniform color scales.     

半连续与连续装置聚酯质量的差异分析

分析2种装置的产品质量所存在的差异及原因,提出相应的改进措施。半连续装置的产品特性黏度偏差值大,端羧基值高,色相差,凝聚粒子多,可过滤性和可纺性差等。产生的原因主要是设备和工艺流程所致。增加预缩聚工序改进终缩聚搅拌器,用循环泵输送物料,安设熔体过滤器等,聚酯切片质量可以达到连续装置的水平。     

化工产品质量评价及应用Applicationofqualityevaluationonchemicalproduction

同样优等品的化工产品在用户端的表现差别很大,其原因之一是当前的质量水平评价方法主要区分“59与60分,不关注60～100分间”的差异。探索增加新的评价指标,可更加灵敏、合理地反映产品质量水平,也可使企业尽早发现问题,采取改善行动。通过分析发现,在不增加检验工作量的情况下,充分利用现有数据（信息资源）进行分析,可发现同一...     

混煤质量评价方法的研究与应用

建立在传统的单种煤基础上的配煤炼焦理论难以适应现代煤源状况,必须依据中国煤炭分类的原则和商品煤反射率分布图来确定炼焦煤的黏结性和结焦性,鉴别其混煤的程度,正确评价混煤的性质及其在炼焦配煤中的作用,通过小焦炉炼焦,制定合适的配煤方案。试验表明,合理利用混煤配煤炼焦,可以消除混煤对炼焦配煤的不利因素,生产出高质量的焦炭,满足高炉生产的要求。     

液体分布器分布质量评价体系综述

液体分布器是影响填料塔性能的关键部件,为了能更合理地对液体分布器分布质量进行评价,文中介绍了Moore分布质量、Preey作图法、L.Sp iegel实测法、K lem as分布质量、K illat分区法、L.Sp iegel润湿指数以及白跃华区域流量测量等几种目前国内外常见的分布质量评价方法,并对其各自优缺点及适用条件进行分析。通过对空分填料塔液体分布器结构形式进行研究,认为基于区域面积液体测量的评价方法更适用于对其液体分布质量进行评价。评价体系的正确选择有利于发现液体分布器存在的问题和提出适当的改进措施。     

樟村坪磷矿岩体质量评价

为进行采场稳定性分析，本文在测试基础数据的基础上，用四种岩体分类方祛对樟村坪磷矿的岩体质量进行了分析评价．     

Sensory evaluation and acceptability study, at the consumer level, of bread supplemented with sweet lupine flour

The purpose of this study was to determine the effect of incorporating sweet lupine flour (SLF) to bread, upon the organoleptic characteristics and acceptability of the product. The substitution levels were 3, 6, 9 and 12%. The sensory evaluation test was done by 25 trained judges using the hedonic scaling method (9 to 1 scoring). Internal and external characteristics of appearance, color, aroma, texture, bitterness and flavor, as well as general acceptability, were measured. Sensory evaluation results of the external characteristics were significant at the 9 and 12% SLF levels for color (p less than 0.05) while the other parameters did not show significant differences. In regard to the internal characteristics, a significant difference for color was found at the 3% level of SLF (p less than 0.05); and at 6, 9 and 12% SLF levels, for appearance (p less than 0.05). The general acceptability was good at all the levels tested, with no significant differences among them. An acceptability study at the consumer level for 9% lupine flour bread was carried out in a group of 90 girls, aged 10-12 years, during a 10-day period. The results showed a very good acceptability of the product (p less than 0.01). The results of this study indicate that the incorporation of 6% SLF to the bread, did not affect adversely its sensory properties. Moreover, the acceptability of bread containing up to 12% SLF was excellent.     

炼焦煤质量的综合评价体系及方法研究

基于层次分析法评价炼焦煤质量体系,通过建立炼焦煤质量的综合评价体系,对炼焦煤各项指标进行了赋值,并对汾西矿业集团的炼焦煤产品进行了有效评价。     

水质中8种有机氯农药的测量不确定评定

根据气相色谱法测定水中8种有机氯农药,分析并计算出影响测定结果的不确定度来源分量,得出相对合成标准不确定度。结果表明,测量重复性和标准曲线拟合过程中引入的不确定度在整个分析过程中贡献最大。