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.     

国外高端品牌护肤霜的感官评价

对26款国外高端品牌护肤霜的感官评价结果进行分析,探讨其肤感。感官评价结果显示,大部分高端护肤霜具有较好的挑起性,偏厚实的质地,较好的涂抹性,适中的吸收速度,适中的油腻感,一定的存留量和黏滞感;使用时皮肤感觉料体轻盈、滋润,使用后皮肤变得柔软、滋润、有光泽。主成分分析结果显示,质感、挑起性、涂抹性、厚重感以及油腻感、皮肤光泽度、黏滞感等指标,可以大致表征高端护肤霜的肤感;可根据油腻感、皮肤光泽度、黏滞感组成的综合指标,将护肤霜按单价是否高于1 000元进行分类。     

羟乙基纤维素在多种面膜基布中肤感及配伍性研究

通过仪器测试和人体感官评价,考察含羟乙基纤维素(简称HEC)的面膜液在多种面膜基布中的肤感及配伍性,并对比研究了HEC与黄原胶应用于面贴膜的性能差异。仪器测试的结果表明对自身结构强度足够的面膜基布,包括中等及厚型面膜基布以及交叉铺网织法且编织较均匀的薄型面膜基布,HEC会使其有适度的延展性。相比黄原胶,HEC一方面可以和面膜基布有更好的配伍性,给面膜基布带来更好的柔软度和浸润性,另一方面能更好的保水和锁水。半脸感官评价的结果表明HEC相比于黄原胶在使用过程中有更好的贴肤性和润滑感,使用后皮肤的滋润度、弹性及光泽度更好,而且能够延长面膜变干的时间,总体上专家评估小组更喜欢HEC的肤感。     

Image quality evaluation for high dynamic range and wide color gamut applications using visual spatial processing of color differences

High dynamic range (HDR) and wide color gamut imagery has an established video ecosystem, spanning image capture to encoding and display. This drives the need for evaluating how image quality is affected by the multitudes of ecosystem parameters. The simplest quality metrics evaluate color differences on a pixel‐by‐pixel basis. In this article, we evaluate a series of these color difference metrics on four HDR and three standard dynamic range publicly available distortion databases consisting of natural images and subjective scores. We compare the performance of the well‐established CIE L*a*b* metrics (ΔE₀₀ , ΔE₉₄ ) alongside two HDR‐specific metrics (ΔE_Z [J_za_zb_z], ΔE_ITP [IC_TC_P]) and a spatial CIE L*a*b* extension (). We also present a novel spatial extension to ΔE_ITP derived by optimizing the opponent color contrast sensitivity functions. We observe that this advanced metric, , outperforms the other color difference metrics, and we quantify the improved performance with the steps of metric advancement.     

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.     

Sensory evaluation of the odour of a sunflower oil emulsion throughout oxidation

Oxidation of unsaturated fatty acids is responsible for off‐flavours, often described as rancid flavours. This study was aimed at describing the evolution of the odour of a sunflower oil‐in‐water emulsion during oxidation at 50 °C in the dark. Appearance of an odour and occurrence of oxidation were first tested for at short‐time aging (0–4 h) by the triangle test and measurements of oxygen consumption, respectively. The odour of the emulsion oxidised for up to 240 h was then characterised by sensory profile, while volatiles issued from lipid oxidation were analysed in the headspace by SPME. From 1 h of aging, while oxygen consumption remained weak, a significant change of the odour was detected by the panel. Up to 21 volatile compounds were identified in the headspace of long‐time‐oxidised emulsions. Beyond the rancid attribute, seven attributes were chosen to describe the odour of oxidised emulsions, four of which referring to solutions of a single volatile oxidation compound. The contribution of the fresh oil attribute, initially dominant, was progressively overtaken from 6 to 24 h of aging by the deep‐fried attribute, which later declined in favour of the painty attribute, predominant after 100 h. Evolution of intensity scores and contribution to odour profiles of attributes could not be easily related to one reference volatile compound or another, confirming the complex relationship between the generated volatile compounds and the perceived odour.     

采用主成分与聚类分析对市售保湿乳液感官评价的研究

以26款市售保湿乳液为研究对象,采用定量描述分析(QDA)法对保湿乳液手部使用结束后0,2和5 min 3个阶段的肤感进行评价。采用主成分(或主分量)分析(PCA)法和凝聚层次聚类(AHC)分析法对评价结果进一步分析。PCA的结果显示,本次考察的感官属性共提取出2个主成分,其特征值分别为4.182和2.611,前2个主成分累计方差贡献率达到84.91%。其中第1主成分描述了皮肤吸收,包括3个阶段的滋润感和柔软性;第2主成分描述了皮肤残留,包括3个阶段的黏滞感。结合AHC分析,结果表明26款市售产品可分为2类,第1和2类分别包含12和14款市售产品。该研究成功将26款市售保湿乳液分布在主成分图中,并对其进行了分类。     

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。