Deformation Testing of Foods.

SUMMARY— A technique is described for using certain of the special characteristics of a universal testing machine which permits small distances to be measured with precision. A number of foods were compressed to a standard force, and the deformations of the foods were then measured off the strip chart recorder which is an integral part of the machine. The high degree of precision is obtained by driving the chart at a speed which is an exact multiple of the speed of the compressing plate. Differences between the deformation characteristics of different foods are shown. The advantage of using a standard size and shape of test piece is discussed. A method is shown for overcoming the effect of small imperfections in shape of standard pieces. It is also shown that a small deforming force will usually give a better resolution between similar samples than does a large deforming force.     

Deformation Testing of Foods. 2. A Simple Spring Model of Deformation

SUMMARY— A model system is described which closely represents the deformation of a food as it is squeezed in the hand. The model consists of a set of true springs of differing heights and with differing Hooke's constants arranged in parallel. One or more springs are required to represent a given food depending upon the degree of curvilinearity of the force-compression curve of the food. No dashpots are needed in this simple model. The one restriction on the model is that it is intended to represent the physical response of the food to a single compression. A graphical method for measuring the number, size and Hooke's constants of the springs in the model is described. The spring model shows that with some foods at least, small compression forces measure differences in softness better than large forces.     

Simultaneous Heat Processing of High- and Low-Acid Foods in Semirigid Containers—A Theoretical Analysis

A one meal-set of military ration consists of heat sterilized, high- and low-acid foods in semirigid containers. These foods are processed separately because of large differences in lethality requirements. We examined the feasibility of simultaneously processing a meal-set consisting of chili con came, white rice, and sliced peach in syrup to minimize costs. Simultaneous processing was not possible by adjusting initial temperaturès according to computer-simulation using food temperature data collected experimentally. However, it was possible when the container for peaches was insulated properly with expanded polystyrene. Proper insulation thickness was slightly dependent on z value of the target factor.     

率管理图在冷饮卫生监督管理中的应用及分析

以黄山市1980~1989年冷饮卫生监督资料,应用率管理图统计方法分析和探讨冷饮食品卫生监督。计算卫生不合格率平均水平P=30．39%及各年上、下管理线(UCL及LCL),绘制管理图。据此评估冷饮卫生质量。分析管理失控原因和讨论监督管理措施。     

北京市顺义区食品中铅、砷、镉污染水平的监测分析

目的了解北京市顺义区食品重金属污染状况,掌握主要食品中铅、砷、镉的污染水平。对主要食品安全进行有效监控。方法3年对8类366件主要食品进行监测。结果样品总体合格率为97．5％,大米、面粉、鲜牛奶、猪肾和果汁饮料样品中铅、砷、镉的污染水平较低,均符舍国家限量标准,蔬菜（5／134）、水果（3／62）、生猪肉（1／24）类样品合格率分别为96．3％、95．2％、95．8％。结论顺义区主要食品重金属污染水平较低,但在各类食品中重金属都有不同程度的检出,需要进一步加强监测,控制污染,保障人群的健康。     

Effect of Reference Foods in Repeated Acceptability Tests: Testing Familiar and Novel Foods Using 2 Acceptability Scales

ABSTRACT:  Hedonic tests are routinely used to assess the acceptance of food products. However, these single tests may not be the best approach for predicting long-term use. The objectives of this study were, first, to check whether a difference from reference score is more sensitive to changes in hedonic scores, second, to assess whether the labeled affective scale (LAM) is more sensitive to differences than the 9-point scale, and third, to assess the effect of repeated exposure on the hedonic scores of neophilic and neophobic panelists for familiar and novel foods. Two groups of 41 panelists were tested with either the 9-point hedonic scale or LAM scale. Panelists received a food neophobia questionnaire and were subsequently classified to neophobic, neophilic, or neutral. Ten foods, including 5 novel and 5 familiar, were used. In each session, 5 to 6 foods were served twice/week for 4 wk. Serving frequency ranged between 1 and 8 times (1, 2, 4, 6, 8). Data analyses were performed 3 times, using either absolute acceptability scores or relative scores, that is, the difference between absolute scores and scores for either the reference (cracker, RELFAM) or a novel food (pickled-ginger, RELNOV) served in every session. The 3 analyses (absolute, RELFAM, and RELNOV) generated similar results with respect to the number of significant differences between foods. There was no major drift in acceptability scores with sessions. A significant food effect was obtained ( P < 0.05) and a significant food × neophobia ( P < 0.05) was noted for 2 novel foods, pickled ginger, and lychee, whereby neophobic panelists were less accepting of them. Both scales were equally sensitive with some advantages for LAM over the 9-point hedonic scale.     

Acrylamide in Foods: Chemistry and Analysis. A Review

Acrylamide is a potential cause of a wide spectrum of toxic effects and is classified as probably “carcinogenic in humans”. The discovery of acrylamide in human foods has given rise to extensive studies exploring its formation mechanisms and levels of exposure and has spurred search into suitable analytical procedures for its determination in foodstuffs. However, the exact chemical mechanisms governing acrylamide formation are not yet known and cheap, convenient, and rapid screening methods are still to be developed. Acrylamide in food is produced by heat-induced reactions between the amino group of asparagine and the carbonyl group of reducing sugars along with thermal treatment of early Maillard reaction products (N-glycosides). Similarly, the decarboxylated Schiff base and decarboxylated Amadori compounds of asparagine as well as the Strecker aldehyde have been proposed as direct precursors and intermediates of acrylamide. Corresponding chromatographic methods are used to determine various structural groups present in Maillard reaction model systems. Gas chromatography-mass spectrometry and liquid chromatography with tandem mass spectrometry analysis are both acknowledged as the main, useful, and authoritative methods for acrylamide determination. This review is an attempt to summarize the state-of-the-art knowledge of acrylamide chemistry, formation mechanisms, and analytical methods. Special attention is given to comparison of different chromatographic techniques, particularly the novel, simple, and low-cost methods of its determination.     

流通领域几种食品质量的评价

本文对近几年流通领域的食品,如饼干、糖果、豆制品、蜂蜜和月饼进行了抽查,并按国家标准进行检测.结果表明,这些食品的质量达标率逐年呈上升趋势,但同时仍然存在一定的质量问题,有些食品甚至是不安全的.     

机器视觉技术在水产食品感官检测方面的应用研究进展

机器视觉技术是一种无损、快速、经济的检测技术。结合国内外的相关研究现状,本文介绍了机器视觉系统的优点和对颜色、形状、尺寸等的检测方法,在此基础上,分别对机器视觉技术在包括鱼、虾、扇贝和牡蛎等水产食品感官检测方面的应用进行了详细阐述和讨论,此外,探究了机器视觉技术目前在水产食品感官检测领域应用的局限性及在深度学习方面的发展前景。本文旨在为水产食品的感官检测提供技术支撑,保障消费者的食用安全。     

Analysis of Isoflavones in Foods

In recent years the nutritional and bioactive properties of foods are being intensively investigated with a view to control, in addition to food quality, their possible influence on human health. Because of this, there is a growing demand for rapid, selective, sensitive, and validated methods for analysis and quantification. Bioactive plant compounds include those with weak estrogenic activity (phytoestrogens), among which are the isoflavones. Some of the beneficial activities that have been attributed to isoflavones are anticarcinogenic activity, the prevention of cardiovascular disease, the improvement of bone health, and antioxidant activity. The objective of this work is to provide an updated review of the methods used in sample preparation and subsequent analysis for the determination of isoflavones in food samples, including both soybean and soy products, as well as other foods with low isoflavone contents. The review focuses on the most common sample preparation techniques used during the last 10 years, including both conventional solvent extraction and other more recent extraction techniques. Separation and detection methods, including current trends in liquid chromatography analysis, such as the use of monolithic columns or ultra‐high‐pressure liquid chromatography, are also discussed.     

酵母菌的益生功能及在食品中的应用

酵母菌与我们生活密不可分,己在食品、饮料、饲料、工业乙醇等领域得到广泛应用.酵母菌除了发酵功能外,在益生方面也显示出了重要作用.与传统益生菌相比,酵母菌在治疗腹泻疾病、提高免疫力、增强营养等方面都有显著效果,且酵母菌的代谢产物(二氧化碳和乙醇)对食品种类和风味都有积极贡献.酵母菌在食品中应用的文献数不胜数,但描述其益生...     

Dietary Fiber and Other Constituents of Some Tongan Foods

Components of dietary fiber (soluble nonstarch polysaccharide, pectin, hemicellulose, cellulose and lignin), water, energy, protein, lipid and starch were measured in banana, breadfruit, cassava, coconut, mango, pawpaw, plantain, sweet potato, taro and Pacific yam, all from the Pacific Island Kingdom of Tonga. The Tongan foods were generally higher in dietary fiber than New Zealand foods, consistent with the hypothesis that dietary fiber is an important factor contributing to a lower incidence of certain gastrointestinal disorders in Tonga, than in New Zealand.     

Analysis and Significance of Tyramine in Foods

SUMMARY— The tyramine levels in different varieties of cheeses, alcoholic drinks, and other foods were determined. Many of the food samples, analyzed by an existing fluorometric method, contained large amounts (up to 2.2 mg/g) of tyramine. Synephrine and octopamine, although rarely present in food, interfered with the fluorometric analysis. A gas chromatographic method was developed in which tyramine was extracted from foods and then analyzed as its trifluoroacetyl derivative using an electron capture detector. The gas chromatographic method was more sensitive and specific than the fluorometric method, and it permitted detection of 0.1–0.2 nanogram tyramine even in the presence of synephrine and octopamine.     

Microwave Assisted Thawing of Model Frozen Foods Using Feed-back Temperature Control and Surface Cooling

An apparatus was developed that combined microwave energy and cold air with different ambient temperatures to reduce thawing time and avoid run-away heating during microwave assisted thawing. Effects of microwave power level, sample thickness and surface air temperature on thawing time were investigated. The microwave power was cycled on and off using two temperature control schemes to maintain a predetermined temperature gradient based on hot and cold points. Thawing time was reduced by as much as a factor of seven compared to convective thawing at ambient temperature when appropriate conditions were used.     

高效液相色谱-串联质谱法测食品中的赭曲霉毒素A

研究建立高效液相色谱-串联质谱联用技术检测食品中赭曲霉毒素A的方法。根据不同样品,用甲醇-2%碳酸氢钠溶液(60:40,V/V)或甲醇-水(80:20,V/V)提取样品中的赭曲霉毒素A,经OchraTest亲和柱净化,以甲醇-5mmol/L(含0.1%甲酸)乙酸铵为流动相,采用正离子模式对赭曲霉毒素A进行检测。结果回收率在82.3%～98.5%之间,检出限为0.1μg/kg。该方法适用不同基质样品,准确性好、灵敏度高、抗干扰能力强,方法检出限可满足欧盟等最新限量要求。     

Computer Simulation of the Attrition Patterns of Particulated and Agglomerated Foods

Attrition processes were simulated using a set of mathematical expressions that describe the bimodal size distribution of the attrited particles and their temporal relationships. It is demonstrated that the dominance of a particle shattering mechanism or surface erosion as well as any of their combinations can be described in terms of the magnitude and ratios of only three empirical parameters, provided the initial conditions and other physical characteristics of the system are known.     

Colour Measurement and Analysis in Fresh and Processed Foods: A Review

Colour is an important quality attribute in the food and bioprocess industries, and it influences consumer’s choice and preferences. Food colour is governed by the chemical, biochemical, microbial and physical changes which occur during growth, maturation, postharvest handling and processing. Colour measurement of food products has been used as an indirect measure of other quality attributes such as flavour and contents of pigments because it is simpler, faster and correlates well with other physicochemical properties. This review discusses the techniques and procedures for the measurement and analysis of colour in food and other biomaterial materials. It focuses on the instrumental (objective) and visual (subjective) measurements for quantifying colour attributes and highlights the range of primary and derived objective colour indices used to characterise the maturity and quality of a wide range of food products and beverages. Different approaches applied to model food colour are described, including reaction mechanisms, response surface methodology and others based on probabilistic and non-isothermal kinetics. Colour is one of the most widely measured product quality attributes in postharvest handling and in the food processing research and industry. Apart from differences in instrumentation, colour measurements are often reported based on different colour indices even for the same product, making it difficult to compare results in the literature. There is a need for standardisation to improve the traceability and transferability of measurements. The correlation between colour and other sensory quality attributes is well established, but future prospects exist in the application of objective non-destructive colour measurement in predictive modelling of the nutritional quality of fresh and processed food products.