FOOD TEXTURE MEASUREMENTS IN CANADA

A survey of the food industry, government agencies and educational institutions dealing with foods has been conducted to establish the nature and extent to which instrumental texture measurements are employed in Canada. Two hundred and fifteen questionnaires were sent out and 123 (57%) returned. Of those replying, 52% were using texture evaluation instruments. Within the food industry the use of texture measuring instruments was as follows: meat 36%; fish 20%; canner/freezer 79%; dairy 42%; confectionery 73%; baking 50%; fats and oils 78%; multi product 77%; beverage 0%. Most widely used instruments in the quality control area were rotational viscometers and penetrometers. The more complex instruments, such as the Universal Testing Machine and the Shear Press, were used to a larger extent in the research area. The use of some instruments appeared to be restricted to particular commodity groups. The questionnaire dealt among other things with the use of taste panels, statistical evaluation of results, and the need for expanded use of instruments. There was general agreement that more standardization of methods is desirable.     

APPLICATION OF ENGINEERING TECHNIQUES TO EVALUATION OF TEXTURE OF SOLID FOOD MATERIALS

Abstract An engineering approach to evaluation of mechanical attributes of texture in solid food materials is presented. The usefulness of such an approach, which is based on sound physical principles, is discussed. An illustrated list of mechanical tests applicable to solid food materials is given along with formulas for computing the mechanical properties which should be related to mechanical attributes of texture. Examples of previous work which have employed these techniques with the intention of correlating the results with some textural parameters of solid foods are reviewed. It is shown that these objective physical measurements have proven to be useful and give more fundamental data than most of the conventional, poorly defined tests employed in the past. The use of these techniques, where applicable, for future studies is recommended.     

物性分析仪在食品质构测定方面的应用

质地特性是食品极其重要的品质因素。一般采用的感官评定方法主观因素偏重，而物性分析仪所反映的主要是与力学特性有关的食品质地特性，其结果具有较高的灵敏性与客观性，故其使用越来越广泛。本文综述了物性分析仪的原理及其在小麦粉制品、肉制品、水产品和乳制品中的应用，以及存在的问题与展望。     

FOOD TEXTURE MEASUREMENTS WITH THE PENETRATION METHOD

Following the work of Bourne, penetration measurements were performed with two sets of punches. The first set had a constant area and various perimeters. The second set had a constant perimeter and various areas. At constant perimeter, the relationship between punch area and force was a straight line with process cheese, butter and margarine, the latter two going through the origin. At constant area, the relationship between punch perimeter and force was a straight line for process cheese, but no definite relation between punch perimeter and force was obtained with butter and margarine. The relationship between the nature of the curves and the physical structure of the food is discussed. It was concluded that penetration tests of cellular products such as fruits studied by Bourne may involve shear and compression factors. In products with strongly bound network structures, e.g. process cheese, the main factors are shear and flow. In products with weakly bound network structures, such as plastic fats, flow is the only major factor involved.     

GENERAL FOODS TEXTUROMETER APPLICATION TO FOOD TEXTURE RESEARCH IN JAPAN

Applications of the General Foods Texturometer to food research in Japan are reviewed based mainly on information published in Japanese scientific journals. The instrument is being used on various food items such as rice, fish, soybeans, gels, meat, cheese and spaghetti. Correlations with sensory evaluation, development of a similar apparatus for crispness characterization of vegetables and new interpretation of Texturometer parameters are also discussed.     

CONSUMER AWARENESS OF AND ATTITUDES TO FOOD TEXTURE

Abstract Although its awareness appears to be present on a subconscious level, texture plays a very essential role in determining people's feelings about foods. Intensity of flavor, socially and culturally learned expectations, psychological and physiological factors, sex, socio-economic class, image of a food, and eating occasions influence awareness of and attitudes to texture among adult consumers. Texture awareness is increased when expectations are violated, associations are made with non-food items, or unpleasant mouth sensations are experienced. Textural qualities are often linked with whole-someness and excellence of food preparation.     

USE OF RHEOLOGICAL TERMS AND CORRELATION OF COMPATIBLE MEASUREMENTS IN FOOD TEXTURE RESEARCH1

The importance of maintaining the purity of rheological terms and using them only when measurements and definitions are in accordance with the accepted rheological definitions is pointed out. It is shown that if rheological terms and methods of measurements and analyses are used correctly, they can be employed in food texture studies even though conditions upon which the theory is based are not fully met. It is proposed that the term “modulus of elasticity” be replaced by the term “modulus of deformabtiity” which considers both recoverable and unrecoverable deformations that often take place when a food sample is subjected to even very small strains. It is also submitted that mechanical properties reflecting the behavior of the material under small strains do not necessarily correlate significantly with mechanical properties which reflect the yielding and fracturing or failure of the material. Published data are examined to test the validity of this hypothesis. In general, correlations between well-defined failure type instrumental tests and panel tests are good, whereas correlations between small-strain instrumental tests and panel tests are poor.     

纹理贴图在装潢设计中的应用

根据映射的基本原理，将由计算机设计制作的图案应用于产品的装潢设计，能产生极佳的装饰效果．映射函数是将平面图形转换到立体产品上的具体算法，选取正确的映射函数是实现纹理贴图的关键．根据常见产品的几何形状，给出了正方体、圆柱体、球体表面的映射函数，通过微机绘图的通用程序，能实现装潢效果图的输出．     

离子交换树脂在食品工业中的应用

离子交换树脂是食品和发酵工业应用中最活跃、最有创造力的一个领域，它对食品工业的发展起着举足轻重的作用：随着我国改革开放的深入和人民生活水平的提高，人们对饮食消费的要求越来越高，食品的安全、卫生、无毒是人们长期以来追求的一大趋势，而离子交换树脂在这方面起了重要作用，因此树脂在食品工业中的应用将越来越广，对树脂的要求也越来越严。本文介绍了有关树脂对食品进行提纯、去味、脱色、分离催化等方面的作用及具体的操作方法，希望能够为相关研究者和企业提供有益的参考？     

THE TERMINOLOGY OF FOOD TEXTURE

The current interest in food texture terminology and previous attempts to develop a system of definitions are noted. A systematic and comprehensive glossary of food texture terms is presented as a basis for discussion with the objective of achieving in due course a generally-agreed terminology.     

TEXTURE OF FRESH-PACK WHOLE CUCUMBER PICKLES: CORRELATION OF INSTRUMENTAL AND SENSORY MEASUREMENTS*

Correlations were determined between Texture Profile Analysis parameters of brittleness, hardness or total work of compression obtained with the Instron testing machine and sensory responses of firmness or crispness in evaluating texture of fresh-pack processed whole cucumbers (1-in. diam) of three ‘firm’ pickling cultivars (Explorer, Chipper, GY 3), two ‘soft’ pickling cultivars (Green F, Mincu) and a parthenocarpic slicer (MSU 6902 G). Further, correlations were determined between the TPA parameters and Magness-Taylor fruit pressure test (FPT) firmness. TPA hardness and total work correlated well with sensory responses; FPT firmness correlated satisfactorily with sensory firmness. Mean textural values from the various methods were compared with those obtained in the same manner for raw cucumbers. TPA brittleness tended to disappear in the processed fruit. Processing reduced mean TPA values across the six varieties to 35-58% of raw fruit values; it decreased mean FPT firmness to only 88%.     

DEFINITION OF OUTLIERS USING UNSUPERVISED PRINCIPAL COMPONENT SIMILARITY ANALYSIS FOR SENSORY EVALUATION OF FOODS

ABSTRACT

As unsupervised classifications, principal component similarity (PCS) and cluster analysis (CA) were compared for outlier detectability in panel evaluation. By rotating the reference, PCS can define outlying panelists based on the similarity of their evaluation patterns with that of the reference panelist. As a result, the outliers detected on PCS scattergrams are dependent on the reference selected, whereas, outliers detected by CA are based on dissimilarity, thus being rather unilateral. The definition of outliers in PCS is new as it is different from the currently most popular definitions based on dissimilarity. For verifying the outliers thus obtained, random-centroid optimization (RCO) was applied for selecting the best samples by each cluster of panelists. This combination of PCS/RCO may be useful in finding the likeness distribution among consumers and then in creating food products to correctly respond to the demands of different consumer groups.     

TEXTURE OF SALT STOCK WHOLE CUCUMBER PICKLES: CORRELATION OF INSTRUMENTAL AND SENSORY MEASUREMENTS*

Correlations were determined between Texture Profile Analysis (TPA) parameters of brittleness, hardness or total work of compression obtained with the Instron testing machine and sensory responses of firmness or crispness in evaluating texture of fermented salt stock whole cucumbers (1-in. diam) of three ‘firm’ pickling cultivars (Explorer, Chipper, GY 3), two ‘soft’ pickling cultivars (Green F, Mincu) and a partheonocarpic slicer (MSU 6902 G). Correlations were also determined between the TPA parameters and Magness-Taylor fruit pressure test (FPT) firmness. Correlations were good between TPA parameters and FPT firmness. Correlations were poorer between instrumental and sensory methods due largely to inordinately high sensory scores assigned to salt stock of the slicer by all panelists. Mean textural values from the various methods were compared with those obtained in the same manner for raw cucumbers. TPA brittleness tended to disappear in salt stock. Processing reduced mean TPA values across the six varieties to 39-86% of raw fruit values. Mean FPT firmness was relatively unchanged at 99% that of raw fruit. Desalting from 16% down to 8 % or 4% NaCl reduced TPA values but increased FPT firmness.     

NEURAL NETWORK WITH PRINCIPAL COMPONENT ANALYSIS FOR POULTRY CARCASS CLASSIFICATION

This paper reports the results of applying principal component analyses (PCA) of spectral reflectance data to reduce the number of input nodes for neural networks for classification of wholesome and unwholesome poultry carcasses. The results showed that the models with PCA pretreatment of input data performed better than those models without pretreatment. When sensing moving poultry carcasses in an environment without room light with a visible/near-infrared spectrophotometer, the neural network classification models with PCA pretreatment achieved 100% accuracies for training, validating, and testing. For carcasses moving at 60 birds/min, 50 factors were required for perfect classification, while for 90 birds/min 30 factors were required. When sensing in room light, the best model was generated with 30 factors for a shackle speed of 60 birds/min, with a test set accuracy of 95.8%. For 90 birds/min, the best model with a test set accuracy of 96.8% was obtained when 15 factors were used. This study showed that PCA reduced the number of input nodes to the neural network classifiers and, in most cases, improved the model's classification accuracy. It also required fewer training samples and reduced training time.     

A COMPREHENSIVE FORMULA FOR THE ACCEPTANCE OF FOOD TEXTURE, AND ITS GENERALIZATION TO OVERALL FOOD ACCEPTANCE

A survey is made of factors contributing to food texture (atoms, molecules, structure, mechanics) together with factors leading to food texture acceptance (stimulus-response, preferences), and a formula is developed for the relations among all these factors. An extension to general acceptance, involving all sensory quality factors, is also made.     

CONSUMER AWARENESS OF AND ATTITUDES TO FOOD TEXTURE II. Children and Teenagers

A discussion of children’s and teenagers’ attitudes to food texture is presented based on published data relative to growth and development and on information obtained from original consumer interviews. It is pointed out that, in this population group, physiological factors appear to be dominant in shaping attitudes to texture. These are modified by psychological, social, cultural, and other factors in the adult consumer. With both children and teenagers, texture is an important attribute of foods influencing their likes and dislikes. In the young child, attitudes to food texture follow the developmental sequence of oral functions, and textures are rejected which are difficult to manipulate in the mouth at a particular stage of physical development. The high degree of texture awareness of teenagers may possibly surpass that of adults. Teenagers also appear to have a better understanding of the concept of texture suggesting that this attribute may assume greater importance with the oncoming generation of adult consumers.     

免疫分析在食品安全检测中的应用

免疫分析利用抗原抗体特异性结合反应为基础,具有特异性强、灵敏度高、方法简捷等优点,被广泛应用于食品安全检测中.本论文综述基于免疫分析原理,包括传统和一些新型的免疫分析技术在食品安全检测中的应用现状.