CHARACTERISATION OF PATTERNS OF CHEWING BEHAVIOUR IN HUMAN SUBJECTS AND THEIR INFLUENCE ON TEXTURE PERCEPTION

Electromyography was used as a noninvasive and unobtrusive technique to characterise chewing patterns for a range of foods. Differences between subjects for a variety of aspects of chewing sequence are recorded for a range of foods (carrot, apple, roast pork, salami, biscuit and toast). Identifiable subgroups of subjects differing in chewing behaviour existed within the random sample of 52 dentate subjects. The five subgroups accounted for 52%, 21%, 11%, 10% and 6% of the sample population. Major discriminating factors between the behavioural groups lie in their chewing time and the muscle work rate during chewing. Sensory ratings for firmness and rubberiness of model foods differed significantly between the subjects exhibiting different chewing behaviours. Chewing behaviour may influence consumers' perceptions about the texture of a food.     

THE INFLUENCE OF ENTEROBACTER AGGLOMERANS ON BEER FLAVOUR

The influence of Enterobacter agglomerans (Erwinia herbicola) on the fermentation process and beer flavour was studied. The presence of E. agglomerans gave rise to increased levels of acetaldehyde, methyl acetate, diacetyl, 2,3-pentanedione and dimethyl sulphide in the final product. The concentration of these compounds was affected by the number of bacterial cells inoculated into the pitched wort.     

STUDY OF FOOD TEXTURES BY RECORDING OF CHEWING AND SWALLOWING MOVEMENTS

Abstract Chewing and swallowing patterns were recorded in three subjects eating freely pieces of foods of various initial textures in an attempt to assess objectively these food textures as sensory stimuli in the mouth. In each phase of masticatory and swallowing movements corresponding to each piece of food, variations were noted differentiating the 16 textures tested. The number of masticatory movements, the time of mastication up to complete swallowing, the time course of the force of mastication and the number and distribution of swallowing movements were found to be the most discriminating parameters. In considering them, foods might be placed on a scale from hard and dry to soft and fluid textures. The results confirm the validity of recording chewing and swallowing movements as a new method for describing the true dimensions of oral sensory stimulations by food textures.     

INFLUENCE OF PARBOILING ON RICE STARCH STRUCTURE AND COOKED-RICE TEXTURE

Four varieties of rice having very high (29.4%) to low (17.6%) amylose-equivalent (AE) were parboiled by steaming at atmospheric (PB-O) and at 3 kg/cm2 (PB-3) gauge pressure. The cooked rice texture of the raw, PB-0 and PB-3 rice was determined by Viscoelastographe. Gel permeation chromatography of rice flour starch on Sepharose CL-2B, in general, indicated thermal breakdown of starch. The extent of starch breakdown and the firmness values of cooked PB-0 and PB-3 rices were reasonably well correlated suggesting that starch breakdown during parboiling may have some role to play in varying the texture of rice by parboiling. The chain profile of rice starch remained unaltered after parboiling.     

INFLUENCE OF CHEWING AND SWALLOWING BEHAVIOR ON VOLATILE RELEASE IN TWO CONFECTIONERY SYSTEMS

Electromyography, electroglottography and turbine airflow technology were used to characterize the chewing, swallowing and breath flow profiles of 35 subjects during the consumption of two different (a gum Arabic‐ and carrageenan‐based) confectionery chews. Simultaneous volatile release measurements were obtained using atmospheric pressure chemical ionization mass spectrometry. Subgroups of subjects displaying different eating characteristics were identified for both products. Parameters accounting for the maximum variance (product 1, 42% and product 2, 52%) between the subgroups were chewing force, chewing rate, proportion of work and total number of chews. Volatile release measurements were significantly different between the subgroups from product 1. The impact of the different eating characteristics on volatile release from product 2 was less defined, and postulated to be a result of the contrasting textural properties. Manipulating in vivo breakdown of chewy confectionery products, by texture modification, may influence consumer's volatile release and subsequent flavor perception.     

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.     

INFLUENCE OF pH ON FLAVOUR STALING DURING BEER STORAGE

A decreasing pH accelerated an increase in the chemiluminescence production and degradation of isohumulones and procyanidins during the storage of beer and using a model system. The sensory test showed that the addition of HCI to fresh beer accelerated the flavour staling during beer storage but that the addition of HCI to stored beer did not significantly accelerate the flavour staling. Therefore, it was thought that the acceleration of beer flavour staling is not dependent on a decrease in pH such that the decreasing pH isolates stale flavour aldehydes by a dissociation from staling-flavour aldehyde adducts but based on the fact that the decreasing pH accelerates the flavour staling reactions, free radical reactions, during beer storage.     

食品包装对环境的影响

食品工业的发展极大地推动了食品包装工业的发展，常用食品包装材料有高分子、金属、纸和玻璃等。这些食品包装材料在生产过程中对环境均有一定的污染，在使用后不正确的处理方法以及食品包装中残留的微生物又导致对环境的进一步污染，同时食品过度包装还造成对环境资源的巨大破坏。为使食品包装工业与环境能协调发展，人们应在食品包装的清洁生产、发展绿色食品包装、简化食品包装以及提高环保意识等方面做出努力。     

TEXTURAL PERCEPTIONS AND FOOD QUALITY1

Consideration of texture within the food quality assessment takes two forms: scoring for the absence of defects and, more positively, addressing the hedonic aspects of food acceptance. The latter approach followed the demonstration that texture affects consumer attitudes to and preference for specific foods, often being equal to (or even surpassing) flavor in importance. It must be recognized that texture is a multi-parameter attribute. Definitions and connotations of specific textural characteristics are reviewed as well as their classification. It is suggested that, having once provided the building blocks for a generalized approach to texture investigations, workers in quality assessment of agricultural products should now capitalize on the significant advancements made by researchers focusing on texture as a subject.     

食品质地及其TPA测试

随着中国食品工业日新月异的发展，尤其质量认证体系在全社会范围的推广与深刻的影响，业内人士越来越希望在面对食品业中大量模糊的感官概念时，能获得一套准确的量值表述，真正实现对传统食品行业的数字化、科技化变革。本文全面介绍了食品质地概念及其多面剖析法和一种客观评价方法-TPA测试。对食品质地评价研究所面临的问题提出了自己的看法。     

FOOD TEXTURE AND ITS EFFECT ON INGESTION, MASTICATION AND SWALLOWING

The oral processing of most semisolid and solid foods can be summarized in terms of two opposing mechanical influences: forces that fracture food particles versus those that make them adhere to each other. During either the ingestion of food into the mouth or the early stages of mastication, the aim of processing solid food particles is usually to fracture them. However, later on towards swallowing, adhesion is desirable in order to try to form a sticky food bolus that could clear the mouth of isolated food fragments. Neither of these tendencies is actually a function of any particular force (or stress) or displacement (or strain) on food particles, but is instead controlled by energy. Food particles can adhere not only to each other but to the mouth's surfaces. This produces friction. While this is essential for the tongue to grip food particles and move them around the mouth, it also adds to the work that mouthparts must do during processing and may affect sensory perception of food quality. Successful processing of foods in the mouth requires a considerable amount of neural feedback from sensory receptors. We focus here on recent evidence about these sensory receptors with an attempt to reinterpret their role in terms of textural perception.     

COLLECTION AND CLASSIFICATION OF WORDS FOR DESCRIPTION OF FOOD TEXTURE

Using a controlled association test, Japanese expressions describing texture were collected in response to 97 food stimulus words. Results were compared with those obtained by Szczesniak in the United States. Frequencies of response were well balanced for some but not for all words with opposite meanings. There were many onomatopoeic words. The median frequency of mention per subject per food was about 3.5 texture words. This became about 7 when words which were mentioned only once were omitted. In the descending order of frequency, the most important words were: hard, soft, juicy, chewy, greasy, viscous, slippery, creamy, crisp (kori-kori), crunchy (kari-kari), and brittle.     

INFLUENCE OF TEMPERATURE AND ADDITIVES ON THE ADSORPTION KINETICS OF FOOD EMULSIFIERS

The influence of temperature (6, 25, and 50C) and additive substances (salt, sugar and vinegar) on the adsorption kinetics of typical food emulsifiers, egg yolk and whey protein concentrate (WPC) were studied using the Wilhelmy plate/burst membrane method to monitor the interfacial tension (IT) at the water soya oil interface. The effect of solutes on the adsorption kinetics depended on emulsifier type. The presence of salt and higher temperatures reduced the IT of egg yolk solutions, while the IT of WPC solutions increased with salt addition. The presence of sugar and vinegar generally increased the IT of both emulsifiers while increased temperature caused the equilibrium IT of both emulsifiers to decrease and attain equilibrium more quickly.     

WORT COMPOSITION AND BEER FLAVOUR. II. THE INFLUENCE OF DIFFERENT CARBOHYDRATES ON THE FORMATION OF SOME FLAVOUR COMPONENTS DURING FERMENTATION

Wort, to which was added various amounts of solutions of glucose, fructose, sucrose or maltose, was fermented, and in the resulting beers the concentrations of the following flavour components were determined by gas chromatography: ethyl acetate, isobutyl acetate, iso-amyl acetate, 2-phenyl ethyl acetate, ethyl caproate, ethyl caprylate, n-propanol, isobutanol, amyl alcohols, 2-phenyl ethanol, caprylic acid and capric acid. The concentrations of these compounds were affected in different ways by the various amounts of sugar added, and some differences were observed etween the different carbohydrates.     

MEAT TEXTURE CHARACTERISATION: COMPARISON OF CHEWING PATTERNS, SENSORY AND MECHANICAL MEASURES

The texture of beef, varied by muscle (semimembranosus and semitendinosus), myofibrillar status (ageing time and cold-shortening) and cooking temperature (60C and 80C), was determined by a sensory profile, chewing patterns (determined from surface electromyograms) and mechanical properties of the cooked meats measured at low and high deformation in compression, shear (cutting) and by dynamic (viscoelasticity) tests. The meat factors were discriminated differently by the different measurements showing that they detected differently the various origins of meat texture. Only the maximum modulus before 70% compression and sensory assessments and EMG gave discrimination among all the meat factors. Two main sensory dimensions were found from the profile: juiciness and tenderness with a third related to the determination of elasticity. Juiciness, which varied most between cooking temperatures, was better related to mechanical parameters at low strain rather than high strain and to initial muscular activity rather than later muscular activity. Conversely, tenderness was better related to high strain mechanical properties and to measurements in the middle or later part of the mastication process suggesting that tenderness assessment requires structural disintegration of meat.     

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.     

食品的质构特性与新产品开发

介绍了在新产品开发中食品质构的构建，以厦开发过程中食品质构的感官评判和仪器分析，并讨论了感官评判结果与仪器分析数据的相关性。食品的质构特性是食品新产品开发中不可忽视的属性，值得研究开发者引起足够的重视。