Resistance to thermal softening

Some edible, non-lignified parenchyma tissues fail to soften during thermal processing. Chinese water chestnut (CWC), Chufa and mature sugarbeet and beetroot contain examples of these tissues (Parker and Waldron, 1995 Parr et al., 1997 Waldron et al, 1997a Ng et al., 1998 Parker et al., 2000). In CWC, the edible tissues consist of thin-walled, starch-rich storage parenchyma with a few thin vascular bundles. After thermal treatments such as cooking or canning, CWC retains its firm and crisp...

Black oxidised olives

In black oxidised processing in the Californian style, the olives, mostly green and cherry, are normally stored in brine with 5-10 NaCl for between two and six months, depending on the needs of production. The brine may be acidified to pH 4 with lactic acid and acetic acid and kept in anaerobic or aerobic conditions. To improve texture, calcium chloride could be added during this period. Once the fresh or stored fruits are sorted and occasionally graded, they are treated with a series of dilute...

Manmade products

Although products with a natural origin, like meat, fruits and vegetables, are eaten fresh, the actual structure of many food products is obtained by processing. Examples of such man-made products are bread, cheese, mayonnaise, etc. The texture of this type of product depends on both composition and structure. Shear, pressure and temperature are the processing parameters that have most effect on the structure. Spontaneous compartmentalisation has to be taken into account (for instance phase...

Cellular stability during processing

High temperature heating of fruit and vegetable tissues causes an initial loss of instrumental firmness due to the disruption of the plasmalemma and an associated loss of turgor (Greve et al, 1994). This may result in the development of a rubbery character. However, the most notable change involves tissue softening which results from an increase in the ease of cell separation in many non-lignified tissues (Van Buren, 1979). Thermally induced cell separation is believed to be due to the...

Texture related to flavour and nutrient release

The organoleptic quality of fruits and vegetables is influenced not only by texture, but also by the taste and aroma (Boyar and Kilcast, 1986 Piggott, 2000). The taste of an ingested plant tissue will be dependent on the extent to which flavours and volatiles within the food are released into the mouth, enabling them to come into contact with saliva and then sensory cells. The most relevant cell-wall influence relates to the fracture or separation of plant cells, and therefore to texture. Cell...

Maintaining texture conventional prefreezing treatments

The two most common problems in frozen fruits and vegetables are chemical reactions that cause changes in flavor, color, texture, and nutrition and physical damage that causes loss of turgor and texture changes (Haard, 1997). Loss of tissue firmness, disruption of the cell membrane, and excessive softness are the major consequences which need to be avoided (Rahman, 1999). Loss of membrane semipermeability and disruption of cellular compartments can be minimized by rapid freezing rate, low...

Mechanical properties

Perhaps the most prevalent objective measurement for crispness is determination via mechanical properties. Mechanical properties are believed to reveal the structural properties of materials by means of resistance to compression by a blade probe and to a tensile fixture that pulls the structure of food material apart by using a universal testing machine or a texture analyzer. The measurement of mechanical properties is easier to conduct than that of structural properties, determined via the...

Determination of water and waterholding capacity in solid food by lowfield NMR relaxation

As pointed out previously, many of the investigations using NMR to predict the contents of water and fat have been carried out without any attempt to predict texture. However, these studies are also relevant in the present context, as water and fat are of importance for texture, and they should be able to give O Mealiness r 0.90 0 Moistness r 0.84 O Mealiness r 0.90 0 Moistness r 0.84 Fig. 8.3 Low-field NMR relaxation curves of four different potato varieties (up) prediction of mealiness and...

The development of firmness testers for pear

The technique of using a small spherical impactor for testing the response of fruits to impact was described for the first time by Chen et al. 1985 (cited in Chen et al., 1996). Chen et al. (1996) determined the effect of impacting mass on firmness sensing of fruits both theoretically and experimentally. They pointed out that the desirable features associated with low impacting mass were increases strength of the measured acceleration signal, thereby facilitating easier detection and maximizing...

Partial air drying

Partial dehydration is generally achieved by air drying. The resulting process is termed dehydrofreezing. The advantages over conventional freezing include (1) energy savings, since the water load to the freezer is reduced, as well as reduced transport, storage and wrapping costs (2) improved quality and stability (color, flavor), as well as better thawing behavior (lower drip loss). When using partial air drying, food ingredients of high water activity (aw > 0.96) are generally obtained,...

Acoustical properties

Perhaps the first impression of a crisp food is the sound burst during biting. Due to the fact that the crushing of crisp or crunchy foods results in fracture and fragmentation, it appears that fracture and sound emission are associated. Attenburrow et al. (1992) reported that the sounds emitted during the crushing of a dry product are due to a sudden release of stored elastic energy. The association between mechanical fracture and sound emission has been further elaborated by Chakra et al....

Hedonic scales

The most commonly used hedonic scale, at least in English speaking countries, is the nine-point hedonic scale (Jones et al. 1955). The main characteristics of the scale are that each category is associated with a verbal descriptor from dislike extremely to like extremely and that the scale has a neutral category neither like nor dislike. Although it has been widely used for almost 50 years, the scale has been equally criticised. The nine-point hedonic scale has been popular because of its...

Mechanism of reactions catalysed by PPOs and peroxidases

PPOs (tyrosinases) are able to catalyse the ortho-hydroxylation of phenolic moieties into the corresponding catechols, and the subsequent oxidation of these catechols into the corresponding quinones (Fig. 12.1). After the formation of quinones, subsequent reaction is possible if a nucleophilic moiety, potentially intramolecularly, is present (Fig. 12.2). This nucleophilic moiety does not necessarily have to be present intramolecularly, which offers the mechanistic basis for the involvement of...

Timeintensity and multitasking

Time-intensity (T-I) techniques involve the recording of specific sensory attributes as a function of time (Lee and Pangborn 1986). Cliff and Heymann (1993) have reviewed the use of T-I techniques and their use for sensory flavour and texture. Wilson and Brown (1997) used combined EMG and TI in a study of mastication and flavour release from gels of differing mechanical properties, where they observed that the act of swallowing was often associated with a marked increase in flavour perception....

The use of acoustics to differentiate between crispness crunchiness and crackliness

In addition to developing an understanding of the sensation of crispness, acoustic techniques have been used to differentiate between the sensation of crispness and those of crunchiness and crackliness. Crunchiness has been shown to be strongly related to crispness (Vickers and Wasserman, 1979 Vickers, 1981), and various definitions indicate their close association. Recently, Fillion and Kilcast (2002) proposed that the crispness of fruit and vegetables can be defined as 'a light and thin...

References

Avitabile leva l, maraboli a, cattaneo t m p and torreggiani d (2000) Improvement of processed pear ingredients using vacuum infusion influence on the quality characteristics of pear yoghurt. In Book of Abstracts (edited by Dipartimiento di Colture Arboree) 8th International Pear Symposium, September 4-9, Ferrara, Bologna, Italy. baker r a and wicker l (1996) Current and potential applications of enzyme infusion in the food industry, Trends Food Sci Technol, 7(9), 279-84. barat J m, albors a,...

Defining pasta

The general category of 'paste products' includes Asian noodles and pasta. Some forms of Asian noodles and pasta have similar appearance, but they are distinguished by differences in manufacturing process and raw material preference. Asian noodles are prepared by passing dough through sheeting rolls (Hatcher, 2001). The main raw material is common wheat flour. Asian noodles are diverse, differentiated based on ingredients and processing following sheeting. Asian noodles may or may not contain...

Application of NIR to fruit and vegetables

While the texture of cereals tends to be an indicator of processing requirements, the texture of fruit and vegetables may often be used as an indicator of ripeness or the presence of damage. In some cases, it also may be used for the prediction of end-use properties such as when differentiating between waxy and floury potatoes. Fundamental to producer and processor, however, is an understanding of the integrity of the material produced or delivered. This has historically been a difficult area...

Quasistatic versus dynamic measurement

Since viscoelastic material is time or loading-rate dependent, its mechanical behavior will be different for different loading rates. For example, the elastic modulus of apple tissue generally increases with loading rate (Petrell et al., 1980). To completely describe this rate-dependent behavior, the test specimen may have to undergo an extended time period (e.g. from many minutes to days) under the creep and or stress relaxation tests. This is not only time-consuming but also impractical, as...

PPOs and PODs structure and mechanisms of action

12.3.1 Molecular structure of PPOs and PODs Homology between various PPOs was shown in a phylogenetic tree that was constructed for 35 PPO sequences from the EMBL and NCBI databases (Wichers et al, 2003). This phylogenetic tree was based on partial sequences, which included the central catalytic domains, flanked by the copper binding domains as defined by Van Gelder et al, (1997). Phylogenetic analysis showed that PPOs clustered in groups for higher plants, vertebrate animals, fungi and...

Mechanical characterization of solid foods 521 Basic concepts

Texture is a quality attribute that is closely related to the structural and mechanical properties of a food. It is, therefore, essential to understand the mechanical properties of foods, in studying their textural properties and measurement techniques. The study of mechanical behavior, i.e. deformation and flow, of foods under applied forces falls within the scope of food rheology, which is a broad, currently active research area covering both solid and liquid foods. A number of textbooks and...

Water loss

Since, with modern technology, water loss is not the major source of firmness decay, and can be kept to a very low level, it will not be considered in this example. Cellulose decay can be completely neglected due to its very slow rate. So, in this example the main emphasis is on firmness loss caused by the decay of pectin. The conditions in which the apples are stored and those at harvest may affect the quality decay and firmness deterioration. Lowering the temperature slows down ripening and...

Elastic materials

Different foods can exhibit very different mechanical behaviors under uniaxial compressive or tensile loading (Fig. 5.3). The force deformation response for a cylindrical apple tissue specimen under compressive loading (Fig. 5.3a) may be divided into three phases. During the first phase of deformation, the relationship between force (or stress) and deformation (or strain) is linear and elastic. (Non-linearity at the beginning of the force deformation curve is mainly caused by the imperfect...

Use of near infrared spectroscopy NIR to evaluate textural properties

Near infrared (NIR) spectroscopy which can avoid the complexity of sensor contact and associated handling problems (Delwiche et al, 1996) has recently been studied as a means of evaluating the texture of intact apples by Cho et al., 1996, Onda et al., 1996, Sohn and Cho, 2000, Lu et al, 2000 and Park et al, 2002 plums by Onda et al., 1996 pear by Sirisomboon, 2001 sweet cherries by Lu, 2001. As described by Robert and Cadet (1998), the spectral information obtained in the NIR spectral region...

Application frozen berries and jams 1641 Potential techniques for berries

Berries can be frozen in syrup or as individual berries. As individual berries, they may be frozen on a tray or individual quick frozen (IQF) on a belt in an air-blast or cryogenic freezer. Depending on the final product, different freezing procedures might be appropriate (Reid, 1996). Freezing berries by fluidization yields products of the same quality as does liquid nitrogen freezing, but requires less time (Miller and Butcher, 2000). Strawberries for commercial preserves, jam, and jelly...

Preserving fruit firmness by calcium or polyamines infusion

The process of dipping whole fruits in aqueous preservative solutions, which is improved by vacuum application, has been used to prolong the post-harvest shelf life of many products apples (Scott and Wills, 1977, 1979 Lidster et al., 1986), lemons (Valero et al., 1998a, b), avocados (Wills and Sirivatanapa, 1988), mangoes (Tirmazi and Wills, 1981), tomatoes (Wills and Tirmazi, 1979), strawberries (Ponappa et al., 1993). The compounds used in the impregnation solution are usually calcium salts...

Crispness vs crunchiness

The definition of crispness is not yet completely understood with only the generalized concept having been established. In general, crispness is a highly valued and universally linked textural characteristic that has many positive connotations (Szczesniak and Kahn, 1971). Crispness in one commodity may not mean the same in terms of textural quality as crispness in another, e.g. crispness in nuts as compared with crispness in potato chips. Historically, crispness was defined as the quality of...

Recording of acoustics produced during mechanical testing

One of the stated advantages of recording an acoustic signature by mechanical testing is the reproducibility and consistency of mechanical tests (Mohamed et al., 1982 van Hecke et al., 1998). However, it is important that the instrumental test selected simulates the conditions to which a food is subjected during chewing (Mohamed et al., 1982). Factors such as the type of probe used and the speed of the crosshead during testing must be carefully considered to ensure that the instrument...

Determination of texture by lowfield NMR relaxation

As mentioned above, NMR relaxation can be used to display different water compartmentalizations in food materials by measuring the relaxation rates of the water protons. Several researchers have stated that NMR relaxation is a rapid, non-invasive and non-destructive method of determining the distribution of water pools with different relaxation rates in foods (Cornillon, 1998 Ruan and Chen, 1998). Water distribution in foods is an important characteristic in relation to food texture quality....

Lignin forming vegetables

Yam tubers begin to harden a few days after harvesting. Hardening becomes so pronounced that two or three weeks later the tubers are inedible, even after extended cooking. This is probably due to lignification reactions. The parenchyma cell walls rapidly lignify, starting from the corners of the cells near intercellular spaces and proceeding along the walls (Sealy et al, 1985). Increased levels of acid and neutral detergent fibres have been shown to characterise the post-harvest hardening of...

Modifying texture by enzyme addition

The vacuum infusion of enzymes in the structure of fruits and vegetables has been mentioned in connection with designing enzymatically modified food (McArdle and Culver, 1994 Baker and Wicker, 1996 Culver et al., 2000). Enzymatic modification of the internal characteristics of intact fruit or vegetables by vacuum infusion leads to an interesting transfer reaction process in food matrix engineering. The applications of enzyme vacuum infusion appear to be numerous, depending on the specific...

Protein content

Protein content and protein quality are fundamentally associated with cooked pasta textural quality and are considered the most important of all the grain components that influence cooking quality (Autran et al, 1986 D'Egidio et al., 1990 Matsuo et al., 1982). Consequently, a minimum hard vitreous kernel (HVK) content is an important physical characteristic because of its relationship to protein content. Generally, as HVK content increases and non-vitreous (commonly referred to as starchy or...

Physical properties of cooked rice

Texture Analysis Cooked Rice Grains

Among various physical properties, hardness and stickiness are the most frequently tested parameters (Table 19.1). Hardness and stickiness of cooked rice measured with an Instron food tester correlate significantly with amylose content, but because stickiness is easily predictable based on amylose content (r -0.92, p < 0.01), texture measurement concentrates on hardness (r 0.77,p < 0.01) (Perez and Juliano, 1979). The instruments used to determine the hardness and texture profile of cooked...

Potential techniques for jams

The four essential ingredients in manufacturing jams are fruit, pectin, sugar, and acid. Optional ingredients include spice, buffering agents, preservatives, and anti-foaming agents. The exact process selected will depend upon the type of product to be manufactured, the raw materials available, and the scale of production. Traditionally, all of the ingredients are blended together as the first stage of processing however, with modern demands for a high degree of consistency in quality, it has...

Quasistatic loading

Quasi-static methods measure the force at a specific level of deformation, or the deformation at a specific level of force, or both. Force measurement methods require controlling the displacement of the probe during testing so that reliable force measurements can be obtained. Verner (1931) developed a firmness tester for stone fruits, which squeezed the fruit between two flat plates for a specified distance. Ross (1949) reported on a fruit firmness tester that used a pneumatic system to press a...

Application of NIR to cereals and their products

In many cases, cereals undergo a milling or comminution step to reduce their particle size for further processing. The way in which cereals are transformed during this stage is a function of a wide range of physical characteristics including size and shape. However, for a number of cereal species, the texture of the grain determines how the grain will function at subsequent stages of the production chain (Evers and Millar, 2003). Depending on the manifestation of the textural attributes in...

Destructive testing

Sound is produced due to the application of a force on the food product. The cell walls of the product snap and energy is released. It is this energy moving through the air (or other sound medium) which is detected and recorded. Destructive testing has been conducted in two ways via recording the sounds produced by the application of a force on the product either by the teeth (during biting and chewing) or by instrumental shear or compression probes (the instrumental element). To record the...

Vacuum infusion technology 1521 Mass transfer phenomena

Comprehension and control of the mass transfer resulting from the application of VI technology are particularly important with respect to the structural effect required for the food product. Indeed, the nature of the mass transfer determines the quantity of the reactive substance which penetrates into the product, its distribution in the plant structure and the possible structural modifications generated by the vacuum step. Compared to a classical diffusion process (candying, salting, soaking,...

Dipping

Softening caused by freezing-thawing can sometimes be minimized by dipping the tissue in different solutions before freezing. Much of the softening results from degradation of the middle lamella of the walls of cortical cells with increased release of pectins from the cell walls. In many fruit, such as tomato, endo-polygalacturonase begins water solubilization of pectins while exo-polygalacturonase completes hydrolysis (Perkins-Veazie, 1995). Firmness changes in strawberries during senescence...

Trends in consumer preference

When considering consumer preference for pasta textural characteristics the Italian tradition of 'al dente' eating properties, characterized by high degrees of firmness and elasticity, generally first comes to mind. However, it should be realized that this consumer preference is not universal and this must be taken into account when evaluating trends. For example, in countries such as Brazil and Colombia, most but not all consumers prefer pasta with softer textural attributes. This preference...

Quantitative descriptive tests

The Texture Profile Method was developed by the General Foods Company specifically to define and measure the textural parameters of foods. Panellists are selected on the basis of ability to discriminate known textural differences in the specific product application for which the panel is to be trained (solid foods, beverages, semi-solid foods, skin care products, fabrics and paper goods). Panellists selected for training are exposed to a wide range of products from the category under...

Correlation spectrum

Simple correlation coefficients between constituents (textural properties and pectin constituents) and absorbance at each measured wavelength for original intact spectra were improved by second derivative transformation. However, the correlation spectrum of juice spectra did not show any improvement in correlation values. The common three broad bands of the high correlation coefficients between both textural properties and pectin constituents with absorbance at each measured wavelength were...

Controlling PPO and POD activity

A number of technological approaches can be considered to control the activity of PPOs and PODs during the food manufacturing process. 12.5.1 Genetic modification of raw material First of all, manipulating the raw materials may control enzyme activity. Examples for this can be found in for instance the development of a potato variety in which PPO was knocked out via antisense technology (Zabeau et al., 1994), and in button mushroom that was transformed with antisense PPO-constructs (Stoop and...

Crispness and turgor pressure

Whilst crispness is not fully understood as a perception, and cannot yet be measured directly by instrumental means, there is little doubt that the crispness Fig. 10.1 (a) Electron micrograph of a cell wall of Chinese waterchestnut. Abbreviations m middle lamella p primary wall. The cell wall is approximately Fig. 10.1 (a) Electron micrograph of a cell wall of Chinese waterchestnut. Abbreviations m middle lamella p primary wall. The cell wall is approximately Fig. 10.1 (b) Electron micrograph...

Processed fruit firming by infusion of gelling agents

The infusion of gelling agents in the fruit or vegetable structure allows texture improvement either by generating intercellular bridges in the pores complementing the plant cell wall network or by forming bonds between the added hydrocolloids and the cell wall components. However, the intercellular gel can modify the texture response only where the porous structure is high and the solute gain is significant, especially as mass transfer phenomena are generally limited by the high viscosity of...

Instrumental methods

An extensive effort has been made to establish instrumental methods for measuring the textural properties of cooked pasta since sensory techniques can be time-consuming, expensive and may exhibit poor reproducibility if proper procedures are not followed. In addition, the use of sensory panels to evaluate a large number of samples or to evaluate samples when sample size is limited is not feasible. Nevertheless, to verify that instrumental values have meaning in terms of sensory ratings of...

Justaboutright scales

Another type of scale used for the optimisation of attribute levels in food products is the just-about-right (JAR) scale. Individual samples can be rated Neither Like Like Like very Like dislike nor slightly moderately much extremely like Fig. 2.1 Distribution of consumer acceptance scores for texture of three candy bars. The question to consumers was worded as follows Considering only the texture of this product, which of these statements best describes your impression Dislike Dislike very...

Pear turgidity

Garc a et al. (1995) investigated the susceptibility to bruising of Blanquilla and Conference pears. They concluded that fruits at harvest were more susceptible to bruising than fruits after storage, due to a decrease in fruit turgidity fruits picked early were less susceptible to bruising than those picked later, due to a decrease in fruit firmness and fruit turgidity and firmness influenced bruise susceptibility independently although their effects combine during fruit ripening (see the...

The mastication process

Mastication needs to be seen as part of the wider oral processing of food, which can be divided into motility and secretory contributions. Oral processes affect breakdown of food in the mouth, and thence sensory perception, and depend on the properties of the food and their time dependence. The motility effect operates through lower jaw, tongue, cheeks and lips. Motility is needed to transport food to the pharynx for swallowing and to reduce particle size and to form a bolus for swallowing. If...

External preference mapping

External preference mapping is a technique designed to explain consumer results from data not generated by consumers (i.e. external data). The most common source of external data is sensory profiling data generated by trained descriptive panels. However, for texture, rheological data can also be used. We will give here several examples of such methods. In Suwansri et al. (2002), external preference mapping principles were applied to understanding the acceptance of Jasmine rice by Asian...

Sources of further information and advice

Department of Food Technology Director Pr P Fito Universidad Politecnica de Valencia PO Box 22012 46071 Valencia, Spain Tel +34 96 387 7360 Fax +34 96 387 7369 Research Laboratory in Food Engineering European AAIR project F-FE 253 97 'Texture of heat processed fruits' Leatherhead Food Research Association European FAIR demonstration project CT 98-3814 'Improvement of processed fruit and vegetable texture by using a new technology vacuum infusion' TMI International 20, Bd Eugene Deruelle 69432...

Correlation of sensory and instrumental texture attributes

Chikubu et al. (1985) demonstrated that overall eating quality, assessed by sensory evaluation, of cooked Japanese rice could be estimated using a multiple regression equation, which was based on protein content, amylograph viscosities, and cooking property. The eating quality was negatively correlated with protein and starch-iodine blue value of residual liquid after cooking, and positively correlated with amylograph viscosities (maximum viscosity, minimum viscosity, and breakdown). The...

Batterbreading and its significance to crispness

The terms batter, breading and coating, are often misused. Suderman (1983) described the distinctions among them. Batter was defined as a liquid mixture comprising water, flour, starch, and seasonings into which food products are dipped prior to cooking. Breading was defined as a dry mixture of flour, starch, and seasonings, applied to moistened or battered food products prior to cooking. Coating was referred to as the batter and or breading adhering to a food product after cooking. Batters and...

Difference tests

In the most common form of the test, two coded samples are presented either sequentially or simultaneously in a balanced presentation order (i.e. AB and BA). There are two variations on the test. In the directional difference variant, the panellists are asked to choose the sample with the greater or lesser amount of a specified characteristic. The panellists are usually instructed to make a choice (forced-choice procedure), even if they have to guess, or they may be allowed to record a...

Future trends

Further research into the option of using natural products or properties such as endogenous enzymes would fit extremely well into a trend to decrease the use of additives to optimise sensory food quality. A better understanding of the role of oxidative enzyme systems in product texture, but also in other sensory properties such as flavour and colour, would offer various openings to further decrease the use of ingredients. For instance, crops with desirable intrinsic properties could be...

Extrusion

The two key stages in the pasta process determining the cooking quality of pasta are extrusion and drying. Extrusion conditions determine the physical properties and internal structure of pasta dough. Over-heated, over-worked dough produces poor quality, sticky, slimy cooked pasta DeFrancisci, 2003 . Correct filling of the extrusion auger is essential to achieve maximum output of extruded product without excessive heating of dough Dalbon et al., 1996 . Mechanical energy is dissipated as heat....

Pectin constituents and related compounds

The relationship between texture and pectin constituents and some related compounds of the Japanese pear Pyrus serotina Rehder var. culta Housui during fruit enlargement and ripening was intensively analyzed by the Kojima research group at Saga university, Japan Sirisomboon et al., 2000b . Among the studied constituents, the alcohol insoluble solids in fresh weight AIS in FW appeared to have a significant effect on the textural properties of the fruit. The textural properties, which correlated...

Methodology for measuring actual and estimating bruise volume and bruise threshold

The results of Kawano et al. 1984 for Japanese pear Nijisseiki indicated that the quasi-static compression test showed a difference in the absorbed energy per unit bruised volume for different harvesting dates whereas the impact test showed no difference. This might be due to the difference in the shape of the bruise. Although both impact and compression cause bruising to spread inwards from immediately under the skin, the impact bruise spreads radially and the compression bruise conically...

Textural changes in bread during storage

Freshly baked bread has very different characteristics to that which has been stored for short periods of time. The nature and magnitude of the changes depends on the conditions under which the product has been kept. If held unwrapped then the products in most cases will dry out as moisture evaporates from the product to the surrounding atmosphere. The rate at which moisture is lost from the product depends in part on the differential in moisture content between product and atmosphere, and it...

Introduction

Pasta comes in diverse shapes and sizes but, in contrast to Asian noodles, which in some cases may have similar appearance, it is generally prepared by extruding semolina dough through a die. Asian noodles are prepared by passing common wheat dough through sheeting rolls. The texture properties of cooked pasta are the primary factor in overall assessment of pasta quality and play a dominant role in influencing consumer acceptance. The main textural properties which are important in cooked pasta...

One model fits all

There is today a body of knowledge developed on how specific texture attributes are governing the acceptability of particular food products. Textural Table 2.1 Relations between textural parameters and popular nomenclature Szczesniak, 1963 Table 2.1 Relations between textural parameters and popular nomenclature Szczesniak, 1963 Particle size and shape Particle shape and orientation Gritty, Grainy, Coarse, etc. Fibrous, Cellular, Crystalline, etc. Primary parameters Moisture content Fat content...

Quantitative evaluation of structuraltextural changes in food

Quantitative interpretation of MR-images is necessary in order to obtain correlations between MR-images and texture. When correlations are established, predictive models for texture using MR-imaging can be developed and subsequent MR-imaging can be used for on-line or at-line quality monitoring. In the following the few papers currently published which deal with a direct correlation between texture of food and MR-images through quantitative interpretation of the MR-images are described....

Empirical imitative and fundamental measurement

Instrumental methods have been classified into three main categories empirical, imitative and fundamental. Empirical tests often measure ill-defined variables that are indicated by practical experience to be related to some aspect of textural quality. Devices have been developed within different sectors of the industry that are appropriate to specific product types. Even for the same product type, different food manufacturers have developed their own in-house devices. Fuller details of the...

Hydration of rice

Soaking of rice in water is one of the unit operations during cooking, parboiling or production of quick cooked rice. Soaking is also an essential step in wet-milling of rice flour Chiang and Yeh, 2002 . During the soaking process water diffuses into the rice and is absorbed by the starch. The absorption of liquid water by rice grain proceeds by a heterogeneous mechanism. Mathematical analysis of non-stationary-state diffusion in solids of arbitrary shape can be simply expressed as follows...