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Effect of water activity on texture profile parameters of apple flesh
Abstract
Fresh apple with a water activity of approximately 0.99 was partially dehydrated, then equilibrated to nine water activity levels down to Aw 0.01. The water desorption isotherm, for apple is given. Instrumental texture profile analysis was performed at each Aw level. As the Aw decreased, hardness increased slowly, then rapidly at Aw 0.12 then decreased again at Aw 0.01; deformation first increased sharply then steadily decreased; springiness increased to Aw 0.33 then decreased; cohesiveness increased down to Aw 0.65, held steady to Aw 0.33 then decreased; gumminess and chewiness increased down to Aw 0.12 then decreased. Fracturability was present only at the extremes (Aw 0.99 and 0.01) and was absent at all other water activity, levels. Complex changes in textural properties occur as apple is dehydrated and most of these changes occur most rapidly near the BET monolayer level of water activity.
... Instrumental TPA of pears during storage is presented in Table 17.1. In the case of fresh fruits, such as pears, peaches, apple, plantain, and dried apple, the curves A 3 and A 4 as shown in Fig. 17.1 could not be observed [24,[73][74][75]. This indicated that during decompression there was no sticking or pull-off force from the material. ...
... Firmness and stickiness are also interrelated [77]. Bourne [74] presented the instrumental TPA attributes of fresh and dried apples (Table 17.2). The hardness of apple within water activity from 0 to 1 Fig. 17.2 Types of TPA graphs for different food products, (a) two positive peaks (i.e. ...
... Cohesiveness was found constant for fresh clingstone peaches for the two ratios of the areas (i.e., the cohesiveness parameter decreased at the same rate as the puncture test) [73], whereas cohesiveness of pears decreased with the ripening [24]. In the case of dried apple, cohesiveness increased with the decrease in water content and showed a plateau and then decreased further at low moisture content [74]. The plateau region was within 20 to 5% water content. ...
Texture is one of the sensory attributes that consumers use to evaluate food acceptability and purchasing decision. It is a very complex attribute where different senses (e.g., vision, hearing, and touch) are used simultaneously to assess different textural properties, such as hardness, cohesiveness, adhesiveness, gumminess, and springiness. These and others are evaluated using different sensory methods including the descriptive method. However, the subjective sensory measurements have limitations. Instrumental Texture Analysis Profile (TPA) is a very important breakthrough in the field of sensory analysis. It is now widely used by the food industry and scientific community. TPA is an objective method, and the parameters defined by this method can be correlated with the sensory textural attributes. Therefore, this method could be fast and needs easy sample preparation and could be used in quality control in the processing line. This chapter addresses the theoretical development of the TPA and its applications in different food products.
... [11][12][13] Texture changes of apple slices at different moisture content were reported by Krokida et al., [3] Lewicki and Lukaszuk, [4] and Bourne. [14] Bourne reported three periods in texture development with a moderate increase in hardness from 8.0 to 0.5 g=g moisture content, followed by a dramatic increase in hardness from 1,000 to 6,000 N at 0.3 g=g and a quick decrease at lower moisture content. In contrast, Krokida et al. reported two periods with hardness decreasing at the beginning of drying and increasing below 1.8 g=g of moisture content. ...
... Instrumental measurements showed an increase in cohesiveness in the range from 8.0 to 1.8 g=g and a decrease below 0.75 g=g. [14] The increase in cohesiveness of dried fruits compared to fresh fruitss was explained as a result of significant shrinkage. [16,17] Springiness reflects the ability of a compressed sample to return back to its original shape after the load is removed. ...
... With a tendency to increase at particular moisture content, springiness was recognized as a good indicator of a rubbery (elastic) state of the dried or semidried product. [7,18] According to Bourne, [14] springiness increased at the beginning of drying and decreased at moisture below 0.75 g=g. Rahman and Al-Farsi found the same trend for drying of dates. ...
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The objective of this study was to investigate the textural changes of apple slices undergoing convective drying. Texture profile analysis (TPA) measurements at 20% compression clearly showed three
periods in texture development: softening, uniform hardness, and hardening. In the period of softening, the initial hardness of 2,260 g exponentially decreased to 40–90 g, remained low in the moisture content range of 3.0–0.5 g/g, and rapidly increased below 0.5 g/g. Cohesiveness, springiness, resilience, and chewiness demonstrated similar three-phase behavior with the dependence on moisture content in the period of softening, constant values in the period of uniform hardness, and an inversion point below 0.5 g/g. In the period of hardening, the texture parameters were dependent on temperature.
... Dried apple chips should have crisp texture, pleasant flavor, and attractive appearance, so that they could be accepted for direct consumption. The above quality attributes are strongly influenced by two factors of temperature and moisture content (water activity, Aw); for example, Bourne (1986) showed that crispness of apple during drying was present only at the extremes aw (0.99 and 0.01) levels and at all intermediate levels of aw the texture is tough, chewy and leathery with zero crispness (Bourne, 1986). Hence, quick tools are required to evaluate the temperature and moisture content (Aw) of apple slices and monitor changes during drying processing. ...
... Dried apple chips should have crisp texture, pleasant flavor, and attractive appearance, so that they could be accepted for direct consumption. The above quality attributes are strongly influenced by two factors of temperature and moisture content (water activity, Aw); for example, Bourne (1986) showed that crispness of apple during drying was present only at the extremes aw (0.99 and 0.01) levels and at all intermediate levels of aw the texture is tough, chewy and leathery with zero crispness (Bourne, 1986). Hence, quick tools are required to evaluate the temperature and moisture content (Aw) of apple slices and monitor changes during drying processing. ...
The efficiency of two different modeling approaches for predicting moisture content of apple slices during drying were evaluated and compared. The experiments were performed at four air‐drying temperatures and at three levels of air velocity in the convective hot air dryer. Moisture content of apple during drying was predicted using theoretical model and Artificial Neural Networks (ANNs) models. The theoretical model was developed by solving heat and mass transfer equations simultaneously using numerical technique. A multilayer perceptron (MLP) neural network and radial basis function (RBF) network were used to develop neural network modeling. The agreement between the experimental results and the theoretical model predictions was quite good by considering the shrinkage dependent effective diffusivity in the model. Among different ANN structures, the best results were obtained for the MLP network with two hidden layers based on the statistical criteria (the coefficient of determination [R²] and mean squared error [MSE]). Although both two approaches could reasonably forecast the moisture content of apple slice during drying, the ANN model demonstrated better goodness of fit than theoretical model.
Practical application
Moisture content and water activity are important parameters in production of dried fruit, which have traditionally been measured by destructive and time‐consuming methods. Hence, quick tools are required to evaluate the moisture concentration and monitor changes during drying. Modeling can be considered as a helpful tool for prediction of moisture content as a function of time and space. The results of this study show that the two types of models can successfully predict changes in moisture content during drying. Applying these models at the commercial level can reduce variability in product quality and improve repeatability of the drying process.
... disulphide bonds) [3]. Physical network structures may originate from electrostatic bonds in the presence of di-or higher-valent cations, such as Ca 2+ , Mg 2+ , etc. Formation of a network structure is likely to be accompanied by significant changes in the rheological behaviour due to the physical gelation process [4]. ...
... TPA analysis [18] (depth of 10.5 mm, probe speed of 2 mm/s, trigger force of 1 g) measurements were performed on a TA.XTplus texture analyser (Stable Micro Systems Ltd., UK) using either a cylinder stainless steel probe (100 mm diameter) or cherry-pitted probe (5 mm diameter). The hardness (maximum force during the penetration), toughness, cohesiveness and gumminess [4] after 7 days' storage at 6.2 °C were determined from measured force-deformation curves. Measurements were carried out in two cycles at 10 °C. ...
Thermal analysis, texture profile analysis, water holding capacity and dynamic mechanical testing methods
were used for study of the physico-chemical and mechanical properties of the model chicken meat batters modified by the addition of amaranth flour. It was found that the addition of the amaranth effectively modified and improved their textural and nutritional properties. Further, the addition of calcium dihydrogen phosphate to the complex meat batter was shown to enhance formation of the creation of the three dimensional gel networks during protein denaturation, which resulted in increased tenderness of the product, as was demonstrated by decreased hardness, toughness and gumminess of the chicken batters with the increase of amaranth concentration. These findings were supported by dynamic mechanical vibration testing experiments and by increased water holding capacity. After amaranth flour addition, the observed frequency dependence of the
measured damping transfer function of the tested samples showed typical viscoelastic behaviour rather than pure elastic behaviour. The first resonance peak frequency shifted from 200 Hz for unmodified chicken batter to 120 Hz for batter with 1 wt% amaranth concentration and 0.45 wt% calcium dihydrogen phosphate. Formation of a hydrocolloid gel structure was confirmed by thermal analysis experiments, which showed decreased DTA protein denaturation temperature peak position from 101.3 °C for the unmodified batter to 90.6 °C for batter with 2 wt% amaranth. Interestingly, after addition of a Ca2+ crosslinking agent into the matrix, thermal resistance of the gel phase increased, which was reflected by the increased latter denaturation peak position
from 93.7 °C (for 1.5 wt% amaranth concentration chicken meat batters without calcium dihydrogen phosphate)
to 108.8 °C for 0.45 wt% crosslinking agent calcium dihydrogen phosphate and 1.5 wt% amaranth concentration
chicken meat batters.
... Structural changes of apple slices in convective drying were reported by Bourne. [32] , Krokida et al., [33] Lewicki et al., [34] and Martynenko et al. [28] Critical moisture content, where hardness dramatically increased, was identified as 1.8 g/g at 70°C. [33,34] or 0.3 g/g at room temperature. ...
... [33,34] or 0.3 g/g at room temperature. [32] These findings are in agreement with Martynenko et al., [28] who associated hardening of apple slices below 2.0 g/g with the glass transition of surface layer and below 0.5 g/g with the glass transition of the core tissue. ...
The purpose of this research was to develop an approach for porosity estimation in the process of convective air drying. Fresh apple slices were exposed to 80 °C drying to equilibrium moisture content 0.2 g/g. Porosity at different stages of drying was estimated using three approaches: (1) direct volume and mass measurements, (2) pycnometer measurements and (3) theoretical model. All three approaches were in good agreement in the range of moisture contents above 1.0 g/g. However, at moisture contents below 0.26 g/g, significant deviation of pycnometer measurements from both experimental estimates and theoretical model was observed. This difference could be explained by transformation of open pores into closed pores due to glass transition phenomenon. This study presents an example of separate quantitative estimation of total, open- and closed-pore porosity.
... In the last decades some studies reported that in some dried solid food matrices small amounts of sorbed water led to increased rigidity and firmness with behaviour similar to the anti-plasticization effect observed in synthetic polymers. This effect has been observed in food systems different for nature, composition and production process: precooked and freeze-dried beef (Kapsalis, Walker, & Wolf, 1970;Reidy & Heldman, 1972); corn meal extruded (Halek, Paik, & Chang, 1989), starch extruded (Shogren et al., 1992), gluten and tapioca starch films (Chang, Abd Karim, & Seow, 2006;Gontard, Guilbert, & Cuq, 1993), air-dried apples (Bourne, 1986), coffee beans (Pittia, Nicoli, & Sacchetti, 2007), extruded flat bread (Fontanet, Davidou, Dacremont, & Le Meste, 1997;Marzec & Lewicki, 2006), breakfast cereals (Gondek & Lewicki, 2006) as well as other more complex starch-meat extruded matrices (Moraru et al., 2002). Harris and Peleg, 1996). ...
... Anti-plasticization effect largely depends on the type of physical structure. Dried cellular structures with rather intact cell walls could undergo to an anti-plasticization effect upon moisture content (Bourne, 1986;Borges & Peleg, 1997;Pittia et al., 2007) and the same behaviour was showed by cell foods such as extruded or puffed foods (Hsieh et al., 1990). ...
Water is the most effective plasticizer in food matrices, decreasing glass transition temperature (Tg) and mechanical resistance and determining a softening effect with the increasing of its concentration. However an opposite effect (i.e. hardening, toughening) could be observed in some food and in specific moisture or aw range and this is referred to an anti-plasticization effect. Several are the possible causes for this phenomenon and various are the factors that have been recognized to affect its occurrence in a food matrix: mechanical testing method, mechanical parameter tested, type of food (composition and micro-macrostructure).In this paper, several studies on anti-plasticization effect of water are reviewed by focusing the attention on the interactions water–food matrix and in particular to those occurring in amorphous cell foods. The different chemical and physical factors that affect this phenomenon are also discussed.The simultaneous occurrence of a plasticization and anti-plasticization effect of water, even if in different aw range, and the results of studies on amorphous food matrices may suggest an important effect of water–matrix interaction on the textural properties.
... The highest reduction was observed in mango, while the lowest in banana and apple fruits. The values of a w examined in our study were pretty in line with those reported by [44] and [45] who observed a w in the range of 0.970 -0.996 in fruits, vegetables and meat. The decrease in water activity of fruits with storage time was attributed to the loss of water by natural drying process. ...
The study aimed to investigate the effect of short-term postharvest storage on the fungal diversity and physicochemical and sensory quality of fresh fruits viz. apple, banana, grapes, guava and mango. The fruits were stored at ambient room temperature (28°C) and evaluated for fungal diversity, total fungal and bacterial counts, moisture content, water activity (a w), vitamin C content and sensory characteristics such as appearance, odour, taste, texture and overall acceptability at the initial (0 day), 7 and 14 days of storage. The dominant fungal genera isolated from all the fruits were Aspergillus niger (35.38%), Penicillium spp. (28.24%), Rhizopus stolonifer (25.35%) and Aspergillus flavus (21.35%) after 14 days of storage. Both the total fungal and bacterial counts increased significantly over storage time. However, the percent moisture content and a w level of all the fruits decreased significantly (P < 0.05) after 14 days storage. The storage time did not significantly (P > 0.05) affect the vitamin C content of fruits. Regarding sensory quality, apple got the highest score for appearance, odour, taste, texture, and overall acceptability followed by grapes whereas banana and guava got the lowest score for overall acceptability after 14 days storage. It was concluded that, at ambient room temperature a diversity of fungal species attacks fresh fruits and their shelf life, nutritional and sensory quality start deteriorating as early as after 3 days of storage.
... Several studies have reported this antiplasticization effect in food systems different by nature, composition and production process: starch extruded, [24] gluten and tapioca starch films, [25] air-dried apples, [26] coffee beans, [27] extruded flat bread, [28,29] breakfast cereals [30] as well as other more complex starch-meat-extruded matrices. [31] Experimental data of T g were well fitted to the Gordon-Taylor model, showing satisfactory R 2 values. ...
The effect of microstructure on the stability of red onion encapsulated by two processes: (a) spray drying and (b) spray freezing into liquid cryogenic, was evaluated in this work. Water sorption isotherms and glass transition temperature of microcapsules conditioned at various water activities were determined and coupled to evaluate conditions of storage stability. The stability of red onion microcapsules was influenced not only by water activity increase but also by microstructural differences between the two types of microcapsules. Critical water content was a useful tool to establish adequate storage conditions for red onion microcapsules.
... Texture is a major concern in food palatability. Among varying texture properties, chewiness is sometimes considered as an undesirable feature of food such as apple (Bourne, 1986), bread (Gray & Bemiller, 2003), meat, and fish (Brauer, 1993;Sveinsdottir et al., 2009;Sveinsdottir, Martinsdottir, Hyldig, & Sigurgisladottir, 2010). However, high elasticity of foods may be popular or necessary in some other products like as Oden sausages which consist of elastic gum-covered meat, Warabimochi, a dessert gel based on plant polysaccharides, Mochi, a gelatinous rice cake which traditionally consumed at New ...
Textural, mechanical, microstructural and thermal properties of reconstituted pimiento alginate‐guar gels subjected to thermal and mechanical stresses during pasteurization process were investigated. Alginate‐guar gelling system at ratio 2:1 at different calcium chloride concentrations (2 to 8%) and varying acid conditions including citric and lactic acid 1% were evaluated. Textural profile analysis (TPA) parameters viz. hardness, springiness, gumminess, cohesiveness, adhesiveness as well as mechanical properties, structural, thermal and morphological characterizations of pimiento strips were examined. Gel strength and elasticity of pimiento strips were increased at higher calcium levels. Fracturability was decreased clearly revealed the gel system, regain its strength in spite of high pulp content (25%) and can maintain its own structure. Increase in hardness and reduction in springiness showed loss of elasticity, which may be attributed to the gel shrinkage during thermal processing, making it more compact and dense. Therefore, the restructured pimiento strips were completely thermo stable at pasteurization temperature. By increasing alginate and calcium level in the pimiento strip, glass transition temperature (Tg) was reduced from 112 to 98 oC. Fourier transform infrared spectroscopy (FTIR) studies confirmed that the gel network structure at acidic conditions was stable and acid type does not have significant effect on the chemical interactions. The microstructural results showed ellipsoidal and compact structure in which can be an evidence of high elasticity and rigidity of pimiento gels. These results completely approved the high elasticity and rigidity of pimiento strips and their ability to sustain successfully thermal and mechanical stresses with appreciable textural integrity during processing such as pasteurization.
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... The detailed conditions and references for such methods have been described in Prof. Bourne's textbook (Bourne, 2002). Based on research by Prof. others in 1965-1985, many factors, such as specimen size (Brinton & Bourne, 1972), the shape and size of the probe (Brennan & Bourne, 1994), the type of deformation (compression, tensile, shear, etc.) (Bourne, 1966;Szczesniak & Bourne, 1969), the degree of deformation (Bourne & Comstock, 1981), the rate of deformation (Brennan & Bourne, 1994), the lubrication of probes (Brennan & Bourne, 1994), environmental conditions (Bourne, 1986), and plant cultivars, growth stages, and cultivation conditions, were found to influence the results of texture studies (listed in references in Bourne, 2002). Vincent, Saunders, & Beyts, 2002). ...
Practical applications:
Food texture studies conducted during the last century are beginning to evolve. Based on previous publications in the Journal of Texture Studies, I believe that several areas can be further examined in this century. First, methods to evaluate the textures of heterogeneous materials, such as fruits and vegetables, require improvements. Second, the monitoring of rapid changes in food texture during oral processing should be considered during the design of food products. Third, a new instrumental method that mimics the movement and breakdown of soft foods by the tongue is being developed. The optimization of food processing to reduce the loss of agro-products and production of high-quality foods both require more attention according to the Sustainable Development Goals adopted by the United Nations in 2015.
... Fresh shrimps have firm texture which turns mushy during storage (Pornrat et al., 2007). Most foods have unique morphological characteristics which depend on the chemical and biophysical characteristics (Bourne, 1986). ...
Shrimp is one of the most popular seafood around
the world. Sensory characteristics, especially textural
parameters are major concerns of consumers
for fish and shellfish. For this reason, it is important
to measure the effect of the processing methods on
texture. This study reports the effect of various
processing methods on the instrumental texture
profile of pacific white shrimp (Litopenaeus vannamei)
and black tiger shrimp (Penaeus monodon).
Hardness 1 of L. vannamei decreased during
blanching, cooking and steaming whereas in P.
monodon the reverse was true. Similar to hardness
1, in cooked L. vannamei hardness 2 value decreased
but it increased in cooked P. monodon. Increase in
chewiness in P. monodon was observed during
cooking and blanching but in L. vannamei, chewiness
decreased during cooking and blanching but increased
during microwave cooking. Variation in
textural parameters was observed with different
processing methods and different shrimp species.
... It has been reported that spectra techniques perform well in the determination the content of water, protein, fat and other composition in fish Masoum et al., 2012;Zhu et al., 2011). Particularly for mechanical properties analysis, the mechanical property is the external performance of some complex chemical and biophysical features, which can be detected as the variations of spectra (Bourne, 1986). Isaksson et al. (2002) employed VIS-NIR spectroscopy technique to evaluate the mechanical properties of farmed Atlantic salmon. ...
The potential of using hyperspectral imaging in the wavelength region of visible and short-wave near infrared range (400-1000 nm) was investigated for the rapid and non-invasive determination of mechanical properties in different parts of prawns (Metapenaeus ensis). Hyperspectral cubes were acquired at the second and fourth segments of prawn and their mean spectral data were extracted. The quantitative relationship between the spectral data and their corresponding reference mechanical properties (measured by Instron universal testing machine) were established by partial least square regression (PLSR) and least-squares support vector machines (LS-SVM) algorithms, respectively. Successive projections algorithm (SPA) was carried out to select the most important and effective wavelengths, which was an optimization process for improving the performance of established models. Then the optimized models were built using PLSR and LS-SVM based on the selected wavelengths and their performances were compared to find the best model for predicting mechanical properties of prawn. As a result, the SPA-LS-SVM model was considered as the best predictive model to determine the hardness, gumminess and chewiness values of prawn with correlation coefficient of prediction (R-p) of 0.8489, 0.8096, and 0.8596 and root mean square error of prediction (RMSEP) of 0.1465, 0.1445, and 0.1258, respectively. Visualization of distribution maps for the mechanical properties within the region of interests (ROI) of prawns was also presented. The overall results revealed that hyperspectral imaging technique had a great ability for predicting the mechanical properties of prawn rapidly and non-invasively. (c) 2014 Elsevier Ltd. All rights reserved.
... Chewiness is not always a desirable textural feature of foods. A leathery texture of apples is clearly undesirable (Bourne, 1986), while it is usually undesirable for bread (Gray & BeMiller, 2003) and often undesirable for meat and fish (Brauer, 1993;Sveinsdottir et al., 2009;Sveinsdottir, Martinsdottir, Hyldig, & Sigurgisladottir, 2010). However, several popular Japanese foods are characterized by very high elasticity and an almost "rubbery" texture that requires prolonged mastication. ...
... Rubbery–leathery transformation was also observed by Seow and Thevamalar (1988) for rice based products when hardness is plotted versus water content. Bourne (1986) studied the hardness of apple with water activity from 0 to 1 and observed a sharp increase at rubbery–leathery transition. ...
Instrumental texture profile analysis (TPA) of date flesh was measured as a function of moisture content. The quality attributes measured were hardness (H), cohesiveness (CO), adhesiveness (A), springiness (S), resilience (R), and chewiness (CH). Hardness, chewiness, and resilience increased exponentially with the decrease of moisture content, whereas adhesiveness, cohesiveness and springiness increased exponentially with the decrease of moisture content and showed a maximum value at critical moisture content 21.5%. Below the critical moisture content, there was a sharp decrease in the attribute values. Two factors: elastic nature (hardness, adhesiveness, and chewiness) and plastic nature (cohesiveness, resilience and springiness) can explain the instrumental TPA attributes of dried dates.
... Rubbery-leathery transformation was observed by Rahman and Al-Farsi [31] who reported that the hardness of dates increased exponentially with the decrease of moisture content. This transformation has been also reported by Bourne [32] for apples, by Seow and Thevamalar [33] for rice-based products, and by Kahyaoglu et al. [34] for cheeses. ...
Alginate based simulated particles with spores of heat resistant microorganisms distributed in them are used in the biological validation studies and the process lethality is usually calculated using initial and final counts. Such particles should be hard enough to save their integrity till the end of the thermal process. Also, they should not adhere to each other inside the can and to the can inner wall. In this study, a response surface methodology was used to determine the optimum conditions that give maximum hardness and minimum adhesiveness of meat and carrot alginate fabricated particles. Sodium alginate concentration (1.5–6.5%), calcium chloride concentration (1.0–3.0%) and immersion time in the calcium chloride solution (4–44 hours) were employed as factors at five levels and the instrumental textural properties were assessed using the texture profile analysis. For each response (hardness and adhesiveness), a second-order polynomial model was developed using multiple linear regression analysis. Hardness of the fabricated particles was found to significantly increase (p < 0.05) with increasing sodium alginate concentration and immersion time in the calcium chloride solution, while calcium chloride concentration had no significant effect. On the other hand, adhesiveness (in absolute values) of the reconstituted particles increased significantly (p < 0.05) with increasing sodium alginate while the other two parameters had no significant effect. Applying desirability function method, optimum conditions were found to be sodium alginate concentration of 4.7%, calcium chloride concentration of 2.6% and immersion time of 32.0 and 30.8 hours for carrot alginate and meat alginate fabricated particles, respectively. Fabricated particles using the optimum conditions did not show any variability in hardness values, unlike real food particles, when subjected to thermal processing. This investigation could help food processors using continuous agitation processing to fabricate firm and thermally stable reconstituted particles to be used in the biological validation studies.
... Kapsalis, Walker, and Wolf (1970) found maximum toughness of freeze-dried beef at a w = 0.18. Maximum hardness of dried apple occurred at a w = 0.12 (Bourne, 1986). Maximum compressive strength of two cornmeal extrudates occurred at 10-15% moisture (Halek, Paik, & Chang, 1989). ...
Flat extruded wheat and rye bread was equilibrated to variable water activities using saturated salt solutions. At those water activities the bread was subjected to compression and three-point breaking tests. Compression test showed that water antiplasticizes both investigated breads. In the range of water activities from 0 to 0.53 for wheat bread, and from 0 to 0.59 for rye bread, the compression force reached 600 N at true strain 0.8. Compression proceeded in two steps; hence the mechanical resistance of the surface layers is larger than that of the center of the slice. Above the critical water activities water plasticizes the breads, and decrease of compression force with increasing water activity is recorded.Three-point breaking test shows that water affects mechanical properties of extruded breads in a complicated fashion. At water activities lower than 0.15, water plasticizes the material. At higher water activities antiplasticizing effect of water is evident. The critical water activities at which the plasticizing effect of water is evident are lower than those in compression test. The respective values are 0.49 and 0.44 for wheat and rye bread, respectively. Three-point breaking test is more sensitive to the kind of investigated material and shows larger differences between wheat and rye bread than the compression test.Critical water activities correspond to hydration levels at which internal dynamics of macromolecules begins. Hence, it is suggested that rotational and translational movements of macromolecules caused by adsorption of water are pronounced by the plastic deformation of the material.
... Maximum hardness was always observed at the lowest RH (33%). Bourne (1986) showed that hardness of apple tissue increased logarithmically as a w decreased (up to a w values of 0.12), similar to what occurs in protein gels (Beveridge, Arntfield, Ko, & Chung, 1980). Fracture of dried food products is a complex phenomenon that depends largely on the material itself, the plasticizing effect of water as well as on the presence and propagation of microscopic cracks induced by processing (Castro & Aguilera, 2007). ...
Blanching, freezing and drying induce major changes in the physical properties of processed foods. Microstructural changes induced by these processes in apple discs were related to the degree and kinetics of browning and to fracture mechanics after drying and later storage at 70 °C under a wide range of relative humidity (RH). Blanched and unblanched apple discs were dehydrated by vacuum drying or freeze-drying to induce the formation of different structures, then equilibrated from 33% to 75% RH and stored at 70 °C in order to promote browning. Color changes on the surface of apple discs were analyzed non-invasively by image analysis using a computerized vision system. Pre-treatments and drying conditions modified the structural characteristics of apple discs, which in turn, changed sorption properties, texture hardness and browning development. Microstructural changes (e.g., loss of cellular integrity) promoted higher browning rates, the rate and degree of browning was analyzed.
Consumers’ demand toward the consumption of various foods is growing rapidly, and sensory or organoleptic properties in this regard play a significant role to maintain the quality standards apart from nutritional, physicochemical, and microbiological properties. Evaluation of sensory properties, e.g., appearance, color, mouthfeel, taste, body and texture, odor, flavor, aroma, and overall acceptability are the important determinants to assess the food quality. The sensory experiences evoked by various foods and processed food products are the key to deliver pleasure, and these are crucial to commercial success. It is very much essential to measure, understand, and optimize consumers’ sensory experiences for designing and marketing food products. The science of sensory evaluation requires a suitable understanding of different sensory methods, and their applicability to solve sensory enquiries and sensory parameters, and their efficient use in describing the quality characteristics of foods and their products. Sensory attributes of food products can be evaluated using two methods, namely, subjective or qualitative and objective or quantitative techniques. Subjective measurement of sensory attributes deals with organoleptic responses to food qualities and is conventionally measured by a hedonic rating test with the active role of trained panelists. An objective or discriminative analysis is essential for routine quality control and usually, the application of instrument or equipment is necessary for testing purposes. The most effective use of sensory evaluation is the establishment of data relationships between consumer responses, instrumental assessment, and descriptive sensory measurements. Both the subjective and the objective methods of sensory evaluation are important in the measurement of food quality attributes and their control in processing and preparation. Therefore, sensory analysis is an essential tool to judge the quality characteristics of the newly developed product and consumers' acceptability. In this chapter, an overview on the sensory attributes and their measurement methods including facilities and panels are presented.
Supercritical fluid extrusion (SCFX) is a novel process combining traditional extrusion and supercritical fluid technologies. The objective of this study was (i) to assess the effect of sugar, maltodextrin and cornstarch on the physical properties of milk protein concentrate (MPC) puffed extrudates and (ii) to compare the physical and textural properties of SCFX puffed MPC products with commercially puffed cereal products. Results showed that the nutritious MPC puffed products with carbohydrates can be made with textural properties (hardness, brittleness and crispness) resembling those of the commercial samples. The porosity of F2 (0.573) was assessed to the commercial product C1 (0.543) and C2 (0.595), the specific length of F3 (50.41) was assessed to C1 (45.51) and F4 (80.14) was assessed to C2 (78.12). The hardness of extrudate F3 (435.49 KPa) was assessed to C2 (482.7 KPa). The Young's modulus of F5 (87.03) was assessed to C2 (80.57). The starches affected the crispness of the extrudates, and sugar affected the hardness and brittleness significantly.
Texture is one of the most important quality attributes of dried foods. It provides the most synthetic information about food quality, which is related to sensory perception, mouthfeel and customer preferences. Since texture is sensitive to drying regime, it is important to observe texture changes in real-time to achieve desirable quality. However, there is still lack of information about fruit textural changes as a function of moisture content. The objective of this study was to measure texture parameters with moisture change during convective drying of apple slices. Drying was performed in a pilot-scale tray dryer UOP8 with regulated temperature and constant air velocity. Effect of moisture content on texture parameters was evaluated from drying experiments at 40, 60 and 80 o C. Texture parameters were measured by texture profile analysis (TPA), using TA-XT Plus texture analyzer in two-cycles, using calibrated 50kg load cell and 2 mm/s compression rate to 20% strain. Effect of non-uniform compression due to the bending and curved surface of apple slices was mitigated through modification of TPA protocol. In our study we used two probes: 2 " cylinder plate probe TA-25A at high and moderate moistures and 0.5 " ball probe T-18 at low moisture content. Measurements showed that texture development during drying undergo three different stages: softening, uniform hardness and hardening. Softening was determined by dropping of turgor pressure with moisture loss (9.5-3.0 g/g). Uniform hardness was determined by equilibrium between volumetric and surface moisture, resulted in viscoelastic behavior of surface layer of semi-dried apple slices (3.0-0.5 g/g). Hardening was observed at the end of drying with moisture below 0.5 g/g. Cohesiveness was increasing with moisture loss to 0.8-0.9, but dropped to 0.15-0.3 at low moisture content due to the hardening of samples at the end of drying. Adhesiveness was dependent of moisture content with the highest value in fresh apples, gradually decreasing to zero at moisture 1.8-2.4 g/g. This preliminary study showed that texture parameters could be used as an early-stage indicators of fruit quality in the process of drying.
The properly cured fresh sand pear (Pyrus pyrifolia) fruit was sliced (quarters and halves) and blanched (10 and12 min) in boiling water and dried osmotically by mixing with dry sugar (fruit:sugar ratio 2:1) followed by mechanical drying at 60°C. The slices were dried to 10, 25 and 40% moisture and packaged in locally available flexible pouches made up of high density polyethylene, polypropylene and aluminium laminated materials, respectively. These pouches were stored at ambient conditions. The sensory evaluation of these slices carried out by a group of semi trained panelists after 6 months storage revealed acceptability of slices with 25% moisture. The average hardness and chewiness corresponding to this was 7967 g f and 1080.0 g f*s in comparison to 6589.2 g f and 1449.5 g f*s for fresh fruit.
The effects of water management and nitrogen fertilization, on yield, quality, and sensory profile of the red table-grape cultivars Redglobe and Michele Palieri were studied. Two irrigation volumes (1000 and 2000 m(3)/ha) and two nitrogen levels (120 and 180 kg/ha) were imposed. The effects of these parameters were cultivar-dependent. For Redglobe, irrigation resulted in significant increases in soluble solids and titratable acidity and significant decreases in resistance to compression and resistance to penetration. Increased nitrogen fertilization level exerted a significant effect only on titratable acidity (increased) and resistance to compression (decreased). Significant interactions between the two practices were demonstrated for soluble solids, pH, and resistance to compression. For Michele Palieri, increased irrigation resulted in significant decreases in soluble solids and resistance to penetration and significant increases in resistance to compression. Higher nitrogen caused decreases in berry weight but increases in soluble solid content and resistance to mechanical stress. Significant interactive effects were highlighted on yield, cluster weight, titratable acidity, and resistance to penetration. The lack of a significant correlation between physical/chemical and sensory results indicated that the changes induced by the agricultural practices on composition and mechanical behavior of berries were not perceptible by a trained panel.
Guava is one of the most important commercial fruit crop of India. It excels most other fruits in terms of productivity, palatability and vitamin C content. But at the same time it has very short shelf life and can not be exported. Modified Atmosphere Packaging (MAP) is intended to create an appropriate gaseous atmosphere around a commodity packaged in film to enhance shelf life and conserve the quality of packaged produce (Rai et al 2002). Hence, the study on design and evaluation for guava was undertaken to select suitable films for extending the shelf life of guava, based on respiration rate of Guava and permeability of commercially available films at different temperatures. The film selected was Low Density Polyethylene (LDPE) with 100 and 150 (0.25% perforations) gauge thickness. The guava fruits of Allahabad Safeda and Lucknow-49 varieties were packed and sealed in these films. The packed fruits were stored under room temperature (11-17°C) and refrigerated temperature (8°C). The quality parameters evaluated were Physiological Loss in Weight (PLW), color change and texture. PLW, color change, cohesiveness and resilience increased with storage time whereas hardness and chewiness followed the reverse trend. On the basis of results and statistical analysis, it was found that Allahabad Safeda and LDPE 100 was the best variety treatment combination for extending the shelf life and maintaining the quality of guava up to 42 days at low temperature and 27 days at room temperature as compared to 18 days for control fruits.
The need for increasing improvements in the quality of food products conducted to an increased interest in osmotic treatment. This technology involves the partial dehydration of a water-rich solid foodstuff, either whole or in pieces, through immersion in an osmotic solution. In fact, osmotic treatment is applied with the goal of modifying the composition of food material through partial water removal and impregnation of solutes, without affecting the structural integrity of products. Three kinds of osmotic treatments have been used, depending on the pressure applied on the system: OD (osmotic dehydration at atmospheric pressure), VOD (osmotic dehydration at vacuum pressure) and PVOD (pulsed vacuum osmotic dehydration). However, the most common are OD and VOD technologies. Some of the potential applications of osmotic treatment in food technology include: (i) the development of compositionally formulated products by introducing functional food ingredients, such as firming agents, antioxidants, antimicrobial and nutraceuticals; (ii) preserving color, texture, natural flavor and aroma and any heat-sensitive nutrient components; and (iii) pre-treatment before freeze-drying for improving final product quality. However, the osmotic treatment on this wide range of applications requires an appropriate choice and control of operating conditions, such as processing temperature, pressure, time, composition, geometry of the food pieces and contact between the food pieces and the solution. The purpose of this chapter is to analyze the main effects of operating conditions and responses of the porous fruits to osmotic treatment, both at atmospheric and vacuum pressure, and to describe the important developments related to this technology in the fruit industry. Quality aspects of osmotic treatments on processed fruits, as well as technical challenges of this technique will also be discussed.
The general objective of this work was to evaluate the changes in the texture of raw white shrimp, stored whole in ice for up to 14 days, by instrumental texture analysis of the flesh after peeling off the carapace. Effect of test method (relaxation, compression, texture profile analysis, cutting, and penetration tests), test speed (0.1, 0.5, and 1.0 mm/s), and test position on sample (second, third, and fourth segments of abdominal musculature) were studied to measure the textural attributes of shrimp. Mechanical parameters (force at yield point, stiffness, toughness, and shear/penetration work) increased significantly during the 14 days of storage. Shrimp muscle maintained firm texture up to 4 days of storage after harvesting. At that time, the texture became soft, stiffness of the skin layer increased, and then pH values in the shrimp reached a value higher than 7 (alkaline). A linear model with a high coefficient of determination (R > 0.75, for all parameters obtained from the penetration test with the spherical probe) described adequately the mechanical properties of iced shrimp during storage. Comparing several methods, the penetration test on the second flesh segment using a spherical probe at a speed of 0.1 mm/s and using penetration work as a parameter gave the best results to clearly indicate the changes in textural properties of iced shrimp with a high correlation coefficient during storage time (R = 0.83), while other test methods failed to provide an indication of deterioration.
Viscoelastic properties for carrot and potato were experimentally determined by stress relaxation tests using uniaxial compressive tests of cylindrical specimens at various deformation rates (5,10 and 20 cm/min). Stress relaxation tests were performed following conventional drying at 70°C and 15% humidity for various moisture contents ranging from 10 to 80%. The tests were performed using a Zwick testing machine and the stress relaxation data were modeled using a two-term Maxwell model. It was shown that the relaxation behavior of carrot and potato was not affected by deformation rate, but it was sensitive to moisture content. The remaining force and relaxation time of the elastic component were found to be depended on moisture content. Drying tends to decrease the remaining force and the elastic relaxation time of carrot and potato until a certain moisture content (1.7 and 1.9 kg/kg db). Further uptake of water tends to increase the remaining force and the elastic relaxation time for both materials. The viscous component of Maxwell model does not seem to be affected by moisture content.
The rheological behavior of osmotically dehydrated apple and banana was examined under uniaxial compression and relaxation tests of cylindrical specimens. Compression and relaxation tests were performed, following air drying of osmotically pre-treated samples, at various moisture contents ranging from 0.1 to 1.5 kg/kg dry basis. The maximum stress and the corresponding strain were correlated to the moisture content using simple mathematical equations. It was shown that both parameters increase as water was removed and their values are significantly higher than the corresponding values for untreated air dried samples. The effect of moisture content on compressive behavior of osmotically dried materials was introduced through its effect on the four model parameters: the maximum stress (σmax) the maximum strain (ϵmax), the elastic parameter (E) and the viscoelastic exponent (p). The stress relaxation data of osmotically treated samples were modeled using a two-term Maxwell model. It was shown that osmotic pre-treatment increased the remaining force and it decreased the relaxation time of dehydrated samples. The osmotic dehydration and therefore the sugar gain tend to increase the viscous nature of fruits and decrease their elasticity for both materials, causing plasticity of the structure.
IntroductionPolymer-Diluent Interactions: Plasticization versus AntiplasticizationWater, the Ubiquitous Diluent, as Antiplasticizer at T < TgConclusion
References
Mechanical properties of dried bread (a cellular baked product) equilibrated at different water activities (Aw) were measured using three-point bending and uniaxial compression to compare their responses to moisture sorption. The glass-to-rubber transition was clearly demarcated in all the mechanical property-Aw curves, although there were differences in critical Aw (0.32–0.56) at which the dramatic changes in mechanical properties occurred. The role of water appeared to be strictly that of a plasticizer where flexural mechanical parameters were concerned, leading to reduced modulus and fracture stress but increased fracture strain with increasing Aw. Uniaxial compression tests revealed moisture-induced mechanical antiplasticization effects on the material in the glassy state which resulted in maximum compressive fracture stress but minimum fracture strain over the Aw range from 0–0.56. Compressive modulus apparently was not affected much by moisture sorption up to an Aw of 0.43, above which it decreased sharply.
W ater Activity in Foods: Fundamentals and Applications is a one-of-a-kind reference text that brings together an international group of food scientists, chemists, and engineers to present a broad but thorough coverage of an important factor known to influence the attributes of foods – water activity (a w). A team of experienced editors designed this book for lasting value as a sound introduction to the concept of water activity for neophytes and seasoned professionals in both academe and industry. Topics have been carefully selected to provide a comprehensive understanding of the mechanisms by which water activity influences the quality, shelf life, and safety of food products. Other approaches for studying water relations in foods are also discussed, including the polymer science approach and water mobility by nuclear magnetic resonance. Concepts in the practical uses and applications of water activity for food formulation, processing, and storage are generously illustrated with practical examples from the food industry that will facilitate later application by professionals in their own laboratories and production facilities. Progressing from the scientific to the practical, the book examines the fundamentals and relationships of water activity, ranging from glass transition theory and the measurement of moisture content, water activity, and isotherms, to ways in which water activity affects microorganisms, chemical reaction rates, and physical properties, to moisture gain and loss through packaging, water activity as a hurdle, and applications of a w management in the food industry and non-food systems. Water Activity in Foods belongs on the shelves of all food science professionals for use in product development, quality control, and food safety. Students and newcomers to these areas will appreciate the instructional approach adopted by the experienced teachers and industry specialists who have contributed chapters to this comprehensive overview.
This chapter contains section titled:
W ater Activity in Foods: Fundamentals and Applications is a one-of-a-kind reference text that brings together an international group of food scientists, chemists, and engineers to present a broad but thorough coverage of an important factor known to influence the attributes of foods – water activity (a w). A team of experienced editors designed this book for lasting value as a sound introduction to the concept of water activity for neophytes and seasoned professionals in both academe and industry. Topics have been carefully selected to provide a comprehensive understanding of the mechanisms by which water activity influences the quality, shelf life, and safety of food products. Other approaches for studying water relations in foods are also discussed, including the polymer science approach and water mobility by nuclear magnetic resonance. Concepts in the practical uses and applications of water activity for food formulation, processing, and storage are generously illustrated with practical examples from the food industry that will facilitate later application by professionals in their own laboratories and production facilities. Progressing from the scientific to the practical, the book examines the fundamentals and relationships of water activity, ranging from glass transition theory and the measurement of moisture content, water activity, and isotherms, to ways in which water activity affects microorganisms, chemical reaction rates, and physical properties, to moisture gain and loss through packaging, water activity as a hurdle, and applications of a w management in the food industry and non-food systems. Water Activity in Foods belongs on the shelves of all food science professionals for use in product development, quality control, and food safety. Students and newcomers to these areas will appreciate the instructional approach adopted by the experienced teachers and industry specialists who have contributed chapters to this comprehensive overview.
W ater Activity in Foods: Fundamentals and Applications is a one-of-a-kind reference text that brings together an international group of food scientists, chemists, and engineers to present a broad but thorough coverage of an important factor known to influence the attributes of foods – water activity (a w). A team of experienced editors designed this book for lasting value as a sound introduction to the concept of water activity for neophytes and seasoned professionals in both academe and industry. Topics have been carefully selected to provide a comprehensive understanding of the mechanisms by which water activity influences the quality, shelf life, and safety of food products. Other approaches for studying water relations in foods are also discussed, including the polymer science approach and water mobility by nuclear magnetic resonance. Concepts in the practical uses and applications of water activity for food formulation, processing, and storage are generously illustrated with practical examples from the food industry that will facilitate later application by professionals in their own laboratories and production facilities. Progressing from the scientific to the practical, the book examines the fundamentals and relationships of water activity, ranging from glass transition theory and the measurement of moisture content, water activity, and isotherms, to ways in which water activity affects microorganisms, chemical reaction rates, and physical properties, to moisture gain and loss through packaging, water activity as a hurdle, and applications of a w management in the food industry and non-food systems. Water Activity in Foods belongs on the shelves of all food science professionals for use in product development, quality control, and food safety. Students and newcomers to these areas will appreciate the instructional approach adopted by the experienced teachers and industry specialists who have contributed chapters to this comprehensive overview.
The cutting resistance, of thin rectangular strips of a restructured dehydrated fruit bar was measured over a range of water activity, 0.30-0.97. There was a 100-fold increase in cutting force as the product was dried from an initial cutting resistance of 4.4 N at aw, = 0.86 to a maximum of 452 N at aw= 0.33. Below a water activity of 0.33, samples became brittle and showed lower cutting resistances; for example, 68 N at aw= 0.30. The major ingredients in the fruit product affecting cutting resistance were the level of apple puree and maltodextrin.
Glycerol improved film extensibility but reduced film puncture strength, elasticity, and water vapor barrier properties. The plasticizing effect of water was highly temperature dependent. During hydration of gluten film, a sharp decrease in puncture strength, elasticity, and an increase of extensibility and water vapor transmission rate were observed at 5, 30 and 50°C for respective water contents of 30 (0,8 aw,), 15 (0,7 aw) and 5% (0,4 aw). This was related to disruptive water-polymer hydrogen bonding and glass-to-rubber transition.
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Two corn meal extrudates with initial moisture contents of 22% and 31% W.B. were partially dried to moisture contents from 7% to 31% W.B. and stored in hermetically sealed containers to allow redistribution of the water. Compressive strength, compressive relaxation and instrumental texture profile analyses (fracturability, cohesiveness, springiness, gumminess and chewiness) were measured. Compressive strength increased with decrease in moisture content from 31-15%, reached a maximum between 15-10% and then decreased below 10%. Stiffness showed a similar relationship, with the maximum occurring between 10-6%. Relaxation modulus increased with decrease in moisture content over the range studied. Relaxation time was a minimum at 15% moisture content. Fracturability had a similar relationship to moisture content as that of compressive strength. The textural behavior was ductile and chewy at moisture contents above 15% but became crisp or crunchy and collapsed with brittle fractures at lower moisture contents. Both compressive properties and texture profile parameters of the corn meal extrudates changed considerably with changes in moisture content.
Rheological properties of Thompson seedless raisins were measured in relation to the water activity of the berry using the compression-relaxation test. The water sorption isotherm of raisins was determined according to the COST 90 procedure.It has been found that the rheological properties of raisins are strongly dependent on water activity. At water activities lower than 0.25, the raisin behaves as a brittle body. It is inferred that sugars in dry raisins are amorphous and the properties of the glass are pivotal to the characteristics of the material. In this state the probability of breakage during compression is high.At water activities above 0.3, a plasticizing effect of water is manifested. The raisin becomes a viscoelastic body but until aw = 0.4, the elastic component is not strong because of the high viscosity of the interior of the berry. Further uptake of water and increase of aw leads to dilution of the sugar solution and increased elasticity of the skin. The relaxation behaviour of compressed raisins changes around aw = 0.4. The elasticity of the skin is sufficiently high to prevent breakage of raisins during the compression test at stresses lower than 0.3 MPa.Water activity higher than 0.7 weakens the skin and eases of the flow of diluted sugar solution. Deformation of the berry is easy and the probability of breakage increases strongly.
A confectionery gel (CG) consists of high sugar components of sucrose and glucose syrup, combined with gelling components such as starch, gelatin, or pectin, along with food acid, flavourings and colourings. Common CG products include jelly snakes, jelly babies, jelly beans, and form a portion of the lucrative confectionery market; however, there are continual consumer demands for more interesting and innovative products that have new and exciting textures, flavors and appearances. Improving or modifying CG textures can meet these demands, but first an understanding of how the behaviour and structure of the gel is developed must be achieved. Companies that will gain a competitive advantage in the confectionery market will be those able to actively manipulate and control sensory properties to meet exacting customer demands. This paper is a review of literature available on confectionery gels, their components, and factors that may affect their microstructure, texture, and rheology.
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.
SUMMARY— Pears of the Ovid variety were harvested at the normal stage of maturity, and ripened in a 70°F storage room. Samples of the fruit were taken out at regular intervals for texture measurements which consisted of the Magness-Taylor pressure test and a modified General Foods Texture Profile. The adhesiveness of the pears was zero. The viscosity of the whole fruit could not be measured. All other parameters of the G. F. Texture Profile (hardness, cohesiveness, elasticity, brittleness, chewiness, and gumminess) decreased during ripening at approximately the same rate as the pressure test. It is suggested that this characteristic of ripening pears is responsible for the success of a simple single measurement (the puncture test) for measuring the complex phenomenon that is called “textural quality” of pears.
The speed of computer readout plus the flexibility of interpretation of the various features of the Texture Profile Analysis (TPA) curves by an experienced operator was accomplished by placing the Instron re- corder charts ouer a digitizer interfaced to a computer. The digitizer provides a 14″× 14″ digitizing area with a resolution of 100 lines per inch. The operator guides a cursor over the TPA curve and the com- puter records X and Y coordinates in units of 0.01 in. A trigger on the cursor allows the operator to select designated foxes, distances and areas to be used by the computer in subsequent calculations of TPA parameters. Correlation coefficients between manually measured TPA parameters and computer-assisted readout of the same force-distance curues using apples, carrots, cream cheese, frankfurters and pretzel sticks were generally higher than r = 0.99.
Standard rating scales of hardness, brittleness, chewiness, gumminess, viscosity, and adhesiveness were established for quantitative evaluation of food texture. The scales cover the entire intensity range found in food products and may be expanded at any desired point for greater precision in a narrower range. Each point on the scale is represented by a food product selected on the basis of availability, familiarity, constancy of textural characteristics, and other criteria. Using the developed scales, correlation was good between sensory and instrumental (texturometer and viscosimeter) evaluations of texture.
SUMMARYA new recording instrument, the “texturometer,” gave good correlation between instrumental values and subjective evaluation by a trained texture profile panel. It was applied to measurement of the mechanical textural parameters: hardness, cohesiveness, viscosity, elasticity, adhesiveness, brittleness, chewiness, and gumminess. Subjective definitions of these parameters are interpreted in terms of physical measurement characterized by the texture “profile.” Examples of representative profiles are included.
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