Influences of Pretreatments and Drying Process Including Fluidized Bed Puffing on Quality Attributes and Microstructural Changes of Banana Slices

Healthy snacks have received more attention because of their low fat content. Color and texture are important to snack quality. Effects of chemical pretreatment, thickness, blanching, and puffing temperature on quality of banana slices were therefore investigated. Banana slices (2.5 and 3.5 mm thickness) were chemically treated by citric acid and sodium metabisulfite, blanched, and dried at a temperature of 90°C to an intermediate moisture content of 25% db. They were then puffed in a fluidized bed dryer at 160 and 180°C for 2 min and dried again at the same drying temperature as the first drying step. Blanching, puffing temperature, and thickness strongly affected the degree of shrinkage, effective moisture diffusivity, morphology, textural properties such as hardness and crispiness, and color, but the chemical treatment did not affect those qualities. Blanching can improve the product appearance; the color was uniform and shiny throughout the surface and golden yellow. However, the textural attributes of the blanched sample had higher hardness and less crispiness than those of unblanched sample.     

Effect of Adsorption Conditions on Effective Diffusivity and Textural Property of Dry Banana Foam Mat

Foamed banana product, a crispy snack, can quickly adsorb the moisture from the moist air, leading to loss of textural property. The main purpose of this research was therefore to study moisture adsorption kinetics of dry banana foam mat and its texture quality change. The adsorption isotherm experiments were carried out with a standard static method using saturated salt solutions over a wide range of relative humidities from 32 to 82% and temperatures of 35, 40, and 45°C. Three dry banana foam densities of 0.21, 0.26, and 0.30 g/cm³ adsorbed water vapor under controlled conditions. Fick's second law coupled with an optimization technique was used to estimate the effective moisture diffusivity at sorption conditions. Empirical equations with two and three constant parameters for describing the dependence of the effective moisture diffusivity on moisture content were tested. The two constant parameters could suitably describe the variation of the effective moisture diffusivity with moisture content. The initial foam density, relative humidity, and temperature significantly affected the effective moisture diffusivity. The banana foam mats for all densities lost their crispy texture at moisture content of 0.078 kg/kg db.     

Quality of Infrared Dried Apple Slices

The aim of this work was to compare quality of apple slices dried by near infrared heating and convection in such parameters in which final material temperature in both methods was similar. The infrared drying was done at the distance between the emitters (with total power of 7.875 kW/m²) and heated surface equal to 10, 20, and 30 cm. Flow of ambient air was set at 0.5, 1.0, and 1.5 m/s. Convective drying was done in the same dryer using hot air at 65 and 75°C flowing with velocity 1.5 m/s. Quality attributes measured in this work included: color, kinetics of water adsorption, mechanical properties, and microstructure. It was stated that the changes in chromaticity coefficients are not dependent on the mode of heat supply, but are related to the final temperature of the dried material. Luminance of dried apple slices was affected by temperature as well. Final material temperature, not the way heat is supplied, could be responsible for the differences in the ability of dry apple slices to adsorb water. The similar correlation was stated for mechanical properties: slope of initial part of the deformation curve (crispness), breaking force (hardness or crispness), and work of breaking were all related to the final material temperature. Microstructure of convective and infrared dried apple were different but it seems that the drying rate can be responsible for observed differences.     

Correlating Perceived Crispness Intensity to Physical Changes in an Amorphous Snack Food

A crispy amorphous food was equilibrated to different moisture contents. These samples were tested for the glass transition temperature (T_g) using mechanical methods. The brittle-ductile transition temperature (T_b) was determined using force-deformation methods. Finally, the temperature where the onset to the sharp decrease in crispness intensity occurred (T_ci) was determined by a 10-member sensory panel rating the crispness intensity. The relationships of the T_g, the T_b, and the T_ci were determined using three different statistical methods. The results of this research indicated that the T_g, the T_b, and the T_ci were related to one another as a function of moisture content.     

New contact acoustic emission detector for texture evaluation of apples

A new contact acoustic emission detector (CAED) was developed for the instrumental texture evaluation of apples. The goal of this work was to determine the relations between instrumental parameters and sensory texture attributes, and to develop calibration models for prediction of the sensory texture of apples with CAED. Seven apple cultivars were used for the construction and validation of the models. CAED is particularly useful for evaluation of sensory crispness, crunchiness and hardness. There is also a significant correlation of acoustic emission counts with juiciness, mealiness and overall texture. Validation of the models indicates better prediction of these sensory attributes by total acoustic emission counts than prediction by puncture firmness in terms of variance explained, root-mean-square of a model prediction, and bias.     

Crispness level of potato chips affects temporal dynamics of flavor perception and mastication patterns in adults of different age groups

Little attention has been paid to the texture–flavor association in solid foods, especially crisp foods. This study aimed to determine whether crispness level affects temporal dynamics of perceived intensity of three types, i.e., plain, cheese, and spicy, of flavored potato chips with respect to three age groups: younger (20–25 years), middle-aged (40–45 years), and older (65+ years) adults. While eating potato chips, participants’ mastication pattern was also assessed by electromyography (EMG). Time–Intensity analysis showed that flavors were rated more intense and maximum flavor perception occurred quicker as crispness of potato chips increased. Overall, the effect of crispness level on flavor perception was more pronounced in the older participants. The average chew strength was greater in the crisper samples and regardless of flavor type the younger participants displayed shorter chew durations than older adults. A partial least squares regression demonstrated that mastication patterns, such as the number of chews, could well predict several key temporal flavor parameters such as the maximum intensity and the area under the curve in the middle age and older age groups. In conclusion, this study extends previous research showing that textural characteristics can influence flavor perception in liquid and soft foods to crisp/brittle foods. In addition, the effect of crispness level on flavor perception varies by flavor type, age group, and mastication pattern.     

On the assessment of fracture in brittle foods II. Biting or chewing?

In this study crispness assessment in different dry-crisp foods were evaluated. Roasted almonds with different degrees of roasting and two different types of extruded snacks, wheat crusts and cheese balls, at different water activities were used as samples. Crispness behaviour was characterised by using coupled sound–texture measurements and by sensory evaluation with the use of a consumer panel. Instrumental texture measurements were made using compression and penetration tests. While in the almond samples the compression test discriminated better than the penetration test among the samples, in both kinds of snacks the compression with the tooth-like probe proved to be as good as penetration tests to assess crispy characteristics. Consumers evaluated the samples by chewing with the back molars or by biting with the incisive teeth. The results obtained in sensory evaluation were similar to instrumental results. Consumers were able to better discriminate between the almond samples by chewing than by biting but in the snacks samples the ratings both by biting and chewing modalities were very similar and showing the same discrimination level. These findings could have useful applications: for panel training, at the time of naming attributes and defining how they are evaluated; also, to obtain the most of sensory-consumer correlations, having in mind that the “ease of breakdown” in the mouth is proved to contribute to the relative preferences among narrow texture ranges within products.     

Performance of three different types of resistant starch in fried battered food

Three different types of commercially available RS (one RS type 2 and two RS type 3) were incorporated in a batter formula and their influence on the rheological properties of the raw batter and on the batter pick-up, texture, colour, and consumer acceptability of the final battered fried product were investigated. RS incorporation affected the rheological properties of the raw batter compared with a control (without RS), although no relation between RS type and the flow and viscoelastic properties was found. In comparison to the control batter, replacement of wheat flour with Novelose 330 (RS3 type) increased significantly batter consistency and the values of the viscoelastic moduli G′ and G″, while replacement with both C*Actistar 11700 (RS3 type) or Hi-maize 260 (RS2 type) produced the opposite effect. Instrumental colour was the only property that gave a clear relationship with the type of RS; the two RS3 starches developed a darker colour than the control and the RS2 starch. The RS2 starch showed the best acceptability evaluated by a consumer panel. All the RS types assayed are considered successful to be used in battered food.     

Texture concepts for consumers: a better understanding of crispy–crunchy sensory perception

Differences in the definitions and terms used by consumers to describe their sensory sensations of crispness/crunchiness were studied, highlighting the relevance of using well-defined terms in consumer studies. A questionnaire was presented to consumers from two different Spanish-speaking countries (Spain and Uruguay, n = 200). The answers showed that the terms crispy and crunchy had different meanings or evoked different perceptions depending on the country. The crispy/crunchy food items most frequently mentioned by consumers were dry-crisp, processed products; vegetables or other wet-crisp products were not often mentioned by the consumers interviewed. The main difference between the two countries was that 38% of Spanish consumers did not know the Spanish term for “crunchy” and 17% thought that “crispy” and “crunchy” had the same meaning. The results contribute to a greater knowledge of the terminology used by the consumers to describe oral sensations related to crispness and crunchiness.