SWEETNESS PERCEPTION IN RELATION TO SOME TEXTURAL CHARACTERISTICS OF HYDROCOLLOID GELS

Analysis of Volatile Compounds in Processed Cream Cheese Models for the Prediction of "Fresh Cream" Aroma Perception

Controlling flavor perception by analyzing volatile and taste compounds is a key challenge for food industries, as flavor is the result of a complex mix of components. Machine-learning methodologies are already used to predict odor perception, but they are used to a lesser extent to predict aroma perception. The objectives of this work were, for the processed cream cheese models studied, to (1) analyze the impact of the composition and process on the sensory perception and VOC release and (2) predict "fresh cream" aroma perception from the VOC characteristics. Sixteen processed cream cheese models were produced according to a three-factor experimental design: the texturing agent type (κ-carrageenan, agar-agar) and level and the heating time. A R-A-T-A test on 59 consumers was carried out to describe the sensory perception of the cheese models. VOC release from the cheese model boli during swallowing was investigated with an in vitro masticator (Oniris device patent), followed by HS-SPME-GC-(ToF)MS analysis. Regression trees and random forests were used to predict "fresh cream" aroma perception, i.e., one of the main drivers of liking of processed cheeses, from the VOC release during swallowing. Agar-agar cheese models were perceived as having a "milk" odor and favored the release of a greater number of VOCs; κ-carrageenan samples were perceived as having a "granular" and "brittle" texture and a "salty" and "sour" taste and displayed a VOC retention capacity. Heating induced firmer cheese models and promoted Maillard VOCs responsible for "cooked" and "chemical" aroma perceptions. Octa-3,5-dien-2-one and octane-2,3-dione were the two main VOCs that contributed positively to the "fresh cream" aroma perception. Thus, regression trees and random forests are powerful statistical tools to provide a first insight into predicting the aroma of cheese models based on VOC characteristics.

Reducing sugar and aroma in a confectionery gel without compromising flavour through addition of air inclusions

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Slight aeration of confectionery gels does not impact chewiness perception.

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Air as a low calorie inclusion in gels enhances sweetness perception over time.

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Reduction of aroma, sugar and calories in gels without affecting flavour perception.

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X-ray computed tomography to measure bubble size and distribution.

Sugar plays an important role in both the flavour and structure of confectionery. Targets have been set to reduce sugar; however, common strategies often result in changes in flavour and consumer rejection. In this study, an approach was developed to reduce sugar in confectionery gels by aeration, without significantly affecting perceived chewiness. Gelatine based gels with a 23% and 38% reduction in density were formulated using aeration. Mean bubble size was consistent across all gels (0.05–0.06 mm). Time-intensity sensory evaluation was carried out by a trained sensory panel (n = 10). With aeration, no significant difference in overall flavour perception was observed in the 23% and 38% reduced sugar and aroma gels. Air inclusions create a greater surface area, therefore accelerating mass transfer of volatiles and release of sucrose at the food-saliva interface. Consequently, we propose that less calorie dense products can be produced without compromising flavour by using gel aeration technologies.

Use of Gum Cordia (Cordia myxa) as a Natural Starch Modifier; Effect on Pasting, Thermal, Textural, and Rheological Properties of Corn Starch

Incorporation of hydrocolloid gums in native starches help to improve their pasting, thermal, rheological and textural properties along with improvement in the stability of starch gels. The use of Cordia gum is not widely studied as a starch modifier and this fact could make this study more interesting and unique. This study investigated the effects of the non-conventional hydrocolloid gum (Cordia gum) on corn starch properties. Corn starch and gum Cordia (GC) blends were prepared at different replacement levels (0%, 3%, 6%, 9%, and 12%). The effect of GC levels on pasting, thermal, rheological, and textural properties were evaluated using rapid viscoanalyzer, differential scanning colorimeter, rheometer, and texture analyzer. The presence of GC significantly increased starch gelatinization temperatures, enthalpies, peak viscosities, final viscosities, and setback viscosities. GC improved freeze thaw stability in starch. The shear rate (1/s) versus shear stress (σ) data of all samples fitted well to the simple power law model (R² = 0.97–0.99). The control had the lowest flow behavior index (n; 0.17), which increased to (0.36–0.56) with increasing GC levels. The consistency index (K) of the starch-gum blends increased with increasing GC levels. The dominance of elastic properties over viscous properties was demonstrated by G′ > G″. The magnitudes of G′ and G″ increased with increasing GC concentration. The outcomes could help to use this modification method as an alternative to chemical and enzymatic modification with respect to cost, safety, less time consumption and less requirement of process modifications.

Structural changes and stress relaxation behavior of κ-carrageenan cold-processed gels: Effects of ultrasonication time and power

Ultrasound has been used for cold gelation of κ-carrageenan hydrocolloid. In this work, the effect of ultrasound conditions such as power (50-150 W) and time (20-240 s) of sonication has been investigated. The application of ultrasound to hydrocolloid dispersion caused an increase in water solubility. The texture profile analysis test was used in order to evaluate the mechanical properties of gels. Textural parameters of κ-carrageenan gels, enhanced with increasing sonication time and power up to a certain level (usually 2.5 min) and longer sonication times had negative effects. In addition, intrinsic viscosities of sonicated specimens were measured to investigate the molecular characteristics of all samples. An increase in the process time and power reduced the intrinsic viscosity. The microstructural observation by scanning electron microscope determined that applying power ultrasound on κ-carrageenan dispersions influenced the formation of gel networks significantly.

Rheological, textural and emulsifying properties of an exopolysaccharide produced by Mesorhizobium loti grown on a crude glycerol-based medium

In the present study, a new extracellular polysaccharide (EPS-M816) was obtained during the growth of Mesorhizobium loti Semia 816 on a crude glycerol-based medium. EPS-M816 precipitate mainly consisted of carbohydrates (82.54%) and proteins (11.31%), and the weight average molecular weight was estimated at 1.646 × 10⁶ Da. The biopolymer was characterized by FT-IR and NMR spectroscopy, and was found to have typical functional groups of other rhizobial polysaccharides. Furthermore, the rheological and emulsifying properties were investigated. The EPS-M816 solution (1.0% w/v) showed typical pseudoplastic non-Newtonian fluid behavior, and the addition of sodium and potassium chloride (1 mol L^-1) increased the apparent viscosity. Regarding its emulsification activity, EPS-M816 formed emulsions with different food-grade vegetable oils (soybean, rice, canola, sunflower and corn oils), showing emulsification index values over 65% in 24 h, indicative of strong emulsion-stabilizing capacity. The biopolymer was able to form gels with texture parameters similar to those reported for xanthan gum and low syneresis. Overall, these results suggest that EPS-M816 is a good candidate for application in the food, cosmetics and pharmaceutical industries as a thickening, gelling, stabilizing and emulsifying agent.

Note. Influence of texture and type of hydrocolloid on perception of basic tastes in carrageenan and gellan gels Nota. Influencia de la textura y del tipo de hidrocoloide en la percepción de los gustos fundamentales en geles de carragenato y de gelana

Preliminary work was carried out on the effect of texture, as represented by gel strength, between around 5 and 20 N of compression maximum force, of both carrageenan and gellan gels on the per ception of the four basic tastes. These were produced by addition of 15% (w/w) sucrose, 0.06%(w/w) caffeine, 0.5% (w/w) sodium chloride, or a mixture of 0.15% (w/w) citric acid and 0.2% (w/w) so dium citrate. Low strength (5-8 N) carrageenan gels were sweeter, more salty and more sour than both medium (11-15 N) and high (18-24 N) strength ones. Differences in bitterness were shown only between low and high texture carrageenan gels. The same differences in sweetness caused by texture were found between low and both medium and high strength gellan samples. Differences in saltiness and sourness were only detected between gellan gels of extreme gel strengths, in favor of the weakest gels. No difference in bitterness was found for any of the pairs of gellan samples. On comparing taste intensity between the two hydrocolloid gels at different strength levels, it was found that both me dium and high strength gellan gels were sweeter and more salty than the corresponding carrageenan gels, confirming the reported flavor-releasing properties of gellan.

Revision: Percepción del gusto. Aspectos fisicoquímicos y psicofísicos / Review: Perception of taste. Physiochemical and psychophysical aspects

Flavor is perceived through two human senses simultaneously: the sense of taste, operating in the mouth, mainly in the tongue, and the sense of smell in the nostrils, where aromas are detected. The stimuli responsible for aroma perception are volatile compounds; their nature and properties as well as the mechanisms of perception have been widely studied. This is not the case for the taste stimuli, consisting of non-volatile compounds responsible for the accepted four basic taste sensations: sweet, sour, salty and bitter. The available information on taste perception is almost exclusively dedicated to sweet taste for obvious economic and nutritional reasons. In this paper, the present knowledge on the nature of the taste stimuli, on the mechanisms of their perception and on the interactions among them is reviewed. The effects of interactions with other sensory attributes (aroma, color, texture) are also reviewed. Interactions may be due to different causes: physical and chemical interactions among food components, competition at the receptor site, changes in the neurophysiological signal, and changes in the psychological response. Food aromas, as part of the flavor sensation, exert their influ ence on taste perception, as taste compounds affect aroma perception. Color may also modify the perception of a particular taste, but very few studies have been dedicated to this effect. On the other hand, the influence of texture (viscosity, consistency, hardness) mainly on the sweet taste has been extensively studied. Some contradictory results on how texture affects sweet or other tastes are still not satisfactorily explained. The study of these effects has been intensified in the last years, mainly because they are an important aspect of the flavor release phenomenon, so decisive for optimization of formulated foods.

Gustatory responses to nongustatory stimuli

Subjects were required to give taste responses to days of the week and states of the USA, as well as colour responses. Some consistency of response was obtained over three sessions held at two-week intervals. The implications of such consistency of response to nongustatory stimuli for psychophysical taste description are discussed.