This work underlines that the role of water, its flow properties and its expulsion from the spatial network during oral processing, cannot be neglected in understanding the relation between gelled food structures and its sensory perception. It is shown that the properties of the included water phase of semi-solids are important as this phase can boost the water content in the oral cavity, and thereby increase taste sensations like sweetness. Moreover, the included water phase also plays a crucial role in how the energy exerted onto the gel during palating is used for either fracture, stored or dissipated in or by the network. To demonstrate this, a series of mixed whey protein/polysaccharide cold-set gels have prepared that were studied for a number of rheological and sensorial properties. Also, information on the expulsed serum volume during uniaxial compression and the breakdown pattern of these gels in the oral cavity was determined. It is shown that expulsion of serum from a gel during oral processing can be substantial and set by the morphology of the formed gel and the stiffness of the matrix. This expulsed serum volume is directly proportional to taste response. Moreover, it is found that both the viscous and elastic flow of serum through the gel upon deformation contribute to the perceived crumbliness of gels by lowering the recoverable energy. The elastic contribution of polysaccharides in the serum impairs with the energy available for fracture during oral processing, thereby affecting the sensory spreadability of the product.

Food gels prepared from the water extract of fish scales (WEFS) are described in this study. The effects of WEFS, sucrose, and NaCl concentration on gel formation and stability, gel texture, and gel sensory attributes were evaluated. The results indicated that an increase in WEFS concentration led to increases in the formation rate, stability, and texture of the gel. Addition of a moderate amount of sucrose (2%–3%, w/v) and NaCl (0.4%–0.6%, w/v) improved the stability, gumminess, chewiness, and cohesiveness of the gel. However, the addition of an excessive amount of sucrose (>4%, w/v) and NaCl (>0.8%, w/v) decreased the stability, gel strength, adhesiveness, and springiness of the gel. The sensory attributes of fish scales (FS) gels were mainly affected by WEFS concentration. On the basis of combined textural analysis and sensory evaluation, the FS gels formed with 4% WEFS, 3% sucrose, or 0.4% NaCl was proposed in this study. The gel microstructure and water distribution obviously showed an apparent variation, together with a change in the structure of FS gels. Competing hydrophilic forces and electrostatic interactions varied with sucrose and NaCl concentration, altering the structure and water distribution of FS gels.

The aim of the present study was to assess the influence of pH (3, 7 and 9) as well as ionic strength of NaCl (0mmol/l, 100mmol/l, 200mmol/l and 400mmol/l) on the retention and release characteristics of diacetyl and (−)-α-pinene in oil-in-water (o/w) emulsions prepared with dried egg yolk (DEY) or starch sodium octenylsuccinate (SOE). Increase of pH from 3 to 9 progressively enhanced retention of diacetyl in emulsions prepared with both DEY and SOE. Whereas, in samples flavoured with (−)-α-pinene, the highest and lowest retention time-courses were detected at pH 9 and pH 7 as well as pH 7 and pH 3 regarding emulsions prepared with DEY as well as SOE, respectively. With increasing salt concentration, the retention of diacetyl was decreased, irrespectively of the applied emulsifier type, whereas generally opposite effects were observed in the case of (−)-α-pinene. The parameters of release characteristics i.e., release rate constants (k) and release mechanism factors (n), were calculated using Avrami’s equation. ANOVA revealed significant effects (p<0.001) of pH and NaCl concentration on k parameters, whereas relationship between applied environmental conditions and n factors was dependent on hydrophobicity of the odourant. Sensory evaluation revealed higher correlation values between odour intensity and aroma compound concentration in emulsions aromatized with (−)-α-pinene than with diacetyl.