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.

In this work, the effects of refrigerator freezing method (RF), spiral tunnel freezing method (SF), and liquid nitrogen spray freezing method (LF) on water distribution, microstructure, retrogradation, and digestion properties of Liangpi are investigated. Results from SEM and water distribution show the starch gel structure of Liangpi after LF treatment is more continuous, and its A₂₁ content is higher, which are closer to fresh Liangpi, followed by SF and RF. XRD and FT‐IR data indicate that as the freezing rate increases, the relative crystallinity and R₁₀₄₇/₁₀₂₂ value of the samples decrease. This is consistent with the data obtained from texture properties. Texture properties of samples treat by LF and SF are closer to fresh Liangpi, especially the hardness index. The in vitro digestibility of Liangpi also shows the same trend. Therefore, the freezing method with a faster rate could inhibit the starch gel retrogradation, improve the texture properties of Liangpi, and guarantee the quality of Liangpi. However, considering the economics of enterprise production, the spiral tunnel freezing method is more suitable for the actual production of frozen Liangpi. The data obtained provide a theoretical guidance for the actual production of frozen Liangpi.

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.

BACKGROUND: Partition coefficients give an indication of the retention of aroma compounds by the food matrix. Data in the literature are obtained by various methods, under various conditions and expressed in various units, and it is thus difficult to compare the results. The aim of the present study was first to obtain gas/water and gas/matrix partition coefficients of selected aroma compounds, at different temperatures, in order to calculate thermodynamic parameters and second to compare the retention of these aroma compounds in different food matrices.RESULTS: Yogurts containing lipids and proteins induced a higher retention of aroma compounds than model gel matrices. The observed effects strongly depend on hydrophobicity of aroma compounds showing a retention for ethyl hexanoate and a salting out effect for ethyl acetate. A small but noticeable decrease in enthalpy of affinity is observed for ethyl butyrate and ethyl hexanoate between water and food matrices, suggesting that the energy needed for the volatilization is lower in matrices than in water.CONCLUSION: The composition and complexity of a food matrix influence gas/matrix partition coefficients or aroma compounds in function of their hydrophobicity and to a lower extent enthalpy of vaporization.

In the present work, titanium dioxide nanowires (TNWs) were synthesised via hydrothermal method. Insertion of ZnFe ₂O ₄ nanoparticles to the surface of TNWs was done by sol gel combustion synthesis of the nanoparticles in the presence of the nanowires. The surface of prepared magnetic TNWs was modified by p -phenylendiamine and then it was used in preconcentration of Cu ²⁺ ion prior to their determination by flame atomic absorption spectroscopy. The sorbent was characterised by Fourier transform infrared spectra, EDX, FE-SEM and VSM techniques. We investigated and optimised various parameters influencing the preconcentration efficiency, such as the media pH, adsorbent quantity, contact time, sample volume and elution conditions. Under optimum conditions, the analytical performance of the method was evaluated. The calibration curve was found to be linear from 10.0 to 150 μg L ⁻¹ (R ² = 0.996). Calculated limit of detection was 0.43 μg L ⁻¹ (n = 5). The estimated relative standard deviation was 2.50% (n = 5). Moreover, the maximum adsorption capacity of the sorbent was 51.5 mg g ⁻¹ and preconcentration factor was 125. Capability of developed method was proved by applying it for preconcentration of Cu ²⁺ ion from food and water samples.