Colour and consistency of semi-solid dairy desserts: Instrumental and sensory measurements

Contact forces and motion behavior of non-Newtonian fluid-solid food by coupled SPH-FEM method

The non-Newtonian fluid-solid interaction food has complex physical properties and complicated contact force, which brings the greater technical challenge to improving the food fetching rate. In this work, we used the smooth particle hydrodynamics and finite element coupling method for a node-to-surface penalty function contact to characterize the contact forces between non-Newtonian fluid food and solid foods. The shear rheological properties and density of non-Newtonian fluid food, including xanthan gum (XG) and guar gum (GG), were investigated by a viscometer and densitometer, respectively. The results showed that the shear viscosity of non-Newtonian fluid food depends to some extent on the mass ratio of the thickening gums. We investigated the effects of the end-effector with different fetching velocities and different inclination angles, and the nut root powder paste (NRPP) food with different ratios of XG and GG, on the fetching rate, stress-strain, and motion behavior. The results showed that the stress increased with increasing v₁ and w; however, the v₂ had less effect on the stress. The sparseness of the distribution of solid food was related to the v₁ and w, whereas it was less influenced by the v₂ . The distribution of solid food became denser in the X-Z plane and sparser in the X-Y plane with increasing inclination angle. The motion behavior of viscoelastic solid foods depended on the mass ratio of XG to GG dissolved in NRPP. The present work can provide a theoretical foundation for meal-assisting robots and robots in the field of food engineering with the task of improving the food fetching rate.

Understanding relations between rheology, tribology, and sensory perception of modified texture foods

The aim of this work was to examine relations between instrumental and sensory parameters in a texture modified food matrix, with and without saliva. Nine pureed carrot samples (eight thickened and a control) were developed with starch (0.4 and 0.8% wt/wt), xanthan (0.2 and 0.4% wt/wt) or starch-xanthan blends that met International Dysphagia Diet Standardisation Initiative (IDDSI) Level 4 guidelines using fork and spoon tests. Rheological and tribological tests were conducted on the food and simulated bolus prepared by adding fresh stimulated saliva to the food (1:5, saliva:food) to mimic oral processing. Perceived sensory properties were identified using a temporal dominance of sensations (TDS) test (n = 16) where panelists were given a list of nine attributes. The area under the curve was extracted from TDS curves for each attribute/sample and this was correlated with rheological (viscosity at 10 s^-1 , G', G″, and tan δ at 1 Hz) and tribological (friction coefficient in three regimes) data. The viscosity of the control sample decreased after adding hydrocolloids (except Starch_0.8%) and with saliva incorporation. G' and G″ either increased or were similar for xanthan and blends and decreased for starch-thickened samples. Hydrocolloid addition increased friction for all samples and was higher with saliva addition. Sensory results showed that samples with starch were perceived as thick and grainy while xanthan was perceived as smooth and slippery. A greater number of sensory attributes correlated with viscoelastic parameters compared to friction coefficients. Correlations were highest with the saliva added samples, further highlighting the importance of including saliva during instrumental testing.

Development of a functional synbiotic beverage fortified with different cereal sprouts and prebiotics

Abstract

The study was devoted to developing a novel synbiotic beverage based on with millet, rye and alfalfa sprouts with a mixed culture of Lactobacillus casei and Lactobacillus plantarum. In this regard, the influences of incorporated prebiotics inulin and oligofructose on probiotics viability during the refrigerated storage (4 ± 1 °C, 28 days) as well as under the simulated gastric condition were investigated. The characteristics such as microbial viability, physicochemical properties (viscosity, pH, titrable acidity and radical scavenging activity) and sensorial evaluation were assessed. The synbiotic beverage produced contained 10⁸ CFU ml^-1 for L. casei, with a good survival throughout the storage period (10⁸ CFU ml^-1) and L. plantarum at sufficient levels (10⁶ CFU ml^-1) after about 21 days. Inulin and oligofructose promoted the growth of the strains and their viability under cold storage while conferring higher sensory scores. In this context, the beverages demonstrated acceptable sensory attributes. The viability (bacterial survival) of over 55% for all the strains was achieved under simulated gastric condition. Therefore, the introduced fermented beverage was a good food matrix from the viability of probiotics as well as under the gastric condition and sensory characteristics.

Graphic abstract

Using the mixture design approach to predict the rheological properties of low-calorie dairy desserts containing gum tragacanth exuded by three Iranian Astragalus species

In this study, the flow behavior and creep parameters of saffron desserts containing gum tragacanth combinations of three species were modeled by the mixture design approach. Flow behavior and creep-recovery experiments were performed and models were predicted for apparent viscosity, consistency index, flow index, instantaneous compliance, and viscoelastic compliance. Five representative samples regarding the range of apparent viscosity at the shear rate of 50 s^-1 were subjected to sensory evaluation. According to rheological measurements, the addition of GT species of A. gossypinus led to the production of a dessert with a strong structure. Then, two samples with the highest consistency index and the lowest creep parameters were compared with two commercial saffron desserts. The results revealed that the overall acceptance of the two selected samples [containing 4% (w/w) A. gossypinus or 2.66% (w/w) A. gossypinus and 1.33% (w/w) A. fluccosus] was similar to those of the two commercial samples.

Rheological properties of lactose-free dairy desserts

People suffering from lactose intolerance cannot digest milk or lactose-containing foods. Lactose-free diet is essential for them since they do not have the ability to produce lactase to breakdown milk sugar. Physical properties of lactose-free dairy desserts will most probably be different than that of lactose containing ones because of lactose hydrolysis. In this study, it was aimed to analyze the rheological and textural behaviors of different lactose-free dessert formulations containing different gum types and different waxy maize starch and sucrose concentrations. Waxy maize starch was used at concentrations of 0.032 g·mL^-1, 0.040 g·mL^-1, and 0.048 g·mL^-1 In addition to waxy maize starch, guar gum, gum arabic, or κ-carrageenan at two different concentrations (1.0% w/w and 0.5% w/w) was added. Sucrose was added at concentrations of 0.14 g·mL^-1 and 0.10 g·mL^-1 in lactose-free desserts. Power law model was found to be suitable to explain the flow behavior of desserts. The storage and loss modulus of lactose-free desserts were higher than that of lactose-containing desserts. The κ-Carrageenan was found to be the most effective gum for structure build-up.

Effect of hydrocolloid on rheology and microstructure of high-protein soy desserts

Due to the rheological and structural basis of texture perceived in semisolid foods, the aim of this work was to study the effects of two thickening agents, on rheology and microstructure of soy protein desserts. As rheological parameter values may not be enough to explain the possible perceived texture differences, the effect of composition on two instrumental indexes of oral consistency (apparent viscosity at 50 s(-1) and complex dynamic viscosity at 8 Hz) was also studied. Samples were prepared at two soy protein isolate (SPI) concentrations (6 and 8 % w/w), each with four modified starch concentrations (2, 2.5, 3 and 3.5 % w/w) or four Carboxymethyl cellulose (CMC) concentrations (0.3, 0.5, 0.7 and 0.9 % w/w). Two more samples without added thickener were prepared as control samples. The flow curves of all systems showed a typical shear-thinning behaviour and observable hysteresis loops. Control sample flow fitted well with the Ostwald-de Waele model and the flow of samples with thickener to the Herschel-Bulkley model. Viscoelastic properties of samples ranged from fluid-like to weak gel, depending on thickener and SPI concentrations. Starch-based samples exhibited a globular structure with SPI aggregates distributed among starch granules. In CMC-based samples, a coarse stranded structure with SPI aggregates partially embedded was observed. Variation of the two thickness index values with composition showed a similar trend with good correlation between them (R(2) = 0.92). Soy desserts with different composition but with similar rheological behaviour or instrumental thickness index values can be obtained.

Potentially synbiotic fermented beverage with aqueous extracts of quinoa (Chenopodium quinoa Willd) and soy

The aim of this study was to develop a potentially synbiotic beverage fermented with Lactobacillus casei LC-1 based on aqueous extracts of soy and quinoa with added fructooligosaccharides (FOS). Five formulations with differing proportions of soy and quinoa extracts were tested. The viability of the microorganism, the pH, and the acidity of all formulations were monitored until the 28th day of storage at 5 ℃. The chemical composition of the extracts and beverages and the rheological and sensory properties of the final products were analyzed. Although an increase in acidity and a decrease in pH were observed during the 28 days of storage, the viability of the probiotic microorganism was maintained at 108 CFU·mL−1 in all formulated beverages throughout the storage period. An increase in viscosity and consistency in the formulations with higher concentrations of quinoa (F1 and F2) was observed. Formulation F4 (70% soy and 30% quinoa extracts) showed the least hysteresis. Formulations F4 and F5 (100% soy extract) had the best sensory acceptance while F4 resulted in the highest intention to purchase from a group of 80 volunteers. For chemical composition, F3 (50% soy and 50% quinoa extracts) and F4 showed the best results compared to similar fermented beverages. The formulation F4 was considered the best beverage overall.

Chilled milk-based desserts as emerging probiotic and prebiotic products

Nowadays, food companies are endeavoring to differentiate their products through creative segmentation and positioning strategies based on superior functionality and quality. Some kinds of dairy desserts have shown a great market potential, as a function of consumers interested in healthier and functional products with fine taste and mouthfeel. In this context, chilled dairy desserts are emerging as attractive options for the incorporation of probiotic cultures and prebiotic ingredients, as seen in the previous launches from the food industry, as well as in the growing number of scientific studies dealing with this subject published in the last years. The main aspects involved in the development of probiotic and/or prebiotic dairy desserts for storage under refrigerated conditions are presented in this review.

Effect of whey protein concentrate on texture of fat-free desserts: sensory and instrumental measurements

It is important to understand how changes in the product formulation can modify its characteristics. Thus, the objective of this study was to investigate the effect of whey protein concentrate (WPC) on the texture of fat-free dairy desserts. The correlation between instrumental and sensory measurements was also investigated. Four formulations were prepared with different WPC concentrations (0, 1.5, 3.0, and 4.5 wt. (%)) and were evaluated using the texture profile analysis (TPA) and rheology. Thickness was evaluated by nine trained panelists. Formulations containing WPC showed higher firmness, elasticity, chewiness, and gumminess and clearly differed from the control as indicated by principal component analysis (PCA). Flow behavior was characterized as time-dependent and pseudoplastic. Formulation with 4.5% WPC at 10 °C showed the highest thixotropic behavior. Experimental data were fitted to Herschel-Bulkley model. The addition of WPC contributed to the texture of the fat-free dairy dessert. The yield stress, apparent viscosity, and perceived thickness in the dairy desserts increased with WPC concentration. The presence of WPC promotes the formation of a stronger gel structure as a result of protein-protein interactions. The correlation between instrumental parameters and thickness provided practical results for food industries.

Quality and sensory acceptability of a chilled functional apple ready-dessert

An apple and dairy based ready-dessert with an added prebiotic was stored and chill temperatures and number of quality attributes were monitored during chill (4 °C) storage for 30 days. All ready-desserts were thermally processed by sous vide (P (90) > 10 min). The stability of the dairy component in ready-desserts was monitored by measuring volatile free fatty acids. Changes in these components were more evident in prebiotic-enriched samples compared to controls. However, no significant differences were observed over storage in control and prebiotic-enriched ready-desserts. This was supported by sensory analysis that showed no significant changes over storage in control or prebiotic-enriched samples. Of the other quality parameters, the addition of prebiotic inclusions resulted in lower L and b values and dry matter (p < 0.05), while increasing (p < 0.05) soluble solids content compared to control samples. Fluctuations in some of the quality parameters were also observed over storage. Rheological characteristics, i.e. flow behaviour (n), consistency index (K), storage (G'), loss (G″) and complex (G*) moduli were unaffected by prebiotic inclusion. However, storage affected the rheological characteristics of ready-desserts. A decrease (p < 0.05) in flow behaviour (n) led to concomitant increases in consistency index (K) and complex modulus (G*) values in control samples.

Sensory acceptability and physical stability evaluation of a prebiotic soy-based dessert developed with passion fruit juice

The aim of this study was to use a factorial design approach for developing a palatable and stable soy-based dessert with the addition of Soy Protein (SP), oligofructose, and Passion Fruit Juice (PFJ). Panelists (n = 50) used a seven-point hedonic scale to assess the overall liking, degree of liking of creaminess, taste, and color of the desserts. In addition, the samples were submitted to a preference ranking test in order to evaluate the products' preference. Water Holding Capacity (WHC) and backscattering (BS) measures were also determined to assess the physical stability of the trials. Sample F3 (35% PFJ and 2% SP) was the only one that presented a WHC index of 94.8%; moreover, none of the developed samples had synerisis after 72 hours of storage indicating adequate physical stability of the emulsion process. Samples F2 (25% PFJ, and 3.0% SP), F4 (35% PFJ, and 3.0% SP), and F5 (30% PFJ, and 2.5% SP) presented mean hedonic scores above 'slightly liked' for all sensory attributes. The acceptance index of samples varied from 62.50 to 88% showing the great sensory potential of such products.