Textural and Rheological Properties of Sliceable Ketchup.

This study investigates the effect of different mixtures of gums [xanthan (Xa), konjac mannan (KM), gellan, and locust bean gum (LBG)] on the physical, rheological (steady and unsteady), and textural properties of sliceable ketchup. Each gum had an individually significant effect (p < 0.05) on viscosity; however, the addition of Xa in combination with other gums had a greater effect on viscosity. By increasing the use of Xa in ketchup formulations, the amount of syneresis decreased such that the lowest amount of syneresis related to the sample prepared with 50% Xa and 50% gellan. Although the use of different levels of gums did not have a significant effect on the brightness (L) and redness (a) indices (p < 0.05), the use of different ratios of gums had a significant effect (p < 0.05) on the yellowness (b) index. The effect of different levels of gums used had a significant effect only on firmness (p < 0.05), and their effects on other textural parameters were not statistically significant (p > 0.05). The ketchup samples produced had a shear-thinning behavior, and the Carreau model was the best model to describe the flow behavior. Based on unsteady rheology, G' was higher than G" for all samples, and no crossover between G' and G" was observed for any of the samples. The constant shear viscosity (η) was lower than the complex viscosity (η*), which showed the weak gel structure. The particle size distribution of the tested samples indicated the monodispersed distribution. Scanning electron microscopy confirmed the viscoelastic properties and particle size distribution.

Faba bean protein in reduced fat/cholesterol mayonnaise: extraction and physico-chemical modification process.

Effect of faba bean enzymatic protein extraction process parameters were investigated at different ultrasound powers (200, 300 and 400 W), sonication times (15, 25 and 35 min), enzyme dosages (0.15, 0.3 and 0.45%) and enzyme treatment times (15, 25 and 35 min). Physico-functional characterization of the protein samples through solubility, zeta potential, color, fat adsorption, emulsifying and foaming capacity measurements suggested faba protein as a promising substituent to egg yolk powder in reduced fat mayonnaise formulation. Reduced-fat mayonnaise formulation containing different faba protein/egg yolk powder ratios were prepared and characterized through rheological analyses as well as emulsion stability, texture, color and microstructural evaluations. The formulations containing equal compositions of faba bean protein and egg yolk powder (0.375%) and also the one with 0.5% faba bean protein and 0.25% egg yolk powder were finally suggested to substitute the conventional formulation.

Chemical, textural, rheological, and sensorial properties of wheyless feta cheese as influenced by replacement of milk protein concentrate with pea protein isolate.

Replacement of milk protein with protein isolates from vegetable resources can significantly influence the characteristics of feta whey less cheese and also decrease the cost of final production. In this study, various blends of milk protein concentrate (MPC) and pea protein isolate (PPI) were mixed at levels of 12% MPC and 0% PPI (MP0), 10% MPC and 2% PPI (MP2), 9% MPC and 3% PPI (MP3), 8% MPC and 4% PPI (MP4), 7% MPC and 5% PPI (MP5), 6% MPC and 6% PPI (MP6) and used in the manufacture of wheyless feta cheese. The chemical, textural, rheological, and sensorial properties, as well as the microstructure of the cheese samples, were evaluated after 1, 15, and 30 days of storage. The general linear model procedure of SAS statistical software was used for statistical analysis. Duncan's multiple range tests was used to compare the means of different treatments. The results showed that all properties of the cheeses were influenced by different levels of PPI due to different total solids content. The use of high concentrations of PPI resulted in a more open protein network, softer structure and decreasing the storage (G') and loss (G″) moduli in the cheeses. Sensory evaluation of the samples revealed that total score in terms of flavor, texture and overall acceptability was gradually decreased with increasing PPI levels, but still preferable for the panelists. Furthermore, for each sample, with increasing levels of PPI, the whiteness and the greenness were decreased, but the yellowness was increased.

Synergistic interactions between konjac-mannan and xanthan/tragacanth gums in tomato ketchup: Physical, rheological, and textural properties.

In this research, simultaneous contribution of konjac-mannan (0.3%), xanthan (0.3%), and tragacanth (0.3%) gums in tomato ketchup was investigated comparing the physicochemical, rheological, texture, and sensory properties with the control sample containing 0.3% xanthan gum. Samples selected through viscosity and syneresis evaluation of the nine prepared samples were analyzed by color, flow behavior, frequency sweep, particle size, texture, and sensory experiments. Results indicated that increasing xanthan concentration did not have any significant effect on the apparent viscosity while considerable improvement was observed in the physical stability of ketchups containing konjac-mannan/xanthan ascribed to smaller particles with larger contact surfaces encouraging gel network formation. Highest a* and a*/b* was observed for konjac-mannan/xanthan (0.075%/0.225%) in which formation of hydrated gel granules of gums intensifies light diffraction due to the decreased particle size. This synergistically formed viscous three-dimensional gel network is responsible for the highest cohesiveness and gumminess of the same sample between the ketchup formulations containing two gums. Organoleptic properties of ketchup samples containing konjac-mannan/xanthan showed no significant difference with the control sample. PRACTICAL APPLICATIONS: Development of modern food technologies along with the lifestyle changes over the past few decades and grown public awareness of the relevance between health and nutrition have considerably increased the consumption of ready meals containing low-fat and fiber-rich functional condiments. Ketchup is a popular sauce thickened with tomato pulp powder, potato or corn starch, modified starch, and severally available hydrocolloids such as carboxymethyl cellulose, xanthan, guar, and locust bean gum. In this research work, mixtures of konjac-mannan and xanthan/tragacanth hydrocolloids are used to produce new ketchups with improved physical and rheological properties and lower prices.

Substitution of modified starch with hydrogen peroxide-modified rice bran in salad dressing formulation: physicochemical, texture, rheological and sensory properties.

Rice bran samples were treated under different conditions including hydrogen peroxide content (1, 4, and 7 wt%) and media pH (10.5, 11.5, and 12.5). Water holding capacity and color measurement results showed acceptable improvements compared with the untreated native bran confirmed by Fourier transform infrared analysis. Optimization of modification conditions upon characterization results suggested the introduction of 7% hydrogen peroxide at pH = 12.5. Accordingly, 1, 2 and 3 wt% of the rice bran treated under the optimized conditions, was used in salad dressing formulation; as for .3 wt% of modified starch in the formulation of blank sample, 1 wt% of treated rice bran dietary fiber was substituted. Biopolymer swelling and formation of a stable viscous gel network promoted by the chemical treatment of lignocellulosic rice bran restrict the mobility of oil droplets dispersed in the continuous phase which would consequently retard the emulsion instability phenomena. This effect was also confirmed by flow behavior and viscoelastic characterization results. Salad dressing samples containing 1 and 2 wt% treated rice bran showed acceptable physicochemical, rheological and organoleptic properties besides superior nutritional characteristics compared with the commercial modified starch traditionally used in salad dressing formulations. PRACTICAL APPLICATIONS: Despite recommended consumption of dietary fibers, addition of unprocessed lignocellulosic materials to food products usually raise negative effects in sensory, color, and texture quality. This study investigates the modification of rice bran, the byproduct of brown rice milling, to substitute modified starch traditionally used in salad dressing formulations to achieve optimum properties desirable for the final product. Optimization of modification conditions upon characterization of the formulated samples in this study would suggest new improved formulation for the commercial product.