Postbiotic characterization of a potential probiotic yeast isolate, and its microencapsulation in alginate beads coated layer-by-layer with chitosan.

Considering biosafety concerns and survivability limitations of probiotics (PRO) under different stresses, application of postbiotics and encapsulated PRO has received considerable attentions. Accordingly, the objective of the present study was to investigate the postbiotic capabilities of a potential PRO yeast isolate and the effect of encapsulation with alginate (Alg) and chitosan (Ch) on its survival under SGI conditions. Sequencing results of the PCR products led to the identification of Saccharomyces cerevisiae as the selected potential PRO yeast isolated from wheat germ sourdough. High survival of the isolate under simulated gastrointestinal (SGI) conditions (95.74%), its proper adhesion abilities, as well as its potent inhibitory activity against Listeria monocytogenes (75.84%) and Aspergillus niger (77.35%) were approved. Interestingly, the yeast cell-free supernatant (CFS) showed the highest antioxidant (84.35%) and phytate-degrading (56.19%) activities compared to the viable and heat-dead cells of the isolate. According to the results of the HPLC-based assay, anti-ochratoxin A (OTA) capability of the dead cells was also significantly (P < 0.05) higher than that of the viable cell. Meanwhile, the yeast CFS had no anti-OTA and antimicrobial activities against the foodborne bacteria and fungi tested. Further, microencapsulation of the yeast isolate in Alg beads coated layer-by-layer with Ch (with 77.02% encapsulation efficacy and diameter of 1059 µm based on the field emission scanning electron microscopy analysis) significantly enhanced its survivability under SGI conditions in comparison with the free cells. In addition, electrostatic cross-linking between negatively charged carboxylic groups of Alg and positively charged amino groups of Ch was verified in accordance with Fourier transform infrared and zeta potential data. Human and/or industrial food trials in future are needed for practical applications of these emerging ingredients.

Rheological Characteristics of Soluble Cress Seed Mucilage and ß-Lactoglobulin Complexes with Salts Addition: Rheological Evidence of Structural Rearrangement.

Functional, physicochemical, and rheological properties of protein-polysaccharide complexes are remarkably under the influence of the quality of solvent or cosolute in a food system. Here, a comprehensive description of the rheological properties and microstructural peculiarities of cress seed mucilage (CSM)-ß-lactoglobulin (Blg) complexes are discussed in the presence of CaCl2 (2-10 mM), (CSM-Blg-Ca), and NaCl (10-100 mM) (CSM-Blg-Na). Our results on steady-flow and oscillatory measurements indicated that shear thinning properties can be fitted well by the Herschel-Bulkley model and by the formation of highly interconnected gel structures in the complexes, respectively. Analyzing the rheological and structural features simultaneously led to an understanding that formations of extra junctions and the rearrangement of the particles in the CSM-Blg-Ca could enhance elasticity and viscosity, as compared with the effect of CSM-Blg complex without salts. NaCl reduced the viscosity and dynamic rheological properties and intrinsic viscosity through the salt screening effect and dissociation of structure. Moreover, the compatibility and homogeneity of complexes were approved by dynamic rheometry based on the Cole-Cole plot supported by intrinsic viscosity and molecular parameters such as stiffness. The results outlined the importance of rheological properties as criteria for investigations that determine the strength of interaction while facilitating the fabrication of new structures in salt-containing foods that incorporate protein-polysaccharide complexes.

Rheological properties for determining the interaction of soluble cress seed mucilage and ß-lactoglobulin nanocomplexes under sucrose and lactose treatments.

Protein-polysaccharide complexes are commonly applied in different food products. Their interaction and their functional properties that arise as a consequence of interactions are remarkably influenced by the presence of co-solutes in the system. In this study, general rheological properties and the aggregation behavior of cress seed mucilage (CSM)-ß-lactoglobulin (Blg) complexes were studied in the presence of sucrose (5-20% w/v) and lactose (5-20% w/v). The highest values of apparent viscosity and stability (zeta potential) in CSM-Blg complexes were measured when the medium contained 5% w/v lactose (10.00 Pa.s at 0.1 s-1, -25 ± 0.8 mV) and 20% w/v sucrose (12.89 Pa.s at 0.1 s-1, -35 ± 0.2 mV). The results of oscillatory experiments indicated that the gel-like feature of the complexes improved, parallel to a decrease in frequency, which highlighted the shear-induced gelation phenomenon. The thermal analysis test demonstrated that the thermal stability of Blg (70.5◦C), with its complexation to CSM, improved through denaturation. Also, the association of CSM-Blg (82◦C) nanocomplexes with lactose (96◦C) can enhance the thermal stability more effectively. Considering the widespread use of protein-polysaccharide complexes in diverse sugar-containing food formulations, the results of this study can contribute to the creation of new compounds with special techno-functional features.

Comparison of binary cress seed mucilage (CSM)/ß-lactoglobulin (BLG) and ternary CSG-BLG-Ca (calcium) complexes as emulsifiers: Interfacial behavior and freeze-thawing stability.

Protein-polysaccharide complexes often exhibit amended techno-functional characteristics when compared to their individual participant biomolecules. In this study, a complex coacervation of cress seed mucilage (CSM)/ß-lactoglobulin (Blg) was used for stabilizing oil-in-water emulsions; they were characterized in terms of physical properties, droplet-size distribution and microstructure. Also, a comprehensive study was carried out on interfacial rheological responses and on the corresponding emulsion stability of different complexes. Freeze-thaw stability of the produced emulsions which had from mixtures of CSM-Blg was also evaluated. More than the size of droplets, interfacial rheological characteristics were associated with the properties of the adsorbed layers and with the stability of emulsions in storage. Using the CSM-Blg-Ca ultimately resulted in emulsions that proved stable against creaming, with no sign of phase separation over 3 weeks. These results show protein-polysaccharide complexes as appropriate emulsifiers that can make emulsion-based products resistant to unwanted changes caused by freeze-thawing.

Vitamin D3 cress seed mucilage -ß-lactoglobulin nanocomplexes: Synthesis, characterization, encapsulation and simulated intestinal fluid in vitro release.

Vitamin D3 (VD3) as an essential lipid-soluble active ingredient with numerous applications in food and pharmaceutical sectors; however, poor water solubility reduces its bioavailability significantly. Application of protein-polysaccharide complexes as a promising way to protect and trigger programmed release of bioactive molecules has established an optimal window in nutraceutical delivery systems. In this study, complexes of ß-lactoglobulin (Blg) and cress seed mucilage (CSM) were used to retain VD3 at undesirable circumstances, such as acidic pH values. The interaction of CSM-Blg was studied by rheological tests and the best formulation was chosen for encapsulation of VD3 via crosslinking with calcium ions (2-10 mM). The results demonstrated that complexation protect VD3 at low pH values with the maximum encapsulation efficiency of 84.2 %. The in vitro study indicated that Blg-CSM-VD3 was more stable in simulated gastric fluid, and in turn VD3 was released in simulated intestinal fluid; the complexes treated with calcium ions had a slower release rate than normal complexes. The release trend of VD3 followed the diffusion-Fickian law and the principal interactions included hydrophobic, electrostatic and hydrogen bonding. The results indicated that Blg-CSM complexes can retain VD3 at acidic environment and induce sustained release, which brings about practical advantages for vitamin delivery in the food and pharmaceutical sectors.

A study on the energy and exergy of Ohmic heating (OH) process of sour orange juice using an artificial neural network (ANN) and response surface methodology (RSM).

The nonmodern statistical methods are often unusable for modeling complex and nonlinear calculations. Therefore, the present research modeled and investigated the energy and exergy of the ohmic heating process using an artificial neural network and response surface method (RSM). The radial basis function (RBF) and the multi-layer perceptron (MLP) networks were used for modeling using sigmoid, linear, and hyperbolic tangent activation functions. The input consisted of voltage gradient; weight loss percentage, duration ohmic, Input flow, Power consumption, electrical conductivity and system performance coefficient and the output included the energy efficiency, exergy efficiency, exergy loss, and improvement potential. The response surface method was also used to predict the data. According to the result, the best prediction amount for energy and exergy efficiencies, exergy loss and improvement potential were in RBF network by sigmoid activation function and after this network, RSM had the best amount for energy efficiency, Also for exergy efficiencies, exergy loss and improvement potential obtained acceptable results in MLP network by a linear activation function. The worst amount was at MLP network by tangent hyperbolic. In general, the neural network can have more ability than the response surface method.

Synthesis and characterization of cellulose nanocrystals derived from walnut shell agricultural residues.

Cellulose nanocrystals (CNCs) have novel and diversified applications in different fields including packaging and nanodelivery systems. This study was dedicated to fabricate CNCs from walnut shell as an abundant source of agricultural byproducts using alkali/acidic hydrolysis method. Moreover, homogenizer and ultrasound devices were applied to produce the CNCs with minimum hazardous solvents in the preparation steps. The physicochemical characteristics of CNCs, such as color, size, yield, and swelling capacity plus their characterization using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR) were studied. The mean equivalent spherical diameter of the fabricated CNCs was about 130 nm and the production efficiency was 91.5%. Besides, the swelling capacity of CNCs was 1.5-fold of cellulose with a swelling of 400%. The crystallinity degree of the cellulose obtained from walnut shell was 49%, which was improved following acidic and alkali hydrolysis (60%). TGA analysis revealed that the thermal stability of the CNCs was lower than cellulose; moreover, the FTIR results demonstrated that there is not a considerable difference between normal cellulose and CNCs. Overall, it was concluded that walnut shell-derived CNCs have the potential to be employed as promising nanocarriers in different sectors, especially in the food and drug delivery sectors.

Experimental and modeling investigation of mass transfer during combined infrared-vacuum drying of Hayward kiwifruits.

In this work, we tried to evaluate mass transfer during a combined infrared-vacuum drying of kiwifruits. Infrared radiation power (200-300 W) and system pressure (5-15 kPa), as drying parameters, are evaluated on drying characteristics of kiwifruits. Both the infrared lamp power and vacuum pressure affected the drying time of kiwifruit slices. Nine different mathematical models were evaluated for moisture ratios using nonlinear regression analysis. The results of regression analysis indicated that the quadratic model is the best to describe the drying behavior with the lowest SE values and highest R value. Also, an increase in the power led to increase in the effective moisture diffusivity between 1.04 and 2.29 × 10-9 m2/s. A negative effect was observed on the ΔE with increasing in infrared power and with rising in infrared radiation power it was increased. Chroma values decreased during drying.

Improvement of quality attributes of sponge cake using infrared dried button mushroom.

Infrared-hot air method, when properly applied, can be used for achieving a high-quality product. The objective of this study was to determine the rheological properties of cake batters and physico-chemical, textural and sensory properties of sponge cake supplemented with four different levels (control, 5 %, 10 %, and 15 %) of button mushroom powder. The button mushroom slices were dried in an infrared-hot air dryer (250 W and 60 °C). The physical (volume, density, color) and chemical (moisture, protein, fat and ash) attributes were determined in the cakes. Increasing the level of substitution from 5 % to 15 % button mushroom powder significantly (p < 0.05) increased the protein and ash. The apparent viscosity in cake batter, and volume, springiness, and cohesiveness values of baked cakes increased with increasing button mushroom powder levels whereas the density, consistency, hardness, gumminess, chewiness and crumb L, b values of samples showed a reverse trend. Sensory evaluation results indicated that cake with 10 % button mushroom powder was rated the most acceptable.

Combined infrared-vacuum drying of pumpkin slices.

Infrared-vacuum dehydration characteristics of pumpkin (Cucurbita moschata) were evaluated in a combined dryer system. The effects of drying parameters, infrared radiation power (204-272 W), system pressure (5-15 kPa), slice thickness (5 and 7 mm) and time (0-220 min) on the drying kinetics and characteristics of pumpkin slices were investigated. The vacuum pressure, lamp power and slice had significant effect on the drying kinetics and various qualities of the dried pumpkin. Moisture ratios were fitted to 10 different mathematical equations using nonlinear regression analysis. The quadratic equation satisfactorily described the drying behavior of pumpkin slices with the highest r value and the lowest SE values. The effective moisture diffusivity increased with power and ranged between 0.71 and 2.86 × 10(-9) m(2)/s. With increasing in infrared radiation power from 204 to 272 W, ß-carotene content of dried pumpkins decreased from 30.04 to 24.55 mg/100 g. The rise in infrared power has a negative effect on the color changes (ΔE). The optimum condition was determined as power, 238W, pressure, 5 kPa and slice thickness, 5mm. These conditions resulted into dried pumpkin slices with maximum B-carotene retention.

Effect of resistant starch and aging conditions on the physicochemical properties of frozen soy yogurt.

The present study investigated the effects of resistant starch concentration (0, 1, 2 %), aging time (2, 13, 24 h) and aging temperature (2, 4, 6 °C) on the physicochemical properties of frozen soy yogurt. The results showed that resistant starch increased viscosity because of its water binding properties. Resistant starch also increased foam stability, fat destabilization, and hardness, but it decreased overrun and meltdown rate. Viscosity, hardness and fat destabilization increased as aging time increased. An increase in aging temperature decreased viscosity, overrun, hardness and fat destabilization of frozen yoghurt, but increased the meltdown rate.

Effect of thermal and freezing treatments on rheological, textural and color properties of basil seed gum.

Hydrocolloids are macromolecular carbohydrates that are added to many foodstuffs to achieve the appropriate rheological and textural properties and to prevent synersis or to increase the viscosity and stability of foodstuffs. In this study the effect of different thermal treatments (25, 50, 75, 100 and 121°C for 20 min) and freezing treatments (-18 and -25 °C for 24 h) on rheological, textural and color change of basil seed gum as a new source of hydrocolloids was investigated. The results demonstrated that basil seed gum solutions had desirable rheological and textural properties. Power law model well described non-newtonian pseudoplastic behavior of basil seed gum in all conditions. When the hydrocolloid samples were heated or frozen, increase in viscosity of basil seed gum solutions was observed. Hardness, adhesiveness and consistency of basil seed gel for control sample were 13.5 g, 16.79, 52.59 g.s, respectively and all increased after thermal treatments. The results revealed that basil seed gum has the excellent ability to stand against heat treatment and the highest hardness, adhesiveness and consistency value of gum gels were observed in sample treated at 121 °C for 20 min. In addition this gum gel has the good ability to stand against freeze-thaw treatment and its textural properties improved after freezing. Therefore, basil seed gum can be employed as a textural and rheological modifier in formulation of foods exposed to thermal and freezing temperatures.

Modeling of extraction process of crude polysaccharides from Basil seeds (Ocimum basilicum l.) as affected by process variables.

Basil seed (Ocimum basilicum L.) has practical amounts of gum with good functional properties. In this work, extraction of gum from Basil seed was studied. Effect of pH, temperature and water/seed ratio on the kinetic and thermodynamic parameters; entropy, enthalpy and free energy of extraction were investigated. The maximum gum yield was 17.95 % at 50 °C for pH=7 and water/seed ratio 30:1. In this study, the experimental data were fitted to a mathematical model of mass transfer and equations constants were obtained. The kinetic of Basil seed gum extraction was found to be a first order mass transfer model. Statistical results indicated that the model used in this study will be able to predict the gum extraction from Basil seed adequately. It also found that ΔH and ΔS were positive and ΔG was negative indicating that the extraction process was spontaneous, irreversible and endothermic. The ΔH, ΔS and ΔG values were 0.26-7.87 kJ/mol, 8.12-33.2 J/mol K and 1.62-4.42 kJ/mol, respectively.

A mixture design approach to optimizing low cholesterol mayonnaise formulation prepared with wheat germ protein isolate.

The aim of this study was to optimize the mixture proportion of low cholesterol mayonnaise containing wheat germ protein isolate (WGPI) and xanthan gum (XG), as emulsifying agents in mayonnaise preparation. The mayonnaise prepared with different combinations of WGPI, egg yolk (0-9 % of each component) and XG (0-0.5 %). The optimized mixture proportions of low cholesterol mayonnaise were determined by applying the optimal mixture design method to acquire the mayonnaise with proper stability, texture, rheological properties and sensory scores. Optimum values of WGPI, XG and egg yolk in the mixture were found to be 7.87 %, 0.2 % and 0.93 %, respectively (of 9 % egg yolk). The WGPI, due to unique functional properties, had the greatest effect on properties of mayonnaise samples. Moreover, combination of XG and WGPI, improved the stability, heat stability, viscosity, consistency coefficient and textural properties of product. However, the overall acceptance was maximum in a mixture contained high amount of WGPI and XG and low amount of egg yolk. The results of this research showed the feasibility of preparation a low cholesterol mayonnaise by application a desirable combination of WGPI, XG, and egg yolk, with comparable properties those of the conventional mayonnaise.

Effect of inulin on the physicochemical properties, flow behavior and probiotic survival of frozen yogurt.

This study investigated the effect of inulin (0, 1 and 2 %), on some physicochemical properties of frozen yogurt, as well as its effect on flow behavior and probiotic survival. The results showed that the addition of inulin improved overrun, viscosity and melting properties significantly (p < 0.05); when added at 2 % level, it also had significant effect on pH. Total acceptability of samples revealed that frozen yogurt with 2 % inulin had the most appealing sensory characteristics. The flow behavior of all samples showed their pseudoplastic nature; power law was the best model to predict their flow behavior. In terms of probiotic survival, the sample with 2 % inulin significantly improved the viability of Lactobacillus acidophilus and Bifidobacterium lactis.

Study of antioxidant activity of sheep visceral protein hydrolysate: Optimization using response surface methodology.

BACKGROUND: The main objective of this experiment was optimal use of none edible protein source to increase nutritional value of production with high biological function, including antioxidant activity. METHODS: Sheep visceral (stomach and intestine) was used as substrate. Response surface methodology (RSM) was used to optimize hydrolysis conditions for preparing protein hydrolysate from the sheep visceral, using alcalase 2.4 l enzyme. The investigated factors were temperature (43-52 °C), time (90-180 min), and enzyme/substrate ratio [60-90 Anson-unit (AU)/kg protein] to achieve maximum antioxidant activity. Experiments were designed according to the central composite design. RESULTS: Each of the studied variables had a significant effect on responses (P < 0.05). Optimal conditions to achieve antioxidant activity were, temperature (48.27 °C), time (158.78), min and enzyme/substrate ratio (83.35) Anson-unit/kg protein. Under these conditions, antioxidant activity was 68.21%, R2 for model was 0.983. The values indicated the high accuracy of the model to predict the reaction conditions considering different variables. The chemical analysis of protein hydrolysate showed high protein content (83.78%) and low fat content (0.34%). CONCLUSION: Our results showed that protein hydrolysate of sheep visceral, can be used as a natural antioxidant with high nutritional value.

Effect of sugars and salts on rheological properties of Balangu seed (Lallemantia royleana) gum.

The effect of different sugars (sucrose, glucose, fructose, and lactose) and salts (NaCl and CaCl2) at various concentrations on rheological properties of Balangu seed gum (BSG, 1% w/w) was investigated. The apparent viscosity was influenced by the sugars and salts concentration and shear rate. Synergistic interaction between BSG gum and sugars improved the viscosity of solutions, whereas addition of salts decreased viscosity of gum solutions. The Power law and Herschel-Bulkley models were fitted to shear stress-shear rate data to obtain the consistency coefficient (K) and flow behavior index (n) for BSG solutions. Power law model well described non-Newtonian pseudoplastic behavior of BSG. Both K and n were sensitive to sugars and salts concentration. Highest values (0.45-0.49) of flow behavior index were observed for glucose at all concentrations. Addition of sucrose, fructose, lactose and salts to BSG led to more pseudoplastic solutions, whereas glucose decreased pseudoplasticity of solutions.

Enhanced biomass delignification and enzymatic saccharification of canola straw by steam-explosion pretreatment.

BACKGROUND: In recent decades, bioconversion of lignocellulosic biomass to biofuel (ethanol and biodiesel) has been extensively investigated. The three main chemical constituents of biomass are cellulose, hemicellulose and lignin. Cellulose and hemicellulose are polysaccharides of primarily fermentable sugars, glucose and xylose respectively. Hemicellulose also includes small fermentable fractions of arabinose, galactose and mannose. The main issue in converting lignocellulosic biomass to fuel ethanol is the accessibility of the polysaccharides for enzymatic breakdown into monosaccharides. This study focused on the use of steam explosion as the pretreatment method for canola straw as lignocellulosic biomass. RESULTS: Result showed that steam explosion treatment of biomass increased cellulose accessibility and it hydrolysis by enzyme hydrolysis. Following 72 h of enzyme hydrolysis, a maximum cellulose conversion to glucose yield of 29.40% was obtained for the steam-exploded sample while the control showed 11.60% glucose yields. Steam explosion pretreatment increased glucose production and glucose yield by 200% and 153.22%, respectively, compared to the control sample. The crystalline index increased from 57.48% in untreated canola straw to 64.72% in steam-exploded samples. CONCLUSION: Steam explosion pretreatment of biomass increased cellulose accessibility, and enzymatic hydrolysis increased glucose production and glucose yield of canola straw.