Optimization of ultrasound-assisted osmotic treatment of Aleo vera gel impregnated with grape pomace phenolic compounds using response surface methodology

This study was focused on investigating the use of pulsed ultrasound-assisted osmotic dehydration (UAOD) for enhancing the infusion of phenolic compounds extracted from grape pomace (GPx) to Aloe vera (Aloe barbadensis Miller,) gel (AVG) using response surface methodology (RSM) and produce a dehydrated product with high antioxidant content. Fresh AVG were initially immersed in a sucrose solution of 50° B with three levels of GPx (10, 20, and 30 v/v) and subjected to pulsed ultrasound (US) treatment with a probe of 2 cm diameter, two levels of ultrasound amplitude (UA) (50 and 100%), and three ultrasound treatment times (UT) (30, 135 and 210 min). The pulsed on and off times were set at 15 and 1 min, respectively. A multiple regression analysis was carried out to develop second-order polynomial models with high coefficients of determination value (R2 > 0.81). The optimal conditions were obtained using the Design Expert software. The best condition obtained for the UAOD optimization was UA = 59%, 20% grape pomace extract in 50% sucrose, UT = 173 min to result in a moisture loss of 51.3 % (predicted 49.9%), solid gain of 4.3 % (5.0%), total phenolic contents of 30.5 mg/g (31.8%), and DPPH radical scavenging activity of 15.3% (15.0%). UAOD therefore appears to be a promising process for antioxidant incorporation and preparing added value product.

Effect of Soluble Solids and High Pressure Treatment on Rheological Properties of Protein Enriched Mango Puree

The effects of high pressure treatment on the rheological properties of protein enriched mango puree were evaluated. In the first part, the original soluble solids in mango puree (28° Brix) was lowered to 26, 23 and 20° Brix, and each was supplemented with 2, 5 and 8% of whey protein to assess the influence of added protein. The samples were then evaluated by dynamic rheology. Pressure treatment resulted in a progressive increase in elastic (G′) and viscous modulii (G″) as well as complex viscosity (η*). Values of G′ were higher than G″ demonstrating that the product behaved more like a gel. Additional tests were carried out by simultaneously varying protein and soluble solids contents, and keeping the total solids at 28%. In this case, the effects of pressure levels and holding times were similar to previous results. However, the positive effects of higher protein were negated by the negative effects of lower soluble solids, resulting in an overall decreasing effect on rheology. The developed models effectively predicted the combined influence of protein and soluble solid concentrations on rheological parameters (R2 > 0.85). Sensory evaluation of 2% and 5% protein supplemented and pressure treated (500 MPa/3 min) mango puree yielded acceptable sensory qualities, resulting in a product with enriched protein content

Optimization of Microwave-Osmotic Pretreatment of Apples with Subsequent Air-Drying for Preparing High-Quality Dried Product

Prepared apple (Red Gala) cylinders were subjected to microwave-osmotic dehydration treatment under continuous flow medium spray (MWODS) conditions and then air-dried to a final 20% moisture content. The dried samples were evaluated for color and textural properties, and rehydration capacity. The MWODS pretreatments were based on a central composite rotatable design and a response surface methodology using five levels of sucrose concentration, temperature, and contact time at a constant flow rate of 2800 mL/min. The air-drying was carried out at 60°C, 15±1% relative humidity, and 0.64±0.02 m/s air velocity. The results were compared to untreated air-dried (AD) (worst-case scenario) and freeze-dried (FD) (best-case scenario) apples without the MWODS treatment. Color properties were affected regardless of the type of treatment. Conventional AD apples were darker in color, whereas MWODS-treated samples were lighter with higher L∗ and b∗ values, higher Hue and Chroma values but lower a∗ value and ΔE. Further the color parameters of MWODS-treated samples were closer or equal to the FD apples. The texture properties were also affected by the osmotic variables with MWODS treatment resulting in softer and chewier products. The AD samples were hard, and FD apples were brittle

Characterization of Caseinate–Carboxymethyl Chitosan-Based Edible Films Formulated with and without Transglutaminase Enzyme

Edible composite packaging has the advantage of complementary functional properties over its individual bio-components. However, film composites made from caseinate (CA) and carboxymethyl chitosan (CMCH) have not yet been well explored. In this study, four types of CA-CMCH composite films were prepared and evaluated with and without transglutaminase (TGase) supplement. Aqueous CA (8%, w/v) and CMCH solutions (2%, w/v) were mixed in different volume ratios of CA: CMCH as 100:0, 75:25, 50:50, 75:25, and 25:75. Those to be supplemented with TGase were incorporated at 10 U/g of caseinate protein level. Results revealed that CMCH incorporation to CA facilitated a smooth and uniform surface microstructure on films and markedly improved the transparency, water barrier properties, mechanical properties, and solubility of the composite film. Furthermore, addition of TGase resulted in an improvement in the water vapor permeability. TGase successfully enforced the formation of CA-CMCH composites with some enhanced functional properties. The resulting composite film offers potential for applications as an alternative edible film or in the preparation of edible packaging films

ELISA Based Immunoreactivity Reduction of Soy Allergens through Thermal Processing

Allergens are proteins and are, therefore, likely to be denatured when subjected to thermal treatment. Traditional cooking has so far been able to reduce allergen sensitivity by around 70–90%. This study was aimed at evaluating the effect of a broad range of thermal treatments on the reduction of soy immunoreactivity (IR) in a 5% slurry using a sandwich ELISA technique. Cooking at 100 °C (10–60 min) and different thermal processing conditions, such as in commercial sterilization (with a process lethality (Fo) between 3 and 5 min) and selected severe thermal processing conditions (Fo > 5 and up to 23 min) were used in the study to evaluate their influence on allergen IR. Based on an IR comparison with an internal soy allergen standard, the allergen concentration in the untreated soy sample was calculated to be equivalent to 333 mg/kg (ppm). Cooking conditions only reduced the IR sensitivity to about 10 mg/kg (~1.5 log reductions), while the thermal processing treatments lowered the allergen IR up to 23 × 10−3 mg/kg (or 23 ppb) (>4 log reductions). FTIR analysis indicated significant changes in protein structure resulting from the thermal processing treatments, with a higher degree of allergen reduction corresponding with a higher value of random coil percentages. The influence of process severity on color and rheological properties was, however, minimal

Application and Evaluation of a Pectin-Based Edible Coating Process for Quality Change Kinetics and Shelf-Life Extension of Lime Fruit (<i>Citrus aurantifolium</i>)

Uncertain storage conditions lead to considerable quality loss in lime fruits, which affect their consumer acceptability. Studies aimed at quantifying the kinetics of quality changes under different storage conditions are valuable for minimizing the product quality loss and improving their marketability. The objective of this study was to quantify the effect of pectin-based coating on the kinetics of quality change in stored limes fruits using a pre-established coating process. Lime fruits were immersed in the coating emulsion and then surface dried, cooled, and evaluated after storage for different times at selected temperatures (10&#8722;25 &#176;C). Quality characteristics evaluated include physical (texture and color), chemical (ascorbic acid, pH, titrable acidity, total soluble solids), and physiological (respiration rate) properties. Results revealed that with the passage of time, the fruits showed progressive increase in shriveling or wilting and loss in green color, and higher temperatures accelerated these changes. The respiration rate in control samples reached 79, 35, and 7 mL CO2/(kg&#183;h) after 7 days at 25 &#176;C and 22 days at 15 and 10 &#176;C, respectively, while those of coated samples were limited to 40, 32, and 1.06 mL CO2/(kg&#183;h) after 11, 25, and 32 days at the same storage temperatures. Control fruits suffered 6%, 10%, and 24% weight loss following 8 days of storage at 10, 15, and 20 &#176;C, respectively, while the losses in coated fruits were lower (2%, 4%, and 17%, respectively). A zero-order model was found appropriate for weight loss, along with a color a value and &#916;E, while a first-order model was found to be better for firmness, brix to acidity ratio, ascorbic acid, and b and L values (R2 &gt; 0.9). The Arrhenius model was suitable for temperature sensitivity of the rate constants