Effect of whey protein isolate films incorporated with montmorillonite and citric acid on the preservation of fresh-cut apples.

The objective of this paper was to evaluate the effect of bioactive whey protein isolate/montmorillonite films containing citric acid on the inhibition of enzymatic browning and physicochemical properties in minimally processed apples. Whey protein isolate films incorporated with montmorillonite (3 g/100 g) and citric acid (5 and 10 g/100 g) were applied to the apples slices. All samples were packaged in polypropylene trays (14.6 cm × 11.4 cm × 6.5 cm) and stored at 5 ±â€¯2 °C and 85 ±â€¯3% RH for eight days. Every two days, the apples samples were evaluated for color, acidity, pH, soluble solids, water activity and polyphenol oxidase and peroxidase enzyme activity. The enzymatic browning of the apples slices was reduced for all films during storage. However, the films containing citric acid maintained the color characteristics, reducing the loss of quality associated the maintenance of acidity, soluble solids, water activity, reduction of polyphenol oxidase and peroxidase activity, thus prolonging the shelf life of the apples.

Effect of replacement of corn starch by whey protein isolate in biodegradable film blends obtained by extrusion.

The aim of this study was to evaluate the effect of replacing corn starch by whey protein isolated (WPI) in biodegradable polymer blends developed by extrusion. X-ray diffraction showed the presence of a Vh-type crystalline arrangement. The films were homogeneous, indicating strong interfacial adhesion between the protein and the thermoplastic starch matrix (TPS) as observed in scanning electron microscopy. The addition of WPI on TPS matrix promoted an increase in the thermal stability of the materials. It was observed 58.5% decrease in the water vapor permeability. The effect of corn starch substitution by WPI on mechanical properties resulted in a more resistant and less flexible film when compared the TPS film. The addition of WPI caused greenish yellow color and less transparent films. The substitution of corn starch by WPI made it possible to obtain polymer blends with improved properties and represents an innovation for application as a packaging material.

Matrix structure selection in the microparticles of essential oil oregano produced by spray dryer.

The goal of this work was to select the best combination of encapsulants for the microencapsulation of oregano essential oil by spray dryer with the addition of Arabic gum (AG), modified starch (MS) and maltodextrin (MA). The simplex-centroid method was used to obtain an optimal objective function with three variables. Analytical methods for carvacrol quantification, water activity, moisture content, wettability, solubility, encapsulation efficiency (ME) and oil retention (RT) were used to evaluate the best combination of encapsulants. The use of AG as a single wall material increased ME up to 93%. Carvacrol is the major phenolic compound existent in the oregano essential oil. Carvacrol exhibits a maximum concentration of 57.8% in the microparticle with the use of 62.5% AG and 37.5% MA. A greater RT (77.39%) was obtained when 74.5% AG; MS 12.7% and 12.7% MA were applied, and ME (93%) was improved with 100% of gum.