Resistant starch: effect on rheology, quality, and staling rate of white wheat bread.

The effect of the partial substitution (0, 10, 15, and 20%) of wheat flour with resistant starch (RS) on dough rheology and structure, and on the quality and staling rate of bread was evaluated. The results from farinograph, extensograph, alveograph, oscillatory rheological tests, and from confocal laser scanning microscopy, indicated that the substitution up to 15% of flour with RS slightly affected the dough structure, weakening it through dilution of gluten protein. Bread made with 15% of RS had specific volume, crumb moisture, and firmness values similar to those of the control bread (without RS), indicating very good quality. During storage, the RS breads had higher crumb moisture, lower firmness, and a lower retrogradation rate than the control bread. The lower retrogradation rate, in conjunction with the higher crumb moisture and high water-retention capacity of RS, was responsible for lower crumb firmness in bread containing up to 15% RS. Using wheat flour of high quality helped to minimize the deleterious effect of RS on the dough and provided high-fiber bread with high quality and low staling.

Effect of ethanol, dry extract and reducing sugars on density and viscosity of Brazilian red wines.

BACKGROUND: Density and viscosity are properties that exert great influence on the body of wines. The present work aimed to evaluate the influence of the alcoholic content, dry extract, and reducing sugar content on density and viscosity of commercial dry red wines at different temperatures. The rheological assays were carried out on a controlled stress rheometer, using concentric cylinder geometry at seven temperatures (2, 8, 14, 16, 18, 20 and 26 °C). RESULTS: Wine viscosity decreased with increasing temperature and density was directly related to the wine alcohol content, whereas viscosity was closely linked to the dry extract. Reducing sugars did not influence viscosity or density. Wines produced from Italian grapes were presented as full-bodied with higher values for density and viscosity, which was linked to the higher alcohol content and dry extract, respectively. CONCLUSION: The results highlighted the major effects of certain physicochemical properties on the physical properties of wines, which in turn is important for guiding sensory assessments.

Influence of different combinations of wall materials on the microencapsulation of jussara pulp (Euterpe edulis) by spray drying.

The objective of this work was to study the spray drying of jussara pulp using ternary mixtures of gum Arabic (GA) and modified starch (MS) together with either whey protein concentrate (WPC) or soy protein isolate (SPI), as the carrier agents. Two experimental mixture designs and triangular response surfaces were used to evaluate the effects of the mixtures on the responses for powders formulated with GA:MS:WPC and GA:MS:SPI, respectively. The spray drying process was selected for each carrier agent mixture, aiming to maximum the process yield (PY), solubility (S), retention of total anthocyanins (RTA) and encapsulation efficiency (EE). It was shown that the ternary formulations showed higher PY, S and RTA than the pure and binary formulations, as well as good results for EE and a low moisture content, showing that the use of GA and MS together with either WPC or SPI provide better microencapsulation of the jussara pulp.

Effect of heat-moisture treatment on the structural, physicochemical, and rheological characteristics of arrowroot starch.

The effect of heat-moisture treatment on structural, physicochemical, and rheological characteristics of arrowroot starch was investigated. Heat-moisture treatment was performed with starch samples conditioned to 28% moisture at 100 ℃ for 2, 4, 8, and 16 h. Structural and physicochemical characterization of native and modified starches, as well as rheological assays with gels of native and 4 h modified starches subjected to acid and sterilization stresses were performed. Arrowroot starch had 23.1% of amylose and a CA-type crystalline pattern that changed over the treatment time to A-type. Modified starches had higher pasting temperature and lower peak viscosity while breakdown viscosity practically disappeared, independently of the treatment time. Gelatinization temperature and crystallinity increased, while enthalpy, swelling power, and solubility decreased with the treatment. Gels from modified starches, independently of the stress conditions, were found to have more stable apparent viscosities and higher G' and G″ than gels from native starch. Heat-moisture treatment caused a reorganization of starch chains that increased molecular interactions. This increase resulted in higher paste stability and strengthened gels that showed higher resistance to shearing and heat, even after acid or sterilization conditions. A treatment time of 4 h was enough to deeply changing the physicochemical properties of starch.