Rheological and technological characterization of red rice modified starch and jaboticaba peel powder mixtures.

Properties of modified starch and its interaction with functional raw materials are of great interest to the food industry. Thus, this study aimed to evaluate the rheological and technological characterization of starches modified by the action of the enzymes α-amylase and amyloglucosidase and their mixtures with jaboticaba peel powder. The parameters of firmness, gumminess, and final viscosity of starches paste increased, and the tendency to setback was reduced with the addition of jaboticaba peel powder. Starches and mixtures presented shear-thinning behavior. The addition of jaboticaba peel powder to starches increased water, oil, and milk absorption capacity, while syneresis remained stable over the storage period. The addition of jaboticaba peel powder had a positive effect on native and modified starches' rheological and technological properties, qualifying it as an alternative for developing new functional food products.

Role of chitosan and transglutaminase on the elaboration of gluten-free bread.

The increasing sensitivity to gluten has aroused interest in gluten-free products like bread. However, one of the biggest challenges of producing gluten-free bread is to get a good quality structure. We hypothesize that using chitosan along with transglutaminase, a network of crosslinks would be generated, guaranteeing a better structure. Thus, in the present work, we produced gluten-free bread using red rice flour and cassava flour, transglutaminase, and chitosan at concentrations of 0%, 1%, and 2%. Loaves of bread were characterized, and the instrumental texture properties during five days were determined. Bread produced with chitosan and transglutaminase presented lighter brown coloration due to incomplete Maillard reaction and low specific volumes varying from 1.64 to 1.48 cm3/g, possibly due to chitosan interfering with yeast fermentation. Rheological tests revealed increases in viscosity before and after fermentation when chitosan was used. Bread with chitosan presented high initial firmness but a lower rate of staling, possibly due to water retention. According to results, a possible network involving chitosan and other proteins promoted by transglutaminase was formed and after optimization could yield better gluten-free bread.

Influence of enzymatic hydrolysis on the properties of red rice starch.

Starch is a technologically challenging polysaccharide that arouses the global interest in its modification to increase its applicability. Thus, the objective of the present work was to study the influence of enzymatic modification on the properties of red rice starch. The enzymatic modification was performed sequentially through the actions of α-amylase enzymes and amyloglucosidase using a design of experiments where several process conditions were used at sub-gelatinization temperatures. Then the native and modified starches were characterized for its physicochemical, physical, centesimal, phytochemical, morphological, and thermal properties. The enzymatic hydrolysis of the starch granules with α-amylase resulted in 4.46% hydrolysis and more 8.63% after the action amyloglucosidase. Results revealed that surface adsorption is more limiting than diffusion. The enzymatic hydrolysis process resulted in a reduction of the amylase and amylopectin content, as well as on all phytochemicals. After hydrolysis, granules starches presented surface alterations and tendency to become spherical. Small differences on crystallinity revealed that the enzymes had more influence on the amorphous fractions of the starch granules.

Production of prebiotic gluten-free bread with red rice flour and different microbial transglutaminase concentrations: modeling, sensory and multivariate data analysis.

The aim of this study was to develop gluten-free bread formulated with red rice flour and microbial transglutaminase and prebiotic (inulin). First, the physicochemical analysis of minerals present in red rice flour was performed. Response surface methodology was used to analyze the effects of microbial transglutaminase (MTgase) [0.5; 1.0 and 1.5%] in combination with fermentation time (FT) [60; 80 and 100 min] on the quality parameters of gluten-free bread. Acceptance test was used to evaluate the sensory characteristics of breads together with multivariate analysis of data. The addition of MTgase increased bread volume, hardness and chewiness. However, the cohesiveness and springiness of all breads remained unaffected. The formulation (1.0% MTgase and 80 min FT) presented the best sensory attributes through PCA (principal component analysis) and greater acceptance. Overall, red rice flour, prebiotic and MTgase are promisingly useful ingredients for the production of gluten-free quality bread.