Propriedades dos amidos in natura de milho e mandioca após um ano de fermentação natural

Abstract

Natural fermentation is a process performed on starch structure for promoting changes to assist or expand their use in the food industry, since in its natural form this polymer has characteristics such as low solubility in cold water and tendency to retrogradation. The objective of this study was to evaluate the effects of prolonged fermentation on the structure and technological properties of this component. Corn and cassava starches acquired in local commerce from Fortaleza-Ce were submitted to natural fermentation for 12 months with sufficient water so that the granules were hydrated and to film forming of at least 10 cm above the sample. After this period was verified acidity, pH and reducing sugars in the supernatant liquid and the fermented starch was characterized as the physico-chemical properties (moisture, ash, fat, protein), gelatinization characteristics in exploratory differential calorimeter (DSC), swelling power and solubility index, paste viscosity and properties in the presence of solutes in Rapid Visco Analyser (RVA), Clarity paste, structural characteristics in scanning electron microscope and expansion through specific volume of biscuits. The acidity analysis was more appropriate to characterize the supernatant liquid and control the fermentation process. Supernatants of fermentation showed potential for use in other products or industrial processes, mainly by reducing sugar content. Fermentation promoted an increase of the levels of ash and protein in the samples and changes in the rheological properties of the granules, reducing the viscosity peak and retrogradation compared to natural samples. The addition of solutes (sucrose and sodium chloride) elevated the temperature of the evaluated pastes and increased maximum viscosity of samples does not fermented corn. The crystallinity index was similar for in natura samples (25,85% - cassava / 23,42% corn) and fermented (25,00% - cassava / 22,78% - corn), showing that the acids and enzymes acted in all areas that composing the granule. The fermented samples showed deformations, holes and cracks. The fermentation time applied not interfere significantly increase the volume of biscuits produced with corn starch in relation to the processed tapioca starch.