Amido de milho modificado por fermentação com ou sem iniciadores e secagem ao sol, e aplicação em biscoitos enriquecidos com gérmen de milho

Abstract

Starch is an available carbohydrate with varied applications in agroindustry. However, there is a need to modify it in order to adapt its properties to specific consumer demands. Natural fermentation followed by sun drying is a form of starch modification performed by the action of enzymes and acids produced by microorganisms. Cassava starch is considered a product with strong commercial appeal in Brazil, however, corn has become in 2022 the main cereal in planted area and world production. Thus, the aim of the present study was to evaluate the physical, chemical, structural and technological properties of corn starches modified by natural fermentation, with and without the backslopping technique, followed by sun drying; to understand the effect of different starters on the fermentation time of the new ingredient, and to apply the modified starch in cheese biscuits type chipa enriched with corn germ flour. A completely randomized design was used for the fermentation and preparation of the cheese biscuits, with three treatments (corn starch without starter, corn starch with fermented corn starch starter, corn starch with sour cassava starch starter) and five treatments (0%, 5%, 10%, 15% and 20% modified corn starch with sour cassava starch starter replaced by corn germ), respectively. The fermentation with starter of cassava sour starch was carried out in 12 days, while the fermentations with fermented corn starch starter and without starter were stopped only after 65 days. Natural fermentation followed by sun drying altered the starch granule surface, pasting properties, and caused slight changes in relative crystallinity as well as amylose content. Starches that underwent the fermentation process for a longer time showed more significant changes. The techniques used were effective to acidify corn starch, and also they promoted changes in ash content, water absorption indexes, and water solubility, but were not sufficient to achieve the degree of expansion of sour cassava starch. The fermented corn starch with sour cassava starch starter was applied as the main ingredient in the formulation of the cheese biscuits enriched with corn germ. The use of corn germ, in different percentages, showed to be efficient for the fortification of the biscuits, once higher contents of ashes (varying from 3.97 % to 9.92 %), proteins (varying from 7.76 % to 24.51 %), and lipids (varying from 5.53 % to 14.89 %); and lowercontents of carbohydrates (varying from 2.38 % to 11.75 %) were observed for biscuits with higher contents of corn germ. Therefore, natural fermentation with the backslopping technique is an alternative to obtain sour corn starch in less time, as well as the starch obtained can be used in the elaboration of baked products in which the expansion property is not a fundamental characteristic for quality.