Determination of the amylose content and the degree of crystallinity of isolated starch granules of bananas and hydrolyzed by the alpha-amylase or beta-amylase

• Grant number: 15/21775-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2016
• End date: December 31, 2016
• Field of knowledge: Agronomical Sciences - Food Science and Technology - Food Science
• Principal Investigator: Beatriz Rosana Cordenunsi
• Grantee: Karen Rebouças Nascimento
• Host Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 13/07914-8 - FoRC - Food Research Center, AP.CEPID

Abstract

The banana is considered a good model to study the sucrose-starch processing, since it accumulates a high starch content during development, which is degraded during fruit ripening. The enzymes involved in starch degradation pathways and sucrose synthesis are: ±-amylase, ²-amylase, starch phosphorylases, debranching enzymes, glucan-water-dikinase (GWD), fosfoglucano-water-dikinase (PWD) and sucrose -phosphate synthase. Of these, ±-amylase, a ²-amylase, isoamylase, the starch phosphorylases have had activity and protein expression established in banana pulp, and the enzymes associated with the already known banana starch granules are: ±-amylase, ²- amylase (protein and activity) and GWD (protein). There are two models for the degradation of starch: (1) at first, the start of degradation depend only on the action of ±-amylase (cereal germination); (2) the second degradation depends on the phosphorylation of starch granules at positions G and G-3P-6P the GWD and PWD enzymes, then the action of ²-amylase. Our work has shown that the enzymes necessary to act on both models are present in the pulp and banana starch and the ±-amylase and ²-amylase appears to have specificity for substrates different in the bead. The objective of this study is to confirm this specificity of substrate by determining the degree of crystallinity and the amylose content of damaged starch granules.