Study of the interaction between montmorillonite and vegetable pigments in acerola juice using ultraviolet-visible spectroscopy and nuclear magnetic resonance

• Grant number: 18/06639-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2018
• End date: April 30, 2019
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Luiz Alberto Colnago
• Grantee: Dayane Aise Menini
• Host Institution: Embrapa Instrumentação Agropecuária. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). São Carlos , SP, Brazil

Abstract

Anthocyanins are phenolic compounds and are the largest class of natural pigments and are responsible for the colors of fruits. Besides the visual aspect they are important antioxidants and therefore are extremely important for the prevention of various diseases, such as cancer. A disadvantage of this class of compounds is their low stability in low acid or neutral pH solutions. At low acid pH these compounds change color quickly and in the case of juices give the impression that it is deteriorated. It has recently been shown that the addition of montorillonite clay in acerola juice prevents this rapid color change. The main hypothesis for this is that the anthocyanins are trapped between the layers of the clay. This hypothesis is based mainly on X-ray diffraction (XRD) data of the material collected after clay precipitation. According to this hypothesis, the flavylium ion of the anthocyanins interacts with the montmorillonite ions, being stabilized by electrostatic interactions. Therefore, the present project aims to study the interaction between montmorillonite and the co-pigments present in acerola juice using ultraviolet-visible spectroscopy and nuclear magnetic resonance. (AU)