343: Nanofibrils Formation From 7S and 11S Globulins of Bogor-Indonesian Nuts (Vigna Subterranea L. Verdc.) for Functional Food Ingredients: Integrated Monitoring of Nanofibril Formation Stages

Introduction

One promising avenue for enhancing the utility of Bogor beans, as explored in this study, is the modification of Bogor bean proteins for food applications. The globular structure of Bogor-Indonesian nuts proteins was ingeniously transformed into a fibrillar structure through fibrillation. This process, conducted in vitro, involved subjecting the proteins to specific treatments, including exposure to temperatures above the denaturation point, low pH, and low ionic strength. These conditions led to the aggregation of peptide fragments from protein hydrolysis into elongated, semiflexible fibrils known as nanofibrils.

The conformational change of proteins from globular to fibrillar structures alters the physical and chemical properties of the fibril surface, providing distinct functionalities from the globular proteins. This structural modification results in increased solution viscosity, changes in flow behavior, and altered surface properties of the fibrils. Consequently, fibrillation enhances the functional characteristics of the proteins, making them suitable for development as food ingredients tailored to the needs of processed food applications.

Methods

Through a meticulous process of gradual pH adjustments, starting at pH 6.4 to precipitate 11S globulin, then the pH of the supernatant to pH 4.8 to precipitate 7S globulin, we successfully isolated both 7S and 11S globulins from Bogor-Indonesian nuts proteins as precursors for nanofibril formation. The combination of initial protein concentration, pH conditions, heating temperature, and stirring speed significantly influenced the successful formation of nanofibrils, laid the foundation for this research.

Results

The formation of nanofibrils was meticulously monitored and comprehensively identified using a range of methods: viscosity measurements with a rheometer, fibril morphology analysis with Transmission Electron Microscopy (TEM), beta-sheet detection in the fibril structure via Fourrier Transform Infrared (FTIR) Spectroscopy, and specific binding of fibrils to Congo Red dye using spectroscopic analysis. This integrated and thorough characterization confirmed that the fibrils derived from 7S and 11S globulins of Bogor-Indonesian nuts indeed exhibit nanofibril or amyloid fibril properties, instilling confidence in the accuracy of these findings.

Significance

This study provides a novel prospect for modifying Bogor-Indonesian nuts protein from a globular to a fibrillar form, thereby enhancing their functional properties as food ingredients with characteristics tailored to the requirements of processed food products.

Authors: Dewi Sarastani*, Dedi Fardiaz, Maggy Thenawidjaja Suhartono, Hanifah Nuryani Lioe, Aulia Irhamni Fajri, Lili Dahliani, Nanik Purwanti