Heat Induced Gels from Coconut Press Cake Proteins

Borges Chambal,Petr Dejmek,Björn Bergenståh

doi:10.4236/fns.2014.56066

Borges Chambal, Petr Dejmek + Show 1 more

Open Access

https://doi.org/10.4236/fns.2014.56066

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Abstract

Freeze-dried coconut press cake powder (CPP), 43% w/w protein, was used to investigate the heat-induced gelation by heating in rheometer to 75℃ in a wide range of pH values, from 4 to 9. Low strain oscillatory method applied the measure visco-elastic propertieson 15% w/w CPP. The gel strength was also assessed by a texture analyzer. SDS-PAGE electrophoresis was conducted to identify the proteins evolved in the gel network structure and the gel micro-structure was also evaluated. At low pH, the CPP proteins formed soft (elastic modulus <100 Pa) particulate gels prone to syneresis, with aggregate size of the order of 4.2 micrometers. In the alkaline region, homogenous gels were induced by heating. Gel strength started to increase dramatically from 64℃ to 67℃, for pH 9 and pH 8 respectively, reaching the maximum gel elastic modulus over 1000 Pa at pH 9. The SDS-PAGE showed that the polypeptide sub-unities at 24, 32 - 34 and 53 kDa were the most prominent in gelation.

Highlights

The functionality of proteins has been shown to play important role in food processing, since they are key components implicated in gelling, foaming, emulsifying and water/oil binding capacities
The coconut press cake proteins (CPP) showed some abilities to form gels induced by heat, this capacity was greatly affected by environmental factors, among which the most important were: the concentration, heating temperature and pH values
Preliminary essays conducted with 13% w/w coconut protein powder (CPP) showed that the gelation occurred at 70 ̊C, in a limited range of pH 8 to 9, while with 20% CPP the onset temperatures dropped down to 60 ̊C, in a wider pH range of 7 to 9

Summary

Introduction

The functionality of proteins has been shown to play important role in food processing, since they are key components implicated in gelling, foaming, emulsifying and water/oil binding capacities. The gel formation is a property under which, a protein solution is turned up into a soft solid, space filling network structure, by a mean of heating, decreasing pH, cooling, etc. [1]-[4], providing to food new rheological and textural properties. Recent studies have shown that high pressure treatments have impact on inducing gelation in some globular proteins [5]. How to cite this paper: Chambal, B., et al (2014) Heat Induced Gels from Coconut Press Cake Proteins. Built up from globular proteins follows, primarily, the changes into the protein structure, by unfolding the native state, which exposes to the solution, the hydrophobic patches, normally hidden inside the protein matrix, which in turn prompts to new protein-protein interactions and the aggregation [4]-[7]. In addition food is generally a complex system of many different ingredients, some even counter-acting against the desired functional properties

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