Texture and antioxidant evolution of naturally green table olives as affected by different sodium chloride brine concentrations

A Piga,A M Sanguinetti,A Del Caro,C Fadda

doi:10.3989/gya.037213

Abstract

The results on the evolution of the texture and antioxidant activity during the processing of naturally fermented green olives are reported in the present study. The olives were brined with two different NaCl concentrations, 4 and 7%. A puncture test and a texture profile analysis (TPA) test were carried out to evaluate texture, while the antioxidant activity was assessed in consideration of the loss of absorbance of a stable radical upon reaction with a polyphenolic olive extract. The puncture test revealed both an increase and decrease in peel and flesh hardness, respectively. The olives processed with 7% NaCl concentration showed higher peel hardness than olives brined with 4% salt. The texture profile analysis did not reveal any difference between the two salt concentrations used, but showed a decrease in the value of all parameters after 30 days of brining. The antioxidant activity of the polyphenolic extract decreased significantly during processing, with a major loss after the first 30 days of processing and was higher in the 7% brined olives, than the sample treated with 4% NaCl.

Highlights

According to International Olive Oil Council (2012), table olives represent about 10% of the total olive processing industry
The chemical-physical evolution of brines and olives during processing has been deeply investigated in our lab and by other authors (Piga and Agabbio, 2003; Poiana and Romeo, 2006; Romeo et al, 2012), but no study on intact green olives has been undertaken so far concerning the instrumental measurements of texture, which is one of the attributes that most affects the consumer acceptance of table olives and may be strongly influenced during processing
Due to the association of sodium intake with hypertension, different authors have reported on the reduction or partial substitution of sodium chloride in brines (BautistaGallego et al, 2010; Bautista-Gallego et al, 2011; Panagou et al, 2011; Moreno-Baquero et al, 2012; Rodríguez-Gómez et al, 2012). In this context we demonstrated that it is possible to successfully process green table olives in the natural style using a low sodium chloride brine concentration (2–4%), assuring that the brines are acidified at pH 4.0 (Piga and Agabbio, 2003)

Summary

Introduction

According to International Olive Oil Council (2012), table olives represent about 10% of the total olive processing industry. Table olive processing includes the removal of the bitter taste of olives and fermentation. For example, produces about 20% of naturally fermented green olives, which are prepared by directly placing fruits in brine, as reported by the International Olive Oil Council (2004). This type of olives is partially debittered by diffusion of the bitter polyphenolic compounds from the flesh to the brine over a time ranging from 5 to 8 months. Factors influencing the activity of hydrolytic enzymes are the pH and NaCl concentrations of brines (Fernández-Bolaños et al, 2001)

Methods

Results

Conclusion