Improvement of the storage process for cracked table olives

The aim of this work was to improve the storage method for cracked table olives. First, a study was carried out of the washing phase in 5% (wt/vol) NaCl brine with ascorbic acid and sodium metabisulphite added to it. Its use removed half the proportion of the initial sugar content in the flesh and markedly decreased the content of polyphenols in the fruits, confirming the effectiveness of this treatment. Washing with 5% NaCl and sodium metabisulphite was selected and applied in storage phase which follows. Storage of the washed cracked olives produced an additional decrease in sugars and polyphenols in the flesh, although the product still retained a fairly high concentration of residual sugars at the end of the storage period. The growth of lactic acid bacteria in this phase was prevented by the high NaCl level (10–13% at the equilibrium) but yeast growth, followed by a decline phase, was found in all storage systems studied. The use of a CO₂ atmosphere led to a partial inactivation of yeasts for about 300 h and showed a protective effect on polyphenols. Application of ozone had a favourable effect on initial solubilisation of sugars and polyphenols but caused a negative effect on fresh appearance, colour retention and polyphenol degradation. CaCl₂ + MgCl₂ treatment led to a significantly faster decline phase of yeasts. A tentative improved process for cracked olive storage may consist of a previous washing of olives for 24 h with a 5% NaCl solution (optionally added with 0.1% sodium metabisulphite), and a subsequent brining in a 15% NaCl solution with 0.25% CaCl₂ + 0.20% MgCl₂ or in a 15% NaCl brine under CO₂ atmosphere.