Effect of calcium chloride on mechanical properties and microbiological characteristics of cv. Conservolea naturally black olives fermented at different sodium chloride levels

Abstract

The effect of calcium chloride (CaCl2)(5 gL-1) and sodium chloride (NaCl) concentration (40, 60 and 8 gL-1) on the microbiological and mechanical properties of naturally black olives of cv. Conservolea in brines was studied. In 40 and 60 g L-1 brines the growth of lactic acid bacteria was favoured over that of yeasts, resulting in rather complete lactic acid fermentation as indicated by high free acidity (9.8–11.5 g lactic acid L-1) and low pH (3.7–3.8). At 80 g L-1 brine, yeasts were the dominant members of the microflora, rendering a product with lower acidity (8 g lactic acid L-1) and higher pH (4.3–4.5). In the presence of CaCl2 there was a consistent increase in the depth of the peripheral region in which cell wall breakage occurred. When cells separated, perforated walls were observed at sites associated with plasmodesmata. The flesh was strongest and stiffest when CaCl2 was added to olives treated with 40 g L-1 brine, consistent with cell wall breakage being the predominant mode of failure. The only observed effect on the mechanical properties of the skin was a stiffening at 60 g L-1 brine on addition of CaCl2

Nutritional and Sensory Quality of Table Olives

“…The texture of edible fruits and vegetables is strongly influenced by the chemical, physical and structural properties of the plant cell walls which surround every cell and, through adhesion to the adjacent ones, provide mechanical strength and protection (Brett & Waldron, 1996). Such properties will be affected by the stage of ripening (Mafra et al, 2001) and processing technologies Tassou et al, 2007). Tissues in which cell-to-cell adhesion is very strong may only be disrupted by breakage of the cell walls: such tissues are usually crunchy in texture.…”

Effect of dry‐salt processing on the textural properties and cell wall polysaccharides of cv. Thasos black olives

“…5 The same trend was observed in naturally black olives of the Conservolea variety, by changing the sodium chloride concentration of the brine solution from 40 to 60 g L −1 , and the opposite behaviour was obtained for higher sodium concentrations (80 g L −1 ). 6 Despite those reports, olives undergoing dry-salt processing, being subjected to distinctly different conditions compared to those usually applied in brine, were never studied for their mechanical properties.…”

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

“…The most important result, however, is that peel break force and hardness increased during brining. Romeo et al (2012) found similar results by brining turning color "Biancolilla" olives at 12%; while Georget et al (2003) and Tassou et al (2007) found a different behavior, but, as stated before, both the different degrees of ripening or Texture and antioxidant evolution of naturally green table olives as affected by different sodium chloride brine concentrations • 5 mechanical testing may have influenced the results. This peel hardening may be explained by the fact that the peel shrivelled due to the contemporary effects of sodium chloride absorption and water loss, thus resulting in the development of a crust.…”

“…These differences were significant after 60 days (Figures 2-3). Tassou et al (2007) did not find differences in skin strength following brining with different sodium chloride concentrations, but they worked with black olives and performed the texture analysis on a peel strip and in tension mode. The most important result, however, is that peel break force and hardness increased during brining.…”

“…An instrumental texture analysis has been applied to Spanish style olives (Jimenez et al, 1997;Morales-Sillero et al, 2008;Rejano-Navarro et al, 2008), Greek style olives (Kanavouras et al, 2005;Tassou et al, 2007;Lanza et al, 2010;Romeo et al, 2012), Californian style (Georget et al, 2003;Romeo et al, 2012) and other styles (Marsilio et al, 2000;Arroyo-López et al, 2007;Romeo et al, 2012). In a recent paper Romeo et al (2012) evaluated the effect of post-processing treatments on the texture of fermented green olives, but no study has been undertaken so far on naturally fermented green table olives.…”