Microbiological, physicochemical and organoleptic changes in dry‐salted olives of Thassos variety stored under different modified atmospheres at 4 and 20 °C

Abstract

Microbiological, physico-chemical and organoleptic changes were studied in dry-salted olives, cv. Thassos, stored under different atmospheres (100% carbon dioxide and nitrogen, 40% CO 2 /30%O 2 /30%N 2 and air) at 4 and 20°C for 180 days. The initial microbial flora comprised of yeasts, no lactic acid bacteria, enterobacteria, pseudomonads or Staphylococcus aureus were detected, as the low water activity/high salt content does not favour their growth. At 4°C, the population of yeasts declined steadily throughout storage but to a different extent depending on the gaseous atmospheres. At 20°C, there was an initial decline in yeast counts in all samples followed by a steady increase until the end of the storage period. The CO 2 atmosphere was most effective at keeping the number of yeasts low at both storage temperatures. All gas atmospheres prevented fungal growth at both temperatures apart from the samples stored in air. The pH, a w and salt content of the olives did not change significantly throughout the storage period. The prevailing yeast species was the salt tolerant Candida famata. The organoleptic characteristics did not differ significantly among differently treated olives. However, increased rancidity and reduced fruit colour was observed in the samples stored at 20°C.

Improvement of the storage process for cracked table olives

“…This level is fairly common in home-made or in dry-salted table olives (Panagou et al, 2002) but not in Manzanilla-Aloreña in which the production of titratable acidity is normal (Garrido Fernández et al, 2002). The fermentation (by yeasts) process of cracked olives was always more rapid than any of the other untreated (natural) fruits, a circumstance that may accelerate the degradation of chlorophylls and the browning of the olive surface and brine (Garrido Fernández et al, 2002).…”

“…The tendency of the olive fruits to loose freshness with storage time may be not only due to the progressive polymerization of phenols but also to the degradation of chlorophylls and the subsequent decrease in the green surface colour (Mínguez-Mosquera et al, 1994). Panagou et al (2002) showed an initial decline in yeast population followed by a steady increase until the end of the storage period of dry-salted olives. In directly brined olives, an initial microbial inactivation was related to a lack of nutrients because of their slow solubilisation from whole fruits (García et al, 1992).…”

“…CO 2 negatively influenced the growth rate of Lactobacillus sake (Devlieghere et al, 1998) and Listeria monocytogenes (in combination with pH, temperature, and NaCl concentration) (Fernán-dez et al, 1997). Panagou et al (2002) found a CO 2 atmosphere most effective at keeping the number of yeasts low in dry-salted olives. The use of CO 2 during the storage process of ManzanillaAloreña olives may displace oxygen and, thus, prevent browning reactions and retard microbial growth.…”

Influence of Temperature and Modified Atmosphere on the Microbial Profile of Packed Gemlik Dry‐salted Olives

“…2008). This method is similar to the methodology applied in other countries (Panagou et al. 2002; Panagou 2006).…”

“…Since dry‐salted olives are not packaged in brine, an alternative would be to use modified atmospheres, such as CO 2 , that could irreversibly impact the survival of fungi (Panagou 2006). Packaging of olives under modified atmospheres effectively controls the growth of fungi, thus minimizing the potential production of mycotoxins (Panagou et al. 2002).…”