Effect of Packaging on Microbial Survival and Physicochemical Characteristics of Non-Thermally Preserved Green Spanish-Style Olives

Spanish-style green olives are one of the main trade preparations in the international market. Nowadays, there is an increasing trend to use plastic packaging due to reduced weight, lower costs, flexibility and convenience. The purpose of this work was to investigate the effect of modified atmosphere packaging of Spanish-style green olives in multilaminated pouches on the microbiological and physicochemical characteristics of olives. Green pitted olives of cv. Conservolea and Halkidiki were packaged in high barrier multilaminated pouches (113 μm thickness; O₂ permeability < 1.5 mL/m²/24 h) under modified atmospheres (30% CO₂ / 70% N₂) and stored at room temperature for 12 months. Microbiological [lactic acid bacteria (LAB), yeasts, enterobacteria] and physicochemical changes (pH, acidity, salt content, texture and color) were monitored during storage together with sensory evaluation. No enterobacteria could be detected in both olive varieties. The initial microbiota consisted of LAB (5.9-6.3 log CFU/g) and yeasts (4.8-5.3 log CFU/g). Yeasts started to decline and could not be detected after 60 days. In the end, LAB dominated in populations exceeding 5.4 and 6.1 log CFU/g for cv. Halkidiki and Conservolea, respectively. pH values increased gradually from 3.51 to 4.19, the mean acidity was ca. 0.2% and the salt content fluctuated between 3.0-3.6%. Color parameters L* (luminance), a* (greenness) and b* did not change during storage in both varieties. Texture analysis showed a decrease in olive hardness from 15-20 N to 8 N. Sensory analysis revealed that cv. Halkidiki olives were crisper and with increased fibrousness compared to cv. Conservolea. The survival of LAB combined with the probiotic potential of this microbial group creates new possibilities for the use of non-thermally preserved olives as a functional food.

Acknowledgement: This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: T1EDK-04110)