Effect of packaging and storage conditions on microbial survival, physicochemical characteristics and colour of non-thermally preserved green Spanish-style Manzanilla olives

This work studies the effect of packaging material (glass jar or plastic pouches), olive environment (covered with brine, under N2 atmosphere or vacuum) and storage temperature (7, 13, and 22 °C) on the microbial survival, brine characteristics and colour of packaged fermented olives (Manzanilla cv.) subjected to preservation only by pH and NaCl levels. The highest lactic acid bacteria counts on olive epidermis (6.2-6.5 log10 CFU/olive) were found in fruits stored in glass jar and plastic pouches at 22 °C which, on the contrary, showed the lowest yeast population levels (5.2-6.5 log10 CFU/olive) due to the opposed growth trend observed between bacteria and yeasts. The pH increase in the packages with brine limited the product shelf life to about 2 months but without brine the shelf life could be longer. Changes in colour parameters did not affect the product's shelf life. The verification of the high lactic acid bacteria on the olive surface, particularly for plastic pouches with brine, and under N2 atmosphere at room temperature, constitutes an essential step for producing probiotic table olives.