Acidic and saline stresses modify microflora composition of table olives produced by spontaneous fermentation.

The main components of the table olive microflora are lactic acid bacteria (LAB) and yeasts. Their growth is affected by both environmental and technological stresses. Among others, nutrient depletion (1), salt concentration and low pH levels (2) can induce a shift from homo- to hetero-fermentative metabolism of LAB (3). When LAB grow in a high salt medium, the structural properties of the cell wall change (4). Several LAB produce exopolysaccharides as a resistance mechanisms phenolic stress (5). On the other hand, under stressing conditions yeasts synthesize a number of bioactive antioxidant compounds (6,7). In order to improve the industrial production process, we tested the effect on the autochthonous LAB and yeasts of acidic (by lactic acid addition) and saline (by NaCl addition) stresses during table olive production. Our preliminary results and the relevant related literature are discussed considering, above all, the industrial advantages and the consequences for starter selection.1.Ruiz-Barba JL and Jiménez-Díaz R - J Appl Bacteriol 76, 350 -355, 19942.Bobillo, M and Marshall VM - J Appl Bacteriol 73, 67 -70, 19923.Panagou EZ et al. - Food Microbiol 25, 348-358, 20084.Piuri M et al. - J Appl Microbiol 98, 84 -95, 20055.Manca de Nadra MC and Strasser de Saad AM - Int J Food Microbiol 27, 101 -106, 19956.Cruz JM et al. - Food Chem 67, 147 -153, 19997.Martinez-Montañés F et al. (2011) Mol Microbiol 79, 1008 -1023, 2011