P. García

Establishment of conditions for green table olive fermentation at low temperature.

Abstract Four Lactobacillus plantarum strains were isolated from table olive cold fermentation brines. Their specific growth rate and acidification in MRS broth and in green table olive brines were studied by means of a mixed 2 pH (4.5 and 5.0)×3 salt (3, 4 and 5%, w/v, NaCl)×3 incubation temperature (9, 12 and 15°C) levels factorial design. In MRS broth, the greatest effect (linear) on acidification was due to temperature. In brine, the effects were considerably less, pH (linear) being the most important for specific growth rate, and temperature (linear) for acidification. In both media, an initial pH of 5.0 led to good acidification at 12–15°C. The effectiveness of the conditions found (initial pH of 5.0; 3%,w/v, NaCl; and incubation at 12°C) was confirmed in simulated green olive fermentations with three of the strains, which proved especially robust. Behaviour in terms of growth and acidification rates was similar for these strains, and comparable to that observed in traditional processes, although mannitol and sucrose were not metabolised and fructose was only partially used. This leads to the possibility of obtaining normal fermentation processes of table olives in cold regions when appropriate initial conditions and starter cultures are used.

Chloride salt mixtures affect Gordal cv. green Spanish-style table olive fermentation

This work studies the effects of different sodium (in the range of 4-10%), potassium (0-4%) and calcium (0-6%) chloride salt mixtures on the fermentation profile of Gordal olives processed according to the Spanish style. For this purpose, response surface methodology based on a simplex centroid mixture design with constrain (sum of salt percentages = 10%) was used. All treatments reached appropriate titratable acidity levels, but this parameter could not be related to the initial chloride salt concentration. The presence of CaCl(2) led to lower initial and after-fermentation pHs, delayed sugar diffusion into the brine, its maximum concentration and titratable acidity formation. CaCl(2) also delayed Enterobacteriaceae and yeast sprang, decreasing their overall growth. This chloride salt also showed a tendency to reduce overall lactic acid bacteria growth. KCl had a similar behaviour to NaCl but, in general, increased overall microbial growth. Thus, a partial substitution of NaCl in Spanish-style green olives with KCl and CaCl(2) does not substantially modify the fermentation profile but does produce some changes, which, when properly managed, could help to improve product processing.

Management of spent brines or osmotic solutions

Spent brines or osmotic solutions are, in general, wastewaters heavily polluted with suspended solids and either inorganic or organic dissolved matter. The possibilities of introducing salt-free or reduced salt processes as well as segregating brines or osmotic solutions from current processes from the general drainage systems should always be considered. The paper especially describes the steps followed during the development of the regeneration treatments with active carbon and ultrafiltration for the fermentation brines of Spanish-style green table olives. Similar methodology might be used in the regeneration of other osmotic solutions. System for brine elimination (evaporation ponds, injection in deep wells, multi-stage evaporation, co-generation, etc.), and results of physico-chemical and biological treatments of wastewaters (including brines) from the table olive industry are also commented.