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The effect of potassium sorbate, sodium benzoate, and ozone in combination with citric, lactic, and acetic acids on the microbial population of seasoned table olives of the olive 'Aloreña' cultivar was studied in both fresh (FF) and stored fruits (SF). The inactivation/growth curves were modeled and the biological parameters estimated, with yeast used as the target microorganism. Regardless of the acid added, potassium sorbate showed a general inactivation effect on yeasts in the products prepared from both FF and SE Sodium benzoate had a rapid inactivation effect with FF, but with SF, it was effective only in the presence of acetic acid. A strain of Issatchenkia occidentalis was found that was resistant to the combination of this preservative with citric or lactic acids. In FF, ozone showed an initial marked inhibition against yeasts, but later, yeasts were again able to grow. In SF, ozone was a strong inactivating agent when it replaced any of the traditional preservatives. Lactic acid bacteria were always absent in products prepared from FF, and apparently were not affected by the different preservative agents in those prepared from SF. The behavior of yeasts and lactic acid bacteria populations in commercial products were similar to those found in experimental treatments.

A global logistic model was used to study the effects of both quantitative variables (NaCl, acid, and potassium sorbate concentrations) and dummy variables (laboratory medium or brine, and citric, lactic, or acetic acids) on growth of Saccharomyces cerevisiae IGAL01. The deduced equations, with the significant coefficients selected by a backward stepwise procedure, allowed estimations of the simultaneous comparison of behaviors of levels of the qualitative variables as a function of the quantitative variables and the development of the growth-no growth limits according to laboratory medium or brine and the different types of acidifying agents. The S. cerevisiae growth region in yeast malt glucose peptone broth was always wider than that in brine, in which this yeast was inhibited by 0.03% potassium sorbate and 6% NaCl, when the acid concentration (regardless of type) was 0.2 to 0.3%. These results demonstrate the applicability of such model designs to include qualitative variables in investigations related to the development of growth-no growth limits.

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Tolerance of Pichia anomala, a strain of yeast associated with olive fermentation, to salt, temperature, and pH was studied in yeast-malt-peptone-glucose medium using a nonfactorial central composite experimental design with three repetitions in the center to account for pure error. Modified Gompertz, logistic, Richards-Stannard, and Baranyi-Roberts models were used to determine maximum specific growth rate (micro(max)) and lag phase period (lambda) from the growth curves (primary models). All models produced a good fit (significant at P < 0.05), but the graphical and statistical analyses of the data indicated that the modified Gompertz and Richards-Stannard models were the most appropriate. The biological parameters obtained with the diverse models were fitted to a response surface secondary model. A significant decrease in micro(max) was observed as temperature decreased and salt increased. A significant increase in lambda was observed as temperature (linear and quadratic effects) and pH decreased and as salt content increased. Effects of interactions were complex and depended on models. Validation revealed acceptable errors and bias in micro(max) and lambda values obtained in independent experiments. Validation growth curves were best reproduced by using the values of micro(max) and lambda predicted by the response surface from the modified Gompertz and Richards-Stannard models. Results from this study can be applied to table olive fermentation or storage and for production of table olives as refrigerated commercial products without the use of preservatives or pasteurization.

Aims:  To study the effects of temperature, NaCl and acid (HCl, citric, acetic and lactic) concentrations on the specific growth rate (μ), lag phase (λ), and h0 of Lactobacillus pentosus IGLAC01. Methods and Results:  Response surface (RS) methodology (D‐optimal design) was used with a dummy variable, to account for the different types of acids. The variable ranges were: 16–30°C, 0–70 g l−1 NaCl, and 0–5 g l−1 acid (or 0–2·5 g l−1 HCl). Time to detection from optical density data was used to deduce μ and λ. The RS models for log2μ and log2λ, according to acid types, were estimated and the effects of variables were quantified by their z‐generalized values. A relationship between  ln h0 with temperature was also found. Conclusions:  The μ of L. pentosus IGLAC01 can be doubled by increasing temperature by 10·3°C or by decreasing NaCl by 48 g l−1 (harmonic, averaged, z values, Z); citric was the least inhibitory acid (z = −96·2) and lactic the strongest (z = −5·7), according to their generalized z values, z. A twofold λ increase was achieved from a decrease of 3·1°C (HCl), or 4·27°C (citric) or 36 g l−1 NaCl increase (both acids) (expressed as z); the same effect was obtained from a decrease of 4·37°C, 54 g l−1 NaCl increase, or 10 g l−1 acetic or lactic acid additions (expressed as Z values). Significance and Impact of the Study:  Valuable information on the effects of environmental variables on the biological parameters of L. pentosus IGLAC01, which could be used for the optimization of olive, cucumber or other vegetable fermentations, is obtained.