Use of Lactobacillus plantarum and glucose to control the fermentation of "Bella di Cerignola" table olives, a traditional variety of Apulian region (Southern Italy).

UNLABELLED

The purpose of this study was to evaluate the use of Lactobacillus plantarum, isolated from table olives "Bella di Cerignola," a traditional variety of Apulian region (Southern Italy), as a starter for this kind of food. We focused on the interaction of the starter with the natural occurring microflora, the quantitative/qualitative composition of yeast population, the decrease of pH, and the content of organic acids. After a preliminary characterization, 3 strains of Lb. plantarum, selected for their probiotic and technological performances, were used as a multiple-strain starter and inoculated (approximately 2%) in olives, processed according to Spanish style, brined at 8% and 10% of NaCl and added with 0.5% of glucose. The combination of the starter and glucose assured a correct fermentation course, decreasing the pH up to a safe value (4.3 to 4.5) and controlled the growth of yeasts. The concentrations of both L- and D-lactic acids increased throughout the fermentation, while citric and malic acids (both the isomers D and L) remained at low levels (0.2 to 0.4 g/L). Concerning yeast species, Candida guilliermondii was mainly isolated at the beginning (7 to 14 d), while C. famata prevailed at the end of fermentation.

PRACTICAL APPLICATIONS

To the question "How to standardize and maintain quality of "Bella di Cerignola" olives (Southern Italy)" we can suggest the following answer: use Lb. plantarum and a low amount of glucose (0.5%). The result is a decrease of the pH below the safety break point.