Fermentation profile and optimization of green olive fermentation using Lactobacillus plantarum LPCO10 as a starter culture

Abstract

The bacteriocin producer Lactobacillus plantarum LPCO10, a strain originally isolated from an olive fermentation, was used as a starter culture for traditional Spanish-style green olive fermentation. By means of a 2 3 (7−4) fractional factorial design, the salt concentration in brines was found to be the most important factor for producing the highest acidity and the highest initial population of the starter culture. To a lesser extent, other factors such as a high inoculum size, use of MRS as carrier for the starter culture, inoculation time, and type of acid to correct the pH had also an overall significant effect on the final acidity or total corrected acidity. For all initial conditions investigated, Lb. plantarum LPCO10 was able to dominate over the natural population of lactic acid bacteria and led to a faster decrease of pH and a faster acidification than the spontaneous process during the first 25 days after brining. Then, wild lactobacilli grew slowly and the population of lactic cocci rose, while LPCO10 decreased. Inoculation also stimulated the growth of yeasts. Thus, the traditional fermentation of Spanish green table olives could be improved by using Lb. plantarum LPCO10 (suspended in MRS) as a starter culture at ⩾10 7 cfu/ml of brine and well defined starting brine parameters, i.e. ⩽4% w/v of NaCl, and initial pH correction (from 4.5 to 6.5) with acetic acid. Inoculation can take place in 1–4 days after brining.