ACIDIFICATION EFFECTS ON MICROBIAL-POPULATIONS DURING INITIATION OF CUCUMBER FERMENTATION

Addition of acetic acid (0.067M) or calcium acetate (0.133 M) to the cover brine (1.94M NaCl) of cucumbers reduced naturally occurring Enterobacteriaceae, but not lactic acid bacteria (LAB), during the first 5 days after brining. Naturally occurring LAB were predominantly heterofermentative (greater-than-or-equal-to 80%) 1 day after brining and homofermentative (greater-than-or-equal-to 90%) on the 5th day. Enterobacteriaceae survived longer within cucumbers than in brine, particularly in nonacidified cucumbers. Starter cultures of Lactobacillus plantarum or Pediococcus pentosaceus decreased 90-99.9% during the first 10 hr after addition and did not increase until about 30 h after brining. Obtaining predominant fermentation of brined cucumbers by added cultures was difficult due to presence of natural microflora on/in the cucumbers and the harsh environment of the brine (high salt, low nutrients).