Biopreservation of Vegetable Foods - Food Biopreservation - page 99

Fermented vegetables are good sources for isolation of LAB producing
bacteriocins. Some examples of antagonistic LAB include L. lactis 23 from fer-
mented carrots (Uhlman et al. 1992 ), L. plantarum strains C-11 and C19 from
cucumber fermentations (Daeschel et al. 1990 ; Atrih et al. 1993 ), Lactobacillus sake
C2 from traditional Chinese fermented cabbage (Gao et al. 2010 ), P. pentosaceus
05-10 isolated from Sichuan Pickle, a traditionally fermented vegetable product
from China (Huang et al. 2009 ), L. plantarum LPCO10 from fermented table olives,
(Jimenez-Diaz et al. 1993 ), L. plantarum strains ST23LD and ST341LD from
spoiled olive brine (Todorov and Dicks 2005 ), Lactobacillus pentosus B96 from
fermenting green olives (Delgado et al. 2005 ), and E. faecium BFE 900 from fer-
mented black olives (Franz et al. 1996 ). These strains offer potential for investiga-
tion as starter or protective cultures in vegetable fermentations, but there are still
only limited numbers of studies on this issue.
During cabbage fermentation, inoculation with a paired culture consisting of a
nisin-producer L. lactis and a nisin-resistant Ln. mesenteroides was tested with the
purpose of improving the fermentation (Harris et al. 1992a , b ). In kimchi, inocula-
tion with a pediocin-producing strain of P. acidilactici was reported to successfully
achieve inhibition of L. monocytogenes , thus improving the product safety (Choi
and Beuchat 1994 ). In a more recent study, kimchi was prepared with Leuconostoc
citreum GJ7 (producer of the bacteriocin kimchicin GJ7), with the objective of pre-
venting growth and/or survival of foodborne pathogens E. coli O157:H7, Salmonella
Typhi, and S. aureus (Chang and Chang 2011 ). Viable cell reductions of 3.85, 4.45,
and 5.19 log CFU/ml were observed 48 h after inoculation. The study concluded
that addition of a starter culture capable of producing bacteriocins could serve as a
strategy to protect the fermented product from delivering pathogens upon consump-
tion and that the kimchi fi ltrate itself may be used as a food preservative.
Table olive fermentations are very popular in countries from the Meditarranean
region. LAB (mainly L. plantarum and L. pentosus ) together with yeasts are the
main bacterial group responsible for these fermentations. These lactobacilli may
produce several different bacteriocins (known as plantaricins), and plantaricin genes
seem to be widely disseminated (Maldonado et al. 2002 ). In the Spanish-style pro-
cess for table olive preparation, green olives are fi rst treated with lye, a treatment
that destroys most of the epiphytic microbiota. The lactic fermentation that takes
place afterwards is often a slow process that relies mostly on the resident microbiota
from the fermentation tanks and manufacturing plant environment. Fast acidifi ca-
tion is crucial for proper preservation of olives and inhibition of adventitious micro-
biota. In some cases, suffi cient lactic acid is not produced to warrant product
preservation, and spoilage may occur unless exogenous acid is supplemented. The
strain L. plantarum LPCO10 (plantaricin S and T producer) has been patented for
application as a starter culture in the fermentation of table olives and other vegetable
foods (Jiménez-Díaz et al. 1993 ; Ruiz-Barba et al. 1994 ; Vega Leal-Sánchez et al.
2003 ). In table olives, inoculation with the plantaricin-producing culture improved
the microbiological control of the fermentation process, increased the lactic acid
yield and provided a consistent high quality product (Ruiz-Barba et al. 1994 ; Vega
Leal-Sánchez et al. 2003 ). The starter culture could also be applied to ensure homo-