F A C T O R Y
STUDY ON
MICROBES
University of Massachusetts Amherst food scientists have mapped and characterised
microbial populations in a vegetable fermentation facility and found that its
microbiome is distinct between production and fermentation areas, and that the raw
vegetables themselves - cabbages destined for sauerkraut - are the main source
of fermentation-related microbes in production areas rather than handling or other
environmental sources.
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Co-authors Jonah Einson, Asha Rani
and senior investigating professor
David Sela say the study resolves
the question of how microbes are
transferred within a food fermentation
production facility. Real Pickles is a worker
owned cooperative in Greenfield (Massachusetts)
and makes pickles, sauerkraut and other
fermented vegetables the old-fashioned way by
natural fermentation and without starter microbial
cultures or other media. Nutritional microbiologist
Sela says that very little is known about
the microbiomes of these facilities. Fermented
foods are increasingly popular internationally
because of their enhanced nutritional properties,
cultural history and tastiness, so the new
information from this study will be of interest to
food scientists, microbiologists and manufacturers
around the world, he says. Company founder
Dan Rosenberg says it is fascinating to learn
about the influence of fresh vegetables in establishing
his facility’s microbiome, and suggests
that the use of organic vegetables is important
to contributing a diverse microbial community
to support fermentation. “It raises interesting
questions about how we can further improve our
production practices to be producing fermented
and probiotic foods of the highest quality. We’re
excited to participate in research that improves
understanding of fermented food production and
nutrition.” The research team used a state-ofthe
art approach, using high-throughput sequencing
and genomics to identify microbial species
present instead of culturing the microbes. This
allowed them to quickly identify more microbes
than conventional methods, to estimate their
relative numbers, predict their likely function and
determine the flow of microbes into and within
the facility.”For the first time, we built a map
of the facility and how it was transformed over
time during fermentation, which has given us a
more complete picture of the population in a real
vegetable fermentation facility. Both cheese and
beer have been done to a certain extent, but we
feel that fermented vegetable facilities could be
better characterised. And because we are using
these new genomic tools, we have a better
understanding of what is there and how they got
there. Using the traditional approach, we couldn’t
possibly culture everything, so we’d have a far
more limited picture,” Sela says. Leuconostoc
and Lactobacillaceae dominated all surfaces
where spontaneous fermentation occurs. Also,
they found that “wall, floor, ceiling and barrel
surfaces host unique microbial signatures,” Sela
says. The team swabbed surfaces in the plant’s
fermentation room, processing area and dry storage
surfaces to collect microbial samples, identify
microbes present before and after cleaning,
and in linking specific microbes to certain food
processing stages. Sela says next steps might
be to see if similar findings may emerge in other
vegetable processing plants around the world,
whether seasonal changes might be observed
and whether microbial populations change with
different cleaning protocols. “It’s not as important
when making traditional sauerkraut,” he
says, “but some other food processing facilities
might face more risk of spoilage and it would be
interesting to see what microbes are present at
various stages. Batches of food do get spoiled
and we never see that as consumers, but it costs
a lot when a whole batch is lost. We might be
able to find a way to predict when that might
happen by understanding the microbiological
communities that surround the processes.”
/www.foodtechnology.co.nz
