A carregar...
Publicação
The microbial ecology of wine grapes
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 368.87 KB | Adobe PDF |
Orientador(es)
Resumo(s)
Grapes have a complex microbial ecology including filamentous fungi, yeasts and bacteria with different
physiological characteristics and effects upon wine production. Some species are only found in grapes,
such as parasitic fungi and environmental bacteria, while others have the ability to survive and grow in
wines, constituting the wine microbial consortium. This consortium covers yeast species, lactic acid bacteria
and acetic acid bacteria. The proportion of these microorganisms depends on the grape ripening stage and on
the availability of nutrients. Grape berries are susceptible to fungal parasites until véraison after which the
microbiota of truly intact berries is similar to that of plant leaves, which is dominated by basidiomycetous
yeasts (e.g. Cryptococcus spp., Rhodotorula spp. Sporobolomyces spp.) and the yeast-like fungus Aureobasidium
pullulans. The cuticle of visually intact berries may bear microfissures and softens with ripening, increasing
nutrient availability and explaining the possible dominance by the oxidative or weakly fermentative ascomycetous
populations (e.g. Candida spp., Hanseniaspora spp., Metschnikowia spp., Pichia spp.) approaching harvest
time. When grape skin is clearly damaged, the availability of high sugar concentrations on the berry
surface favours the increase of ascomycetes with higher fermentative activity like Pichia spp. and Zygoascus
hellenicus, including dangerous wine spoilage yeasts (e.g. Zygosaccharomyces spp., Torulaspora spp.), and of
acetic acid bacteria (e.g. Gluconobacter spp., Acetobacter spp.). The sugar fermenting species Saccharomyces
cerevisiae is rarely found on unblemished berries, being favoured by grape damage. Lactic acid bacteria are
minor partners of grape microbiota and while being the typical agent of malolactic fermentation, Oenococcus
oeni has been seldom isolated from grapes in the vineyard. Environmental ubiquitous bacteria of the genus
Enterobacter spp., Enterococcus spp., Bacillus spp., Burkholderia spp., Serratia spp., Staphylococcus spp.,
among others, have been isolated from grapes but do not have the ability to grow in wines. Saprophytic
moulds, like Botrytis cinerea, causing grey rot, or Aspergillus spp., possibly producing ochratoxin, are only active
in the vineyard, although their metabolites may affect wine quality during grape processing.
The impact of damaged grapes in yeast ecology has been underestimated mostly because of inaccurate grape
sampling. Injured berries hidden in apparently sound bunches explain the recovery of a higher number of
species when whole bunches are picked. Grape health status is the main factor affecting the microbial ecology
of grapes, increasing both microbial numbers and species diversity. Therefore, the influence of abiotic
(e.g. climate, rain, hail), biotic (e.g. insects, birds, phytopathogenic and saprophytic moulds) and viticultural
(e.g. fungicides) factors is dependent on their primary damaging effect.
Descrição
Available at ScienceDirect
Palavras-chave
grapes microbial ecology damaged grapes spoilage yeasts acetic acid bacteria lactic acid bacteria
Contexto Educativo
Citação
"International Journal of Food Microbiology". ISSN 0168-1605. 153 (2012) 243-259