Impact ofPediococcusspp. on Pinot noir Wine Quality and Growth ofBrettanomyces

Abstract

Pediococcus spp. were isolated from commercial wines from Oregon and Washington state, and the impacts of these isolates on the chemistry, microbiology, and sensory quality of Pinot noir wines were investigated. The pediococci isolates were inoculated into wines after alcoholic fermentation, and the wines were then chemically and sensorially analyzed after 60 days. All pediococci isolates partially degraded l-malic acid, with P. damnosus OW2 and P. parvulus OW7 completing malolactic fermentation (MLF). Despite having extensively large cell populations (>106 cfu/mL), the fermented wines had low concentrations of biogenic amines ( 5 mg/L). Production of d-lactic acid varied among the isolates, with strain OW7 producing the highest concentration (264 mg/L). Diacetyl concentrations also varied, with some wines containing low levels ( 15 mg/L). Furthermore, growth of some pediococci resulted in loss of red color and polymeric pigment content, potentially due to acetaldehyde degradation. Sensory analyses revealed differences in aroma (“floral”, “overall fruit”, “red fruit”, and “buttery”) and flavor (“sour” and “astringency”) among wines inoculated with different Pediococcus species or strains. Co-inoculation of P. parvulus and Brettanomyces bruxellensis resulted in wines having lower concentrations of 4-ethylphenol but reaching higher populations than in separate inoculations. This study has demonstrated the variability among Pediococcus species and strains in the production of various spoilage products and highlights the range of potential sensory effects these bacteria may have on a Pinot noir wine.