Abstract
The potential of the application of pulsed electric fields (PEF) to induce accelerate autolysis of a commercial strain of Saccharomyces cerevisiae for winemaking use was evaluated. The influence of PEF treatments of different intensity (5–25 kV/cm for 30–240 μs) on cell viability, cytoplasmic membrane permeabilization and release of mannoproteins and compounds absorbing at 260 and 280 nm has been investigated. After 8 days of incubation at 25°C the Abs600 of the suspension containing the control cells was kept constant while the Abs600 of the suspension containing the cells treated by PEF decreased. The measurement of the absorbance at 260 and 280 nm revealed no release of UV absorbing material from untreated cells after 8 days of incubation but the amount of UV absorbing material released drastically increased in the samples that contained cells treated by PEF after the same storage period. After 18 days of storage the amount of mannoproteins released from the untreated cell was negligible. Conversely, mannoprotein concentration increased linearly for the samples containing cells of S. cerevisiae treated by PEF. After 18 days of incubation the concentration of mannoproteins in the supernatant increased 4.2 times for the samples containing cells treated by PEF at 15 and 25 kV/cm for 45 and 150 μs. Results obtained in this study indicates that PEF could be used in winemaking to accelerate the sur lie aging or to obtain mannoproteins from yeast cultures.
Highlights
Yeast cell wall, which represents up to 20% of yeast cell dry weight, is mainly composed of β-glucans and mannoproteins
It has been shown that mannoproteins reduce haze formation, prevent the precipitation of tartaric salt, contribute to the mouthfeel, influence the intensity of the aroma of wine and can interact with phenolic compounds, improving color stability and reducing the astringency of wine (Pérez-Serradilla and De Castro, 2008)
The aim of this study was to evaluate the potential application of pulsed electric fields (PEF) to induce accelerate autolysis of a commercial strain of Saccharomyces cerevisiae for winemaking use
Summary
Yeast cell wall, which represents up to 20% of yeast cell dry weight, is mainly composed of β-glucans and mannoproteins. These mannoproteins are highly glycosylated (∼90% sugars, mainly mannose) and are located in the outermost layer of the yeast cells acting as structural components (Quiros et al, 2012). It has been shown that mannoproteins reduce haze formation, prevent the precipitation of tartaric salt, contribute to the mouthfeel, influence the intensity of the aroma of wine and can interact with phenolic compounds, improving color stability and reducing the astringency of wine (Pérez-Serradilla and De Castro, 2008). Different studies have demonstrated important emulsifying and stabilizing properties of mannoproteins due to the amphipathic structure of their molecule (da Silva Araújo et al, 2014).
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