Modifications of Saccharomyces pastorianus cell wall polysaccharides with brewing process

Abstract

The cell wall polysaccharides of brewers spent yeast Saccharomyces pastorianus (BSY) and the inoculum yeast (IY) were studied in order to understand the changes induced by the brewing process. The hot water and alkali extractions performed solubilized mainly mannoproteins, more branched for BSY than those of IY. Also, (31)P solid state NMR showed that the BSY mannoproteins were 3 times more phosphorylated. By electron microscopy it was observed that the final residues of alkali sequential extraction until 4M KOH preserved the yeast three-dimensional structure. The final residues, composed mainly by glucans (92%), showed that the BSY, when compared with IY, contained higher amount of (1→4)-linked Glc (43% for BSY and 16% for IY) and lower (1→3)-linked Glc (17% for BSY and 42% for IY). The enzymatic treatment of final residue showed that both BSY and IY had (α1→4)-linked Glc and (β1→4)-linked Glc, in a 2:1 ratio, showing that S. pastorianus increases their cellulose-like linkages with the brewing process.

Deep Eutectic Solvent Aqueous Solutions as Efficient Media for the Solubilization of Hardwood Xylans

“…Then, the samples were placed in an ice bath and 0.15 % m / v m ‐phenylphenol in 0.5 % m / v NaOH (100 μL) was added. The samples and blanks were left in the dark for 30 min and their absorbance was measured at 520 nm …”

“…The samples and blanks were left in the dark for 30 min and their absorbance was measured at 520 nm. [46,47] Xylan solubility assays Xylan from beechwood was added in excess to 2.0 AE 0.1 go fp ure DES, DES aqueous solutions, ChCl, urea, choline acetate aqueous solution, 1.67 m aqueous NaOH, and pure water.T he solvents and pure xylan were put in sealed glass vials and allowed to equilibrate at constant temperature (70, 80, and 90 8C) with stirring (800 rpm) on as tirring plate with heat control Agimatic-N Sensoterm II from P-selecta and as pecific aluminum disk to support the sealed glass vials with as tirring bar.B ecause the obtained solutions had ah igh viscosity,i tw as not possible to separate the different phases so the glass vials were placed in an aired oven at the temperature of the assays overnight to equilibrate and for the undissolved xylan to deposit in the bottom of the vials. Then, the concentration of dissolved xylan in the different solvents was measured by FTIR-ATR, following as imilar approach to the one reported by Soares et al [21,48] for the quantification of dissolved lignin, but in this case using the xylan band at 1045 cm À1 typical of CÀOH stretching and CÀOÀCd eformation in polysaccharides.…”

Impact of Glucose Concentration and NaCl Osmotic Stress on Yeast Cell Wall β-d-Glucan Formation during Anaerobic Fermentation Process

“…This study could comprise a quantitative indicator for the industrial production of yeast β-glucan from defined cell cultures but also from other yeast sources like breweries' [23] and wineries' spent yeast biomass [40].…”

An evaluation study of different methods for the production ofβ‐D‐glucan from yeast biomass

“…Another important factor which impacts the yeast cell wall polysaccharide composition, structure, and morphology, are the growth conditions (pH, temperature, aeration, carbon source) of yeast cells, the conditions during alcoholic fermentation process for beer production, as well as the supplement of additives during yeast cultivation for β ‐glucan production . These parameters must be taken into consideration in the design of a β ‐glucan extraction protocol as, too, the different primary sources of yeast cells (yeast produced in bioreactor, commercial yeast, winery and brewery wastes, yeast cell walls etc.)…”

“…Spent brewer's yeast can be recovered for β ‐glucan production . The spent yeast material from the beer‐making process has been treated for β ‐glucan production . The produced β ‐glucan from breweries spent yeast by‐product has been already proposed for potential applications in food industry as a new ingredient, a stabilizer in mayonnaise, an additive, a potential immunostimulant in shrimp feed, and a supplement in animal diet .…”