Mannitol bioproduction from surplus grape musts and wine lees

Abstract

Biological mannitol production at industrial scale is hindered by the elevated costs of fructose-rich feedstocks. Grape must could be an interesting feedstock for this process, due to its large production and to the commercial imbalance caused by unsold wine stocks in producing countries. The feasibility of employing red must and white must for mannitol production was assessed with Lactobacillus fermentum CECT 285, Leuconostoc mesenteroides CECT 8146 and Lactobacillus intermedius NRRL B-3693. By means of experimental design based on response surface methodology (RSM), it was determined that nutrient supplementation could be limited to the addition of manganese and yeast extract, and that grape must should be diluted with water to improve mannitol production. Under optimal conditions, Lb. intermedius NRRL B-3693 produced 68.9 ± 0.57 g/L mannitol from red must and 79.8 ± 0.25 g/L mannitol from white must in 48 h, attaining yields of 0.888 ± 0.014 and 0.895 ± 0.001 mol/mol, respectively. In order to further reduce costs, yeast extract was replaced by wine lees. Red wine lees (RWL) performed better than white wine lees (WWL) as nitrogen source for mannitol production. Grape musts supplemented with manganese and RWL produced 59.4 ± 0.13 g/L mannitol in the case of red must and 65.6 ± 0.06 g/L mannitol in the case of white must in 144 h with Lb. intermedius NRRL B-3693. Therefore, winery surplus and by-products could be used to produce mannitol, thus opening new biorefinery opportunities for rural areas devoted to winegrowing.

Valorisation of wine wastes by de novo biosynthesis of resveratrol using a recombinant xylose-consuming industrial Saccharomyces cerevisiae strain

“…Grape must (GM) used in this study are derived from white grapes (variety Verdejo), collected in September 2020, and were provided by the Oenological Station of Castile and Leon – ITACyL (Rueda, Spain) and stored at −20 °C until used. GM density is 1.09 kg L −1 and contained composed of 111 g L −1 glucose, 116 g L −1 fructose 0.69 g L −1 total Kjeldahl nitrogen and 0.15 g L −1 total phenolic compounds, previously characterised by Hijosa-Valsero et al 16 Grape must pH was adjusted to 6 prior sterilisation, then autoclaved at 121 °C for 15 min. Grape must was dissolved in the fermentation media in percentages from 12.5% to 90% (v/v) and supplemented with 7.5 g L −1 of yeast extract.…”

“…Grape must can be an interesting carbon source for biotechnological processes for value-added products generation, being already reported for the production of erythritol or mannitol. 16,17 Furthermore, vine pruning, which consists of the necessary removal of parts of a grapevine to renew its canes, generates significant amounts of lignocellulosic biomass, being the major by-product of viticulture, and their polysaccharides (cellulose and hemicellulose) constituents can be valuable substrates for biotechnological processes. 18 To attain fermentable sugars from vine pruning, pretreatment and hydrolysis are mandatory steps to break down the recalcitrant and typical structure of lignocellulosic biomasses.…”

“…Wine lees consist of residual fermentative yeast and other particles, and have high nitrogen and organic content, including acids, phenols, and ethanol. 15 They have been previously proposed as low-cost nutrients for microbial production of biochemical products, 16 but could also be used as substrate due to their ethanol content. Additionally, there are substantial volumes of grape must, rich in glucose and fructose, that are not used for wine production, due to being a surplus or having low quality.…”

Bioproduction of 2-Phenylethanol through Yeast Fermentation on Synthetic Media and on Agro-Industrial Waste and By-Products: A Review

“…In Europe alone, a total of 14.5 million tons of grape by-products, including grape musts, are produced annually [ 63 ]. In fact, the price of bulk grape must, in Spain in 2019, was around 0.3037 €/L [ 64 ].…”

Revisiting the production of L( +)-lactic acid from vine shoots: bioconversion improvements by employing thermotolerant bacteria

“…Red wine lees had a density of 1.05 g/L and contained 99.3 g/L ethanol, 12.2 g/L total Kjeldahl nitrogen, and 1.51 g/L total phenolic compounds. Their chemical composition in terms of anions and cations is provided elsewhere (Hijosa-Valsero et al 2021).…”