Towards multi-purpose biorefinery platforms for the valorisation of red grape pomace: production of polyphenols, volatile fatty acids, polyhydroxyalkanoates and biogas

Abstract

The development of a multi-purpose four step-cascading biorefinery scheme for the valorization of red grape pomace (GP) was proposed. The consecutive processes were respectively dedicated to (a) the recovery of polyphenols by supercritical CO2 extraction, (b) the production of volatile fatty acids (VFAs) by anaerobic acidogenic digestion, (c) the exploitation of produced VFAs as the precursors for the biotechnological production of polyhydroxyalkanoates (PHAs) and (d) the production of a CH4-rich biogas by the anaerobic digestion of solid leftovers from the acidogenic process. More than 2.7 g of total polyphenols (as gallic acid equivalents) per 100 g of dry matter were extracted. A high content of valuable proanthocyanidins occurred in the recovered polyphenolic fraction. The dephenolized GP was anaerobically digested under batch acidogenic conditions, obtaining about 20 g L-1 of total VFAs in the liquid effluent. The latter matrix was employed to feed a pure culture of a Cupriavidus necator strain, which was induced to produce and store PHAs under nitrogen-limiting conditions. The process was carried out in 0.5 L-shake flasks by using a two-step production approach. In particular, pre-grown biomass was fed with different concentrations of the acidic effluent (20 or 40% v/v) in two sequential batch processes. Poly(3-hydroxybutyrate) was accumulated up to 63% of the cells dry weight when pre-grown biomass was fed with 40% of the acidic effluent. No inhibitory effects due to non-VFA compounds occurring in the actual acidogenic effluent were observed. Finally, the anaerobic digestion of the exhausted solid fraction from the acidogenic process allowed obtaining 113 mL of biomethane per gram of fed volatile solids. © The Royal Society of Chemistry 2016

Refining of wine lees and cheese whey for the production of microbial oil, polyphenol‐rich extracts and value‐added co‐products

“…Many studies reported the utilization of wine lees for the production of various commercial products, such as ethanol, tartaric acid and phenolic compounds . Wine lees have also been proposed as nutrient supplements in several fermentation processes, including lactic acid, xylitol and PHAs production …”

“…[2][3][4][5] Wine lees have also been proposed as nutrient supplements in several fermentation processes, including lactic acid, xylitol and PHAs production. [6][7][8][9] The worldwide annual production capacity of cheese whey could be estimated at about 160 million t. 10 Cheese whey retains most of the milk lactose (39-60 g L −1 ) as well as proteins (1.4-33.5 g L −1 ), fats (0.99-10.58 g L −1 ), and mineral salts (0.46-10%) among others. 11 Many studies have focused on the recovery of value-added components from cheese whey (e.g.…”

Fruits By-Products – A Source of Valuable Active Principles. A Short Review

“…On the other hand, grape waste represents a good source of vitamins, minerals, lipids, proteins, carbohydrates and polyphenolic compounds (especially phenolic acids, ellagitannins, flavonols, flavan-3-ols such as catechins and their isomers, anthocyanins, pro-anthocyanidins and the stilbene derivative, resveratrol) (Nowshehri et al, 2015). Grape wastes are not considered hazardous waste, but in large amounts they can contribute to the pollution, due to the high chemical and biological oxygen demand (Martinez et al, 2016).…”

In vivo bioavailability of polyphenols from grape by‐product extracts, and effect on lipemia of normocholesterolemic Wistar rats

“…In terms of natural sources of grape phenolics, innovative methods for the purification of polyphenols from grape pomace have been proposed (e.g. by supercritical CO 2 extraction), although such methods require long process and expensive technologies . For these reasons, there is interest in assessing the effect of grape pomace from industry by‐products without purification or extraction of the sole polyphenols.…”

“…by supercritical CO 2 extraction), although such methods require long process and expensive technologies. 24 For these reasons, there is interest in assessing the effect of grape pomace from industry by-products without purification or extraction of the sole polyphenols. The use of such extract was recently reported by Sanz-Buenhombre et al 25 who used in vitro gastrointestinal digestion to assess the bioavailability of polyphenols from grape extract and polyphenol degradation during the simulated digestion.…”