Vermicomposting grape marc yields high quality organic biofertiliser and bioactive polyphenols

Abstract

Grape is the largest fruit crop in the world, and most (80%) of the harvested fruit is used to make wine. The main by-product of the wine industry is called grape marc, which consists of the stalks, skin, pulp and seeds that remain after pressing the grapes. The aim of this study was to evaluate whether grape marc could be processed by vermicomposting on an industrial scale to yield both a high-quality organic, polyphenol-free fertiliser and grape seeds (as a source of bioactive polyphenols). Vermicomposting reduced the biomass of grape marc substantially (by 58%), mainly as a result of the loss of volatile solids. After 2 weeks, the process yielded a nutrient-rich, microbiologically active and stabilised peat-like material that was easily separated from the seeds by sieving. Although the polyphenol content of the seeds was considerably reduced, this disadvantage was outweighed by the ease of separation of the seeds. Separation of the seeds also eliminated the polyphenol-associated phytotoxicity from the vermicompost. The seeds still contained useful amounts of polyphenols, which could be directly extracted for use in the pharmaceutical, cosmetic and food industries. The procedure described is effective, simple and economical, and could easily be scaled up for industrial application.

Optimizing Acidity and Extraction Time for Polyphenolic Recovery and Antioxidant Capacity in Grape Pomace Skin Extracts with Response Surface Methodology Approach

“…Approximately 80% of all produced grape is utilized for winemaking with grape pomace being the main waste by‐product (Dominguez et al . ). After grapes is pressed, grape pomace accounts for 20% of the original raw material (Llobera and Cañellas ).…”

“…Overproduction of pomace in wineries can be challenging and costly for the waste management, also it can be used as animal feed, soil enrichment agent and valuable raw material for the production of functional products in food, pharmaceutical and cosmetic industry (Dominguez et al . ). Functional foods market showed fastest expansion in worldwide food production (Wang and Li ) stressing importance and the value of processing raw materials such as grape pomace.…”

Eco-friendly vermitechnological winery waste management: a pilot-scale study

“…Vermitechnology is used to facilitate the stabilization and maturation of a wide variety of anthropogenic organic wastes generated by industries such as sugar refining [7], paper [8], food [9], distilleries [10], beverages [11], tanning [12], and olive-oil milling [13]. Vermitechnology has mainly been studied in relation to small-scale stabilization of grape marc over short periods of time [3,14], while other wine-making waste, such as lees cake and vinasse sludge, have been scarcely studied [6].…”

Influence of Acidity and Extraction Time on the Recovery of Flavonoids from Grape Skin Pomace Optimized by Response Surface Methodology

“…Twenty percent of the grape in wine production accounts for by-products, such as grape pomace 3 , totaling nearly 11 million tons of grape by-products per year (other recent sources reported pomace production of 5-14 million tons) 4 . Overproduction of grape pomace can be challenging for industrial waste management 5 , or it can be prudently used as a valuable raw material for functional food production 6 . The functional foods can be engineered from any sources 7 .…”