Unripe grapes (UGs) are a waste product of grapevine cultivation and an emerging source of several compounds, such as organic acids, phenolic compounds, vitamins and mineral salts, of great economic importance to the pharmaceutical, cosmetic and food industries. Traditionally, products made from UGs, such as verjuice and sour grape sauces, have been used as seasoning or acidifying agents. The health effects of grape compounds are described as anti-inflammatory, cardioprotective, anticancer and antidiabetic, as often demonstrated by both in vitro and in vivo studies. Recently, UGs have received renewed attention because of the innovative potential applications of their extracts in food and beverages for purposes of preservation and enrichment with healthy compounds, or for direct use in the human diet. The aim of this article is to review the composition and properties of UG products and their traditional and innovative application in food and beverages.

Unripe grapes are a potential source of bioactive compounds which can exert antioxidant and antimicrobial activity. However, very little information is available about the composition of unripe grapes extracts and their extraction techniques. This study aims to evaluate the recovery of bioactive compounds and the antioxidant activity of the extract from unripe Sangiovese grapes obtained at an industrial-scale and the composition of the extract during processing. The extraction yield was approximately 75%. During the extraction, the total phenol (TP), antioxidant activity (AA) total anthocyanin (TAnt), pantothenic acid and choline content significantly increased. High concentrations of TP (2522 mgCATeq/L), AA (8227 μmolTEAC/L) and total water-soluble vitamins (1397 μg/L) were reached at the end of process. The antioxidant activity of the extract was positively correlated with all the phenol compounds and the highest correlations were found with procyanidin B1 (r = 0.994; p-value < 0.004), procyanidin B2 (r = 0.989; p-value < 0.004), kaempferol 3-O-glucoside (r = 0.995; p-value < 0.004) and quercetin 3-O-hexoside (r = 0.995; p-value < 0.071). Our findings contribute to the knowledge of the bioactive composition of unripe grapes. An efficient industrial-scale “green” extraction method, ready to be transferred to the wine sector, was developed to obtain a safe extract with a high concentration of bioactive compounds.

One of the food industry’s priorities is to recover byproducts and move towards more sustainable systems. Among wine-chain byproducts, unripe grapes represent a promising source of antioxidants. However, the development of new foods enriched using phenol-rich ingredients is challenging due to their sensory attributes. The aims of the present study were to (1) use phenol-rich extract from unripe grapes to enrich a model plant-based food (beetroot puree—BP); (2) evaluate consumers’ acceptance and expectations for the beetroot purée samples. The effect of information about the sustainability and pro-health activity of value-added ingredients on consumers’ responses was also investigated. Four beetroot purees with increasing concentrations of phenol extract (0–1.93 g/kg) added were evaluated by 101 participants in three tasting conditions (blind: only samples; expected: only information without tasting; real: both samples and information).Liking slightly decreased with increasing concentrations of phenol extract, even if all the samples were considered acceptable. The health and sustainability information increased the hedonic expectations, although it was not assimilated by all consumers involved. The development of new phenol-enriched foods using functional ingredients from unripe grapes is challenging. However, it is also promising, since all the samples were generally accepted by the consumers and they presented phenol levels that were stable over time and that could have positive health effects when consumed.