Use of unripe grape juice (verjuice) as a novel acidifying agent: a sensory study of pickles

Verjuice is an unfermented juice made by pressing unripe grapes whose culinary and medicinal utilization dates back to very ancient times. Recently, verjuice has been shown to be a valid alternative to lemon juice and vinegar in different food preparations such as salad seasoning, flavoring agent, digestive drinks and some cocktails, although the sensorial consequences of its use as a preserving agent for direct acidification of vegetables has never been investigated. In this study, pickled cucumber preserves were industrially prepared using two dilutions of verjuice as acidifying agent and compared with the traditional vinegar-pickled samples. Samples were chemically characterized and subjected to sensory analyses using both a trained panel and consumers. The different acidifying agents resulted in pickled cucumbers with different olfactory and gustatory characteristics. No differences in appearance and texture were found. Despite showing chemical and sensory differences, pickles preserved with verjuice and vinegar had similar overall liking scores for visual, olfactory and gustatory aspects. A key feature of pickles prepared with verjuice is the presence of non-volatile tartaric and malic acids instead of acetic acid, potentially conferring them an additional value. This suggest that verjuice represents a viable alternative to vinegar for the production of pickles with unique sensorial properties. This approach may extend its application to other types of food such as onions, cauliflower or carrots. Verjuice has the advantage of being produced from a byproduct of the grape and wine industries (e.g. thinned grapes). Moreover, its method of production is quite simple as it requires only a few processing steps.