Assessment of pear juice and puree as a fermentation matrix for water kefir

Abstract

Preservation of fruits causes loss of phenolics and high sugar content (jams processing). In contrast, fermentation has been shown to increase the antioxidant content of foods while consuming sugars. Therefore, this study evaluated pear juice and puree as substrates for the production of water kefir, a probiotic beverage obtained from symbiotic fermentation of sweetened solutions. Results indicated that the antioxidant capacity of the puree resulted in a minor loss of scavenging ability, while the fermented juice resulted in 10% higher antioxidant ability. Phenolics underwent minor changes during fermentation, with a significant decrease only for bound phenolics in the puree kefir. Overall, pear juice and kefir were demonstrated to be acceptable matrices for the fermentation of water kefir. Panelists rated the puree kefir sweeter than the juice counterpart, possibly due to the release of soluble carbohydrates and the precipitation of the insoluble counterparts. Novelty impact statement An alternative approach to food preservation is proposed. Symbiotic fermentation of fruits (in the form of juice or puree) allows for longer shelf life, without the deleterious changes occurring with traditional preservation techniques such as pasteurization and marmalade making. In addition, health-promoting probiotic bacteria will grow in such a food system.

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