Production of licorice juice enriched with functional properties via enzyme and fermentation: Determination of aroma-active, phenolic compounds, sensory and bioactive properties

Liquorice (Glycyrrhiza glabra L.) is a significant plant that has been used for medicinal and industrial purposes since ancient times. This study aimed to optimize the production conditions of liquorice juice and evaluate the effects of lactic acid fermentation on the bioactive and aroma-active compounds of liquorice juice samples, as well as their potential health impacts. The optimization study determined that the optimal conditions suggested by the Response Surface Methodology (RSM) fulfilled the desirability criteria. These optimal conditions were identified as a temperature of 50°C, a solid-to-liquid ratio of 0.68, and a extraction time of 3 hours. Liquorice juices produced under these optimal conditions were found to exhibit high total phenolic content, sugar content, glycyrrhizic acid concentration, and antioxidant activity based on various analyses. Phenolic and aroma compounds of liquorice juices were analyzed using LC-MS/MS and GC-MS, respectively. Phenolic compounds such as liquiritin, isoliquiritin, isoviolanthin, and liquiritin apioside were identified as dominant in liquorice root. Additionally, aroma-active compounds in the samples were identified using the Aroma Extract Dilution Analysis (AEDA) method. According to AEDA results, the characteristic aroma of liquorice juice was determined to originate from alcohols, ketones, volatile phenols, and pyranones. Enzyme applications and fermentation were found to positively influence the properties of liquorice juice, significantly enhancing phenolic content, antioxidant activity, antihypertensive activity, and the in vitro bioavailability of bioactive compounds. Although storage after fermentation led to a slight reduction in aroma, phenolic compounds, and antioxidant activity of liquorice juice, these effects were not significant. Sensory analysis revealed that liquorice juices fermented with Lactobacillus acidophilus and treated with enzymes received the highest scores for aroma and overall acceptability, followed by samples fermented with Lactiplantibacillus plantarum. As a result, this study recommends the production and consumption of fermented liquorice juice for its health benefits and as a way to utilize liquorice roots more effectively in Türkiye.