The Manufacturing of Lotus Root Kombucha with Lactobacillus plantarum and Yoghurt Stock Culture and Investigation of Its Physicochemical and Sensory Properties

The objectives of this study were to manufacture low-caffeine lotus root kombucha (LRK) by using Lactobacillus plantarum or yoghurt stock culture as adjunct cultures and to investigate the physicochemical and sensory properties of LRK. Lotus root tea was first fermented with a symbiotic culture of bacteria and yeast (SCOBY) at 25°C until pH was reached 3.8, followed by secondary fermentation for 2 days with L. plantarum (0.2%, 0.5%, or 1.0% v/v) or yoghurt stock culture (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, 0.2% v/v). The viable cell counts of L. plantarum were maintained at approximately 1.0–2.0 × 109 CFU/mL during 28 days of storage at 4°C, whereas no viable cells were detected in the yoghurt stock culture group at 4°C and 37°C. In the sensory evaluation, color was significantly (p < 0.05) higher in whole SCOBY samples with 0.2% yoghurt stock culture treatment than whole SCOBY samples without probiotics, whereas flavor and overall preference were significantly (p < 0.05) higher in whole SCOBY samples than other LRK, regardless of the probiotic type. In conclusion, lotus root can be used as a low-caffeine substrate for kombucha production, and L. plantarum can serve as an effective adjunct culture to improve the physicochemical and sensory properties of LRK.