Formulation and quality determination of herbal carbonated soda enriched with coriander, tamarind and green apple as natural base ingredients

Herbal-inspired beverages represent a promising avenue for developing functional, naturally flavored carbonated drinks. This study aimed to formulate and characterize three soda formulations based on coriander (Coriandrum sativum), tamarind (Tamarindus indica), and green apple (Malus domestica), enriched with commercially available ingredients such as dried barley seeds (Hordeum vulgare L.), dried ginger (Zingiber officinale), fresh beetroot (Beta vulgaris) (for coriander formulation), dried ashwagandha (Withania somnifera) roots (tamarind formulation) and dried tulsi  (Ocimum tenuiflorum) leaves (for green apple formulation). Each formulation was  evaluated under three sweetening systems: bee honey, stevia, and a sugar–stevia blend to identify the most acceptable sensory profile (9-point hedonic scale, n=35). Sensory analysis indicated that the sugar–stevia blend consistently achieved the highest overall acceptability across all formulations, with mean ranks of 2.23 (coriander), 2.93 (tamarind), and 2.43 (green apple). Physicochemical evaluation revealed that the formulated sodas exhibited higher pH values (4.76, 2.70, 3.01) compared with a commercial cola (2.63), lower total soluble solids (4.29 – 6.04 oBrix vs 10.08 °Brix), reduced total and reducing sugars (2.27 – 9.02 g/100 mL vs 10.51 g/100 mL), and markedly lower sodium content (1.50 – 8.31 mg/L vs 51.23 mg/L). Carbonation levels were lower (1.08–1.14 volumes CO₂) relative to cola (3.74 volumes CO₂). Functional analysis demonstrated enhanced bioactive properties, with ascorbic acid concentrations ranging from 6.28 to 20.99 mg/100 mL, total phenolic content of 192 – 374 mg GAE/L, and DPPH radical-scavenging activity up to 58.58% in coriander soda. Total plate count analysis confirmed microbiological stability during 14 days of refrigerated storage, with no significant increase (p0.05) in microbial counts, which ranged from 730 – 1000 CFU/mL at baseline to 590 – 600 CFU/mL after storage. The pH of all soda formulations increased during storage (from 2.70 – 4.76 to 2.86 –  4.89), with greater increases observed at elevated storage temperatures (25 and 40°C) than under refrigerated conditions (4°C). These findings indicate that herbal carbonated sodas can deliver a nutritionally enriched, low-sugar (total and reducing sugar), and sensory-acceptable alternative to conventional soft drinks.