Survival and stability of Lactobacillus plantarum KJ03 as a freeze-dried autochthonous starter culture for application in stink bean fermentation (Sataw-Dong)

Nowadays, consumer’s demand for functional foods, which are healthy and protect the body from various diseases, is increasing. The selection of microorganisms with probiotic potential for use as a starter is a simple approach to generate fermented food products. This study investigated the improvement of viability and stability of fermented stink beans (Sataw-Dong) using freeze-dried Lactobacillus plantarum KJ03 as an autochthonous starter culture. Sucrose, mannitol, and monosodium glutamate (MSG) effectively enhanced bacterial survival (>75% viability; >1.6 × 10⁷ CFU/ml) at optimal concentrations of 10%, 5%, and 2.5%, respectively. Suitable initial cell loads of these protective agents were 10⁹ CFU/ml (mannitol) and 10¹⁰ CFU/ml (sucrose and MSG). Survival improvement by sucrose or mannitol protectants formulated with stressed cells induced by 0.8 M NaCl during cultivation was obtained with viabilities of 89.2% (1.5 × 10⁸ CFU/ml) and 64.7% (1.25 × 10⁶ CFU/ml), respectively, after 15 days of storage at room temperature. No significant differences were observed when MSG was used. During storage for 6 months, the viability of freeze-dried cells depended on the protectant used and storage temperature. For sucrose and MSG, the stability was noticeably higher when stored at 4°C compared to 30°C. MSG displayed the highest protective effect, maintaining a viability of 70% (5.25 × 10⁶ CFU/ml) at 30°C. The lowest viability was detected when mannitol was used as a protectant, with the viability ranging 17%–35%. Sataw-Dong produced using freeze-dried L. plantarum KJ03 showed slightly lower overall acceptance score values in sensory analysis than commercial Sataw-Dong products in terms of appearance, color, flavor, firmness, sourness, and pungency. The results revealed an alternative way to introduce a freeze-dried starter culture into Sataw-Dong production as a non-dairy probiotic product. Practical applications: In Thailand, traditional spontaneous fermentation has been used to produce fermented stink beans (Sataw-Dong). Using starter cultures with probiotic properties for Sataw-Dong production increases its food safety, and it could also be a functional food product. The present study evaluated the viability and stability of using Lactobacillus plantarum KJ03 as a freeze-dried autochthonous bacterial starter culture in the production of Sataw-Dong. The ability of this starter powder to preserve cell viability during long-term storage for six months has not been lost. Inoculating freeze-dried starter in Sataw-Dong shortened the fermentation time, inhibited pathogenic bacteria, and improved sensory acceptance of the finished product. This could be further applied with other vegetables to make value-added fermented products.