Addition of Lactiplantibacillus plantarum subsp. plantarum WGK4 to Pressure-cooked Komak (Lablab purpureus (L.) Sweet) to Decrease Soaking Time and Water Requirement during Acid Fermentation in Tempe Processing

Background and Objective:Komak beans include high nutritional values, making them promising raw materials for alternative food sources such as tempe. Because the beans are hard, they need soaking in water for 72 h with the water change every 12 h. Soybeans only need soaking for 24 h without changing the water during tempe processing. In this study,pressure cooking was used for Komak beans prior to soaking and a starter culture of Lactiplantibacillus plantarumsubsp. plantarumWGK4 was added to the soaking water to decrease the quantity of water soaking and soaking time.Material and Methods:Komak beans were pretreated by pressure-cooking for various times and texture and anti-nutritional factors were assessed. The selected pressure-cooked Komakbeans were soaked in water and inoculated with Lactiplantibacillusplantarumsubsp. plantarumWGK4. The pH, titratable acidity, soluble protein and minerals wereassessed in the soaked water and Komakbeans. The soaking water was assessed for viable lactic acid bacteria and anti-nutritional and volatile compounds were assessed in the soaked Komakbeans. Mold fermentation was carried out by adding 0.2% (w.w-1) tempe starter culture to the drained Komakbeans and incubating for 48 h at room temperature. Results and Conclusion:Dehulled Komakbeans that were pressure-cooked for 15 min included a hardness value of 34.47 N, which was close to the hardness of boiled soybeans in traditional tempe preparing. Pressure-cooking Komakbeans significantly decreased anti-nutritional factors. Addition of Lactiplantibacillusplantarumsubsp. plantarumWGK4 during the 24-h soaking step decreased pH of Komakbean from 6.7 to 4.5. Decreases in tannin concentration was observed. Volatile compounds responsible for the beany flavor were not detected in the Komakbeans at the end of the soaking. Pressure-cooking and addition of Lactiplantibacillus plantarumsubsp.plantarumWGK4 significantly shortened the soaking time and decreased water needed for Komak Tempe processing. This process provides tempe as an affordable plant-based protein alternative.