Optimization of production parameters for preparation of natto-pigeon pea with immobilized Bacillus natto and sensory evaluations of the product

• Pigeon pea was used for the preparation of natto-pigeon pea with immobilized Bacillus natto, compared with preparation of natto-soybean.
• The fibrinolytic activity of natto-pigeon pea reached 1895.05 ± 0.24 IU/g, which was higher than that of natto-soybean (1355.37 ± 0.28 IU/g).
• The natto-pigeon pea possessed significantly higher sensory scores than that of natto-soybean on flintiness, brightness, flavor, solubleness, chewiness and off-odor, and no obvious differences in overall color homogenicity, stringiness, adhesiveness, color intensity and grainy.
• The method could be potentially applied in the agricultural industry.

In the present investigation, the production parameters for the preparation of natto-pigeon pea with immobilized Bacillus natto were optimized and its sensory evaluations were analyzed. The optimal immobilization conditions for Bacillus natto were as follows: alginate concentration 7%, CaCl2 concentration 2.5%, concentration of bacteria 7.4 log cfu/mL and alginate bead diameter 5.0 mm. Fermentation parameters of natto-pigeon pea were optimized by single-factor experiments and central composite design with the index of fibrinolytic activity. The fibrinolytic activity of natto-pigeon pea reached 1895.05 ± 0.24 IU/g under the optimal conditions: wet weight of beads with Bacillus natto 0.8 g/g material, ratio of liquid to solid 15: 1 mL/g, pH 6.5, temperature 38 °C and time 48 h. Moreover, the sensory evaluations of the natto-pigeon pea were superior to that of natto-soybean because of the advantages of pigeon pea on fermentation. Sensory results indicated that the method was an accepted procedure for the production of natto-pigeon pea.Industrial RelevanceFermentation with immobilized microorganisms processing is an emerging technology for the production of functional and safe food with a higher efficiency and quality than conventional solid fermentation. Quantitative data on the fibrinolytic activity and sensory evaluations were essential to demonstrate that the process was indeed safe and efficient. The current work is one of the first to provide such data on natto-pigeon pea with immobilized Bacillus natto, which is of most importance for industrial scale applications as well as agricultural industry.