Optimization of Mixing Conditions for Improving Lactobacillus Paracasei Cba L74 S Growth During Lactic Fermentation of Cooked Navy Beans and Functional Characterization of the Fermented Products
Lactic acid fermentation of legume-based matrices has been gaining an increasing interest in recent years to
produce pro- and post-biotic functional foods at high protein content. The optimization of the main process
conditions is necessary to improve bacterial growth, microbial metabolic activity, thus the consequent
functional properties of the resulting fermented products. A preliminary study of feasibility about the potential
of using a leguminous substrate as growth medium for Lactobacillus paracasei CBA L74 was already
conducted in previous experimentations. In this work, the effect of improving mixing conditions of a cooked
navy bean suspension during the lactic acid fermentation process was investigated and some chemical and
physical properties of the resulting fermented products were studied to verify their potential application as
functional ingredients in food formulations. The mixing system was optimized by designing an impeller that
guarantees a more homogeneous distribution of nutrients and avoids concentration gradients that could inhibit
the microorganism proliferation. Bacterial growth, lactic acid production, sugar, and starch consumption were
compared with those obtained during previous experimentations carried out with a different impeller. The
major availability of nutrients in the fermenting medium reached with the customized impeller allowed a faster
achievement of the maximum microbial load (1×109 CFU/mL after 14 h of process) and a lower doubling time
of 1.53 h. Furthermore, fermentation led to a reduction in water absorption, oil binding, and foam capacity of
the fermented bean powders. Total phenolic and flavonoid content and their antioxidant capacity were not
influenced by the fermentation process itself but favored by the previous thermal treatment of sterilization