Harnessing Bacillus subtilis C6 as a bioprotective starter: A strategy for histamine mitigation and product quality in fermented Parkia biglobosa

InformationThe accumulation of histamine, a biogenic amine, in fermented foods poses health risk.Therefore, there is a need to reduce the quantity in food.Alongside existing interventions, starter cultures, capable of degrading and/or incapable of producing these amines have been proposed for mitigation.This study investigated the potential of Bacillus sp.starter culture, in reducing histamine formation in fermented locust beans (Parkia biglobosa).Isolated bacteria were screened for safe use as starter and decarboxylase activity.Molecular identification of the selected isolates was done using standard methods.Process optimization was estimated by spectrophotometric method.Tyramine content was quantified with high-performance liquid chromatography while proximate estimation was done on fermented product.Selected Bacillus subtilis C6 (MW 287212.1)was histidine decarboxylase-negative, non-hemolytic, DNase and gelatinase negative.The isolate showed optimal growth at pH 10 (0.712), 72 h (1.650), 35 o C (1.648), 0.1% NaCl (0.298), sucrose (0.731) carbon source, beef extract (2.047) and NaNO3 (1.746) as organic and inorganic nitrogen sources at a wavelength of 600 nm.Histamine content in unfermented locust bean was 6.35 mg/mL, while the spontaneously-fermented and starter-fermented samples had 6.81 mg/mL and 6.67 mg/mL, respectively.Fermentation with Bacillus subtilis C6 elevated the ash (1.01 ± 0.02%), fat (10.33 ± 0.02%), crude fibre (8.00 ± 0.01%), and carbohydrate (9.30 ± 0.07%) contents, with slight reduction in moisture (63.60 ± 0.02%) and protein (15.76 ± 0.05%), compared to the unfermented sample.These findings established Bacillus subtilis C6 as a safe and functional starter culture for reducing the histamine content of fermented locust beans, while retaining their overall nutritional properties, thus, proving its effectiveness in mitigating the accumulation of histamine.