BIOTRANSFORMATION OF NITRATE INTO NITRITE IN ARUGULA AND BEET EXTRACTS: INFLUENCE OF STARTER CROP CONCENTRATION, PROCESSING TIME AND CONDITIONS

The search for natural alternatives to commercial sodium nitrite has gained prominence in the food industry, driven by the demand for healthier products and sustainable production processes. The use of nitrate-rich vegetables, such as beets (Beta vulgaris L.) and arugula (Eruca sativa L.), associated with starter cultures containing nitrate-reducing microorganisms, such as Staphylococcus carnosus and Staphylococcus xylosus, represents a promising strategy for obtaining natural nitrite. However, the efficiency of this conversion depends on factors such as the microbial concentration, the incubation time, and the processing applied. Thus, this study aimed to evaluate the conversion of nitrate to nitrite in plant extracts under different conditions, identifying the most favorable to the formation and stability of NO₂⁻. The experiment was conducted in two stages. Initially, the effect of six starter crop concentrations (0.002, 0.04, 0.08, 0.16, 0.32 and 0.64 g/100 mL) on nitrite formation in beet and arugula extracts was evaluated in a completely randomized design. Then, a 2³ × 3 factorial design was used, considering extract (arugula/beet), filtration (filtered/unfiltered), sterilization (yes/no) and time (0, 24 and 48 h). NO₂⁻ determinations were performed by visible spectrophotometry (540 nm). The inversely proportional behavior between the concentration of the starter culture and the nitrite content formed was verified, and the lowest concentration (0.002 g/100 mL) resulted in the highest values in both extracts