Proceedings of International Congress on Bioactive Compounds and International Workshop on Bioactive Compounds
Proceedings of 2nd International Congress on Bioactive Compounds

Ascorbic acid, or vitamin C, is a compound not synthesized by the human body, but which has important functions, requiring its intake from exogenous sources. However, as it is easily oxidized, its degradation occurs quickly. To circumvent this problem, biosorption, although little explored in the food area, presents an alternative to incorporate bioactives from interactions between sorbent and sorbate. For this, biological materials are used, such as brewer’s spent yeasts (BSY), which have low added value, wide availability and high nutritional value. However, some of these biomasses may have their sorption capacity increased after physical and chemical pre-treatments, which may expose the binding sites present in the material. Thus, this work proposes the use of BSY in natura and after pre-treatments of plasmolysis, acid modification, alkaline modification and thermal inactivation, in order to evaluate their influence on ascorbic acid biosorption. The plasmolysis procedure was carried out with a NaCl 10% solution kept in contact with the biomass under constant agitation for 48 hours, while for the acid and basic modifications, H2SO4 0.1 mol/L and NaOH 0.1 mol/L were used, respectively. As for the thermal modification, the BSY were autoclaved for 15 minutes at 121°C. The biosorption parameters were fixed using a 100 μg/mL ascorbic acid solution at pH 3.0, dosage of 7.5 g/L and a contact time of 2, 6 and 24 hours. The quantification of vitamin C remaining in the supernatants after sorption was performed using High Performance Liquid Chromatography under previously optimized conditions. From the results, it was possible to notice that the in natura yeast showed a gradual increase in the percentage of sorption with time (12.91% ± 0.48 in 2 hours, 25.72% ± 0.09 in 6 hours, and 56.92% ± 2.94 at 24 hours). The plasmolyzed and autoclaved yeast biosorbents did not present significant results, with maximum sorption of 8.84% ± 1.91 and zero, respectively, in 24 hours. The acid modification promoted great sorption (37.72% ± 1.63 at 2 hours, 82.01 ± 2.73 at 6 hours, and 100% at 24 hours), but showed interfering peaks between 4.4 and 5.3 min, coinciding with ascorbic acid retention time (4.6 to 4.9 min), which made its quantification difficult, influencing the reliability of results. On the other hand, the Saccharomyces cerevisiae with the alkaline modification showed the best results, with only 8.07% ± 0.73 sorption at 2 hours, but at 6 and 24 hours, the material promoted 100% of vitamin C sorption, demonstrating a slightly slower kinetics, but with very promising results. It is worth mentioning that the maximum degradation of ascorbic acid was 10.28% in 24 hours under the proposed experimental conditions, and this value was considered for the calculations. In this way, the biosorption technique showed potential for enrichment of yeast cells with ascorbic acid, mainly after the alkaline modification, which proved to be effective to remove interfering sites and provide other functional groups present in the biomass, for their interaction with the vitamin C, aiming at decrease nutritional losses.