Optimization of polyphenol extraction from aquaculture waste in a biofloc system
The use of biofloc technology has stood out, as it offers aquaculture a sustainable production tool, characterized by minimal or zero water exchange. However, despite being a more environmentally sustainable system than traditional systems, it still performs effluent discharge at the end of cultivation cycles, in addition to clarification processes to remove excess particulate matter in suspension during cultivation. Thus, the development of efficient and sustainable waste treatment methods is an important part of the wider use of these systems. Biofloc extracts showed the presence of phenolic compounds and antioxidant capacity, and technological applications could be explored, for example, their use as nutritional supplements. The extraction of polyphenols using the ultrasound-assisted technique is a simple, efficient and low-cost alternative. The response surface methodology (MSR) is a statistical mechanism used in optimization processes, effective to assess the influence of different factors on the expected response of a given process. The aim of the study was to examine parameters such as temperature (25 - 65 °C), extraction time (30 - 150 min), concentration of ethanol in the solvent (0 - 100%) and solvent-solid ratio (sol-sol ) (5-25 mL/g) in biofloc extractions, to obtain the best levels of polyphenols and antioxidant activity, and carry out the economic analysis of the process. The results showed that all factors studied were significant for polyphenol extraction. For the antioxidant activity against the DPPH radical, the ethanol concentration and the solvent-solid ratio were significant. The time and concentration of ethanol were determinant in production costs. Only the ethanol concentration was significant for the cost benefit ratio. The MRS was an efficient tool to improve the polyphenol extraction process and the antioxidant activity of bioflocs for its use as a bioactive compound, however the economic analyzes showed a high cost in the production stage.