Preparation of red seaweed extract for use as a flocculant agent in sugarcane juice and comparison between two experimental designs

The sugar-energy sector is seeking to reduce its negative environment impact through productivity gains and process savings as a result of research and development of new technologies. For example, during the processing of sugarcane and the extraction of the juice, unwanted compounds are removed, requiring treatments such as clarification, which uses acrylamide compounds in the processing. However, there is a need to reduce the presence of these compounds in the process as they present carcinogenic potential. In this context, the present study aimed to develop a natural flocculant from red seaweed, based on carrageenan extraction. The best conditions for its preparation, dosage, and application in the treatment of sugarcane juice were determined by comparing two experimental designs. The experiment was carried out at the Universidade do Estado de Minas Gerais, Frutal, Brazil, using sugarcane variety CTC072361 (2022/2023 Harvest). Seaweed samples were purchased from commercial centers. Regarding the red seaweed extract, the study was carried out in two stages. First, a univariate experimental design was used to determine the relevant variables that could influence the preparation of the seaweed extract. There was no direct correlation between the parameters. Subsequently, a multivariate design was carried out to verify the interaction between the assessed parameters. Thus, the seaweed samples were previously dried in an oven at 65 ºC, and the standardization and characterization procedures of the seaweed extracts were evaluated, considering the analysis parameters: drying time, granulometry, concentration, pH, temperature, and mixing time, in triplicate. Then, the dosage tests were carried out using a decanter, performing 12 different tests with doses of red seaweed extract (0, 5, 10, 35, 50, 75, 100, 150, 250, 400, 500 and 1000 mg.L-1) for univariate experimental design, and (0, 10, 100, 125, 275, 350, 425, 500, 800, 900, 1000 and 1200 mg.L-1) for the multivariate experimental design. After the retention time, the clarified juice was recovered by siphoning determining its Brix, Total Reducing Sugars, pH, Acidity, and Total Phenolic Compounds. This was used for checking whether the treatments differed from each other. Therefore, by comparing the experimental designs, significant differences were verified between the treatments applied, with emphasis on dosages of 500 mg.L-1 (multivariate design) and 1000 mg.L-1 (univariate design). For both experimental des