Valorization of hibiscus leaves by obtaining extracts rich in bioactives by microwave-assisted extraction

• Grant number: 23/11830-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date until: November 01, 2023
• End date until: August 16, 2024
• Field of knowledge: Agronomical Sciences - Food Science and Technology - Food Engineering
• Principal Investigator: Luiz Henrique Fasolin
• Grantee: Beatriz Chignolli Castro
• Host Institution: Faculdade de Engenharia de Alimentos (FEA). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Hibiscus sabdariffa L. is a plant that contains several bioactive compounds in its composition. The majority of studies related to these compounds focus on their presence in their flowers and calix. The leaves are generally underrated, despite of being the largest part of the plant. However, some studies report the presence of relevant compounds with high biological activity in the leaves. The recovery of phytochemical compounds in plant matrices is commonly carried out through conventional techniques. They are generally associated with the use organic solvents and high temperatures for extended periods of time, being not environmentally friendly. In this context, microwave-assisted extraction has emerged as an alternative technique to conventional processes, offering the benefits of time, energy, and cost savings. Therefore, this work aims recovering and characterizing bioactive compounds from Hibiscus sabdariffa L. leaves using microwave-assisted extraction. For this purpose, a 2³ central composite rotational design will be used. The independent variables will be the type of solvent, power, and solvent/sample ratio. The time and temperature will be set at 10 minutes and 50 °C, respectively. The dependent variables will include overall yield, specific compound yields (total phenolics, total flavonoids, monomeric anthocyanins, and tannins), and antioxidant activity assessed through ABTS and FRAP methods. After determining the optimal conditions, the best temperature and extraction time will be defined. At the end of this study, it is expect that extracts rich in bioactive compounds with high antioxidant activity will be produced using a method that requires lower solvent and time.