A field-applicable low-tech method for extracting capsaicinoids from red chili pepper

Red chili pepper is a common crop found in southern countries often extracted to be use as animal repellent. It contributes managing human-wildlife conflicts in countries where this subject has become a major concern. Previous studies have highlighted the operating conditions which optimize the diffusion of capsaicinoids. However, they did not allow the precise identification of the realistic low-tech operating conditions which should be employed in the field. By the means of two Doehlert experimental designs, this work explored the impact of temperature, ratio solid/liquid and proportion of hydroalcoholic solution and soybean oil as extraction solvents on capsaicinoid content and yield, measured by HPLC and taken as an indicators of the repellent’s strength. Kinetics was used to establish that 15 min was sufficient to obtain the best extract for both type of solvents, with a limited number of operation units. Surface response showed that on one hand hydroalcoholic extraction with a 1/10 ratio led to total yields < 50 % and capsaicinoid concentrations to 400 mg·L -1 , which is 6-fold lower in capsaicinoids that conventional unleaded petroleum extract and so less efficient. However, the operation units are easier to deploy as lengthy evaporation times or filtration of a viscous extract are unnecessary. Moreover, the residue re-employable. On the other hand, oil extraction achieved yields between 40 % and 70 % and capsaicinoid concentrations between 600 and 3600 mg·L -1 , although the extraction process involves viscous filtration which is a more time consuming. However, capsaicinoid content was 1.5 times higher than in conventional petrol extract. Schematized low-tech procedures have been proposed to farmers. • Development of low-tech methods for extracting capsaicinoids from red chili pepper. • Optimization of extraction conditions based on yields and capsaicinoid contents. • Use of Doehlert response surface methodology to identify practical field applications. • Design of a natural repellent for managing human-wildlife conflict. • Field-adaptable application protocol proposed for use under resource-limited conditions.