The largest producer in the world, Brazil was responsible for harvesting more than 680 thousand tons of passion fruit in 2021, according to data from the Brazilian Institute of Geography and Statistics (IBGE). However, in addition to the pulp for fresh consumption or for the manufacture of juices and other products, the agro-industrial processing of the fruit generates around 390 thousand tons of peels per year which, despite being rich in pectin (a natural substance responsible for the gel-like texture of foods such as jellies and traditionally obtained from orange and lemon peels), are almost always wasted – only a fraction is destined for the production of animal feed, fertilizer and flour. To give the waste a more noble destination, researchers from the State University of Campinas (Unicamp) developed an efficient and sustainable method of extracting the gelling agent.
The success in testing the new technique, which was supported by FAPESP, led Inova Unicamp, the university's innovation agency, to file an application for an invention patent with the National Institute of Industrial Property (INPI) last February. .
“Our idea was to use passion fruit peels that would otherwise be discarded in a way that combines sustainability and efficiency and, therefore, we investigated the extraction of pectin using pressurized liquids from the fruit peel and its residual biomass obtained after processing. extraction of bioactive compounds”, explains Débora Tamires Vitor Pereira, author of the work. “We also study several natural solvents that do not harm the environment and human health [such as pure water and different combinations of deep eutectic solvents]. Water and the combination of citric acid, glucose and pressurized water were the best solvents for extracting pectin from passion fruit peel.”
Unlike the traditional industrial process for obtaining pectin, which is based on heating the raw material with toxic acids and takes long hours, the new technique is conducted in minutes, exclusively with emerging technologies that increase efficiency and yield and reduce energy consumption. Furthermore, it proved capable of generating two products with different applications: pectin with a high degree of esterification, used as a gelling agent, stabilizer, emulsifier and thickener in jellies, and pectin with a low degree of esterification, applied in dietetic or low-fat products. calorie as a fat substitute.
The first stage of the extraction process involves drying the fresh peels at 60°C and 15% moisture content, which are then ground and sieved. Pectin is extracted from this powder. If the objective is to obtain a gelling agent with a high degree of esterification, the process is with pressurized pure water; for low-grade, deep eutectic solvents are applied – traditionally, to achieve this second type, it is necessary to de-esterify the high-grade pectin, an extra process that requires additional steps and greater use of toxic solvents.
“It is also important to consider that the solvents used in our method, in addition to being natural, meeting a growing demand from society, are food-grade substances, that is, they can be used in food processing without legal restrictions and toxicity problems” , adds Julian Martínez, professor at the Department of Food Engineering and Technology at the Faculty of Food Engineering (FEA) at Unicamp and advisor of the study.
Additional studies
Among the next steps towards a possible application of the technique in industry should be a study of the techno-functional properties of the pectin obtained, as well as an economic viability analysis that includes the calculation of the necessary investment in equipment, since it is a new technology.
“With the help of Inova, potential companies and clients that may be interested in using the technology must also be prospected,” says Martínez.
Part of the work was carried out at the Foodomics Laboratory of the Food Science Research Institute (CSIC-CIAL) at the Autonomous University of Madrid (Spain) and at the Prebioin Laboratory (Spain), under the supervision of CSIC-CIAL professor Elena Ibañez.
