Secagem de folha de brócolis para obtenção de extrato seco.

Abstract

Broccoli (Brassica oleracea var. Itálica) is a vegetable grown in different parts of the world as it is a food with recognized nutritional potential and rich in natural antioxidants. However, there is an inappropriate destination for residues from broccoli processing, such as its leaves, as several studies highlight that residue of natural food origin such as this, originating from vegetables, contain a considerable amount of phytochemical compounds that can be extracted and used as a source of compounds that can play an important nutritional enrichment role. Therefore, it is interesting that an increasing number of solutions for using them are proposed. Therefore, given this context, it is possible to identify an increase in research that seeks to develop processes to enable the use of various products existing in agricultural waste in new applications. An important step to enable this use is the extraction of these phytochemicals and the subsequent drying of this extract, necessary to maintain the quality of the extracted material, thus providing its potential industrial use. A process that has been researched is drying in a fluid-dynamically active bed and the spouted bed appears to be equipment with a very high potential to be applied in these drying processes. Therefore, the objective of this work was to obtain the dry extract of broccoli leaves, with food potential, through the spouted bed drying process. The experimental tests were carried out at the Agricultural Products Storage and Processing Laboratory (LAPPA), Food Engineering Laboratory (LEA) and Biomass Chemistry Laboratory (LQB), all at the Federal University of Campina Grande. A chemical and physical chemical characterization of the fresh broccoli leaf was carried out, after this process, a drying kinetics of the broccoli leaves was carried out, as well as the application of 10 mathematical models. In addition to calculating the main thermodynamic properties such as: effective diffusivity, enthalpy, entropy and Gibbs free energy. Two extracts from broccoli leaf flour were obtained, one hydroalcoholic and the other concentrated using a rotary evaporator. All these processes were characterized physicochemically and bioactive compounds were determined, such as: flavonoids, anthocyanins, phenolic compounds, tannins, carotenoids and total chlorophylls. The concentrated extract was dried in a spouted bed with the variables (maltodextrin concentration, drying air inlet temperature and feed flow) varying according to an experimental design (DOE) 2³ + 3 experiments at the central point. After carrying out the tests, the powders obtained were chemically and physicochemically characterized. It was concluded that the drying kinetics of broccoli leaves in a convective dryer was successfully conducted. The Midilli model was the one that best adjusted the drying kinetics. The average ix yield of powders from concentrated broccoli leaf extract after drying in a spouted bed was close to 50%, the flavonoid content was on average 48,340mg/100g, making it possible to state that broccoli leaf powder has properties antioxidants.