Myrtaceae leaves grown in Agroforestry: a sustainable alternative to producing natural antioxidants extracts

Myrtaceae species such as uvaia, grumixama, and feijoa have been used in Brazil’s Agroforestry Systems (AFS). In AFS, frequent pruning occurs, and leaves are discarded. However, the leaves contain specific phenolic compounds (PC) that, when appropriately extracted, produce extracts with antioxidant activity (AA). These extracts meet the demand for natural and sustainable food ingredients. Therefore, the drying study (40, 50, and 60 °C) of uvaia, grumixama, and feijoa leaves obtained from AFS was carried out, and the effect of drying on the PC profile (LC-ESI-MS/MS) and AA were evaluated. In the uvaia extracts, the major compounds were EGCG, gallic acid, and isoquercitin, accounting for 94% of their PC, and leaves dried at 50 °C promoted a better phenolic extraction. The gallic acid, 2.5 DHBA and isoqueticitrin represent 79% of the relative composition of PC in grumixama extracts, and leaves dried at 60 °C were the condition that allowed a greater extraction. While, epicatechin, catechin, gallic acid and isoquercitrin correspond to 66% of the PC composition of feijoa leaves. Grumixama had the highest values for AA by the FCRC and DPPH while feijoa had significant values for FRAP in all treatments. Dried leaves at 50 °C showed higher AA for all methods, except for grumixama which showed this behavior at 60 °C. These results indicate that these matrices proved promising sustainable sources of various phenolic compounds. The drying process of the leaves at 50 and 60 °C had a greater extraction of compounds with antioxidant activity, with potential industrial applications.