Assessment of physicochemical parameters in argentinian Yerba Mate: Variability among different commercial brands

Abstract

Yerba mate (YM) is a traditional plant-based product used in the preparation of hot beverages. YM is composed of dried leaves of Ilex paraguariensis A. St.-Hil., which are slightly toasted and milled. The present study analyses the variability of physicochemical sensorial-linked characteristics among six of the most renowned argentinian brands of YM. The samples consist of particles that were categorised as coarse (61%), intermediate (34%), and fine (5%). The average moisture and ash content were 7.8% and 5.4%, respectively, and their average loose bulk density was 285 g/L. The average colour parameters were L* = 49, a* = − 1.25, b* = 15.5, with the total colour difference being lower than 1 among samples of the same brand. On average, 1 g of YM absorb 2.6 g of hot water. This study introduced a description of the mechanical response to compression for YM. All samples underwent easy compression under small stresses owing to the material’s open structure; compressibility exhibited a positive correlation with moisture due to the plasticizing effect of water. The relaxation response of the YM was associated with its spatial arrangement and the presence of smaller particles that could facilitate elastic behaviour. Mate tea presented an average pH of 5.77 and a refractive index of 1.3340. The content of phenolics in mate teas significantly differs among the studied YM brands, with its average equivalent to 2.32 g of chlorogenic acid per litre and its antioxidant capacity equivalent to 15 mM of Trolox. The phenolic concentration showed a negative correlation with the quantity of fine fraction and moisture content, and positive correlation was observed with water absorption capacity. This suggests that greater microporosity of the material might facilitate increased water-solid interaction, consequently leading to higher phenolic extraction. These results may contribute to explaining certain sensory attributes observed in YM samples.