Color Parameters to Predict Moisture and Tannin Content in Yerba Mate Process

Changes in the Physicochemical and Bioactive Properties of Yerba Mate Depending on the Brewing Conditions

“…Green leaves were characterized by negative (−a) values in the range from −8.50 ± 0.69 to 4.48 ± 1.16, after bleaching (2-3 min burning at 500-600 • C) the values of the a* component ranged from −7.96 ± 0.66 to −6.04 ± 1.31 (organic and conventional cultivation, respectively). On the other hand, the drying and grinding processes gradually led to the loss of green color, reaching values from −3.92 ± 1.74 to 3.49 ± 0.65, and after storage from −2.03 ± 0.19 to 0.12 ± 0.47 [19], which was close to the values in this study. A similar trend was found by Schmalko and Alzamora (2001) [47], although their values for the coordinate (−a) were much lower (from 9.13 in fresh to −5.46 in dried Yerba Mate leaves).…”

“…In the studies of Frizon and Nisgoski (2020) [19], in the industrial Yerba Mate production, dried samples reached values for the chromatic coordinate b* from 17.87 ± 1.87 to 31.59 ± 3.77, and therefore similar to those in this study (Table 1), lower values for parameter b* (from 17 to 21) was found by Schmalko and Alzamora (2001) [47]. These differences can be explained by age of leaves, varied content of chlorophyll a and b in fresh leaves and the rate of degradation of these pigments depending on the time and temperature of leaf drying [19,47], as well as the degree of fragmentation and the rate of tissue dehydration during the Yerba Mate production [47]. Differences in color, especially in the brightness of dried Yerba Mate, also depend on the growing conditions (conventional vs. organic), storage time, or moisture content [19].…”

“…As a result of heat treatment, in addition to the loss of green color (−a*), the intensity of yellow color (b*) and lightness (L*) also increase [19]. In the studies of Frizon and Nisgoski (2020) [19], in the industrial Yerba Mate production, dried samples reached values for the chromatic coordinate b* from 17.87 ± 1.87 to 31.59 ± 3.77, and therefore similar to those in this study (Table 1), lower values for parameter b* (from 17 to 21) was found by Schmalko and Alzamora (2001) [47].…”

“…As a result of heat treatment, in addition to the loss of green color (−a*), the intensity of yellow color (b*) and lightness (L*) also increase [19]. In the studies of Frizon and Nisgoski (2020) [19], in the industrial Yerba Mate production, dried samples reached values for the chromatic coordinate b* from 17.87 ± 1.87 to 31.59 ± 3.77, and therefore similar to those in this study (Table 1), lower values for parameter b* (from 17 to 21) was found by Schmalko and Alzamora (2001) [47]. These differences can be explained by age of leaves, varied content of chlorophyll a and b in fresh leaves and the rate of degradation of these pigments depending on the time and temperature of leaf drying [19,47], as well as the degree of fragmentation and the rate of tissue dehydration during the Yerba Mate production [47].…”

The Impact of the Drying Process on the Antioxidant and Anti-Inflammatory Potential of Dried Ripe Coffee Cherry Pulp Soluble Powder

“…Moisture content has been linked to changes in colour parameters. Nara Tobaldini et al [58] concluded that colour parameters can be applied for a preliminary assessment of moisture content in yerba mate leaves.…”