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The aim of this paper is to evaluate the effects of ultraviolet (UV) light on the color, secondary metabolites and sensory acceptance of processed yerba-mate.

Samples were exposed to UV light for 72 hours. The colorimetric coordinates (L*, a* and b*) were analyzed every 6 hours, while secondary metabolites and sensory acceptance were assessed at the beginning and at the end of the experiment. Methylxanthines and phenolic compounds were quantified by ultra performance liquid chromatography photodiode array detectors and vegetable pigments by UV/visible spectrophotometry.

Decreases in methylxanthines, rutin and isomers of chlorogenic acids were found, along with an increase in isomers of dicaffeoylquinic acids. The product showed less sensory acceptance compared to the control. These results show that UV light treatment of yerba-mate accelerates the maturation process.

UV light can be used in yerba-mate maturation with a reduction time and can ensure microbiological safety with small changes in its phytochemical profile.

This paper is the first report of a novel strategy to investigate the yerba-mate maturation using UV light.

The purpose of this paper was to assess the changes in secondary metabolites and color during yerba-mate aging under controlled conditions. In Uruguay and Paraguay, the yerba-mate matured, in which chlorophyll degradation occurs, is preferred. For the matured product, the yerba-mate is stored for six months to one year.

Processed yerba-mate was submitted to 35°C and 80 per cent humidity during 42 days in a climatic chamber. Samples were collected every seven days, and the phenolic compounds/methylxanthines were quantified by ultra-performance liquid chromatography – photodiode array and chlorophylls/phaeophytins by spectrophotometry. L*, a* and b* colorimetric coordinates were measured.

The most expressive changes in the color occur in the first 14 days. At this time, 23.161 ± 2.984 per cent of total chlorophyll was degraded, considering that in 42 days, 37.458 ± 0.955 per cent is degraded, according to an exponential model. A positive correlation between theobromine amount and maturation time was found. This was verified by an increase in dicaffeoylquinic acid concentrations and small changes in chlorogenic acid isomers.

The results indicate that this is a viable accelerated yerba-mate maturation process according to economics and nutraceutics.

The paper has reported here a novel strategy to promote the yerba-mate maturation using controlled conditions.