Drying temperature of the onion skin for making tea

Abstract

The objective of this work was to perform the reuse of the onion residue, specifically the bark, to obtain the powder through the convective drying process, analyzing the physical parameters for later application as tea. The powders and teas were submitted to the physical, chemical and physico-chemical characterization. In the statistical treatment, the experimental design of completely randomized blocks with 4 treatments and 3 replicates was used, the data were submitted to analysis of variance and the means comparison was done by the Tukey test at 5% probability. The onion peel has a higher acid content in pyruvic acid than the dry (powder) samples. The onion peels have a clear luminosity, as does tea at both temperatures, noting that it did not change this parameter in the two forms (bark and tea). The temperature interfered satisfactorily in the bark for the flavonoid values; in contrast, the anthocyanins, chlorophylls and carotenoids values were unsatisfactory; for the teas, it was observed that the values of flavonoids, carotenoids, chlorophyll and anthocyanins decreased and presented a change in the values with the change in temperature. Therefore, it can be concluded that the use of different drying temperatures becomes impracticable, and the preparation of the tea with the bark in natura provides the highest levels of the components.