Preparation of a filter from dried leaves of Borago officinalisL. “borage”, determination of its polyphenol content and antioxidant capacity

This research sought to obtain the ideal drying conditions for the delicate and fragile borage leaves, to develop a filter and to determine the total polyphenolic content and antioxidant capacity in the filter infusion. To do this, fresh borage leaves were dehydrated. Infusions of fresh whole and cut leaves, whole and ground dried leaves (filter) were prepared. All infusions contained the equivalent of 1 g of dry leaf in 250 mL of infusion. The concentration of total polyphenols was determined with the Folin Ciocalteau reagent, expressing the results in gallic acid equivalent. The antioxidant capacity was determined by the DPPH and ABTS methods, expressing results in their Trolox equivalent. The results of total polyphenols in infusions of fresh leaves (whole and cut), whole dried leaves and in filter were 9.60, 28.08, 26.59 and 10.75 mg gallic acid/g dry leaf, respectively. The antioxidant capacity against the DPPH radical was 19.27 (whole fresh leaf), 58.56 (fresh leaf in pieces or cut), 39.06 (whole dry leaf) and 13.83 (filter) mg Trolox/g dry leaf. The antioxidant capacity against the ABTS radical was 13.85 (whole fresh leaf); 53.74 (fresh leaf in pieces or cut), 55.37 (whole dry leaf) and 21.78 (filter) in mg Trolox/g dry leaf. The filter complied with the microbiological regulations and received a positive sensory evaluation, suggesting its commercial viability. It is concluded that the filter of ground dried borage leaves is an accessible and manageable source of antioxidants, with potential for commercialization.