Biological activity and quantification of bioative compounds in yerba mate extract and its application in fish hamburger

Abstract

The yerba mate has a high content of biologically active compounds with industrial application. Caffeine, rutin and chlorogenic acid present in this product have antioxidant activity and the latter one is also an antimicrobial agent. This \paper aimed to assess the biological activity of yerba mate extract and quantify its bioactive compounds, as well as apply the extract in fish hamburger to determine its preservative activity. The antioxidant power was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power). Total phenolic compounds and flavonoids were quantified by spectrophotometry, and caffeine, rutin and chlorogenic acid by ultra-performance liquid chromatography. The antimicrobial activity was assessed by Minimum Inhibitory Concentration (MIC). Associations of extract with the synthetic preservative butyl hydroxyanisole (BHA) were tested. Fish hamburgers incorporated with yerba mate were prepared; centesimal composition, lipid and microbiological oxidation were carried out during 28 days. Results: DPPH IC₅₀ of 7.91 µg mL^-1 in the extract, FRAP of 4922.67 µmol for Fe (II) g^-1, 104.54 EAG g^-1 of total phenolics, 23.11 EQ g^-1 of flavonoids, and 49.6, 34.5 and 23.1 mg g^-1 of chlorogenic acid, caffeine and rutin, respectively. The extract presented a CIM of 10, 5 and 10 mg mL^-1 against Escherichia coli, Staphylococcus aureus and Salmonella enterica, respectively. The combination of extract and BHA reduced the amount of synthetic preservative for the same antioxidant activity and presented an additive effect to S. aureus. The fish hamburgers with 1% of extract or with BHA showed statistical difference in mesophiles counting from the control group. Thus, the yerba mate extract presented biological activity and the growth of mesophiles was inhibited in fish hamburguers incorporated with BHA or 1% of extract, indicating that the quantified phenolic compounds are likely to be preservative agents.

Keywords:
Antioxidant activity; Antimicrobial activity; Checkerboard; Natural preservative; Ilex paraguariesis; Oreochromis niloticus