Spray-dried extracts of Thymus serpyllum

Abstract

In the present study, spray-dried Thymus serpyllum extracts obtained by using four extraction techniques (maceration, heat-assisted extraction, extraction in ultrasound bath and extraction by ultrasound probe) were characterized through determination of total polyphenols and total flavonoids contents, antioxidant capacity, zeta potential, bulk density and solubility. Polyphenols yield was statistically higher in the extract obtained by ultrasound probe, in comparison to the extracts prepared using maceration, heat-assisted extraction and extraction in ultrasound bath. On the other hand, extraction technique did not show statistically significant influence on the flavonoids concentration. Furthermore, extraction procedures did not show significant effect on antioxidant neutralization of DPPH radicals, while flavonoids yield had correlation with the DPPH radical-scavenging capacity assay. However, the extracts obtained using maceration and ultrasound waves (ultrasound bath) have shown significantly better antioxidant capacity in the preservation of β-carotene, compared to the extracts prepared by using high temperature and ultrasound probe. The extract obtained in maceration has shown statistically better stability (higher absolute value of zeta potential), compared to the extracts prepared using high temperature and ultrasound waves. According to the results of Pharmacopoeia test, bulk density of spray-dried T. serpyllum extracts was ranked by significance in the following order: heatassisted extraction>ultrasound bath and ultrasound probe>maceration. Relatively high solubility of spray-dried extracts has been found in the following order: maceration>ultrasound bath and ultrasound probe>heat-assisted extraction. Spray-dried T. serpyllum extract prepared using maceration represents a powder with satisfying physicochemical properties, as well as a good source of substances with significant antioxidant activity, particularly in emulsions, which enable its use in functional food and pharmaceutical products.