Influence of particle size and extraction solvent on antioxidant properties of extracts of tea, ginger, and tea-ginger blend.

Solomon A Makanjuola

doi:10.1002/fsn3.509

Abstract

The influence of particle size and extraction solvent on the antioxidant properties of aqueous and ethanolic extracts of tea (Camellia sinensis), ginger (Zingiber officinale), and tea–ginger (2:1) blend was investigated. The powder sizes studied were 0.425, 0.710, and 1.180 mm. Extracts were analyzed for DPPH radical scavenging activity, ABTS radical scavenging activity, total phenol content (TPC), iron chelating activity, total flavonoid content, and peroxide scavenging activity. The powder with the lowest particle size of 0.425 mm tends to produce aqueous extracts of tea, ginger, and tea–ginger with highest antioxidant content. At this lowest particle size all the antioxidant properties assayed were maximized. The TPC of aqueous extracts obtained from the 0.425 mm tea, ginger, and tea–ginger powders were 685.44 ± 175, 283.58 ± 19, and 483.02 ± 176 mg gallic acid equivalent (GAE) L−1, respectively. The TPC of aqueous extracts obtained from the 0.710 mm tea, ginger, and tea–ginger powders were 679.06 ± 169, 208.94 ± 147, and 400.10 ± 130 mg GAE L−1, respectively. However, for the aqueous ethanolic and ethanolic extracts, the particle size that maximized the antioxidant extraction varied depending on the antioxidant property that was being assayed. The study suggests that particle size influences the extraction of antioxidants. Also, the optimum powder size that would maximize antioxidant extraction is dependent on the solvent used and the antioxidant property being measured.

Highlights

| MATERIALS AND METHODSTea leaves were harvested from Obudu Mountain in Cross River State and the ginger rhizomes were obtained from Kaduna State, both in Nigeria
Tea (Camellia sinensis) and ginger (Zingiber officinale) are plants with health benefits
It would be useful to study the effect of particle size on the ethanolic extraction of tea—as this can present some advantages with respect to preparation of tea nutraceuticals—as the ethanolic solvent could enhance the extraction of some polyphenols that cannot be extracted by aqueous extraction

Summary

| MATERIALS AND METHODS

Tea leaves were harvested from Obudu Mountain in Cross River State and the ginger rhizomes were obtained from Kaduna State, both in Nigeria. No significant differences (p < .05) were observed between the particle sizes (0.425 mm and 0.710 mm) for total flavonoid content, ABTS radical scavenging activity, peroxide scavenging activity, and DPPH radical scavenging activity (Table 3) for ginger powder extraction. No significant differences (p < .05) were observed between the particle sizes (0.425 mm and 0.710 mm) for total flavonoid content, peroxide scavenging activity, iron chelating activity, and DPPH radical scavenging activity of tea–ginger extract (Table 3). The total flavonoid content, peroxide scavenging activity, iron chelating activity, and DPPH radical scavenging activity of the 0.425 mm tea–ginger powder were 8,975.00 mg CE L−1, 74.84%, 87.13%, and TABLE 3 Influence of particle size on antioxidant properties of aqueous extracts. No significant differences (p > .05) were observed in the total flavonoid contents and the DPPH radical scavenging activities of the aqueous ethanolic extracts for the three tea powder sizes (Table 5). No significant differences were observed in all the other antioxidant properties that were determined for the 0.425 mm and 0.710 mm aqueous ethanolic ginger powder extracts

Findings

| DISCUSSION

| CONCLUSION