Articles
Leveraging postharvest processing for livestock nutritional and health benefits from South African medicinal plants
Article number
1466_26
Pages
213 – 222
Language
English
Abstract
Postharvest drying is a critical determinant of medicinal plant quality, directly influencing the preservation of bioactive compounds essential for therapeutic efficacy.
This study evaluated the effects of oven-drying (50°C) and shade-drying (32°C, 34.4% relative humidity) on the physicochemical properties, phytochemical content, and in vitro antioxidant activity of three prominent South African ethnoveterinary plants: Artemisia afra Jacq. ex Willd., Peltophorum africanum Sond, and Ziziphus mucronata Willd.
Freeze-drying was used as a benchmark to evaluate the performance of the two conventional drying methods.
A consistent ultrasound-assisted extraction protocol with 70% ethanol was applied across all samples.
Oven-dried samples achieved lower moisture content (8.5-9.8%) and water activity (0.43-0.57) than shade-dried samples (11.5-11.8% and 0.60-0.63), but this was accompanied by pronounced colour degradation (a*: 3.5-5.0), indicating significant thermal damage compared to the preserved greenness of freeze-dried samples (a*: -1.8 to -3.5). Phytochemically, shade-drying retained a greater proportion of total phenolics and flavonoids (20-30% reduction relative to freeze-drying) than oven-drying, which exhibited substantially higher losses (40-45%). This trend was consistent in antioxidant activity, where shade-dried samples showed stronger radical scavenging capacity (DPPH IC50: 0.78-0.93 mg mL‑1; FRAP: 435-543 mg TE g‑1) than oven-dried samples (DPPH IC50: 0.96-1.10 mg mL‑1; FRAP: 330-352 mg TE g‑1), indicating greater thermal degradation under oven-drying.
Although species differences were significant, with A. afra exhibiting the highest phytochemical richness, the relative performance of drying methods remained consistent across all species.
Overall, despite its lower drying efficiency, shade-drying better preserves phytochemical integrity and antioxidant activity than oven-drying, making it the more suitable low-cost option for ethnoveterinary applications.
This study evaluated the effects of oven-drying (50°C) and shade-drying (32°C, 34.4% relative humidity) on the physicochemical properties, phytochemical content, and in vitro antioxidant activity of three prominent South African ethnoveterinary plants: Artemisia afra Jacq. ex Willd., Peltophorum africanum Sond, and Ziziphus mucronata Willd.
Freeze-drying was used as a benchmark to evaluate the performance of the two conventional drying methods.
A consistent ultrasound-assisted extraction protocol with 70% ethanol was applied across all samples.
Oven-dried samples achieved lower moisture content (8.5-9.8%) and water activity (0.43-0.57) than shade-dried samples (11.5-11.8% and 0.60-0.63), but this was accompanied by pronounced colour degradation (a*: 3.5-5.0), indicating significant thermal damage compared to the preserved greenness of freeze-dried samples (a*: -1.8 to -3.5). Phytochemically, shade-drying retained a greater proportion of total phenolics and flavonoids (20-30% reduction relative to freeze-drying) than oven-drying, which exhibited substantially higher losses (40-45%). This trend was consistent in antioxidant activity, where shade-dried samples showed stronger radical scavenging capacity (DPPH IC50: 0.78-0.93 mg mL‑1; FRAP: 435-543 mg TE g‑1) than oven-dried samples (DPPH IC50: 0.96-1.10 mg mL‑1; FRAP: 330-352 mg TE g‑1), indicating greater thermal degradation under oven-drying.
Although species differences were significant, with A. afra exhibiting the highest phytochemical richness, the relative performance of drying methods remained consistent across all species.
Overall, despite its lower drying efficiency, shade-drying better preserves phytochemical integrity and antioxidant activity than oven-drying, making it the more suitable low-cost option for ethnoveterinary applications.
Publication
Authors
E. Cekwane, T. Kaseke, N.A. Masondo, O.A. Fawole
Keywords
antioxidants, Artemisia afra, ethnoveterinary, freeze-drying, phenolics postharvest processing, Peltophorum africanum, Ziziphus mucronata
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