By-product of honeybush (Cyclopia maculata) tea processing as source of hesperidin-enriched nutraceutical extract

•Cyclopia maculata stems have a high hesperidin content.•C. maculata tea processing by-product is a good source of hesperidin.•Extraction using 59% ethanol is recommended.•Recommended values for other parameters depend on the extract application.•Hesperidin recovery from by-product ranged between 48 and 74%.

Cyclopia maculata (honeybush) plant material was evaluated to determine its potential as renewable source material for hesperidin-enriched extract preparation. Stems contained significantly higher hesperidin levels than leaves, while “fermentation” (high-temperature oxidation process), an essential processing step of the herbal tea product, honeybush, had no effect (P > 0.05) on hesperidin content. Extraction of hesperidin from the by-product of honeybush tea processing, containing mostly stems, was optimised using response surface methodology (RSM). Four extraction parameters, namely ethanol concentration (% v/v), time (min), temperature (°C), and solvent:solid ratio (mL/g), were evaluated. Second order polynomial mathematical models for hesperidin yield and hesperidin content of the extract were constructed from RSM results and verification experiments indicated good accuracy and predictive ability. Practical process restrictions limited global optimisation and only an optimum for ethanol concentration could be predicted. The choice of process parameter values, feasible for industrial application, will depend on the product application and a cost-benefit analysis of the unit operations of the process.