The rising demand for sustainable and circular approaches in the agro-industrial sector has generated interest in repurposing herbal tea residues as sources of high-value bioactive compounds. This work focusses on recovering phytochemicals from Rosa canina L. peel and seed dust (by-products of processing of herbal tea in filter tea bags) using green extraction techniques. Two environmentally friendly technologies were used: ultrasound-assisted extraction (UAE) with a sonotrode and subcritical fluid extraction (SBFE). The extracts were qualitatively profiled using (HR) LC-ESI-QToF-MS/MS and quantified using HPLC-PDA. Both by-products contained phenolic substances, including gallic acid derivatives, ellagic acid, and flavonoids such as quercetin and quercetin-3-O-glucoside (only in the peel). Additionally, Folin–Ciocalteu’s assay was used to determine Total Phenolic content (TP). The extraction efficiency was considered in terms of phenolic compound recovery and total phenolic content obtained under the respective experimental conditions. The maximum TP for SBFE was reported in samples extracted with ethanol–water (48:52) at 180 °C, producing 3876.67 GAE mg/L for peel and 1648.57 GAE mg/L for seeds. In the UAE, extraction with ethanol–water (48:52) for 10 min yielded the maximum TP of 2773.81 GAE mg/L for peel and 957.86 GAE mg/L for seeds. These findings highlight the potential of R. canina infusion by-products as long-term sources of bioactive compounds for use in nutraceutical, cosmetic, and pharmaceutical industries.
Masala et al. (Fri,) studied this question.