Rapid Screening and Triage of a Propolis Extract Used in Dietary Supplement Lozenges: Volatile Fingerprinting, Thermogravimetric Profiling and SEM–EDS Surface Assessment (Case Study)

Abstract Routine quality control of botanical raw materials in dietary supplements requires accessible analytical workflows for identification of atypical batches prior to manufacturing. This case study presents a rapid screening and triage protocol applied to a commercial propolis extract labelled as ‘Italian origin’ and incorporated into throat lozenges. The protocol integrates HS–SPME–GC–MS, TGA, the Folin–Ciocalteu assay (TPC), SEM–EDS and a disk-diffusion bioassay against Streptococcus salivarius ATCC 13419 as a resistant biological indicator. The volatile fraction was dominated by menthol (44.15 ± 4.21% in the extract; 58.28 ± 0.58% in the lozenge), an atypical pattern for poplar-type propolis whose reference profile is rich in sesquiterpenes. Total polyphenol content reached 2.67% w/w GAE in the raw extract, an order of magnitude below benchmarks reported for European poplar-type propolis. Thermal analysis confirmed a two-stage decomposition (Tpeak 85.1 ± 1.1 °C; 310.9 ± 0.3 °C) for the extract and a saccharide-dominated three-stage profile for the lozenge. No measurable inhibition of S. salivarius was observed under the applied conditions for either the extract or the lozenge. SEM–EDS revealed discrete high-density particulates carrying X-ray emission lines characteristic of lead, arsenic and mercury, persisting in the post-TGA inorganic residue. SEM–EDS is reported here strictly as a surface screening tool. The combined readings flag the batch for confirmatory testing (ICP-MS, HPLC–DAD/LC–MS) before manufacturing, demonstrating the diagnostic value of accessible techniques in tiered quality control. The study is intended as a method demonstration via case study, not a market survey.