Integrating ARTP Pretreatment and PLE Extraction for Maximized Rosemary Phenolic Recovery: RSM Optimization and Comparison with E392 Extracts

Abstract

In recent years, consumers have been turning to natural products. Following this trend, the European Union has now recognized natural rosemary extract as a natural preservative (E392) in various foods. Considering this, the current study aimed to extract antioxidant compounds from rosemary leaves employing green techniques. More specifically, non-toxic solvents (water-ethanol) and green extraction techniques, such as Atmospheric Room Temperature Plasma (ARTP) for pretreatment of rosemary leaves and subsequently Pressurized Liquid Extraction (PLE) for the recovery of the antioxidant compounds, were used. Response Surface Methodology (RSM) was applied to optimize ARTP operating parameters, and the optimized ARTP + PLE extract was evaluated using spectrophotometric assays and HPLC-DAD. Under optimal conditions, the extract yielded a total polyphenol content (TPC) of ~72 mg gallic acid equivalents per g and an ascorbic-acid-associated reducing capacity (AACRC) of ~19 mg/g, while the extract exhibited relatively high antioxidant capacity as assessed by the FRAP (ferric-reducing antioxidant power) assay (~924 μmol ascorbic acid equivalents per g) and DPPH radical scavenging activity (~467 μmol ascorbic acid equivalents per g). Compared with the untreated PLE control, the ARTP-PLE extract showed increases of 3.1% in TPC, 2.03% in FRAP, 5.61% in DPPH and 25.86% in AACRC. Four commercial rosemary antioxidant preparations (E392) of different formulation types were also analyzed to contextualize the composition of the optimized extract. The commercial products, analyzed in their native form, displayed compositional patterns characteristic of oil-based formulations, whereas the ARTP + PLE extract reflected the profile of hydroethanolic rosemary extracts. These differences arise from extraction conditions and solvent systems. The comparison is descriptive and does not imply quality ranking or stability differences. Overall, the study provides insight into how plasma pretreatment can influence the composition of rosemary extracts within hydroethanolic systems.