Comparative Studies on Antioxidant Capacity, Antimicrobial Activity and Phytochemical Profile of Origanum majorana L. by Household Cooking Processes

Abstract

Marjoram (Origanum majorana L.) is an aromatic herb rich in phenolic compounds, flavonoids and essential oils, traditionally utilized for managing gastrointestinal, respiratory, cardiac, rheumatologic, menstrual and neurological disorders. As domestic cooking practices may alter the nutritional and phytochemical composition of plant foods, the present study investigated the effects of five common household processing techniques i.e. boiling, pressure cooking, steaming, sautéing and microwave cooking on the antioxidant activity, vitamin C, β-carotene, antimicrobial activity and phytochemical profile of fresh marjoram leaves. Antioxidant activity was evaluated using the DPPH radical scavenging assay, while ascorbic acid and β-carotene contents were quantified through titrimetric and spectrophotometric methods, respectively. Phytochemical profiling involved both qualitative screening and quantitative estimation of total phenolics (TPC) and flavonoids (TFC). All processing treatments significantly (p≤0.05) influenced the nutrient and phytochemical composition of marjoram leaves. Enhanced antioxidant activity was observed following sautéing (77.16%), boiling (75.86%), and microwave cooking (73.92%), with sauteing exhibiting the highest radical scavenging capacity. Flavonoid retention was greatest in sautéed samples (114.73%) followed by microwave cooking (74.58%) in comparison to raw sample. Conversely, substantial reductions were recorded in ascorbic acid (87.42–92.81%) and β-carotene (31.14–71.49%) across treatments. Notably, total phenolic content increased markedly (205.43–351.53%) in processed samples. Extract of marjoram leaves demonstrated moderate antimicrobial activity against S. aureus and C. albicans, particularly in raw and pressure-cooked forms, while no activity was observed against E. coli. Qualitative analysis confirmed the consistent presence of carbohydrates, proteins, amino acids, phenols, flavonoids and mucilage although with variations in intensity among treatments. Overall, sautéing were most effective in preserving the nutritional and functional attributes of marjoram leaves. These findings provide important insights for optimizing culinary practices to maximize the health-promoting potential of this traditional medicinal herb.