Document Type : Research Paper
Authors
1 Research Institute of Food Science and Technology (RIFST)
2 Department of Food Hygiene and Aquaculture, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad
Abstract
Abstract
Background/Objective: Cuminum cyminum (C. cyminum), having numerous bioactive compounds including flavonoids, terpenoids, and phenolics, is known as a valuable source for medicinal and therapeutic properties. One of the major challenges in this industry is the production waste, especially C. cyminum husks, which are often left unused. This study focuses on C. cyminum husk wastes to investigate and develop various methods for extracting bioactive compounds from these wastes, and to evaluate the antimicrobial and antioxidant properties of these compounds. The main goal of this research is to promote the optimal use of agricultural waste and turn it into valuable resources using therapeutic and industrial applications, as well as to introduce scientific innovations in extracting and exploiting these resources.
Materials and Methods: Green cumin husks were collected as waste from a cumin processing factory in Mashhad, Iran. After thorough washing to remove soil and impurities, the husks were air-dried on cotton cloth in shaded conditions. After drying, the husks were powdered using a semi-industrial mill. In order to extract the bioactive compounds, a solvent extraction method and three types of solvents including aqueous, alcoholic, and hydroalcoholic were used. The total phenolic content (TPC) of the extracts was measured using the Folin–Ciocalteu method with gallic acid as the standard, and identified by chromatography analyses. Antioxidant capacity was assessed via the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay. To determine the antimicrobial activity, the broth microdilution method was used to establish the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Three pathogenic bacterial strains were tested: Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. The results were analyzed using Minitab software, and significant differences between means were examined using Tukey's test at a 95% confidence level.
Results: The extraction yield varied depending on the method used: aqueous extract yielded 25%, alcoholic extract 5%, and hydroalcoholic extract 8.76%. The highest total phenolic content was found in the alcoholic extract, measuring 251.76 mg gallic acid equivalent per gram (±0.01), while the aqueous extract had the lowest, at 152.80 mg/g. Chemical analysis of the extracts revealed the presence of several major compounds, including 6-methoxy-8-nitroquinoline, benzeneacetic acid, and p-xylene. Among the three methods, the hydroalcoholic extract showed the highest antimicrobial activity. At concentrations of 500, 800, and 1000 mg/mL, inhibition zones against Staphylococcus aureus measured 15 mm, 19 mm, and 22.5 mm, respectively. For Pseudomonas aeruginosa, the inhibition zones were 11 mm, 12 mm, and 13 mm, respectively. However, no inhibitory effect was observed against Escherichia coli, indicating a limited antimicrobial spectrum. These findings suggest that the extraction method has a significant impact on both the yield and biological activity of the obtained extracts.
Conclusion: The present study showed that cumin husks, despite being ignored in the industry as agricultural waste, have a high capacity in providing phenolic and bioactive compounds. Hydroalcoholic extraction of cumin husks was identified as the best method in terms of antioxidant and antimicrobial activities. These findings can pave the way for scientific and industrial exploitation of these plant wastes and the development of new medicinal and natural products.
Keywords
- Cuminum cyminum husk
- antimicrobial properties
- antioxidant properties
- aqueous extract
- hydroalcoholic extract
- green cumin
Main Subjects
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