Potential antimicrobial, anti-glycation and antioxidant properties of bioactive compounds of Indian spices and herbs extracted using ultrasound-assisted extraction process

Bajwa, S (2020) Potential antimicrobial, anti-glycation and antioxidant properties of bioactive compounds of Indian spices and herbs extracted using ultrasound-assisted extraction process. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Food safety is a fundamental health concern for consumers and an ongoing challenge for food producers particularly in light of recent trends towards ‘clean label’ and minimally processed foods. Natural antimicrobial such as spice and herbs contain a variety of secondary metabolites such as phenolic acid, flavonoids, and terpenes compounds, which may be present in various parts of the plants possessing antimicrobial properties. These compounds have application in the preservation of foodstuffs, through inhibition of lipid oxidation, and inhibition of foodborne pathogens. The aim of the study was to investigate potential antimicrobial, anti-glycation and antioxidant properties of selected spices and herbs extracts obtained using ultrasound-assisted extraction in relation to their bioactive phenolic component. Thirty-five India herbs and spice extracts prepared using ultrasound-assisted extraction process were screened for their antimicrobial properties against Bacillus cereus, Listeria monocytogenes, Kocuria rhizohilia, E.coli, Salmonella typhi, and Pseudomonas aeruginosa. Out of the 35 spices and herbs extracts, six spices that showed strong antimicrobial effectiveness, including ajwain, bay leaves, nutmeg, cumin, clove and Indian gooseberry were selected for further study. Antimicrobial properties were evaluated using Zone of Inhibition (ZoI), Minimum inhibition concentration (MIC) and Minimum bacterial concentration (MBC). Scanned electron microscopy (SEM) was used to evaluate the effect of spice extracts on the morphology and changes in cellular structure of the selected microorganisms. GasChromatography Mass-Spectrometry (GCMS) and High-performance liquid chromatography (HPLC) was used to establish the bioactive phytochemical components responsible for antimicrobial properties of different ajwain varieties (which showed the highest antimicrobial effectiveness). The spice and herbs ethanolic extracts were also evaluated for their antiglycation and antioxidant properties in vitro. The results highlight strong antimicrobial, anti-glycation and antioxidant properties of ajwain due to good source of phenolic compounds. The quantification of bioactive phytochemical component in spice (ajwain) extract showed potential could be relevant to quality maker for producers wishing to use natural plant-based extracts as alternative to synthetic chemical preservatives in food safety and preservation.