ORIGINAL ARTICLE The effect of non-thermal processing on chemical constituents and antibacterial properties of turmeric rhizome volatile oil Saeideh Esmaeili 1 | Mohsen Barzegar 1 | Mohammad Ali Sahari 1 | Samira Berenji-Ardestani 2 | Azam Sheikhi 3 1 Department of Food Science and Technology, Tarbiat Modares University, Tehran, Iran 2 Research School of Radiation Applications, Nuclear Science and Technology Research Institute, AEOI, Tehran, Iran 3 Medicinal Plants Research Center, Institute of Medicinal Plants, ACECR, Karaj, Iran Correspondence Mohsen Barzegar, Department of Food Science and Technology, Tarbiat Modares University, P. O. Box 14115-336, Tehran, Iran. Email: mbb@modares.ac.ir Funding information Tarbiat Modares University Research Council Abstract The effect of gamma irradiation under various packaging atmospheres on chemical constituents and antibacterial properties of turmeric rhizome volatile oil has been studied. The turmeric rhizome pow- der was packaged under different atmospheres (air, N₂, and vacuum) by high-barrier multilayered film (Pet/EVOH–PA/LDPE) and they were gamma irradiated at dose of 5, 10, and 15 kGy. Accord- ing to the results, gamma irradiation under different atmospheres of packaging did not change antibacterial properties of the volatile oil. However, oxygenated sesquiterpenes which are the major chemical constituent of the volatile oil increased by irradiation significantly by 6.45% (at 15 kGy under air packaging) (p < .05). Also, modified atmosphere packaging (MAP) was more effective to improve these active compounds, significantly (p < .05). Since gamma irradiation may cause chemi- cal oxidation, isomerization, and hydroxylation of volatile oil’s constituents, it concluded that these changes could be minimized under MAP in turmeric rhizome volatile oil, significantly. Practical applications Ionizing radiation as a cold-pasteurization method has widespread and growing applications in decon- tamination of spice and condiments but, there are lack of information or contradictory results on the effects of irradiation on chemical constituents and physicochemical properties of them. Our results showed that gamma irradiation caused quantitative not qualitative changes on chemical constituents of turmeric's volatile oil. Irradiation did not have effect on antibacterial properties of turmeric volatile oils in all doses under different packaging atmospheres. The outcome of this research demonstrated irradiation resulted in improving oxygenated sesquiterpenes contents which are the major compo- nents of turmeric volatile oil. It should be noted that irradiation under modified atmosphere (N 2 and vacuum) was more effective in improving these constituents, too. Statistically, the effect of N 2 and vacuum was the same but practically vacuum packaging is recommended. 1 | INTRODUCTION Turmeric (Curcuma longa L.) is a very famous Indian spice derived from Zingiberaceae family which is known as functional foodstuff with health- ful characteristics. It is considered to have anticancer, antidiabetic, anti- rheumatic, anti-Alzheimer’s, anti-venomous, anti-viral, anti-inflammatory, anti-HIV, liver protecting, antioxidant, antibiotic, antifungal, antibacterial, choleratic, hypocholesterolemic, cytotoxic, and spasmolytic properties (Maheshwari, 2016; Nasri et al., 2014; Prasad & Aggarwal, 2011). So, an increased interest has been existed in turmeric and its medicinal properties over the past few decades (Ravindran, Nirmal Babu, & Shiva, 2007). Moreover, other than many biological properties, it has wide industrial applications in medicine, pharmaceutical, cosmetic, dye color, and food science (Attokaran, 2011; Kwon & Magnuson, 2009; Lal, 2012). Turmeric is the most commonly used spice in Iran. According to FAO the major importer of turmeric in the middle-east is Iran that annually around 5,000 tones is imported (Asghari, Mostajeran, & Shebli, 2010). Two major secondary metabolites and two chemically active frac- tions in turmeric rhizomes are the volatile and nonvolatile compounds which are responsible for healthful properties of turmeric. The volatile Received: 13 December 2017 Revised: 6 May 2018 Accepted: 7 May 2018 DOI: 10.1111/jfpe.12827 J Food Process Eng. 2018;e12827. wileyonlinelibrary.com/journal/jfpe © 2018 Wiley Periodicals, Inc. 1 of 8 https://doi.org/10.1111/jfpe.12827