Chemical and biological studies on cumin fruits irradiated by gamma rays for conservation

This study was carried out at the Ornamental Hort. Dept., Fac. Agric., Cairo Univ. and ýthe National Center for Radiation Res. and Tech., Nasr City, Cairo, Egypt and the Central ýlaboratory. Hort. Res. Inst., A.R.C., Giza. Egypt from 2008/2010 seasons. The aim of this ýstudy was to investigate the effect of different doses of gamma irradiation (0, 5, 10 and ýý15 KGy) and different storage periods (0, 3 and 6 months) in different package materials ýý(cotton or polyethylene bags) on essential oil quality and chemical composition of cumin ýý(Cuminum cyminum) fruits. On the other hand antimicrobial activity of treated cumin ýfruits essential oil and its extracts at 0, 5000, 10000, 20000 and 40000 ppm were ýinvestigated. Results showed that the highest essential oil% was obtained from fruits ýstored for 3 months in cotton bag without gamma irradiation. Concerning the effect of ýessential oil as antimicrobial agent, the highest antibacterial activity was obtained by ýessential oil isolated from irradiated polyethylene packed fruits at 5 KGy then stored for 3 ýmonths (Staphylococcus aureus) or irradiated polyethylene packed ones at 15 KGy ýwithout storage (Salmonella gphimurium). On the other hand, the highest -antifungal ýactivity' against lsperigillus niger and Penicillium digitalurn was obtained by essential oil ýisolated from unirradiated packed in polyethylene fruits then stored for 6 months. Non-ýstored packed in cotton bag fruits irradiated with gamma rays at 10 KGy produced ýessential oil with highest antiycastal activity. Cumin fruits extract at 40000 ppm when ýcombined with different treatments presented the highest antimicrobial activity ýý(represents as inhibition zone) against all studied microbes except with P. digitatrun. ýCumin extract at 40000 ppm when extracted from irradiated packed fruits in polyethylene ýbags with gamma rays at 5 KGy without storage or with 6 months storage or irradiated at ýý15 KGy of packed fruits in cotton bag with storage for 3 months presented the highest ýsignificant inhibition zones against S. aureus. The same concentration of extracted cumin ýfrom uniradiated packed in cotton bag fruits and storage for 6 months presented the ýhighest inhibition zone of S. tephimurium. Also, with the same concentration, extracted ýcumin from irradiated at 10 KGy of packed in cotton bag fruits without aorage or in ýpolyethylene and stored for 3 months presented the highest inhibition zones of A. niger. ýCumin extract at 5000 ppm when extracted from irradiation at 10 KGy of packed in ýcotton bag fruits and stored for 3 months presented the highest values of P. digitatum. On ýthe other hand, the superior concentration of cumin extract (40000 ppm) presented the ýhighest antiyeastal effect when extracted from irradiated packed in polyethylene fruits at ýý10 KGy and stored for 6 months. ý