Origanum syriacum L. (common names: zaatar, bible hyssop, Syrian oregano, Lebanon oregano) is considered one the most commonly used aromatic herbs in the mediterranean diet. The objective of this study to evaluate the effect of vacuum packaging and storage conditions on the shelf life of fresh leaves of Origanum syriacum by employing. In this study, 132 samples of fresh oregano have been prepared in vacuum packs and divided into four treatments (n=33/treatments). The treatments were labeled as A (fresh oregano100%), B (fresh oregano 63.2%, fresh onion 15%, olive oil 20%, NaCl 1.8%), C (fresh oregano 61.91%, fresh onion 15%, olive oil 20%, NaCl 1.8%, sumac powder 1.29%), and D (Fresh oregano 59.2%, 15% Fresh onion, 20% oil, 1.8% salt, 4% lactic Acid, ultimate pH 4.4). The potential growth of Clostridium botulinum by using Clostridium sporogenes DSM795 as a surrogate microbe has been assessed. Moreover, color traits (L*a*b*), microbiological counts (aerobic, anaerobic, and psychrotrophic as well as yeast and molds), and pH- values have been evaluated during the storage period (42 days). Both spot and spreading agar journey methods showed that groups B and D could resist the growth of Clostridium sporogenes DSM 795. It was found that lactic acid was the most effective ingredient
against aerobic, anaerobic, and psychrotrophic bacteria if compared to sumac and onion. On another hand, Group C showed significantly (p<0.05) the lowest L* and b*-values if compared with other groups. In conclusion, there is a possibility to extend the shelf life of fresh oregano by employing hurdle technology (vacuum packaging combined with natural additives).
Keywords: Oregano, color traits, Clostridium sporogenes, vacuum, sumac.