Effect of Vacuum Packaging and Natural Ingredients on the Physical and Microbiological Properties of Fresh Oregano (Origanum syriacum) Products

Fresh oregano (Origanum syriacum L.) is considered one of the most commonly used aromatic herbs in the Mediterranean diet. This study aimed to evaluate the possibility to extend the shelf life of fresh oregano leaves by employing vacuum packaging and natural ingredients. In this study, 132 samples of fresh oregano have been prepared in vacuum packs and divided into four treatments (n=33/treatments). The oregano recipes treatments were labeled as A (Only fresh oregano leaves 100%, Control), 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 attributes (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 be resisted 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, the addition of lactic acid (group D) was the most effective antimicrobial agent in comparison with other ingredients. In addition, lactic acid enhanced the safety of the product by inhibition of the growth of Clostridium sporogenes DSM 795.