الفهرس 
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Abstract
concretes” Essential oils and concretes are very important products extracted from various parts of medicinal and aromatic plants. These essential oils generally recognized as safe (GRAS), and can be used in diverse applications especially in food sector i.e. flavoring, preservatives, functional foods, and antimicrobial against food-borne pathogens. The preservatives properties effect of essential oils because they consist of a variety of active constituents e.g. terpenes, aldehydes, phenols, terpenoids, carotenoids, and flavonoids, that have great significance in the food industry. Thus, the various properties of essential oils offer the possibility of using natural, safe, eco-friendly, cost-effective, renewable and easily bio-degradable antimicrobials for food commodity preservation activities against a wide range of microbial pathogens in the near future.
The present study was performed to explore the present situation of the characteristics of four mostly Egyptian essential oils and concretes, which include cumin oil, thyme oil, jasmine concrete, and bitter orange concrete, as well Syrian cumin oil. The aim of current study was to evaluate the effect of distillation time, harvest period and storage conditions up to 12 months at room temperature (25±1°C) and refrigerator (4±1°C) on the yield, stability, physicochemical properties, chemical composition, and sensory attributes of cumin oil, thyme oil, jasmine concrete and bitter orange concrete. As well as, the antioxidant activity and the efficiency of cumin and thyme oils on growth of food-borne pathogenic bacteria and prolong the shelf life of fish products.
This study was conducted in Pharaonic Essential Oils Company (Phatrade) during seasonal 2016, 2017 and 2018.
The obtained results could be summarized as follows:
Part 1: Cumin essential oil
1- The results showed that the proximate chemical composition of Egyptian and Syrian cumin seeds contains moisture of 7.75 and 8.84%, ash 6.19 and 7.54%, fiber 22.67 and 25.23%, fats 10.45 and 9.11%, Protein 17.66 and 15.82%, and nitrogen free extract (NFE) 31.04 and 30.1%, respectively.
2- The results indicated that the storage of cumin seeds at room temperature (25±1°C) for a month before distillation lead to increasing the yield percentage of essential oil (4.2-5.6%).
3- The results showed that the yield percent of Egyptian cumin oil (4.20%) is higher than the Syrian cumin (3.36%).
4- The results confirmed that the most yields (" ~ "90- 94%) of CEOs and best quality were obtained in the first 6 h of distillation (F1).
5- The physicochemical properties of Egyptian and Syrian cumin essential oils were found to be as follows: specific gravity at 20°C 0.8897, 0.8898; refractive index at 20°C 1.5044, 1.5041; acid value 1.41, 1.21; optical rotation + 4° 33´, + 4 ° 26´; and solubility of alcohol 80%: 1 vol. oil in 8 vol. of ethanol, respectively.
6- The results showed that the specific gravity, refractive index, and optical rotation of CEOs decreased gradually during distillation time (fractions), while acid value increased.
7- GC and GC/MS analysis of cumin oil indicated that 18 components were identified (" ~ "94%). The main components were -pinene, p-cymene, -terpinene, 3-paramentha-diene-7-al, cuminaldehyde, 1,3paramentha-diene-7-al, and 1,4paramentha-diene-7-al.
8- The results of GC analysis showed that the storage of cumin seeds for different periods before distillation increased the cuminaldehyde from 19.42% to 31.08% after storage up to 12 months, as well p-cymene increased from 4.28% to 10.36%, while other components were decreased such as -pinene and -terpinene.
9- The results indicated that the highest percentages of total aldehydes (as cuminaldehyde) separation in the first 6 h of distillation (F1), then decreased in F2 and F3, and conversely, the -pinene, p-cymene,and -terpinene.
10- The results showed that the cumin oil affected by storage at room temperature and refrigerator up to 12 months as follows:
The Egyptian cumin oil has a high stability during storage compared to Syrian cumin oil.
A- The cumin oil which stored at low temperature maintains the oil quality more than storage at room temperature.
B- A significant change in physicochemical properties of Egyptian cumin oil during storage at 25±1°C and 4±1°C and contrary in Syrian. A significant