COMPARATIVE EFFECTS OF THERMAL TREATMENTS AND -IRRADIATION ON THE VOLATILE, NON-VOLATILE AND ANTIRADICAL ACTIVITY OF EGYPTIAN ANISE ESSENTIAL OIL

Abstract

The effect of various thermal treatments (electric oven, microwave) and -irradiation at three doses (6, 8 and 10 KGy) on the composition of volatile and non-volatile of anise essential oil and also their antioxidant properties were considered. The hydrodistilled oil (HD) of control and treated samples were subjected to gas chromatography– mass spectrometry (GC/MS) analysis. The volatile profile of raw HD oil of anise consisted mainly of transe-anethole (79.68%) followed by hexahydrofarnesyl acetone (6.95%), paraanisaldehyde (5.49%); -himachalene (2.53%) and estragole (0.76%). Although the effect of roasting didn’t cause significant changes in the total yield of major compounds of HD anise oil which are phenylpropanoid derivative (transe anethole , paraanisaldehyde, cis-anethole and estragole (=methylchavicol), it is found that gamma irradiation revealed the same behavior at the 10 KGy irradiated sample but decrease the total yield of these compounds in 6.8 KGy irradiated sample compared to control one. also the thermal and irradiation caused drastic increase in the total yield of sesquiterpenes whereas decreased oxygenated compounds in all samples under investigation compared to control one. Such changes affected the antioxidant activity of the treated samples 1.1-diphenyl-2picrylhydrazyl (DPPH) free radical scavenging as well as β-carotene bleaching test against butylated hydroxy toluene (BHT). The strongest effect of reduction of DPPH radical as well as the highest inhibiting effect of the oxidation of linoleic acid and the subsequent bleaching of β-carotene was by 8 KGy irradiated sample which comprised (84.57%±1.43); (85.21% ± 0.12) respectively, in comparison to BHT (98% ± 0.0) at the same concentration 30 μg/mL besides all samples under investigation revealed high antioxidant activities due to their high content of phenylpropanoid and oxygenated compounds. These confirmed by total phenolic content. High performance liquid chromatography (HPLC) method was used for the analysis of phenolic compounds in the selected sample. Polyphenolic compounds were analysed on C18 Reversed Phase (RP) HPLC. A total of 9 phenolic compounds were identified, the obtained results showed that the predominant compound was Pqumaric acid (43.36%) followed by ferulic acid (21.06%). INTRODUCTION Mostafa Ismail; Mohamed Abass; Magda Abd El-Mageed; Fouad. Osman; Karima Mahmoud; Engy Mohamed and Gamil Ibrahim Arab Univ. J. Agric. Sci., 23(1), 2015 122 Recently, spices have received attention also in their useful physiological functions and antimicrobial activity. There are a lot of reports about antimicrobial activity of spice extracts and its essential oils. However, the available information's are for a small group of microorganisms and they are tested at high concentrations which are no practical use. More research is required on antimicrobial effects to food-related bacteria such as food spoilage bacteria and food borne bacterial pathogens (Roby et al 2013). In food processing, lipid oxidation not only causes a loss in nutritional and gustative quality of foods but also generates oxidized products such as free radicals which lead to various undesirable chemical reactions. To avoid or delay this autoxidation process, conventional artificial antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxy toluene (BHT), propyl gallate (PG) and tertiarybutylhydroquinone (TBHQ) have been used for more than five decades (Li and Yi., 2003). However, these synthetic antioxidants have been suspected to or promote negative health effects. For this reason, there is a growing interest in studies of natural additives as potential antioxidants. Many sources of antioxidants of plant origin have been studied in recent years. Among these, the antioxidant properties of many aromatic and medicinal plants have shown to be effective in retarding the process of lipid peroxidation in oils and fatty foods and have gained the interest of many research groups (Kulisic et al 2004). Therefore, the demands for these plants are increasing in industrialized and non-industrialized countries which lead to increasing their prices. Anise (Pimpinella anisum L.) is one of the most widely used plants in the world; anise seed is used as a spice (Leela and Vipin, 2008). and Anise seed essential oil has a number of applications as an aromatic agent in the food and liquor industry (Leela & Vipin, 2008 and Tonutti & Liddle, 2010). Commercial production of anise seed and anise essential oil is concentrated in countries in south Asia, Europe, North Africa as Egypt, and also in Russia. P. anisum is primarily cultivated for its fruits, commercially called “seeds” that are currently used for flavouring. Anise fruits are widely used in the preparation of traditional bread and baking goods, in liquor, and for aromatization of traditional Bulgarian liquor annasonliika, whereas anise essential oil is used as an aromatic agent in the pharmaceutical, perfumery, cosmetics, and candy production industries (Tonutti and Liddle, 2010). Many folk medicinal systems from Asia to the Mediterranean are still using anise seed as a medicinal plant (Leela and Vipin, 2008). For example, Bulgarian traditional medicine has been using anise seed or anise seed extract as an anesthetic, antispasmodic, carminative, for treating coughs, bronchitis, asthma, other inflammatory diseases, kidney stones, and for increasing lactation in nursing mothers (Stojanov, 1973). With the increased use of herbs and spices for food preservation and their inclusion in nutritional recommendations (Tapsell et al 2006), the importance for adequate preservation methods for herbs has become more important. Treatment with ionizing radiation is an accredited preservation method. Although the safety of irradiated food is well documented (World Health organization "WHO", 1999), little is known about the effects of irradiation on the antioxidant activity of phytochemicals. The Joint FAO/IAEA/WHO Expert Committee confirmed that irradiation up to 10 kGy does not produce toxicological hazards and nutritional or microbiological problems in foods (WHO, 1981). Dried foods, such as fennel powder, are less sensitive to irradiation than hydrated ones, and their irradiation has been authorized at a maximum dose of 10 kGy and 30 kGy in Korea and in the United States, respectively (Olson, 1998). An irradiation dose of 5 to 10 kGy is sufficient to reduce the population of microbes without changing essential quality attributes, and the spice flavuor remained intact up to 7.5 kGy (Farkas, 1985). However, unsaturated hydrocarbons were created in gamma-irradiated ground chili and paprika at 5 and 10 kGy and increased with the dose of irradiation (Bendini et al 1998). Furthermore, spices are usually irradiated in prepackaged form to prevent postcontamination. In this case, possible abnormal compounds from packaging materials may be created by irradiation and may migrate into the foods. Consequently, this migration may be potentially harmful and impact food flavour (Krzymien et al 2001). In addition, microwave energy has been used in food processing applications mainly for its heating properties. Therefore, it seems natural to adapt microwave radiation to pasteurize or even sterilize foods at lower temperatures or for shorter times than conventional methods require (Fung and Cunningham, 1980). Research during the past 30 years on spices and herbs proved that treatment with ionizing radiation is an effective process for destroying insects and Comparative effects of thermal treatments and -irradiation on the volatile, non-volatile and Antiradical activity of Egyptian anise essential oil Arab Univ. J. Agric. Sci., 23(1), 2015 123 micro-organisms parkas, Ionizing radiation requires no additives and is a safe physical process with a controllable technology. A major advantage for ionizing radiation is that it is cold treatment and hence this treatment does not cause any loss of the volatile components of the spices. The use of microwave energy for heating has been around for 40 years (Basaran and Akhan, 2010). Its potential use in the food processing industry for pasteurizing, sterilizing, defrosting, blanching, dehydration and cooking has opened a new dimension in food preparation at home and in food service operation (Thostenson and Chou, 1999 and AbdElmageed et al 2011, 2012, 2014)). Commercial and legal requirements regarding the safety, quality and storage of food products have still focused attention on the development and improvement of decontamination methods. Microwave processing and cooking of foods is a recent development, which is gaining momentum in household as well as large scale food applications (Basaran and Akhan, 2010). Microwave energy has been used in food applications mainly for its heating properties. It seems natural, therefore, to adapt microwave radiation to pasteurize or even sterilize foods at low temperatures in shorter times than required by conventional methods (Akgul et al 2008 and Abd-Elmageed et al 2011, 2012). Due to the absorption of electromagnetic energy, temperature of material of high dielectric capacity increases after microwave pasteurization. Therefore, microwave pasteurization offers similar benefits to conventional methods, but with an improved product quality and reduced time of exposure to energy (Hashem and Alamri, 2010). Processing of spices using microwaves is a newer dimension. This alternative methodology is preferred, due to the convenience and ease of handling (Abd-Elmageed, 2007). Cooking or roasting alters the nature of many food constituents such as starches and proteins by changing their physical, chemical and nutritional characteristics (Belitz and Grosch, 1987). Heat processing also changes the bioavailability of proteins, carbohydrates, lipids and vitamins. Little information is available on the extent of destruction of bioactive principles of spices during food processing. Since t