In the last few years, more and more studies on the biological properties of essential oils (EOs) especially antimicrobial and antioxidant properties in vitro and food model have been published in all parts of the world. But so far no comprehensive reports of these studies have been reported in food model from Iran. The focus of this overview lies in the using of EOs from some indigenous medicinal plants of Iran (including Mentha longifolia, Cuminum cyminum, Teucrium polium, Pimpinella anisum and Allium ascalonicum) in probiotic dairy products (especially cheese, yoghurt and Aryan) in recent years. Recently, consumers have developed an ever-increasing interest in natural products as alternatives for artificial additives or pharmacologically relevant agents. Among them, EOs have gained great popularity in the food, cosmetic as well as pharmaceutical industries. Despite the reportedly strong antimicrobial activity of EOs against food-borne pathogens and spoilage microorganisms, their practical application as preservatives is currently limited owing to the undesirable flavour changes they cause in food products. Nonetheless, more studies are necessary to the applicability of various EOs on other food models in Iran and other countries.
- functional dairy foods
- natural preservative
- sensory quality
Today, due to the adverse effects of chemical preservatives, regarding the carcinogenic potential and toxicity to humans, as well as the high levels of antimicrobial agents present in plants, there is a growing interest in the use of natural preservatives derived from natural sources . Food storage methods which maintain the quality and extend the shelf life of food because of improved production, supply and trading are important. Humans are familiar in keeping foods by different methods such as the use of heating, cooling, salting, etc. a long time ago, but for inhibition of pathogen growth and also prevention of food spoilage, a new method is more in need; therefore one of these methods is the use of essential oils and natural materials as antimicrobial additives in food .
Essential oils are composed of lipophilic and highly volatile secondary plant metabolites . As defined by the International Organisation for Standardisation (ISO), the term “EOs” is reserved for a product obtained from vegetable raw material, either by distillation with water or steam, or from the epicarp of citrus fruits by a mechanical process, or by dry distillation, that is, by physical means only. EOs have been proposed as natural preservatives and are used as alternatives for the control of pathogenic microorganisms. Herbal EOs are aromatic oil liquids, extracted from various parts of plants, and are used as flavouring agents in foods; thus the importance of the use of medicinal plants in food products can be multiple times .
2. How plants work
Preservatives are used to limit the growth and microbial activity in pharmaceutical products, food and cosmetics, and by interfering with cell membranes, enzymes and genetic structure of microorganisms have a preventive effect. To apply the essential oils as chemical preservatives in food, investigating their antibacterial activities alone and in combination with other factors affecting the growth of microorganisms in food and nutrition is essential in laboratory models . The use of natural antimicrobial compounds such as essential oils, herbal extracts and spices for the protection of food against microbial spoilage has led to the identification of some of their unique features such as taste effects and antioxidant activity . EOs have been used in human health as functional food, food additives, medicine, nutritional supplements and cosmetic manufacturing [4, 6, 7].
Essential oils and plant extracts with various biological compounds have very high potential for using as new drug combinations, healthcare and human and animal diseases as well due to the presence of anti-microbial compounds especially against Gram-Positive and Gram-Negative pathogens, Anticancer, Antioxidant and Free Radical Removal Factors as one of the most important natural sources for the using of them in medicines and foods . Essential oils and extracts from medicinal herbs with antimicrobial, anticancer and antioxidant compounds (due to the presence of free radicals eliminating agents) have importance as new and natural drug combinations, both in the field of health and disease management and in the protection of raw and processed foods .
3. Importance of food-borne pathogens
Food-borne diseases recognised as one of the major public health problems worldwide, especially in developing countries, and, on the other hand, increasing incidence of food-borne disease along with its social and economic consequences have led to conducting extensive research in order to produce safer food and develop new antimicrobial agents; among them, the extensive use of probiotics and bacteriocins as biological additives is of considerable importance. With increase of urban population, tourism, immigration, a variety of food with different components, improve technology in the food industry, changes in food consumption culture and approach to food consumption, food preparation, and finally international trade in food, overburdened the more food illness in the present age, so that about 30 per cent of people in developed countries at least once a year to develop food-borne diseases . Despite the reportedly strong antimicrobial activity of EOs against food-borne pathogens and spoilage microorganisms, their practical application as preservatives is currently limited owing to the undesirable flavour changes they cause in food products [6, 9, 10, 11].
4. Some of the most important plants that can be used in foods
This plant is belonging to the mint family, plateau, a height of 10 to 30 cm, with a white cottony appearance, usually in poor areas (nutrients and organic matter), rocky areas and sand dunes in Europe, the Mediterranean region, north of Africa and south west of Asia, including Iran, especially Khorasan province . The studies have shown that this herb has antioxidant effects and antipyretic, antimicrobial and antispasmodic effects . It has been reported that the ethanol extract of this herb has also an antibacterial activity against Gram-positive and Gram-negative microorganisms of the show itself .
Aloe veragel ( Aloe barbadensis Miller)
5. The sensitivity of some important food-borne pathogens to plant extracts and EOs
Food-borne diseases are one of the major public health problems worldwide, and recent reports indicate that
In the study of Ehsani et al. , the results have shown that treatments of 0.1%
In the result of one study, essential oil of
Today, the importance of biofilm formation in the food industry is also high, so studies have also been carried out and are expanding. In these studies, vegetable oils are used to prevent and eliminate biofilms. For example, the compounds in essential oils such as SAB, C3 and C4 are highly effective against biofilms created by
6. Herbal medicines appear relatively safe
Traditional medicine has brought the foundation of health care around the world from the earliest days of human beings. Medicinal plants have been known for many years as a rich source of well-known therapeutic agents for the treatment and prevention of various diseases, the most important of which is the social, cultural, spiritual and medicinal fields. Over the past centuries, severe changes in human lifestyle and dietary habits have led to the emergence of various chronic pathologies. Recently, “herbal renaissance” is a visible phenomenon worldwide, and two-thirds of the plant species in the world may have medicinal value. The World Health Organisation believes that 80% of the population in Africa and Asia uses traditional medicine as the first source for their health-care needs. Also, in the United States, more than 40% of the population has recently been identified with complementary and alternative supplements, including herbal supplements .
Herbal drugs appear to be relatively safe, but human research or prospective data on adverse effects and plant and drug interactions are limited. They generally have fewer drugs than their pure relatives because they contain a mixture of chemicals that are in low amounts. According to studies, the importance of edible oral pathogens is not covered for everyone. According to studies, the importance of food-borne pathogen bacteria is not covered for everyone. On the other hand, due to the harmful effects of chemical preservatives and also the increase of drug resistance, the use of plants and their essential oils is very important. Essences and their effective compounds can be used to prevent poisoning and disease and to prevent the transmission of bacteria from food and food industry like dairy.