Today, citrus essential oils are used to preserve food, which is eco-friendly and economically tenable. In the past, chemical preservatives and other synthetic antioxidants such as sodium nitrite, nitrates, or benzoates were used in food preservation. Citrus essential oils are mainly obtained from citrus peels, which are often disposed of as waste and cause environmental problems. With increasing production of citrus crops and wide spread consumption of the processed citrus-based products, the quantity of discarded waste is mounting every year and causing environmental problems. Extracting citrus oil from waste peels not only preserves the environment but can also be used in a variety of applications, including food preservation. The use of citrus essential oil is very diverse. It is commonly used to preserve fruits, vegetables, meat, fish and processed foods as a result of recent advances.
Essential Oils (EOs) are aromatic compounds found in considerable quantities in oil bags or sebaceous glands located at different depths in the peel of the fruit, mostly the flavedo part and cuticles.
Essential oils (oils) are soluble in alcohol, ether and natural oils but insoluble in water. Citrus essential oil is a complex mixture of approximately 400 compounds and their content (properties) depends on the species, cultivar and variety and cultivar, cultivation, extraction and separation methods.
Extraction of citrus essential oils
EOs are mainly found at different depths in the peels and fruit cuticles. The amount of the main classes of EOs in fresh and dried citrus peels differ. EOs are released when oil bags are crushed while extracting juice an essential oil’s main ingredient is d-limonene, which is used as a green solvent to determine fats and oils. EOs are usually extracted by cold pressing. Traditional and semi-industrial processes include cold pressing and distillation. In cold pressing, peels and cuticle oils are removed mechanically. The yield is an aqueous emulsion which is then centrifuged to retrieve EOs.
Application of essential oils is not limited to food preservation but is also used in cosmetics, perfumery, toiletries, aromatherapy including massage, inhalation, bath, and other personal hygiene products. It also acts as an odor mask in the textile, plastics and paint industries, plastics and paint industries. It is also used as an important ingredient in pharmaceutical formulations. Due to increasing concerns and consumer demand for food safety, essential oils have recently received much attention as a natural antimicrobial agent in the food and packaging industries. EOs have had a variety of applications in the past. EOs have had a variety of applications in the past.
Storage of processed food; Antimicrobial packaging for food products; Edible thin films and antimicrobial packaging films; Nanoemulsions for storing vegetables and fruits; Combinations in soda/citrus concentrates; Flavoring agent in carbonated colas, soft drinks; Preservation of meat, fish and seafood.
Challenges and visions
While food research has focused on EOs because of their natural origin, it is difficult to standardize the amounts used to achieve optimal laboratory conditions for preserving meat or fish. There is a particular challenge in this regard because the volatile compounds in EOs may interact with proteins in meat, resulting in EOs becoming unstable and the formation of new compounds and undesirable properties. As a result, its active antimicrobial effects are reduced. In order to preserve meat, more EOs are needed, but using more can alter the taste, aroma, and quality of meat and processed foods, resulting in reduced consumption. However, the strong flavor of citrus EOs exerts good effects at low concentrations and simultaneously limits negative organoleptic changes.
Citrus EOs are considered safe for consumption due to their non-toxic nature and anti-allergic hypoallergenicity, but in some cases, they have been found to irritate the skin and cause allergies. An option for solving this problem would be to encapsulate EOs in a biodegradable shell that could be controlled to release active compounds only when needed. This method not only reduces the instability of EOs (reactivity to substrate proteins) but also ensures antimicrobial properties through controlled release. It is also a challenge to combine EOs in meat because, in addition to killing the target microbe population, it can also promote the growth of other unfavorable microbes that lead to spoilage.
Extensive research is required on overcoming the challenges regarding allergies and obtaining safer dosage limits. A shift toward greener technologies indicates an optimistic future towards safer utilization of citrus-based EOs in food preservation.