Citrus contains a range of highly beneficial bioactive compounds, such as polyphenols, carotenoids, and vitamins that show antimicrobial and antioxidant properties and help in building the body’s immune system. On consumption or processing, approximately 50% of the fruit remains as inedible waste, which includes peels, seeds, pulp, and segment residues. This waste still consists of substantial quantities of bioactive compounds that cause environmental pollution and are harmful to the ecosystem because of their high biological oxygen demand. In recent years, citrus cultivation and the production of processed foods have become a major agricultural industry. In addition to being a substantial source of economy, it is an ideal and sustainable and renewable resource for obtaining bioactive compounds and co-products for food and pharmaceutical industries. In the present article, the various methods of extraction, conventional and modern, as well as separation and isolation of individual bioactive compounds from the extraction mixture and their determination have been reviewed. This article presents both aspects of extraction methods, i.e., on a small laboratory scale and on an industrial mass scale. These methods and techniques have been extensively and critically reviewed with anticipated future perspectives towards the maximum utilization of the citrus waste.
Citrus EOs is an economic, eco-friendly and natural alternatives to chemical preservatives and other synthetic antioxidants, such as sodium nitrites, nitrates or benzoates, commonly utilized in food preservation. Citrus based EOs is obtained mainly from the peels of citrus fruits which are largely discarded as wastes and cause environmental problems. The extraction of citrus oils from the waste peels not only saves environment but can be used in various applications including food preservation. The present article presents elaborated viewpoints on the nature and chemical composition of different EOs present in main citrus varieties widely grown across the globe; extraction, characterization and authentication techniques/methods of the citrus EOs; and reviews the recent advances in the application of citrus EOs for the preservation of fruits, vegetables, meat, fish and processed food stuffs. The probable reaction mechanism of the EOs based thin films formation with biodegradable polymers is presented. Other formulation, viz., EOs microencapsulation incorporating biodegradable polymers, nanoemulsion coatings, spray applications and antibacterial action mechanism of the active compounds present in the EOs have been elaborated. Extensive research is required on overcoming the challenges regarding allergies and obtaining safer dosage limits. Shift towards greener technologies indicate optimistic future towards safer utilization of citrus based EOs in food preservation.
AbstractCitrus is one of the largest and most popular fruit crops commercially grown across the globe. It is not only important in terms of economy but is also popular for its nutritional benefits to human and farm animals. Citrus is available in several varieties, all with attractive colors. It is consumed either fresh or in processed form. After processing, approximately 50% of the fruit remains unconsumed and discarded as waste. The latter includes fruit pith residue, peels and seeds. Direct disposal of these wastes to the environment causes serious problems as these contain bioactive compounds. Release of these bioactive compounds to the open landfills cause bad odor and spread of diseases, and disposal to water bodies or seepage to the underground water table deteriorates water quality and harms aquatic life. In this regard, a number of research are being focused on the development of better reuse methods to obtain value-added phytochemicals as well as for safe disposal. The important phytochemicals obtained from citrus include essential oils, flavonoids, citric acid, pectin, etc., which have now become popular topics in industrial research, food and synthetic chemistry. The present article reviews recent advances in exploring the effects of flavonoids obtained from citrus wastes, the extraction procedure and their usage in view of various health benefits.
Onion (Allium cepa L.) is one of the most commonly cultivated crops across the globe, and its production is increasing every year due to increasing consumer demand. Simultaneously, huge amounts of waste are produced from different parts of the onion, which ultimately affect the environment in various ways. Hence, proper usage as well as disposal of this waste is important from the environmental aspect. This review summarizes various usage methods of onion waste material, and processes involved to achieve maximum benefits. Processing industries produce the largest amount of onion waste. Other sources are storage systems, domestic usage and cultivation fields. Particular emphasis has been given to the methods used for better extraction and usage of onion waste under specific topics: viz. organic synthesis, production of biogas, absorbent for pollutants and value added products.
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