**5.** *Citrus* **byproducts utilization**

*Citrus* juice, the principal product of processing firms is strong in vitamin C and is frequently employed in the production of nutrient-dense drinks. A large portion of this garbage is thrown on nearby landfills or burnt, resulting in contamination and a decrease in the dissolved oxygen concentration of contaminated water. The best way to handle these residues is to extract macro and micronutrients from by-products, use fiber-rich components in confectionery goods, fortify nutrient-rich animal feed, and bio-oils, and produce organic fertilizers, ethanol, and essential oils [81].

*Citrus* peel wastes are partially utilized in livestock feed, either fresh or after dehydration, but a significant amount of *Citrus* pulp is ended up lost in the fresh state owing to the complexity of handling and disposal of a significant amount of garbage generated in a very short period, and a considerable portion of it is nevertheless discarded into the atmosphere, possibly creating several ecological difficulties. As a result, the disposal of these *Citrus* by-products is a major issue for the *Citrus* industry all over the world [82].

Many studies are available on the handling of *Citrus* trash for the extraction of organic value-added substances, such as fiber and bioactive chemicals, such as flavonoids [83]. After processing *Citrus* fruits, more than 60 thousand tons of *Citrus* pomaces (CPs) are generated in South Korea each year. Public demand for nonsynthetic, better natural food raw materials has fueled research into the recuperation of natural value-added chemicals from *Citrus* trash [84].

*Citrus* waste phytochemicals and value-added substances are used in the development of healthful meals, flavoring enhancers in food processing, health and power beverages, preservatives, and vitamin supplements. These aid in improving the flavor and scent of meals as well as correcting inadequacies. *Citrus* waste-derived phytochemicals are also used in skin, hair, and nail care products, as well as antibacterial antifungal lotions, toiletries, fragrances, and soaps [85].

Mucilage & pectin are elevated chemicals generated from *Citrus* waste. Pectin is a natural vegetable substance that is useful as a cosmetic and nutritional supplement, in pharmaceutical sectors owing to its stabilizing, thickening, and gelling qualities [86]. They are starches classified as "dietary fiber." Mucilages are the soluble dietary fiber that may be discovered in *Citrus* waste as well as other plants. They are also vegetable polysaccharides that are identical to pectin but varied in their uronic acid and sugar content. They, like pectin, may be employed in the culinary, nutritional, cosmetic, and pharmaceutical industries; new research has emphasized the anti-inflammatory properties of lemon mucilage [87].

Flavonoids, which are known antioxidants and are abundant in fruits and vegetables, are another fascinating substance that may be derived from *Citrus* trash. The same is used in both the pharmaceutical and food industries. Hesperidin, which can be isolated from orange and lemon peel, is particularly useful in the pharma industry due to its anti-inflammatory and vasodilatory effects [87].

*Citrus* trash may be converted into limonene, ethanol, and other byproducts. Limonene is used as a flavoring ingredient for medicinal purposes, and it has several applications in the chemical sector and home items. *Citrus* trash also contains a significant quantity of coloring pigment. They are possible sources of natural clouding agents, which are widely used in the soft drinks industry [85].

The solid residue may be used to extract essential oils, while the liquid can be utilized to make enzymes. Separation of hydrophobic substances from the skin may be used to make biodegradable polymers, packaging material, and food-grade kraft paper, reducing the requirement for petroleum-based polyesters [81].
