Citrus fruit in the context of "Incense trade route"

Limonene (/ˈlɪmənˌiːn/) is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the essential oil of citrus fruit peels. The (+)-isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring agent in food manufacturing. It is also used in chemical synthesis as a precursor to carvone and as a renewables-based solvent in cleaning products. The less common (−)-isomer has a piny, turpentine-like odor, and is found in the edible parts of such plants as caraway, dill, and bergamot orange plants.

Shellac (/ʃəˈlæk/) is a resin secreted by the female lac bug on trees in the forests of India and Thailand. Chemically, it is mainly composed of aleuritic acid, jalaric acid, shellolic acid, and other natural waxes. It is processed and sold as dry flakes and dissolved in alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish. Shellac functions as a tough natural primer, sanding sealant, tannin-blocker, odor-blocker, stain, and high-gloss varnish. Shellac was once used in electrical applications as it is a good insulator and seals out moisture. Phonograph and 78 rpm gramophone records were made of shellac until it was replaced by vinyl.

From the time shellac replaced oil and wax finishes in the 19th century, it was one of the dominant wood finishes in the western world until it was largely replaced by nitrocellulose lacquer in the 1920s and 1930s. Besides wood finishing, shellac is used as an ingredient in food, medication and candy as confectioner's glaze, and to preserve harvested citrus fruit.

Pectin (Ancient Greek: πηκτικός pēktikós: 'congealed' and 'curdled') is a heteropolysaccharide, a structural polymer contained in the cell walls and middle lamellae of terrestrial plants. The principal chemical component of pectin is galacturonic acid (a sugar acid derived from galactose) which was isolated and described by Henri Braconnot in 1825. Commercially produced pectin is a white-to-light-brown powder, produced from citrus fruits for use as an edible gelling agent, especially in jams and jellies, dessert fillings, medications, and sweets; as a food stabiliser in fruit juices and milk drinks; and as a source of dietary fiber.

The juice vesicles, also known as citrus kernels (in aggregate, citrus pulp), of a citrus fruit are the membranous content of the fruit's endocarp. The vesicles contain the juice of the fruit and appear shiny and saclike. Vesicles come in two shapes: the superior and inferior, and these are distinct. Citrus fruits with more vesicles generally weigh more than those with fewer vesicles. Fruits with many segments, such as the grapefruit or pomelo, have more vesicles per segment than fruits with fewer segments, such as the kumquat and mandarin. Each vesicle in a segment in citrus fruits has approximately the same shape, size, and weight. About 5% of the weight of an average orange is made up of the membranes of the juice vesicles.

Juice vesicles of the endocarp contain the components that provide the aroma typically associated with citrus fruit. These components are also found in the flavedo oil sacs. The vesicles and their inner juices contain many vitamins and minerals as well as the taste and sweet acid fragrance.