The juice vesicles, also known as citrus kernels (in aggregate, citrus pulp), of a

citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...

fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

are the membranous content of the fruit's

endocarp Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Fruitlike structures may develop directly from the seed itself rather th ...

. The vesicles contain the

juice Juice is a drink made from the extraction or Cold-pressed juice, pressing of the natural liquid contained in fruit and vegetables. It can also refer to liquids that are flavored with concentrate or other biological food sources, such as meat ...

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 The grapefruit (''Citrus'' × ''paradisi'') is a subtropical citrus tree known for its relatively large, sour to semi-sweet, somewhat bitter fruit. The flesh of the fruit is segmented and varies in color from pale yellow to dark red. Grapefru ...

pomelo The pomelo ( ; or pummelo, ''Citrus maxima''), also known as a shaddock, is the largest citrus fruit. It is an ancestor of several cultivated citrus species, including the bitter orange and the grapefruit. It is a natural, non-hybrid citrus fr ...

, have more vesicles per segment than fruits with fewer segments, such as the

kumquat Kumquats ( ), or cumquats in Australian English, are a group of small, angiosperm, fruit-bearing trees in the family Rutaceae. Their taxonomy is disputed. They were previously classified as forming the now-historical genus ''Fortunella'' or plac ...

and

mandarin Mandarin or The Mandarin may refer to: Language * Mandarin Chinese, branch of Chinese originally spoken in northern parts of the country ** Standard Chinese or Modern Standard Mandarin, the official language of China ** Taiwanese Mandarin, Stand ...

. 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

contain the components that provide the

aroma An odor (American English) or odour (Commonwealth English; see spelling differences) is a smell or a scent caused by one or more volatilized chemical compounds generally found in low concentrations that humans and many animals can perceive v ...

typically associated with citrus fruit. These components are also found in the

flavedo Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Fruitlike structures may develop directly from the seed itself rather than ...

oil sacs. The vesicles and their inner juices contain many

vitamin Vitamins are Organic compound, organic molecules (or a set of closely related molecules called vitamer, vitamers) that are essential to an organism in small quantities for proper metabolism, metabolic function. Nutrient#Essential nutrients, ...

s and

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

s as well as the taste and sweet

acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

fragrance. Pulp cells often have thin membranes, and they are less regular in shape than other plant cells. They are also very large and protect the

seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

s of the fruit. The color of the pulp is variable, depending on the

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

and the ripening stage. Usually, it has the color of the outer peel (

exocarp Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Fruitlike structures may develop directly from the seed itself rather th ...

Extraction and preservation

The juice held within juice vesicles can be recovered through various extraction processes. The pulp is usually removed from the juice by

filtering Filtration is a physical process that separates solid matter and fluid from a mixture. Filter, filtering, filters or filtration may also refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Fil ...

it out. The juiciness of the pulp depends on the

, variety, season, and the tree on which it grew. Close to 90% of the citrus fruit juice solids are recovered with extractors. Pectic enzymes can sometimes be added to lessen the thickness of these solids. The juice along with these solids can be combined to increase primary juice yields or sold as bases for fruit beverages. The juice solids become opaque from the pulp washing process, resulting in a less expensive source of fruit solids for food labeling in comparison to regular juice. The juice solids can also be pasteurized, dried, and sold, but appear dark brown in color if they have not been washed properly before drying. The solids can also be stored frozen or sold to beverage manufacturers. They provide fruit beverages that are sold with a higher appeal to a consumer and improved texture in the juice. These opaque juice solids are known as cloud.

Drum drying Drum drying is a method used for drying out liquids from raw materials with a drying drum. In the drum-drying process, pureed raw ingredients are dried at relatively low temperatures over rotating, high-capacity drums that produce sheets of drum-dr ...

or freezing are two processes for preserving juice solids. When product

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

s are deactivated through heat stabilization, they are frozen. Light and air are used for drum-drying, but this process often decreases the flavor and color of the solids.

Use

One of the main uses for juice vesicles is for added substance to animal feed. Residue from juice vesicle extraction, once dried, can be added to cattle feed. Cattle feed often contains citrus pulp. This pulp helps in the long term to preserve nutrition, improve color, and create a more pleasant odor to the feed. Adding juice pulp provides cattle with a richer source of vitamins and minerals in addition to a more palatable taste. The green

fodder Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food ...

used for cattle can be supplemented with this feed containing juice vesicles. The other common use for juice vesicles is for enhancing beverages or creating inexpensive beverage bases. Jams and jellies, pulp in juice-based drinks, whole juices, and

yogurt Yogurt (; , from , ; also spelled yoghurt, yogourt or yoghourt) is a food produced by bacterial Fermentation (food), fermentation of milk. Fermentation of sugars in the milk by these bacteria produces lactic acid, which acts on milk protein to ...

products contain extracted juice vesicle residue that was also dried. Some juices, juice concentrates, and drinks containing juice also contain previously frozen juice vesicles. The cloud resulting from the vesicles have sugar solids containing

vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription di ...

. This cloud from vesicles is a popular alternative to brominated vegetable oil or glycerol ester of wood rosin, which are other clouding agents. The citrus in the vesicles is more often used for cloud especially for shipping products overseas. In

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, many yogurts and beverages include added enlarged citrus juice vesicles. These vesicles combined with enzymes are removed from fruit. This results from the heat of the enzymes. When eaten, teeth break the vesicles and provide a fresh squirt of citrus juice to the beverage or yogurt which can create a pleasurable drinking or eating experience.

References

{{Authority control Citrus Plant anatomy