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.
