Citron
The citron ("Citrus medica") is a large fragrant citrus fruit with a thick rind. It is one of the original citrus fruits from which all other citrus types developed through natural hybrid speciation or artificial hybridization. Though citron cultivars take on a wide variety of physical forms, they are all closely related genetically. It is used widely in Asian cuisine, and also in traditional medicines, perfume, and for religious rituals and offerings. Hybrids of citrons with other citrus are commercially prominent, notably lemons and many limes.
Preserved lemon
Although lemons contain citric acid, most citric acid is produced by fermentation uses microbes that can convert sugars into citric acid, which is the most important organic acid produced in tonnage and is extensively used in food and pharmaceutical industries. It is produced mainly by submerged fermentation using "Aspergillus niger" or "Candida" spp. from different sources of carbohydrates, such as molasses and starch-based media. The food and beverage industries use this acid extensively as a food additive globally.