Fruit juices and their concentrates are popular drinks consumed by people of all ages for their sensory and nutritional qualities. In this paper, the physicochemical and rheological properties of african star apple, apple, apricot, banana, cherry, goldenberry, grape, guava, mango, medlar, orange, peach, pear, plum, pomegranate and pomelo juices, and their concentrates were reviewed. The selection of cultivars is a critical factor for the production of juices rich in healthy compounds and the quality of fruit juice strongly depends on processing technology. In summary, carbohydrates (fructose, glucose, sorbitol and sucrose), organic acids (ascorbic, citric, malic and shikimic acids), amino acids (asparagine, proline, glycine, serine, methionine and alanine) and phenolic compounds (catechin, chlorogenic acid and rutin) are among the significant constituents of fruit juices, and their concentrates. Also, the content of organic acids in fruit juices not only influence their taste and flavour but also their nutrition, stability, acceptability and keeping quality. Understanding of rheological properties of fruit juice is essential for quality control, process engineering application (designing and selection of proper equipment including heat exchangers, transport systems, evaporators and pumps), calculating energy usage and power requirement for mixing. The rheological behaviour of fruit juices and concentrates can be described by different rheological models depending on the nature of the juices. Several investigators used and suggested the Newtonian and Herschel-Bulkley models describe the rheological behaviour of various fruit juices. The apparent viscosity of fruit juice decreased considerably at higher temperatures. The effect of temperature on the apparent viscosity is generally expressed by the Arrhenius relationship and the activation energy (Ea) for fruit juices flow increased with the concentration of the juices. Higher activation energy means that the apparent
