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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 viscosity is relatively more sensitive to temperature change. [ABSTRACT FROM AUTHOR]

The effect of the temperature and concentration on rheological behavior of Cabernet Sauvignon juice concentrates was assessed using a rheometer over a wide range of temperature (1–66 °C) and concentrations (13.6–45.0 Brix) at shear rates of 0.84–212.1 1/s. The Ostwald-De Waele was the best rheological model fitted the data (R 2 = 0.99957 and relative error = 7.77%). The Cabernet Sauvignon juice concentrates presented a non-Newtonian pseudoplastic behavior (n < 1). The consistency levels were significantly reduced with the increase of temperature and increased with the increase of the concentrations. The flow activation energy ranged from 28.87 (45.0 Brix) to 38.05 KJ/mol (37.0 Brix) with a R 2 = 0.9798 for both cases. Density and specific heat were influenced by both temperature and concentration; however, thermal conductivity was only influenced by concentration. The Cabernet Sauvignon juice concentrates will be useful as wine chaptalization agent in future studies. [ABSTRACT FROM AUTHOR]

Highlights: [•] Master curve technique to model overall rheological properties of juice. [•] Double shifting steps to superposition temperature and concentration over shear rate. [•] Rheological modelling of soursop juice concentrates using available models. [•] Description of consistency coefficient with temperature via Arrhenius relationship. [•] Exponential relationship to describe consistency coefficient with concentration. [Copyright &y& Elsevier]