Grape juice viscosity

Apple, pear, orange and grape juices are all clarified by ultrafiltration. Ultrafiltration of apple juice is a particularly successful application. Approximately 200 plants have been installed, and almost all US apple juice is clarified by this method. In the traditional process, crude filtration was performed directly after crushing the fruit. Pectinase was added to hydrolyze pectin, which reduced the viscosity of the juice before it was passed through a series of decantation and... 

The Arrhenius equation did not describe very well the influence of temperature on viscosity data of concentrated apple and grape juices in the range 60-68 °Brix (Rao et al., 1984, 1986). From non-linear regression analysis, it was determined that the empirical Fulcher equation (see Ferry, 1980 p. 289, Soesanto and Williams, 1981) described the viscosity versus temperature data on those juice samples better than the Arrhenius model (Rao et al., 1986) ... 

BecaiKe depectinized and filtered apple and grape Juices are Newtonian fluids, equations were derived by Bayindirli (1992,1993) that can be used to estimate their viscosities as a function of concentration and temperature. The equation for viscosity of both apple and grape Juices is of the form ... 

Rao et al. (1984) studied the role of concentration and temperature on the viscosity of concentrated depectinized and filtered apple and grape juices. At a constant temperature, the effect of concentration could be well described by an exponential relationship. For example, at 20°C, the effect of concentration ( 41-68 °Brix) on the viscosity of apple concentrates was described by the equation (7 = 0.947) ... 

Thus a more accurate estimate of the viscosities of concentrated apple and grape juices can be obtained by incorporating the value of calculated using either Equation 5.7 or 5.8 at a specific concentration in Equation 5.6. Although two separate equations were derived for the apple and grape juice concentrates, one could easily justify a single equation that would be reasonably applicable to both concentrates. 

Bayindirli, L. 1993. Density and viscosity of grape juice as a function of concentration and temperature. J. Food Proc. Preser. 17 147-151. 

Enhancement of transmembrane flux has been shown in OMD of grape juice pretreated by UF [131]. The increase in flux has been attributed to a reduction in the viscosity of the concentrated juice-membrane boundary layer as the result of removal of high-molecular weight biopolymers present in juice. UF is a powerful method for removing natural polymers (polysaccharides, proteins) from fruit and vegetable juices. Lukanin et al. [12] have improved the concept of (UF + OMD), by enzymatic pretreatment of the apple juice prior to the UF step. Introduction of an additional enzymatic deproteinization step with the pectinase/amylase treatment of apple juice followed by UF has yielded minimal biopolymer content. Such a treatment is found to enhance transmembrane flux during concentration of clarified juice by MD. As in the case of grape juice this has been... 

The reduction in viscosity of the juice extracted from such mashes facilitates the concentration and significantly increases the juice yield from apple mash by over 10% [12]. Especially important is the enzyme support for juice extraction from fmit containing large amounts of pectins, e.g. black currants, certain grapes and other fmit. 

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