Juice viscosity

Viscosity. In freshly extracted juice, viscosity imparted by pectin is a desirable characteristic, commonly referred to as body. If this viscosity is not present, or is lost through destruction of the pectin colloid, juice is described as thin,... 

Also Umetani (U4) noted variations in the polarogram of human gastric juice, especially in gastric cancer. There was no correlation, however, between gastric juice viscosity, actual gastric juice pH, and polarogram. 

Figure 6 represents the relationship between tomato juice viscosity and flow velocity. The measurement was done with the juice prepared from canned paste, using a disc rotating viscosimeter. The value, viscosity multiplied by velocity was nearly Independent of the velocity. This suggests that the effect of flow velocity on the pressure drop would be small. This allows the variation of juice feed velocity in a wide range without significant change in pressure drop. 

Fruit juices Pectinases To improve fruit-juice extraction and reduce juice viscosity... 

Developments continue on citrus fruit processing. The membrane configurations most often used in juice clarification are tubular membranes or hollow fibre modules, as well as plate and frame systems using flat sheet membranes. The traditional method of concentrating juices and purees has been evaporation, but nowadays reverse osmosis is proving successful. Reverse osmosis plant performance depends on juice viscosity, the osmotic pressure of the solution, and the constraints imposed by the need for a particular product quality. 

The observed increase in serum and efflux viscosity of juice from transgenic tomato fruits was most likely due to changes in pectin chemistry as a result of reduced levels of PME activity. Since viscosity is affected by the volume occupied by the molecule or the extent of molecular association in solution, both molecular weight and DOM will enhance the viscosity of the juice [26]. Since juice from... 

Takada and Nelson [25] reported a correlation between PPT value and Bostwick and efflux viscosity of tomato products. Thakur et al. [22] also showed a correlation between Bostwick and efflux viscosity and PPT value. They also reported a linear relationship between PPT value and serum viscosity (r =0.979), described by the equation, Y = 33 X-255 (X, PPT value Y, serum viscosity). As juice from transgenic fruits contained higher PPT value, its higher viscosity values are in line with the reported literature. 

Added to the mash, these enzyme activities decrease its viscosity and improve its pressability. The free run juice volume is larger. The yield and then the capacity of the press are increased. 

If we compare liquefaction to maceration, more activities are needed to liquefy the cell wall. Since 1991, new pectinases activities such as rhamnogalacturonase, pectin acetylesterase and xyloglucanases complex have been found to be important in the apple liquefaction by Henck Schols, Jean-Paul Vincken and Voragen [3]. The cellulose-xyloglucan complex accounts approximatively 57% of the apple cell-wall matrix. In a liquefaction process, an efficient enzymic degradation of this complex is crucial to increase the sugars extraction, to decrease the viscosity of the pulp then to be able to ultra-filtrate the juice without second depectinisation, at last to have negative alcohol tests required by some concentrate customers. 

Apples were chopped and mashed to a fine puree. Apple mash was treated with enzyme preparation and incubated for 2 hours at 55°C. Viscosity of mash was measured several times using a Brookfield DC3 viscometer with Helipath stand attachment and TD spindle. After two hours of incubation sanple was coitriftig for 20 minutes at 10.000 rpm. Volume, clarity, pH and brix of the juices were measured. The pectin level of the juices was assessed by a standard alcohol test. 

Apple application e)q)aiments for producing ple juice show a clear benificial effect liumnogalacturonase in combination with a pectinase was added to the process. As can be seen from figure 5 rhamnogalacturonase has a clear positive influence on viscosity-reduction. Rhamnogalacturonase also prevents formation of haze in juices and therefore gives a stable juice. 

Pulp from ripe Golden apple was pressed in a mortar and filtered, thus obtaining a cloudy and dense juice. Potassium metabisulphite was added as antioxidant at a final concentration of 0.15 mg/mL. The pH of the prepared apple juices was 4.1 4.3. Depectinisation experiments were carried out loading the juice in the packed bed reactor and recycling for 30 min at 25 "C. The reaction mixture was then collected and the percentage reduction of viscosity measured as above described. The y-alumina spheres were abundantly washed with distilled water before performing the successive batch reaction. 

The immobilised Pectolyase Y-23 was used to perform consecutive depectinisations of a cloudy apple juice in batch reactions. After five reaction cycles, the percentage reduction of viscosity was greater than 90%. The viscosity of the apple juice feed through a bed of inactive y-alumina spheres remains unchanged thus confirming that the viscosity loss attributable to pectin adsorption on the carrier is negligible. The alcohol tests, performed on the juices previously treated with the... 

A summary of how physiological factors affect the dissolution rate is given in Table 21.2. The effective surface area will be affected by the wetting properties of the bile acids and other surface-active agents in the gastrointestinal tract. The dif-fusivity of a drug molecule in the intestinal juice will be altered by changes in viscosity that are induced, for instance, by meal components. An increased dissolution rate could be obtained at more intense intestinal motility patterns or increased... 

Acidulants. The other component of any system of chemical leavening based on sodium hydrogen carbonate is an acid. The original acidulants were sour milk (lactic acid), vinegar (acetic acid), lemon juice (citric acid) and cream of tartar (potassium acid tartrate). All of these will react immediately on mixing so that the carbon dioxide is released straight away. The product had to be baked before the carbon dioxide escaped from the batter or product. The only delay possible was that allowed by the batter viscosity. 

An)nvay, the principal use of artificial tongues is within the food sciences. The applications concern almost exclusively liquid food mainly wine (about 18% of the studies examined), fruit juices (almost 15%), mineral water (about 13%), followed by infusions like tea and coffee, soft drinks, milk, beer, and other alcoholic beverages. All these liquid foods are characterized by both low-viscosity and high-polarity values. 

Figure 6 shows the dependency ijl T) for eight different liquids with greatly different temperature coefficients of the viscosity, whose viscosities cover six decades within the range of T= 20-80°C. Figure 7 depicts the standard representation of this behavior. Surprisingly this proves that all these liquids behave similarly in the /r(I) respect. In addition, it proves that this standard representation is invariant to reference temperature. Water is a special juice it behaves like the other liquids only in the vicinity of the standardization range yo(2 —To) 0. 

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