Clarification juice

Figure 6.24 Ultrafiltration flux in apple juice clarification as a function of the volumetric feed-to-residue concentration factor. Tubular polysulfone membranes at 55 °C [27]. Reprinted from R.G. Blanck and W. Eykamp, Fruit Juice Ultrafiltration, in Recent Advances in Separation Techniques-III, N.N. Li (ed.), AIChE Symposium Series Number 250, 82 (1986). Reproduced by permission of the American Institute of Chemical Engineers. Copyright 1986 AIChE. All rights reserved...

Juice clarification is an important technique in North Coast quality wine production. Removal of suspended solids from the juice prior to fermentation results in a wine described as fruity, clean tasting, fresh, delicate (19, 20). Level of solids in clarified juice ranges from 0.5 to 2.5 percent. Juice clarification also reduces the level of elemental sulfur, reducing potential for later H2S production. 

Vacuum filtration is used less often for juice clarification. It is very efficient for juice solids removal on a high throughput basis but introduces a... 

Juice solids have a critical effect not only on wine quality (discussed under juice clarification) but also on yeast activity. A juice that is too clean, from excessive pectic enzyme treatment, filtration, or centrifuging, may have difficulty completing fermentation. Groat and Ough (24) and others have reported that juice solids levels below 0.1 to 0.5 percent resulted in slower fermentations. Levels of 0.5-2.5 percent solids are used commonly in the North Coast. 

Doherty, W.O.S., Greenwood, J., Pilaski, D., and Wright, P.G., The Effect of Liming Conditions in Juice Clarification, Proc. Australian Soc. Sugar Cane Technologists, 24, 443-451 (2002). 

Fungal pectin esterases have lower pH optima (ca 4.5) than plant pectin esterases (7,8) and are less heat stable (3 5,26 ). A commercially available fungal PE preparation has been introduced for industrial application in cider and lemon juice clarification (52,60). A process for the manufacture of low-ester pectins with a lower sensitivity for calcium has been patented by Ishii et al. 

Such applications appear to be more attractive for the use of bioreactors than traditional uses of endopeptidases for chillproofing beer, juice clarification, and curd formation in cheesemaking which currently use well established soluble enzyme processes. In the case of curd formation, hydrolysis of micellar k-casein by immobilized chymosin is questionable (56). 

Dumont, A., Dulau, L. (1997) The role of yeasts in the formation of wine flavours. In M. AUen, P. Leske, G. Baldwin (Eds.), Advances in juice clarification and yeast inoculation proceedings of a seminar 15 August 1996 Melbourne, Victoria (pp. 14—16). Adelaide S.A Australian Society of Viticulture and Oenology. 

Leong, L.S., Hocking, A.D., Scott, E.S. (2006b). The effect of juice clarification, static or rotary fermentation and fining on ochratoxin A in wine. Aust. J. Grape Wine Res., 12, 245-252. 

The enzymes used for juice clarification are almost exclusively pec-tolytic. The reasons for the clarification effect are as follows. Pectin stabilizes the suspended solids in the juice. Through addition of the enzyme, the pectin is converted to a dissolved form and broken down. This is associated with a significant decrease in viscosity. In addition, pectins that have been made soluble act as protective colloids for many of the suspended particles. As soon as the protective effect of pectin is lost, these suspended particles coagulate and are precipitated. A significant decrease in viscosity is accompanied by a significant increase in filtration performance. 

ENZYMATIC HYDROLYSIS OF STARCH. Starch is a substance used for storing energy reserve in plants, where it is deposited in the form of starch granules. Starch may be noticed in fruit juice as a milky haze. This haze disappears when the juice is heated, but re-appears after it is cooled to less than 10°C. Like pectin, starch has a protective colloid effect on suspended particles and thus makes juice clarification more difficult. 

Okada et at 189) reported an unknown enzyme from Aspergillus niger which was not a polygalacturonase nor a pectinesterase but which was a potent clarifier of citrus juices. This factor had no effect by itself, but it strongly accelerated juice clarification when added with polygalacturonase. In subsequent papers 190, 191) the enzyme was reported purified and found to be a hemicellulase. 

Amino acid production by fermentation started around 1960 in Japan. Initially glutamic acid was the main product. It was sold as sodium salt, monosodium glutamate (MSG), a flavor enhancer on oriental cuisine. Other amino acids soon followed. They are used in food and feed to increase the efficiency of low protein substrates. Microbiologically produced enzymes were introduced around 1970. They are used in grain processing, sugar production, fruit juice clarification, and as detergent additives (Table 9.1). 

Clarification of other fruit juices. Clarification of cranberry juice has also been practiced commercially using ceramic membranes recently. Through a series of tests with alumina microfilters, Venkataraman et al. [1988] determined that the optimal pore diameter is about 0.45 pm with respect to the permeate flux and the clarity of the... 

Venkataraman, K., M.T. Giles and P.K. Silverberg, 1988, Ceramic membrane applications in juice clarification a case study, presented at 2nd Annual Meeting of North Am. Membr. Soc., Syracuse, N.Y., USA (details given in Inorganic Membr. Synth., Charact. Appl., RR. Bhave, Ed., p. 239). 

Riedl K., Girard B., and Lencki W., Influence of membrane stmeture on fouUng layer morphology during apple juice clarification. Journal of Membrane Science 139 1998 155-166. 

Some of the laboratory separations which may be effected and some suggestive of possible commercial separations are bacteria from water, emulsions and serums, pigment from paint, fractional separation of clay particles, clarification of fruit juices, clarification of varnishes and glues, and the separation of emulsified oils from an unemulsified portion. 

Fruit juice clarification by hydrolysis of pectins, hemicellulose and starch Pectinase a.o. 

Classic juice clarification gets better new method raises yield 2-5% in 2 hours or less, Food Engineering, 137,(March 1984)... 

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