Enzymatic liquefaction

Fig. 1. Enzymatic liquefaction processes (9). Alpha-S is the a-amylase from bacillus subtilis alpha-L/ST are a-amylases from B. licheniformis oi B.

Enzymatic liquefaction is a relatively new process for the production of juices from fruits and vegetables [1]. Essentially the process is as follows the material is crushed to obtun a pulp which is treated with a combination of pectinases and cellulases. After a certain incubation time, the material becomes a liquid and the Juice can be recovered by decantation. 

Initial optimization of the CGTase dose requirements suggests that the dose can be lowered to 3.58 Phadebas units per gram DS without compromising viscosity reduction and dextrose yields upon saccharification. This dosage enables the CGTase to be competitive with Termamyl in enzymatic liquefaction. 

Enzyme—Heat—Enzyme Process. The enzyme—heat—enzyme (EHE) process was the first industrial enzymatic liquefaction procedure developed and utilizes a B. subtilis, also referred to as B. amyloBquefaciens, a-amylase for hydrolysis. The enzyme can be used at temperatures up to about 90°C before a significant loss in activity occurs. After an initial hydrolysis step a high temperature heat treatment step is needed to solubilize residual starch present as a fatty acid/amylose complex. The heat treatment inactivates the a-amylase, thus a second addition of enzyme is required to complete the reaction. 

ENZYMATIC LIQUEFACTION OF THE RAW MATERIAL. Mixtures of pectinolytic and cellulolytic enzymes are used. Together they bring about a stepwise degradation, with initial loosening and separation of the cell aggregates, then breakdown of the cell walls and finally conversion of cellulose to sugar. After liquefaction of the mash, the remaining solids are usually separated off in a decanter. 

H36. Hollander, F., and Janowitz, H. D., A reply to Glass and Boyd concerning enzymatic liquefaction of gastric mucus. Gastroenterology 27, 672-675 (1951). 

Enzymatic liquefaction of the pulp makes pressings redundant. Besides pectinase, the liquefaction process also requires cellulase (endo-cellulase, cellobiohydolase, P-glu-cosidase). Industrial liquefaction processes became possible when Trichoderma spp. cellulase became available. The combination of pectinase and cellulase leads to a very low viscosity liquid. This liquid is treated further by centrifugation and (ultra)filtra-tion to obtain the final clear fmit juice. 

Table XI. Aroma compounds of apple juices obtained from pulp by pressing and by enzymatic liquefaction.

Nearly 95,000 tons of glucose and dextrose are produced by enzymatic liquefaction of starch, mainly tapioca (cassava). Since lactic acid-based biodegradable polymers like polyglycolide and polylactide are not produced in India, consumption of lactic acid is confined to food processing and the pro-... 

The main causes of viscosity loss of cellulose ethers are of microbial (b u teria, fungi and enzyme) and chemical (redox process) natures. Biocides are used to kill bacteria and fVingi but they are usually not effective against enzymes. The enzymatic liquefaction is known to be the strongest process. Studies have been made on different cellulosic thickeners with bacteria, fungi and commercial cellulase enzyme juid the overall conclusion was that cellulase is the most significant cause of viscosity loss. ... 

Springle, W. R. (1989). Enzymatic liquefaction of emulsion paints and cellulosic thickeners. Chemspec Europe 89 BAGS Symposium, pp. 33-7. 

Dairy products and beverages are processed under mildly acidic conditions favoring the use of enzymes of fungal origin. However, in the processing of beer, the enzymes from selected Bacillus strains play an essential role. The a-amylase from Bacillus amyloliquefaciens is used to improve the enzymatic liquefaction potential of the malt. A P-glucanase from the same bacterium (Hofemeister et al. 1986) is used to reduce the viscosity of the wort, which improves the filtration of the beer. 

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