Enzymes tannase

Instant tea produced as described above will dissolve completely in hot water but not in cold water, as the caffeine-polyphenol complexes are insoluble under those conditions. Since virtually all instant tea manufacture in the U.S. is for iced tea preparation, process modification is required. This initial extract may be cooled to 5 to 10°C and the cold water insoluble material or cream be allowed to precipitate. Under these conditions, 20 to 35% of the extract solids may be separated by centrifugation. The supernatant solids will reconstitute in cold water after concentration and drying.105 It is also possible to process the cream to make a portion of it compatible with the product and thereby retain the caffeine and some polyphenolic components that are present in this fraction.106 Commercial use of the enzyme Tannase, which removes gallic acid from gallated tea polyphenols107 and reduces cream formation108 can be used to reduce cream losses and manufacture instant teas retaining more of the natural polyphenol content. 

In 1913, Knudson (17) reported that tannic acid (the commercial name of the Chinese gall tannin) could be degraded by a strain of Aspergillus niger previously the French scientist Pottevin (in 1900) had named this enzyme tannase (10). Since then, most of the progress on elucidating the mechanisms of hydrolysable tannin biodegradation has occurred since 1960. 

The enzyme tannase, produced by Aspergillus niger, specifically cleaves the galloyl linkage to yield gallic acid and a polyol, but it does not cleave hexahydroxydiphenyl-con-taining esters. This reaction can be used to estimate the number of galloyl units per polyol. The same enzyme cleaves condensed tannins to yield flavonoids (Porter, 1989). 

Degradation of Gallotannins. Different investigations on tannase revealed that this enzyme was not equally efficient on all hydrolyzable tannins. This was particularly true for yeast, whose tannase was effective only on tannic... 

Enzymes found in grapes include peroxidase, polyphenoloxidases, catalases, invertase, tannases, and pectic enzymes (2). Within this list, polyphenoloxidase has received considerable attention in grapes because of its detrimental effect on wine quality. 

Work on tannase and other enzymes, further supports the premise that many previously unknown commercially feasible applications for enzymes exist if the eflFort is made to identify the need and seek a solution. While, at this time, there is insufficient data to determine whether the proportion of projects which were or will become commercially profitable, justifies the research investment, it seems likely with the continued inflation rate in Japan that this type of research, if not already uneconomical, will in the future be no more economically done in Japan than in the United States. 

Hydrolysable Tannins These may be hydrolysed by acids or enzymes such as tannase. They are formed from several molecules of phenolic acids such as gallic and ellagic acids which are united by ester linkages to a central glucose residue. 

This method of enzyme production has had a very long history in Japan and evolved to a very high technical level there. Not surprisingly Japan leads the world not only in terms of the sheer bulk of the enzymes produced by this method, but also in terms of production techniques and production yields. Enzymes produced by solid state fermentation and currently available commercially include Glucoamylase, Alpha amylase, Pectinase, Protease, Xylanase, Lactase, Naringinase, Microbial rennet. Phosphatase, Phytase, Cellulase, Tannase, etc. 

The observations by Suseela and Nandy [28] led to the conclusion that two separate enzymes are involved in tannic acid decomposition. Further studies on P. chrysogenum tannase by Suseela and Nandy[26] showed the enzyme to have a molecular weight of 300,000 on Sephadex (t-200, which is highw as compared to the tannases from other microbial sources. Upon denaturation, the molecular weight of the en me was found to be 158,000, suggesting that the enzyme consists of two subunits of same molecular weight. 

Among those reported are oxidase, tannase, invertase, pectinase, ascorbase, catalase, peroxidase, dehydrase, polyphenoloxidase, esterase, and a proteolytic enzyme. 

---