Malt Preparation

Amylases are either produced by bacteria or yeasts (Table 2.20) or they belong to the components of malt preparations. The high temperature-resistant bacterial amylases, particularly those of Bac. licheniformis (Fig. 2.49) are of interest for the hydrolysis of corn starch (gelatinization at 105-110 °C). The hydrolysis rate of these enzymes can be enhanced further... 

Mix 3 g. of starch well with loml. of water in a test-tube and pour the mixture into 90 ml. of boiling water contained in a 300 ml. conical flask, stirring at the same time. Cool to about 70 and then place in a water-bath maintained at 65-70 , but not higher. Now add 2-3 ml. of the malt extract prepared as above, mix well and allow the hydrolysis to proceed. Take a series of test -tubes and in each put 10 ml. of water and 2 drops of a 1 % iodine solution. At intervals of about 4 minutes (depending upon the activity of the enzyme solution), remove 1 ml. of the reaction mixture, cool and add it to one of the test-tubes and note the colour obtained. At the beginning of the experiment the colour will be blue due to the starch alone. As the reaction proceeds, the colour gradually becomes violet, reddish, yellowish and finally colourless. 

Approximately 95% of the malt produced is used to make beet while small amounts are used as distillers and food malts. Distillers malt, which is used to convert starch-containing grains into fermentable sugars, is prepared almost exclusively for its enzymes, especially a-amylase (see Beverage SPIRITS, distilled). Food malts are sold for their davor and/or enzyme contribution to food products. 

Such symps are used in the preparation of confections, preserves, and other foodstuffs. The maltose in malt symps is important in brewing (see Beer). Intravenous feeding (primarily in Europe and Japan) and sports beverage formulations take advantage of the fact that energy release from maltose becomes accessible to the body at a slower rate than energy suppHed by monosaccharides (31). 

Malted barley contains a- and P-amylases along with proteases and phytases. Most standardi2ed microbial en2yme preparations for industrial starch conversion contain approximately 100 times more amylase activity than malt. In beermaking, malt is not just valuable for its en2ymes but also for flavor compounds. 

A small fermentation tank (5,000 parts by volume capacity) was charged with 3,000 parts by volume of a culture medium (pH 6.0) comprising 3% glucose, 1 % polypepton, 0.5% yeast extract and 0.5% malt extract. The medium was sterilized by heating in a conventional manner and cooled. This medium was inoculated with 150 parts by volume of a pre[Pg.1565]

The term fermentation was obtained from the Latin verb fervere which describes the action of yeast or malt on sugar or fruit extracts and grain. The boiling is due to the production of carbon dioxide bubbles from the aqueous phase under the anaerobic catabolism of carbohydrates in the fermentation media. The art of fermentation is defined as the chemical transformation of organic compounds with the aid of enzymes. The ability of yeast to make alcohol was known to the Babylonians and Sumerians before 6000 bc. The Egyptians discovered the generation of carbon dioxide by brewer s yeast in the preparation... 

On the other hand, in crude aqueous extracts of malted barley the alpha amylase is much more sensitive to high hydrogen ion activities than the beta amylase. This difference between the two amylases also was utilized by Ohlsson28 to inactivate the alpha amylase and to prepare beta amylase relatively free from alpha amylase. 

Very highly purified preparations of alpha amylase of malted barley give a value of approximately 4 to 1 for the ratio of their dextrinogenic to their saccharogenic activities when the measurements are made at 40° with Lintner s soluble potato starch.81 Under the same conditions approximately the same value is obtained with products precipitated by alcohol from malted barley extracts which had been treated to inactivate beta amylase.23 81 However, a constant value for these ratios is not proof that beta amylase is entirely absent. There is at present no satisfactory way of making certain that malted barley alpha amylase is not contaminated with traces of beta amylase. The crystallization of alpha amylase from malted barley has been reported since this manuscript was written.79... 

Arrow root starch, approximately 2% pH 5.3 amylase prepared from malted barley extract according to Ohlsson23 and purified by precipitation with alcohol. 

An interesting comparison is also given in Table XI86 of the action of malted barley alpha amylase upon corn starch, beta dextrins obtained from corn starch by the action of beta amylase, and upon corn amylose prepared according to the method of Meyer.6 90 These data show that, with equivalent amounts of enzyme, amylose was hydrolyzed much more rapidly and more extensively than unfractionated corn starch. Although the beta dextrins were hydrolyzed by this amylase, they were hydrolyzed much more slowly and less extensively than either of the other two substrates. These results are similar to those already considered for pancreatic amylase.41 64... 

BMOV, was reported in 1972 159) and in 1987 160). Its electrochemical preparation was described in 1978 92a), and EPR monitoring of its redox behavior, in chloroform, in 1987 160). However this now-important compound seems not to have been properly characterized until 1992 161). Since then complexes of several 3-hydroxy-4-pyridinones 162—164), and of l-hydroxy-2-pyridinone 165), have been synthesized and characterized, especially by EPR 164). VO(malt)2 exists as a cis trans equilibrium mixture in aqueous solution, and generally crystallizes as a mixture of the two isomers. However the crystal structure of the trans structure was eventually solved, confirming the expected square-pyramidal stereochemistry 166). The relative stabilities of the cis and trans forms of V 0L2 complexes depend on the nature of the bidentate ligand L , with the cis configuration favored by VO(malt)2 and VO(koj)2 167), but the trans by 3-hydroxy-4-pyridinonate ligands 164). 

L — maltolate the coordination environment of the vanadium in K[V02(malt)2] H2O is approximately octahedral, the two 0x0 ligands being in cis positions. [K(H20)e] units link adjacent vanadium(V) complex anions to give a chain structure 166). The main products of aerobic oxidation of [V O(dmpp)2l in aqueous solution are [V02(dmpp)] and [VOo(dmpp)2]. High pH favors these V products, whereas at low pH V species predominate 171). Vanadium(V) also forms a VO(OR)(malt)2 series, readily prepared from ammonium vanadate, maltol, and the appropriate alcohol in a water-alcohol-dichloromethane medium 172), and 3-hydroxy-4-pyridinonate analogues V0(0R)L2 on oxidation of their oxovanadium(IV) precursors in solution in the appropriate alcohol ROH 168). 

Fish and seafood are generally responsible for infections caused by C. botulinum type E (Centers for Disease Control and Prevention, 1998). Many verified cases of botulism type E have been reported in Japan (166 cases and 58 deaths between 1951 and 1960). In 2003, C. botulinum type E was involved in the outbreak in western Alaska linked to consumption of a beached whale (Anonymous, 2003). Many outbreaks were also associated with a Japanese izuschi dish containing fermented raw fish, vegetables, and cooked and malted rice (okji). In Canada, Alaska, or Scandinavia, botulism is caused by consumption of fish and fermented meat dishes, very often prepared as traditional native dishes (Kotev et ah, 1987 Knubley et ah, 1995). 

Maltose, prepared from starch by treatment with barley malt extract and repeatedly recrystallized from 90 % alcohol, showed the same... 

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