Starch enzymatic conversion

Prior to fermentation, the wort is then cooled to temperatures below 85°F (30°C), and the pH is adjusted to about 5. Yeast such as Saccharomyces cerevisiae, Saccharomyces carlsbergensis or Candida brassicae are added and fermentation proceeds for 2 to 3 days under batch processing conditions. Yeast produces the enzymes maltase, zymase, and invertase. Maltase converts maltose to glucose. Zymase converts glucose to ethanol. Invertase converts any sucrose present to fermentable sugar. The following equations illustrate the enzymatic conversion of starch to ethanol ... 

Hydrolysis. The chemical reaction of a substance with water to form one or more new substances. Examples of hydrolysis are the catalytic conversion of starch into glucose the catalytic or enzymatic conversion of sucrose into glucose and fructose the conversion of natural fats into fatty acids and glycerin... 

Trehalose is a relatively new bulk sweetener with potential for use in soft drinks. It is a di-glucose sugar and it occurs in nature in shellfish and mushrooms, where it confers a degree of protection to plant and animal cells in conditions causing dehydration. This led to its use as a cryoprotectant in freeze-drying systems in the pharmaceutical industry. In food markets, its potential use is as a bulk sweetener. It is manufactured using the Hayashibara patented process using starch as a raw material. The process involves enzymatic conversion and crystallisation to the trehalose dehydrate crystal (LFRA, 2001). 

Research into the enzymatic conversion of starch 134 into D-fructose 37 [387] was hampered by the inability of the authors to find a phosphatase that was specific for fructose 6-phosphate 38. The task could be completed by... 

As mentioned above, this process now serves mainly as an adjunct to enzymatic conversion of starch and is rarely used alone. A starch slurry containing 35-45 percent solids is acidified with hydrochloric acid to about pH 1.8-1.9. The suspension is pumped into an autoclave (converter) where live steam is gradually admitted to a pressure of 30-45 psi. The conversion time largely determines the DE of the hydrolyzate for example, eight min... 

High-Fructose Corn Syrup (HFCS) occurs as a water white to light yellow, somewhat viscous liquid that darkens at high temperatures. It is a saccharide mixture prepared as a clear, aqueous solution from high-dextrose-equivalent corn starch hydrolysate by the partial enzymatic conversion of glucose (dextrose) to fructose, using an insoluble glucose isomerase preparation that complies with 21 CFR 184.1372 and that has been obtained from a pure culture fermentation that produces no antibiotics. It is miscible in all proportions with water. 

Trehalose occurs as a nonhygroscopic, white, crystalline powder. It is obtained through enzymatic conversion of food-grade starch into a stable, nonreducing disaccharide with two glucose molecules linked in an a,a-1,1 configuration. The powder is freely soluble or readily dispersible in water. Trehalose is typically used in its dihydrate form. 

Recently there has been interest in the enzymatic conversion of glucose to an equal mixture with fructose since this has the same sweetness as sucrose. Glucose, readily available from starch by the action of amylolytic enzymes, has been submitted on a large scale to the action of glucose isomerase in an insolubilised form (ref.76) to achieve this transformation. 

A particularly interesting enzyme is CGTase, which has the unique capability of forming CDs from starch. Commonly CGTase is employed along with a-amylase. First starch is liquefied either by heat treatment or using a-amylase, then CGTase is added for the enzymatic conversion. 

Higher yield and lower costs of production can be achieved if the enzymatic conversion is performed in the presence of toluene at appropriate pH, temperature and reaction time. The main product is P-CD, since it forms an insoluble complex with toluene (Figure 16.5). The complex formation drives the conversion of starch towards the synthesis of the precipitated CD, thus enriching its content in the final mixture of products. The continuous removal of P-CD from the system shifts the equilibrium in favor of the product. 

Starch and sugar a-Amylases Glucoamylase Enzymatic conversion of starch to fructose liquefaction, saccharification and isomerization Liquefaction of starch... 

Size press starch may be non-ionic, from in-mill enzymatic conversion or thermo-chemical conversion of native starch. It may be anionie if an oxidised starch is used. (Note this refers to chemically modified oxidised starch. Many American texts wrongly refer to any viscosity-reduced starch - including enzyme-converted and thermo-chetnically converted stareh - as oxidised stareh. Such processes do not form any carboxyl or carbonyl groups on the starch.) Furthermore, cationic and amphoteric starches are frequently tpplied on multi-purpose office paper for improved ink-jet printability. 

An example is shown below for a gap former maehine that changed from oxidised (anionic) size press starch to enzymatic conversion of native tapioca starch. The graph shows the accumulated lost time due to size press breaks over a 120-day period - 60 days before the change and 60 days after. 

During the process of enzymatic conversion of starch, the organic solvent is usually added in the reaction system to form complexes with CDs. The complex can... 

Liquefied starch J. CGTase from cerans Enzymatic conversion at 60°C... 

In the enzymatic conversion process the depolymerization of starch, i.e., the cleavage of the 1,4- and 1,6-bridges is performed by hydrolases, specifically by glycosidase enzymes. Naturally occurring hydrolases capable of converting starch into specific products are... 

There is an essential difference in hydrolytic behavior between gelatinized, soluble, and raw starch not every enzyme or microorganism is capable of degrading raw starch. This is why the starch granules must be gelatinized prior to the enzymatic treatment. Accordingly, one must distinguish three process steps in the enzymatic conversion of starch carried out as a batch process or as a continuous process ... 

Tomasik P,Horton D.Enzymatic conversions of starch. Adr Catbohydr Chem Biochem 2012 68 59-436. http //dx.doi.Org/10.1016/B978-0-12-396523-3.00001-4. 

The cydodextrins are produced from starch by enzymatic conversions and are composed of 5-32 units, but the typical cydodextrins for chromatographic use consists of 6 units (a-cyclodextrin), 7 units (P-cydodextrin), or 8 units (y-cydodextrin). 

Figure 16 Scheme of the sequential enzymatic conversion of starch by glucoamylase (GA) and by glucose oxidase (GOD) in multilayers prepared by ESA. (Adapted from M. Onda, Y. Lvov, K. Ariga, andT. Kunitake. J. Ferment. Bioeng. 82 502,1996. With permission.)... 

---