PHYSICAL AND CHEMICAL METHODS OF EVALUATION FOODS

Determination of the effect of amylase(s) upon starch dispersions. to Top

INTRODUCTION: The action of the enzyme amylase has been established since the beginning of enzymology; whereas the result of the action of the enzyme has been known since the beginning of wine production. In the current experiment, the amylases (Rhozyme H-39 amylase mixture/Mix123/Rohm & Hasas; Takadiastase/Parke, Davis &), which are well documented as being widespread throughout nature, were investigated in regard to their liquefying effect upon the three starches: sweetpotato, corn, and waxy corn (W-13 Stabilzer Waxy Corn Starch) starch.

EXPERIMENTAL PROCEDURE: Starch dispersions were made using a prepared buffer (3 mL acetic acid, 4.1 g anhydrous sodium acetate, 1 liter water, NaCl) solution at pH 4.6-4,8 and appropriate starch (Collins, 1971). A 4% solution of sweetpotato starch was made using 5 g of starch per 125 milliliters of buffer solution (It is hypothesized that 3.5 to 3.75% would have been closer to "optimum testing viscosity".). After dispersion of starch in 25 milliliters of cold buffer the remaining 100 milliliters of boiling solvent was added and beaker and contents were held in boiling water for 2 minutes and probable partial gelatinization occurred. The mixture was cooled and adjusted to correct volume.

Ten milliliters of starch solution in the Oswaltd Viscosimeter was placed in a water bath at 30C and temperature was allowed to equilibrate. Using a stop watch, which several trials indicated to be a necessity, initial viscosity was determined. Takadiastase (1/2% solution) in 4 drops was added, mixed immediately and readings were taken at convenient intervals as frequently as possible. Readings were recorded until amylase activity appeared no longher to hydrolyze the starch. At this point, calculations were undertaken to express viscosity as percent loss in viscosity of the 4% starch solution. Replacing Takadiastase with Rhozyme H-39 (1/2% solution), the identical procedure was undertaken for this enzyme.

RESULTS AND DISCUSSION: Amylases serve to bring about the hydrolysis of the glucose polymer, starch. This reaction is facilitated by the gelatinization of the starch. In the current experiment, starch gelatinization was partially accomplished by the use of the boiling solvent and short heating time of the dispersion.

Due to the lack of concrete information the enzyme preparation's amylase composition it is felt that it is of interest and import to emphasize some of the characteristics of alpha- and beta-amylase. In any discussion of the two enzymes it is necessary to be recognizant of the fact that source, species and purification procedures all will serve to influence the reactions that the amylases undergo and that transferance of information from one source to another must be done with care.

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