3.2. Determination of extract content of malt

Materials and reagents: water bath, refractometer or densitometer, thermometer, technical scales, chemical bottles volume 200 and 1000 ml, glass stick, cylinder volume 200 ml, a funnel for filtering, filtering paper.

Work procedure

Take 50,00 g weight charge of malt to preliminary weighed glass and add 200 ml of the distilled water of 47 °С. Glass contents mixing for receiving the homogeneous suspension and set it on a water bath with temperature 45 °С. At such temperature and periodic mixing maintain 30 minutes then temperature gradually raise up to 70 °С.

When the temperature reach 70 °С add the 100 ml of the distilled water heated to 70°С. At this temperature suspension sugarise throughout 1 h then cool to a room temperature.

Wash off the thermometer and a glass stick with small portions of the distilled water. On the technical scales glass contents pour the distilled water till 450 ml. Mix carefully mix and filter through the folded filter to the dry glass.

The first portions of a filtrate return on the filter, till the transparent solution appearance. Define contents of solids in a filtrate with the help of refractometer (shown on fig 3.1) in %.

Experimental data processing

Extract content malt Е₁, and also its recalculation on a solid of malt Е₂ count by such formulas:

E₁ = e (800 + W) / (100 - e); E₂ = E₁ × 100 / (100-W)

Where W - humidity of the mash, %,

e - Extract content.

Example:

Analyzed malt of humidity 5,2 %. The maintenance of solids in a mash 8,2 %. Then extract content malt

Е₁=8,2 (800+5,2) / (100-8,2 =71,92 %, and in recalculation on a malt solid extract content:

Е₂=71,92 (100 / (100-5,2) = 75,86 %.

3.3. Determination of malt sugarising duration

Materials and reagents: water bath, thermometer, technical scales, chemical glass 1000 ml, glass stick, iodine solution.

After the suspension will reach 70 ° C temperature, every 5 minutes take a drop of suspension by glass stick and place it with a solution of iodine on a white plate. Tilt the plate, mix two drops and watch the changing color.

It is believed that sugarising completed if the color of iodine does not change.

Analysis of obtained results

According to the tasks, student must give a comparative characteristic of methods for determining the amylolytic activity of the raw material and finished products.

Test questions

1. What are the enzymes? How to classify enzymes by catalyzed reaction type?

2. How significant are variety classes of enzymes for technological processes of manufactures?

3. What amylolytic enzyme activity the fresh malt characterizes?

4. What products of hydrolysis of starch are not painted by iodine?

5. What is understood under sugarising duration of malt? How to define it?

6. What is the determination method of extract content malt consist of?

Fig. 4.1. Alcoholmeter

Laboratory work 4