Effect of electrochemically activated systems on malt enzymes

Effect of electrochemically activated systems on malt enzymes

S. N. Khrapenkov, M. V. Gernet

Moscow State University of Food Industry

V. M. Bakhir

ОАО NPO EKRAN

Over 20 years have passed since the time when the electrochemical activation effect (ECA) was discovered. Water and weak saline solutions subjected to treatment in the anodic or cathodic chambers of a diaphragm-type electrolyzer convert into a meta-stable state, which is different from a stable one in that they have anomalous values of physical and chemical parameters, for instance, those of рН and oxidative-reductive potential (ORP) [1].

There are several factors responsible for their properties: electrochemically synthesized alkali in catholyte and acids in anolyte — their concentration is proportional to mineralization of water and quantity of electricity consumed in the given process; superactive meta-stable compounds with high oxidative (anolyte) and reductive (catholyte) ability, though in the process of application they quickly disappear and play the role of catalysts; electrochemically active micro-bubbles of electrolysis gases - in ECA solutions the bubbles do not float to the surface since their distribution is governed by Coulomb interactions; meta-stable water structure emerging in the process of magnetic field action.

These properties remain intact for a long time. Of all the factors, only the first one was not called in question. Recently, numerous theoretical and experimental data have been obtained on the second factor [1].

ECA-solutions are used in medicine, microbiology, agriculture and other fields [2]. There were rather successful attempts of applying ECA-components in food industry, in particular, in fermentation processes.

In connection with the above-indicated facts, it would be very interesting to combine the action of enzymes engaged in the process of wort preparation and the action of ECA-solutions.

The aim of the experiment is to determine the influence of electrochemically activated water on the activity of malt enzymes and preparations of microbial origin with a various scope of action.

The experiment was carried out using solutions of enzymatic preparation AP Subtilin A of 1 mg/cm3 concentration manufactured by Biosintez plant (Vilnyus, Lithuania). The amylolytic enzyme activity was determined by a drip method according to Klimovsky and Rodzevich, and for a substrate, 1% starch solution was taken. For enzyme control solution, AP Subtilin P preparation solution was used prepared on the basis of distilled water of the same concentration.

Experimental samples were prepared with water produced by a STEL-2 device (catholyte and anolyte). Characteristics of the resulting water are given in Table 1.

The enzymatic preparation solutions were incubated at T 30 oС for an hour. The amylolytic enzyme activity was determined immediately following the solution preparation after 15, 30 and 60-minute exposure.

Fig. 1 shows that the activity of enzyme solution prepared on the basis of anolyte is higher than that of the control sample as early as at the zero point, which is likely to be due to more vigorous diffusion in ECA solutions [2], and that is observed throughout the experiment. The activity of the catholyte-based sample is considerably lower than that of the control sample due to the catholyte’s high pH value.

The maximal values of amylolytic enzyme activity are achieved by the 15-th minute, and further exposure produces no desired effect (Fig. 2). The control sample’s activity is taken as 100 %.

Table 1

Component

рН of solution раствора

Redox potential, mV

Source tap water

7,2-7,6

360-390

Catholyte

9.20-10.0

- (720-950)

Anolyte

6.20-6.70

500-750

Table 2

Component

Quantity of formed amine nitrogen, mg/ml

Proteolytic activity, un./g

Exposure effectiveness, %

Control

0.273

544

100

Anolyte

0.343

685

125

Catholyte

0.161

321

59

Table 3

Component

рН

ЕЕ, mV

Saccharification time, min

Extract content, %

Activation effect, %

Control

7.36

298

15

70.2

100

Catholyte

6.38

-774

15,5

71.4

101.7

Anolyte

9.88

625

13

72.6

103.4

Table 4

Sample

Extract content, %

Saccharification time, min

Control

66.0

100.0

26

Mashing with the catholyte-based enzyme solution

66.4

100.6

>30

Mashing with the anolyte-based enzyme solution

67.6

102.4

24

Mashing with the anolyte-based enzyme solution; enzyme quantity being reduced by 12 %

66.0

100.0

27

In the following experiment, Protosubtilin G 10х enzymatic preparation was used; the proteolytic activity was determined using the Willstätter and Waldschmidt-Leutz method modified. For the substrate, 5% gelatin solution was taken.

Since the former experiment indicated that activation occurred as early as by the 15-th minute, subsequent experiments were carried out with 15-minute exposure. For a unit, we took enzyme quantity forming 1 mg of amine nitrogen within an hour (Table 2).

Table 2 shows that the anolyte activates proteases by 25 % as compared to the control, and the catholyte, on the contrary, inhibits them almost twice.

In a subsequent experiment, test mashing was performed with the use of light barley malt, whose parameters conformed to the GOST. To estimate the extract content, a standard method was used. The control sample was the tap water precipitated for 24 hours to remove chlorine. The results of the experiment are given in Table 3.

Table 3 data show that the extract content increases by 1-2 % in test samples in comparison with the control ones. In a mash with anolyte, saccharification takes 13 minutes, which is by 2 minutes less than in control. The extract content increases both in catholyte, and in anolyte samples.

As seen from the previous experiments, both malt enzymes and preparations of bacterial origin become more active if exposed to ECA components. Their combined action is used when over 15% of unmalted materials are used. Unmalted materials can include rice, maize, barley, etc. We deliberately took barley as unmalted material, though this raw material is more complicated than rice or maize. In the course of its processing, there can be problems, because 3-glucan may dissolve insufficiently, and so it will not perfectly decompose [3]. That is why in the following experiment, test mashing was performed with the help of light barley malt (70 %), barley (30 %) and enzymatic preparation AP Subtilin P (0.3 % from batch mass). Estimation was also performed using a standard method. For control, mashing with enzyme aqueous solution was carried out. In test samples, anolyte- and catholyte-based enzyme solutions were used (Table 4).

Data in Table 4 indicate that applying ECA solutions increases the extract content by 1-2 %. Besides, the time spent on saccharification decreases when anolyte-activated solutions are used.

In all the experiments, the anolyte-based solutions of enzymes and extracts demonstrated an elevated activity, which suggests enzymatic activation. The experiments also indicate that the optimal exposure time is 15 minutes, and further activation does not lead to desired results. When ECA enzyme solutions are used, the malt and unmalted materials’ extract content increases by 1-2% in comparison with control. Besides, when the quantity of enzymes added is reduced by 12 % the extract content and saccharification time remain the same as in control, which allows saving costly enzymatic preparations. Using ECA components is extremely promising.

REFERENCES

  1. “Electrochemical activation-97”. First International Symposium. “ECA in medicine, agriculture, industry”. — Moscow, 1997.
  2. “Electrochemical activation-99”. Second International Symposium. — Moscow, 1999.
  3. Kuntze V., Mit G. Malt and Beer Technology /Translated from German. — St-Petersburg: Publishing House “Professiya”, 2001.

Published in the journal “Pivo i Napitki”, Issue 5, 2002.