Application of ECA solutions and enzyme preparations for hop extraction

S.N. Khrapenkov, M.V. Gernet, D.A. Sviridov

Moscow State University of Food Production

K.V. Kobelev

GU VNII of brewing, nonalcoholic and wine industry (Moscow)

V.M. Bakhir

ОАО NPO EKRAN (Moscow)

Today, because of intense competition on the Russian brewing market, many enterprises search for ways to reduce unit costs. A possible way to solve the problem is to lower the cost of hop and end-products of its processing.

Bitterness of hopped products is due to a±-acids. In hop products, they are normally present in a low-soluble state. In the process of boiling, humulon, adhumulon, cohumulon and other a±-acids convert into isomerized forms. Isohumulon yield is known to depend on рН value. Higher рН values always provide for better isomerization. Based on the above, it was suggested to obtain a catholyte-based extract — a product of unipolar treatment of aqueous solution with electric current generated on cathode [4]. The first goal of the experiment was to find optimal temperature of hop processing. Non-stable catholyte substances are known to decompose during heating, therefore the following temperatures were suggested: 30, 35, 40, 42 °С [1, 2]. Extraction was carried out under the following conditions: hop cones (a = 6.3; da = 10.3 %) were covered with catholyte solution (рН 9-10 and ф= -700...-800) and kept for 1 hour at predetermined temperatures. In the given experiment, STEL-20АК device for producing ECA (electrochemically activated) solutions was used. On the basis of performed experiments, wort hopping with obtained extracts was carried out. The results of the experiment are presented in the Table.

Isohumulon content in hop extract, mg/l

30 °С

35 °С

40 °С

42 °С

Control

28.2

100%

29.1

100%

29.8

100%

30.6

100%

Catholyte

32.1

113%

30.8

106%

30.1

101%

29.7

97%

Isohumulon content in hopped wort, mg/l

30 оС

35 °С

40 °С

42 °С

Control

20.4

100%

22.8

100%

24.9

100%

25.2

100%

Catholyte

22.8

112%

25.2

111%

26.7

108%

24.8

98%

According to the Table, catholyte added at T 30...35 °С allows increasing isohumulon content by 11-12 % correspondingly. In this connection, hop feeding rate was suggested to be reduced by 10 %. As control sample, hop extract prepared on distilled water with conventional hop feeding rate per 1 liter of wort was used. The experiment’s conditions were similar to those of the previous experiment. The obtained extract was used to hop wort with 12 % dry matter content. The wort was boiled during 1 hour. The findings are shown in Fig.1.

Today, because of intense competition on the Russian brewing market, many enterprises search for ways to reduce unit costs. A possible way to solve the problem is to lower the cost of hop and end-products of its processing.

As may be seen from Fig. 1, a 10% reduction of fed hop norm during catholyte treatment does not result in lower isohumulon content in the wort as compared to control.

Another method to increase a±-acid yield in the process of wort hopping is to produce extracts using enzyme preparations. For this purpose two enzyme preparations — Cellobranin G3х and Xyloglucanophoetidin P10х were chosen. The choice of enzyme preparations was caused by the composition of cellular walls of plant raw materials — cellulose, hemi-cellulose and pectin substances. The enzyme preparations were used for treating cone hop at T 45 °С during 1 hour. Fig. 2 demonstrates the experiment’s results. The data include the amount of residuary acid in oil-seed meal after the action of enzyme preparations. As control, water extraction was taken at the same temperature and during the same exposure time. The action of the enzyme preparation Cellobranin is shown to be more preferable than that of Xyloglucanophoetidin, since residual a±-acid in the first case is nearly twice lower than that of the second preparation. Most likely, this is due to the fact that a complex of cellulolytic enzymes, which are a component of Cellobranin G3х, more efficiently hydrolyzes non-starchy hop polysaccharides. Thus, the effect of cellobiohydrolase and endoglucanase is almost twice higher than that of Xyloglucanophoetidin P10х.

Fig.1 Effect of ECA treatment on isohumulon yield in wort; Isohumulon content in wort, mg/l; Hopping method; Hop extract on catholyte; Hop extract on catholyte with 10% reduced hop feeding rate; Cone hop (control)

Fig.2 Effect of enzyme preparations on the degree of a±-acid extraction from cone hop; Residual a±-acid in hop oil-seed meal, %; Pre-treatment with enzyme preparations; Hop treatment with Cellobranin G3x; Treatment with Xyloglucanophoetidin P10x; Treatment with water (control)

Fig.3 Effect of treating hop with ECA water and enzyme preparations on a±-acid yield; Residual a±-acid in hop oil-seed meal, %; Pre-treatment with enzyme preparations; Hop treatment with catholyte and Cellobranin G3x; Hop treatment with catholyte and Xyloglucanophoetidin P10x; Hop treatment with catholyte (control)

Fig.4 Effect of combined treatment of hop with ECA water and Cellobranin G3x; Isohumulon content in wort, %; Hopping method; Compressed hop (control); Hop extract obtained using catholyte and enzyme preparation Cellobranin G3x

Previous studies demonstrated a possibility of enzyme preparations’ activation [1, 2]. Therefore, the following stage of the study was dedicated to a possibility of combined application of enzyme preparations and ECA solutions.

Cone hop was first treated with catholyte during 1 hour at T 30 °С, and then subjected to the action of enzyme preparations at T 45 °С. For control catholyte extraction was chosen. As becomes evident from Fig. 3, the greatest effect is produced by Cellobranin G3x exposure. Residual a±-acid in this case is 10 % of its initial content, which is almost 4 times less than under the action of aqueous solutions. A similar dependence is observed in case of Xyloglucanophoetidin P10x.

This effect is most likely due to enzymes’ activation by ECA solutions and substrate preparation to enzymatic hydrolysis.

Isohumulon yield is the most important parameter in the process of wort hopping. To estimate the quantity of isohumulon, the following experiment was carried out: after 15minutes of wort boiling the obtained extracts were added, and boiling went on for another hour. The results are presented in Fig. 4.

As seen from Fig. 4, combined application of catholyte and the enzyme preparation Cellobranin G3x results in a 27 % increase in isohumulon output.

Therefore, combined application of catholyte at рН 9-10 and j = -700... -800 and the enzyme preparations Cellobranin G3x and Xyloglucanophoetidin P10x allows to halve a±-acid loss as compared to their separate employment and increase isohumulon output by 27 %. Reduction of hop feeding rate using treatment conditions selected by our team is cost-effective and has no adverse effects on the quality of produced beer.

REFERENCES

  1. Khrapenkov S.N., Gernet M.V., Bakhir V.M. Effect of electrochemically activated systems on malt enzymes // Pivo i Napitki, 2002, N 5, pp. 20-21.
  2. Khrapenkov S.N., Gernet M.V., Sviridov D.A., Kobelev K.V., Bakhir V.M. Electrochemical activation in wort production // Pivo i Napitki, 2003, N 4, pp. 18-19.
  3. Kuptze V., Mit G. Malt and beer technology: translated from German. — St. Petersburg: Professiya, 2001.
  4. Electrochemical Activation - 9. First International Symposium “ECA in medicine, agriculture and industry”— Moscow, 1997.

Published in the journal “Pivo i Napitki”, N 2, 2004.