Czech
Czech

 

Contents:

Hop research and its mission

Experimental brewery

Experimental brewery batches with a new and traditional hop varieties

The groups of Hop varieties

Experimental brews and results of the degustations in 1998

Experimental brews and results of the degustations in 1999

1. Trial brews with chosen hop varieties

2. The influence of polyphenols upon the quality of beer taste

3. Evaluation of optimal distribution of aroma hops dosage

Saaz hops - important raw material for quality lager beers production

Expected effect

A/ FOR BREW INDUSTRY

B/ FOR HOP GROWERS

 

Hop research and its mission

   Hop research has within Czech hop cultivation a long tradition and important position. The beginning of its activity can be shown since 1925, it is the time when hop station was established.

   In 1950 Hop Research Institute was put into operation. The main objective of it is not only hop breeding but hop protection against pests and diseases as well.

   Within hop cultivation technologies Hop Research Institute solved the problematic of reconstruction to wide-spacing planting of hop stock, progressive methods in hop cultivation, development in mechanisation, hops harvesting and processing. A great deal of attention was devoted to hop breeding of Saaz semi-early red bine hops.

   Breeding work is contemporary aimed at breeding of new varieties. We are trying to get new hybrid aroma and bitter hops which could be utilised in brewing industry.

 

 

 

Experimental brewery

 

   Pilot brewery has more than 30 year tradition. The volume of one batch is 60 litres. The same technology procedure is preserved during beer production, the only way of hopping or hop variety changes. Beer is prepared by traditional technology of fermentation (brewhouse, fermentation room, lagering cellar) from standard raw materials - barley malt, water, hops. Brewing quality of prospective new crossbreeding are compared with market hop varieties. The influence of individual hops components (bitter acids, hop oils) to beer quality is tested too. Pilot brewery is used by some notable breweries for making testing batches before change of varietal structure in hopping of their beers.

   As mentioned above beers are made by means of traditional technology using two stage decoction mashing. Wort boiling lasts 90 minutes. Hot wort is cooled down and pitched by brewing yeast. Bottom fermentation is carried out in room in open stainless steel tubs. Lagering runs in lager cellar for two months. After filtration by desk filter beer is adjusted to 0,33 l glass bottles. Beer is stored at the temperature of 7 °C until consumption.

 

 

Experimental brewery batches
with a new and traditional hop varieties

   Nowadays brewing industry has an opportunity to choose from wide assortment of traditional and new hop varieties which are offered by world market.

   Hops are delivered in the form of hop products, just only small portion of crop is used in the form of hop cones. Most of crop is processed to pellets 90 that have the same content of brewing substances compared to cones. Pellets 45 have higher content of α -bitter acids. High-alpha varieties are preferably used to hop extracts production.

   According to market quality, brewing properties and genetic affinity world hop varieties are sorted to four basic groups. Following classification is used on the basis of hop aroma,
α -bitter acids content, cohumulone proportion and farnesene content.

 

The groups of Hop varieties

Hop varieties can be divided on the base the contents of α -bitter acids, their structure and quality of hop aroma into the common groups. At the beginning of the tests Czech varieties (Saaz, Sládek, Premiant and Bor) were drawn up into those groups on the base of chemical analysis.

The results of brewing tests in 1998 and 1999 (see page 6 and 7) show following:

- Žatecký - Saaz (CZSSA) confirms its position among the best fine aroma hops

- Sládek (CZSL) it belongs to the groups of the first rate aroma hops with the character of “Saaz aroma”.

- Premiant (CZPR) on the base of chemical structure it was lined up among bitter hops. Nevertheless, brewing tests confirmed that it is comparable to Perle (HPE). Those varieties (Perle and Premiant) have their origin in the breeding process between aroma and bitter hops. Brew tests show that these varieties do not unambiguously belong to any of these groups. They may create a dividing line between aroma and bitter hops.

- Bor (CZBO) from the reason of low growing area of this variety it is impossible to which group it belongs to (from the point of chemical analysis it belongs to the group of bitter hops).

Variety

provenience

Denotation

EBC 7.5

α - %

Cohumulone

% rel.

Farnesene

% rel.

1/ FINE AROMA

1.1. Žatecký - Saaz

Czech Republic

CZSSA

3,5

24 - 26

16,1 - 17,8

1.2. Tettnang

Tettnang

TTE

4,0

25 - 29

15,8

1.3. Spalt

Spalt

SSP

4,1

25 - 28

14,9

1.4. Lublin

Poland

PLLU

4,0

25 - 30

10,0 - 12,0

2/ AROMA

2.1. Hersbrucker

Hallertau

HHE

3,5

19 - 22

0,0

2.2. Hallertauer

Hallertau

HHA

4,3

23 - 26

0,1

2.3. Fuggle

Oregon

USFU

4,5 - 5,5

25 - 32

4 - 5

2.4. Willamette

Oregon

USWI

4,5 - 6,0

30 - 35

5 - 6

2.5. Select

Spalt

SSE

4,5

22 - 23

19,5

2.6. Perle

Hallertau

HPE

6,5

28 - 32

0,0

2.7. Golding

Slovenia

SIGO

5,0

25 - 30

2,5

2.8. Sládek

Czech Republic

CZSL

6,5

25 - 28

0,5

2.9. Tradition

Hallertau

HHT

5,0

27 - 29

0,1

2.10. Cascade

Yakima

USCA

4,5 - 7,0

34 - 40

4 - 8

3/ BITTER

3.1. Northern Brewer

Hallertau

HNB

8,0

28 - 31

0,1

3.2. Super Steier

Slovenia

SISU

8,0

25 - 30

2,5

3.3. Premiant

Czech Republic

CZPR

9,0

25 - 28

1,5

3.4. Marynka

Poland

PLMA

8,5

27 - 29

2,0

3.5. Bor

Czech Republic

CZBO

8,0

 

0,6

4/ HIGH ALPHA

4.1. Magnum

Hallertau

HHM

13,0

24 - 25

0,1

4.2. Taurus

Hallertau

HTU

13,0

23 - 25

0,2

4.3. Nugget

Hallertau

HNU

11,0

26 - 30

0,2

4.4. Target

Hallertau

HTA

10,0

36 - 39

<0,1

4.5. Columbus

Yakima

USCO

15,0

30 - 35

<0,1

In individual groups the main important varieties are mentioned. The marking of hop varieties is used by world hop market in which variety provenance is distinguished, for example:

 

HHM = Magnum grown in Hallertau German hop growing area, or

CZSSA = Saaz semi-early red-bine hop grown in Saaz hop growing area

 

1st group varieties belongs to Saaz genetic family. These varieties came into existence owing to export of Saaz planting stock to Germany and Poland in 14th century.

 

2nd group varieties is formed by original Bavarian variety Perle and new Czech hybrid variety Sládek, that is marked by “Saaz aroma”. The varieties bred from English variety Fuggle Savinski Golding,, Willamette and Cascade belong to this group.

 

3rd group varieties is typical by higher content of α -bitter acids at the range of 6 – 9 % m/m. Their influence to beer quality is similar to Northern Brewer variety, which has been used in Czech breweries for many years.

 

4th group comprises varieties with high α -acids content that are suitable for hop extracts production but pellets 45 or 90 are possible to make on customer request. Hop extract is possible to prepare from any variety of other groups.

 

Beer quality is influenced by the structure of brewing substances in hop cones. Low cohumulone content in α -bitter acids at the level of about 25 % rel. ensures beer to have pleasant bitterness. Higher farnesene content in hop oils contributes to get finer aroma and taste. Hop polyphenols contained in varieties of 1st and 2nd group positively influence the taste of beer too.

Total portion of hops during wort boiling is used to be divided to two parts if light beers are prepared. First part is formed by extracts or pellets from 4th group applied at the beginning of wort boiling. Second part are pellets from 1st or 2nd group.

If lager beers of “Premium” type are produced, total portion of hops is divided to three parts. First portion is applied at the beginning of wort boiling at the form of CO2 extract or pellets from 3rd or 4th group. Second portion of 45 pellets from 3rd group follows. Third portion, which forms pellets 45 from 1st group, is applied before the end of wort boiling.

Continuous and successful sale of beer depends on homogenous quality, stabilised taste and aroma and its favour by regular consumers. Therefore the same raw materials and same technology procedure is necessary to use in production of specific type of beer.

To obtain additional knowledge about influence of hop variety to beer quality we prepared large varietal brewing test in experimental brewery of Hop Research Institute in Žatec. Sixteen world market hop varieties sorted to four groups were included into the test. The composition of individual groups was arranged by Reality Trading Co., Ltd, Žatec. The same company delivered hops samples for experimental batches performance.

   We have prepared dosing of the hops in the trial brewhouse of the Hop Research Institute Žatec (capacity 60 l of worth) as follows:

   For the first dosage we have used 50 % of high-alpha variety Nugget in form of PE-90, next 25 % of the whole hopping has followed after 40 minutes from the start of the brew (it was PE-90 or PE-45 of tested variety) and 20 minutes before the end has been added remaining 25 % of the tested variety. Only varieties Bor and Premiant were used in form of raw hops (R.H.), because pellets were not available.

   By the II. and III. sets, which have been done in first stage, have been agreed dosage of 6 g of alpha acids for 60 l of worth and by I. and IV. sets have been dosage decreased on 4,8 g of alpha acids for 60 l of worth. General dosage of pellets of the Nugget variety with 12 % of alpha acids content has been in case II. and III. 43 g in the start of the brew and by the sets of I. and IV. 36 g, which means 50 % of the whole hopping in the both cases.

 

 

 

Experimental brews and results of the degustations in 1998:

 

   Sets II. and III. have been sensorialy evaluated on June 30th, 1998 in presence of 24 brewmasters and experts

   Sets I. and IV. have been sensorialy evaluated on August 11th, 1998 in presence of 25 brewmasters and experts

Set

Brew

Nr.

Tested

variety

Mean. α %

EBC 7.3.2.

Dosage

(g/brew)

Type of

pellets

Intensity of

bitterness

GLOBAL

EVALUATION

pts.

order

pts.

order

I.

1.

Žatec

4,24

95

90

78

2

82

1

2.

Tettnang

8,00

50

45

75

3

69

3

3.

Spalt

8,00

50

45

68

4

78

2

4.

Lublin

5,10

84

90

81

1

65

4

II.

1.

Sládek

7,55

71,5

90

62

1

55

2

2.

Perle

14,0

38,5

45

49

4

48

3

3.

Styrian Golding

5,00

108

90

57

2

41

4

4.

Hallertau Trad.

8,00

67

45

53

3

59

1

III.

1.

Bor   

8,03

67

R.H.

60

1

61

2

2

Northern Brewer

15,0

36

45

51

3

58

3

3.

Willamette

5,00

108

90

46

4

34

4

4.

Spalter Select

6,50

83

90

58

2

62

1

IV.

1

Premiant    

10,8

37

R.H.

62

3

75

1

2

Hallertau Mittelf.

8,00

50

45

80

1

55

4

3.

Hersbrucker Spät

7,00

58

45

77

2

58

3

4

Columbus

16,4

26

90

59

4

67

2

 

   The table shows the varieties used in the several sets and their dosage by the testing brews. Next to these figures there are the results of the sensorial evaluation organised in presence of brewmasters from the important Czech breweries and brewing and hop experts.

   The results of testing have been evaluated from the point of view of the taste of the beer and intensity of the bitterness. Czech varieties took always the 1st or 2nd order from the taste of the beer point of view.

   Final results in beer taste and bitterness intensity agree that new hybrid varieties have brewing properties comparable with foreign varieties of the same type.

   Next co-operation of the Reality Trading, Co., Ltd., and Hop Research Institute, Co., Ltd., will be focused on the tests of hop varieties, used by leading world breweries for brewing of “Premium” beer type.

   That is why will be evaluated influence of the following varieties on the final taste of beer in May 1999.

 

 

Experimental brews and results of the degustations in 1999:

 

1. Trial brews with chosen hop varieties

Sets I. and II. have been sensorialy evaluated on May 11th, 1999 in presence of 40 brewmasters and experts

Set

Brew

Nr.

Tested

variety

Mean. α %

EBC 7.3.2.

Type of

pellets

Intensity of

bitterness

GLOBAL

EVALUATION

pts.

order

pts.

order

I.

 

 

 

1.

Premiant   

8,79

90

93

3

82

2-3

2.

Saaz

3,89

90

95

2

95

1

3.

Marynka   

8,54

90

88

4

81

4

4.

Perle

8,78

90

96

1

82

2-3

II.

 

 

 

1.

Sládek

5,51

90

94

2

111

1

2.

Lublin

4,83

90

80

4

108

2

3.

Hersbrucker

3,65

90

86

3

88

3

4.

Savin. Golding

5,63

90

119

1

60

4

 

Agreed dosage: 4,8 g of α -acids for 60 l of worth

1. dosage:    extract CO2 Hallertauer MAGNUM - (α = 54,3 %) EBC 7.7. in the start of the                   brew    = 60 % of whole hopping = 5,3 g product

2. dosage :    TEST = 20 % of hopping - after 40 minutes

3. dosage:    TEST = 20 % - of hopping - 20 minutes before the end worth boiling

   Another experimental brews are prepared with the aim to get knowledge about influence of hop substances to beer quality. Different dosing of the aroma varieties will be tested too.

2. The influence of polyphenols upon the quality of beer taste

Dosages:   4,8 g of α -acids per 60 l hopped wort

Brew no. 1:

25 % CO2Ex

ŽATEC/SAAZ

10 min. after the beginning of boiling

50 % CO2Ex

ŽATEC/SAAZ

60 min. after the beginning of boiling

25 % CO2Ex

ŽATEC/SAAZ

10 min. before the end of boiling

Brew no. 2:

25 % PE 45/90

ŽATEC/SAAZ

10 min. after the beginning of boiling

50 % PE 45/90

ŽATEC/SAAZ

60 min. after the beginning of boiling

25 % PE 45/90

ŽATEC/SAAZ

10 min. before the end of boiling

 

Trial brews were evaluated in a sensorial way on July 22, 1999. Eighteen tasters were presented.

Brew

no.

Contents of polyphenols

(mg/l)

Bitterness

EBC units   

Results of degustation

total points

order

1

203,05

15,22   

21

2

2

262,81

19,11   

33

1

   From the table it is obvious that beer boiled from PE 45/90 shows higher contents of polyphenols which favourably influences flavour of beer. The difference in the contents of polyphenols in trial brews ensues from the fact that CO2Ex does not contain hop polyphenols. Although the dosage of α -acids was the same sample no. 2 shows higher bitterness.

 

 

 

3. Evaluation of optimal distribution of aroma hops dosage

Dosages:    6 g of α -acids per 60 l of hopped wort

1. dosage: extract CO2 Hallertauer MAGNUM (α = 54,3 % EBC 7.7)

       10 min. after the beginning of boiling = 40 % from the total dosage of hops

2. dosage:     PE 45/90 PREMIANT (α = 8,79 % EBC 7.7)

       60 min. before the end of boiling = 40 % from the total dosage of hops

3. dosage: TEST PE 45/90 ŽATEC/SAAZ (α = 3,89 % EBC 7.7) = 20 % from the total dosage of hops

   Trial brews were evaluated in a sensorial way on August 11, and 18, 1999. Taste panel comprised 20 people.

TEST no.

Term of the

3rd dosage   

Bitterness

EBC units   

Results of degustation

total points

order

I.

20 min. before the end of boiling

22,60

44

2

II.

10 min. before the end of boiling

20,90

55

1

III.

5 min. before the end of boiling

20,00

41

3

IV.

at the end of boiling   

19,60

34

4

   It is obvious from the table that optimal term of the third dosage of hopping is 10 minutes before the end of boiling. On the contrary, hopping at the end of boiling shows lower values of EBC units. Direct dependence of the term of the 3rd dosage and the bitterness expressed in EBC units is perceptible as well.

 

 

Saaz hops - important raw material
for quality lager beers production

 

   Saaz semi-early red bine hop is typical representative for fine aroma hops. These hops give beer delicious bitterness and fine hop aroma. Excellent properties of Saaz hop are derived from its chemical composition.

   Average chemical composition of Saaz semi-early red bine hops:

water

9 - 13 % m/m

 

hop oils

0,5 - 1,0 % m/m

total resins

13 - 16 % m/m

 

polyphenols

3 - 5 % m/m

α -bitter acids   

3 - 5 % m/m

 

β -bitter acids   

7,1 - 7,6 % m/m

 

   Hop resins and above all α -bitter acids are the most important natural hop component from the bitterness point of view. Many research papers unambiguously proved that isomerisation products of α -bitter acids are responsible for beer bitterness. The efficiency of other components of hop resins, β -bitter acids, hard resins and non specific soft resins is substantially lower. Therefore proportions of individual hop resins components are very important.

   While quantitative aspect of beer bitterness seems to be sufficiently elucidated, the influence of individual groups of hop resins to character of bitterness has not yet been fully understood. Fine aroma hops of Saaz provenance are typical by lower ratio of α -bitter acids to β -bitter acids that is usually 1 : 1,5. Some published data report that sensory bitterness of oxidation products of β -bitter acids give beer more pleasant bitterness. These information are important from the theoretical study of transformation hop resins during wort boiling point of view on one hand and from practical utilisation in brewing technology point of view on the other hand. This knowledge is in accordance with many years experience of Czech brewers. It can be stated that fine aroma hops with higher content of β -bitter acids give beer finer and more delicious bitterness that complements global taste harmony. It is important above all for high quality lager beers.

   Another typical feature of Saaz hops is ratio of humulone analogues in natural mixture of
α -bitter acids. Cohumulone and humulone prevail according to variety and stage of maturity.

   Cohumulone ratio in fine aroma hops is max. 26 % rel. Genetically different hop varieties, as for example European bitter hops, have cohumulone ratio up to 40 % rel. Low cohumulone ratio ensures beers to have more delicious bitterness because isocohumulone is carrier of coarse bitterness compared to other analogues.

   Hop oils are another important component of hops. Fresh hops contain 0,5-2,0 % m/m of oils that are a mixture of several hundred individual substances. Hop oils are carrier of hop aroma.
Its quality is dependant on genetic origin of hop variety, provenance and stage of maturity. Saaz fine aroma hops considerably differ from the others by quality of hop aroma.

   Hydrocarbons form approximately 3/4 of total hop oils amount. Myrcene and limonene are the most important representatives from the group of monoterpens. Humulene, caryophyllene and farnesene belong to sesquiterpene group. Saaz semi-early red bine hop is typical by high farnesene content in hop oil. Most of other market varieties have low or none farnesene content.

   Hop oils in hop products or in raw hops applied to kettle during wort boiling impart wort and beer hop aroma and taste. This combination of both sensory perceptions is usually called “hop character”. Excellent properties of Saaz aroma hops consist in balanced and harmonic content of individual components that influence sensory profile of beer. Low content of sulphur substances in hop oils is another merit of Saaz aroma hops.

   Content of polyphenols substances in Saaz hops is relatively high. Positive influence of polyphenols to beer body was described.

   An antioxidative potential was proved in α - and β -bitter acids, the later are more efficient. This fact seems to be a new aspect in assessment of brewing value of fine aroma hops.

   The trend of hop production and hop market is directed to production of new hop varieties that meet requirements of brewing industry. These requirements comprise technological, ecological, hygiene, legislative and economy aspects. That means in practice price, fine aroma, high content of α -bitter acids, high yield, low content of undesirable substances (pesticide residues, nitrates), long-term stability of composition and wide assortment.

   Saaz fine aroma hops are widely used in brewing technology also under this difficult conditions. Their further application depends on improvement of quality and brewing value. Improvement of α -bitter acids and increase of yield are necessary to be competitive with other comparable varieties. It is attainable with the help of convenient breeding and other biotechnological methods. Content of undesirable substances (nitrates, residues of pesticides) have to be reduced as much as possible. New varieties should be resistant to pest and diseases and in consequence of it will require minimum pesticides treatments.

   By improvement of parameters mentioned above the interest of brewers for fine aroma hop even more increase. It is confirmed by current trends when quality aroma hops are applied in competition with bitter ones.

 

 

Expected effect

 

         A/      FOR BREW INDUSTRY

1/ To give the basic information to breweries concerning individual hop varieties influence to taste of beer

2/ Obtained knowledge from experimental brew batches can served for breweries in the time when hops are purchased, at first in those cases when it is necessary for a new approach concerning the change of used hop varieties. Change in beer taste and usual volume of sold beer should not be influenced in a bad way.

3/ The possibility of test brewing service in the experimental brewery of Hop Research Institute, Co., Ltd. in Žatec.

 

         B/      FOR HOP GROWERS

1/ The evaluation of obtained results and demand of breweries for certain hop varieties help the growers and hop trades to determine suitable structure of hop varieties, which is necessary to be solved with regard to the future hop planting.

2/ It is supposed to help hop breeders and Hop Research Institute, Co., Ltd. to aim their activity in this field at purposeful methods.

 

 


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