CZ201376A3 - Process for preparing bittering substances from hop beta acids - Google Patents

Abstract

The method for preparing mustard substances from beta acids of hop consists in mixing a solution containing 20 parts by weight of beta acids and 60 to 120 parts by weight of ethanol at least 99.9% by volume with a suspension containing 100 parts by weight of an inert carrier and 200 to 300 parts by weight of ethanol, then the mixture is homogenized, then the ethanol is evaporated therefrom under a pressure of 60 to 80 kPa, and then it is reacted with air oxygen for 20 to 200 hours at a temperature of -18 to 25 degC.

Description

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a process for preparing mustard substances from hop acids.

BACKGROUND OF THE INVENTION

Hop resins are the most important components of the hops. Their transformation products, which are formed in the brewing plant, are a source of typical bitterness of beer, stabilize beer foam and, due to antiseptic effects, increase the biological shelf life of beer (Haas, G.J .: J. Food Protection 57, 59-61, 1994). The most important part of the overall bitterness of beer is the transformation products of alpha hops acids, which isomerized to the corresponding cis- and trans-iso-α-acids in the hopping plant (Jaskula, B .: J. Am. Soc. Brew. Chem. 67, 44- 57, 2009). Their bitterness, changes in beer aging, autooxidation reactions and other properties are well described (Hughes, P .: J. Am. Soc. Brew. Chem. 54, 234-237, 1996). Kinetic studies of the hop isomerization reaction of alpha acids under various conditions of the brewing plant were also carried out (Malowicki, M. G., J. Agric. Food Chem. 53, 4434-4439, 2005).

Behavior of hop beta acids under the same conditions is quite different. Since they do not contain a tertiary alcohol group in the aromatic ring, they cannot isomerize as hop alpha acids.

alpha acids beta acids 4 ♦,,,,,,,,, 4, 4,, 4 4,

9 »» * 4 * 1 tt «« · and »· t · ♦« ··

The beta acids present in the hops are sensitive to air-initiated oxidation reactions (Laws, D. R., J. Inst. Brew. 74, 178-182, 1968). Greater oxidation occurs during long-term storage of unprocessed heads. The longest known oxidation products of hop beta acid decomposition are hulupones (Aitken, R. A., J. Inst. Brew. 76, 29-36, 1970). Unlike other substances, the existence of hulupones has been confirmed in recent studies (Haseleu et al .: J. Agric. Food. Chem. 57, 7480-7489, 2009). The concentration of hulupons in beer is estimated to be 1 to 2 mg / l. Hulupons are also produced in hops during long-term storage.

In freshly harvested hops, the content of hulupons is not more than 0.5% by weight, and increases during aging. However, the data on their content in hops is different.

In brewing, mainly degradation and transformation products of hops beta acids are sensoryly applied (Haseleu, G .: Food Chemistry, 116, 71-81, 2009). Recent work has brought new information that has already taken advantage of modern chromatographic methods such as liquid chromatography with mass spectrometry (LC-MS) and detection systems such as flight time analyzer (TOF), nuclear magnetic resonance (NMR), etc. Haseleu et. al. (J. Agric. Food. Chem. 58, 7930-7939, 2010) discovered seven hitherto unknown degradation products of hop beta acids showing bitter taste in fractionated hop extracts which they subjected to model hopping plants. In addition to the previously known hulupones, the structures of other substances, 2 epimers of hydroxytricyclolupulone, 2 epimers of dehydrotricyclolupulone, 2 epimers of hydroperoxytricyclolupulone and nortricyclolupulone were determined in the medium. According to the authors of the study, all newly identified degradation products exhibited bitterness adhering to a sensory threshold in the range of 38 to 90 qmol / l. In contrast, the hulupons exhibited a briefly lingering mild bitterness similar to that of the iso-α-acids of hops. Of all the substances studied, hulupons had the lowest sensory bitterness threshold in the range of 8 to 15 gmol / l.

However, the influence of hop beta acids on the sensory quality of beer is not yet fully understood. An important feature of hop beta acids are strong antibacterial effects against many strains of bacteria. This property is industrially used in the protection of foodstuffs against bacterial contamination of Listeria monocytogenes. Hops beta acids are applied at concentrations of 6-15 ppm in the form of an alkaline solution (Millis, I, Schendel, M .: US Patent 5,286,506; 1992). Another field of application of the antiseptic properties of hops beta acids is the sugar industry, where they replaced the formaldehyde used to suppress bacterial contamination in the production process (Hein, W., Pollach, G .: Zuckerindustrie, 122, Nr. 12, 940-949, 1997). The activity of hops beta acids in food formulations is increased by dissolving the active substance in food grade ethanol or propylene glycol i <

with the addition of an organic acid, a potassium salt and an antioxidant (Seman, D., Hirchley, J. A.,

Milkowski, A., Barney, M., British Patent 2,399,484, 2003).

The process for the preparation of mustard compounds from the hop acids of the invention useful in the production of beer has not been described in the literature.

SUMMARY OF THE INVENTION

A process for preparing mustard compounds from hop beta acids is characterized in that a solution containing 20 parts by weight of pure beta acid of hops and 60 to 120 parts by weight of ethanol having a purity of at least 99.9% by volume is mixed with a suspension containing 100 parts by weight of inert carrier. up to 300 parts by weight of ethanol, the mixture is homogenized, ethanol is evaporated therefrom at 60 to 80 kPa and then reacted with atmospheric oxygen for 20 to 200 hours at -18 to 25 ° C.

The process for preparing the mustard compounds of hop acids according to the invention makes it possible to apply the hop acids to the surface of the inert carrier in a thin layer. In such a form, hop beta acids are easily and rapidly oxidizable by the action of atmospheric oxygen. The controlled oxidation, which is the final stage of the process for preparing the mustard substances from the beta acids of the hops according to the invention, is carried out by leaving the blank at different temperatures for a defined period of time. During the exposure, the original hop acids of the hops are transformed into a mixture of oxidation products, which, when added to the brewing plant during the brewing process, will show a significant bitterness.

At 20 ° C, more than 95% of the original hops beta acids are transformed in 24 hours. Transformation at lower temperatures is noticeably slower. The degree of transformation is determined by chromatographic analysis of the products based on the residual beta acid content of the hops. Transformation products represent a complex mixture of substances of various structures, among which hulupones and polycyclic derivatives of hops beta acids predominate.

Comparative boiling experiments have shown that the mustard yield of the substances produced by the process of preparing the mustard compounds of the hop beta acids of the invention reaches about 40% of the bitterness of the hop alpha acids added under comparable conditions.

The process for preparing the mustard compounds of the hop acids of the present invention has been developed based on the finding that when added to the hop beta acid hopper, the beer will not be bitter at all. Only when hops beta acids are allowed to oxidize in air, «

i i

. Only the oxidation products cause the beer to burn. The mustard substances in this case are decomposition products of hop beta acids.

The process for preparing the mustard compounds from the hop beta acids according to the invention is based on the oxidation of the hop beta acids deposited on a solid support. The dispersion of the hop beta acids into a thin layer on the surface of the inert carrier results in the oxidation of the hop beta acids at a very rapid temperature at 20-25 ° C. By controlling the temperature during oxidation, the rate of transformation can be influenced.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Weigh 20 grams of pure hops beta acids into a 250-ml beaker and dissolve in 80 g of 99,9% pure ethanol. In a 500-ml beaker, simultaneously prepare a suspension of 100 grams of an inert carrier which is a solid sorbent, in this case, micronized cellulose, in 240 g of pure ethanol at a concentration of 99.9% by volume. The ethanolic solution of the hop beta acids is then mixed with a suspension of the solid sorbent in ethanol. The mixture was thoroughly homogenized by mechanical shaking for 2 minutes. After homogenization, the ethanol is evaporated under reduced pressure from 60 to 80 kPa in a rotary evaporator. The result is a free-flowing semi-product that is allowed to react with atmospheric oxygen for 24 / A / r4 on a Petri dish in a dark room at 20 ° C.

Alternatively, the semi-product can be placed in a refrigerator at + 4 ° C or in a freezer at -18 ° C and allowed to react freely in air with air oxygen, in these cases for up to 168 hours.

During oxidation, the original hop acids of the hops are transformed into a mixture of oxidation products that can be used in beer hopping to achieve the desired sensory bitterness.

Table 1 shows values expressing the rate of oxidation of hop beta acids by air oxygen as the relative loss of original hop beta acids over time (% rel) after the application of hop beta acids to micronized cellulose, which characterizes the transformation dynamics as a function of temperature and reaction time.

Table 1 - Rate of oxidation of hops beta acids in air after application to inert carrier micronized cellulose (% rel.)

Location Temperature (° C) Oxidation time (hours) 24 48 96 168 dark room 20 May 96.9% 98.3% 98.6% 98.8% fridge +4 32.2% 85.7% 94.0% 95.5% freeze box -18 11.1% 17.0% 25.7% 29.8%

Table 2 shows the bitterness of worts, young beers and ready-to-drink beers after the addition of the substances produced by the process of preparing the mustard substances of the beta acids of the hop according to the invention to the brewing plant at different times.

Table 2 - Analytical bitterness of wort, young beers and beers

Time and temperature of oxidation, dosing time at the brewery Dose* (g / hl) Bitterness (IBU **) wort young beer beer 48 hours of oxidation at 20 ° C, dosing at the beginning of the brewery 20.0 39.7 28.5 26.6 48 hours oxidation at 20 ° C, dosing 15 minutes before the end of the brewery 20.0 38.2 29.3 28.5

^ amount of original beta acids of hops before transformation ** IBU - International Bitterness Unit

Example 2

The process for preparing the mustard substances from the beta acids of hops is carried out as in Example 1, except that instead of micronized cellulose, ground hops are used as the inert carrier after extraction of the hops with carbon dioxide or ethanol. Table 3 shows the values expressing the rate of oxidation of hop beta acids by air oxygen as the relative loss of hop beta acids over time (% rel) after the application of hop beta acids, the hop milled bitter hop.

Table 3 - Rate of oxidation of hops beta acid in air after application to inert carrier - finely ground bitter hop (% rel.)

Location Temperature (° C) Oxidation time (hours) 24 48 96 168 dark room 20 May 50.0% 73.1% 86.0% 97.4% fridge +4 20.1% 45,5% 66.8% 93.3% freeze box -18 7.8% 10.1% 18.9% 25.9%

The rate of oxidation of hop beta acids is slower compared to Example I, in which micronized cellulose was used, since the thickness of the hop beta acid layer on the surface of the ground hop particles is stronger and hops beta acids are more difficult to access by the oxidative action of air oxygen.

Industrial applicability

The method of preparation of mustard substances from beta acids of hops is industrially applicable in brewing production for hopping of special beers.

Claims (1)

A process for preparing mustard substances from beta hop acids, characterized in that a solution containing 20 parts by weight of beta acid of hops and 60 to 120 parts by weight of ethanol having a purity of at least 99.9% by volume is mixed with a suspension containing 100 parts by weight of an inert carrier and 200 to 300 parts by weight of ethanol, the mixture is homogenized, ethanol is evaporated therefrom at 60 to 80 kPa, and then reacted with atmospheric oxygen for 20 to 200 hours at -18 to 25 ° C. .