GB2280908A - Process for clarifying a beverage brew - Google Patents

Abstract

The process comprises adding to the brew wort a mixture of a linear sulphated polysaccharide and silica sol, preferably at a wort temperature of 60 - 100 DEG C. The polysaccharide may be carrageenan, particularly Kappa-carrageenan.

Description

CLARIFICATION OF LIOUIDS The present invention relates to a process for the treatment of liquids, particularly to the treatment of wort in order to remove proteinaceous material and thereby improve clarity.

The production of beer first involves the extraction of sugars from a malted or part malted grist source.

Following the mashing process, as it is termed, hops are added to the sweet wort thus obtained and the mixture vigorously boiled. Boiling serves several purposes. The wort is sterilized as wild yeasts, bacteria and moulds are eliminated. Flavour and aroma chemicals are extracted from the hops. Taste chemicals are developed by the cooking process. Enzymes required for the conversion of grist starches to sugars are denatured and thereby deactivated. Undesirable volatile materials are evaporated off and finally proteinaceous matter derived from the grist is denatured. It is to removal of this proteinaceous matter that the present invention relates.

Clarity of alcoholic beverages is demanded by all consumers. It is therefore essential that cloud-causing substances are removed. The removal of these substances usually takes place after the boil, prior to fermentation, and after fermentation, either by filtration or 'fining'.

The term 'fining' is applied to the process of clarification of liquids, in particular fermented beverages such as beer and wine. Finings are generally used to remove cloud-causing substances, such as protein and yeast cells, although they do have an effect upon colour, odour, and taste. Benefits are also gained in terms of filterability and storage stability.

All fining agents interact with small haze-forming particles, resulting in the formation of larger aggregates. This action dramatically reduces the settling time, according to Stokes Law. It has been well documented that the clarity of the fermented finished beer is related directly to the clarity of the unfermented wort feedstock. A wort containing a low fine particle count will generally produce a brighter, easily clarified beer, whereas a turbid wort results in a beer which is difficult to clarify.

The clarification of wort is achieved by the application of copper finings. Also known as kettle finings, they are added to the wort towards the end of the boil or post boiling.

Upon treatment with copper finings, the proteinaceous materials in the wort form an insoluble precipitate known as trub. The point at which this trub becomes insoluble, forming flocs, is known as the break. A break forms rapidly on or about the boiling temperature of the wort.

This is known as the "hot break". In the brewing process the trub formed from this break is removed by various means. For example, by filtration utilising the whole hops as a natural filter bed in a receptacle known as a hop back, or more commonly by the use of a device known as a whirlpool. The whirlpool is a carefully designed vessel into which the hot wort is pumped tangentially in order to set up a swirling motion. This causes the trub to be thrown to the centre of the tank forming a compact cone.

The clear wort is run off from an opening in the side of the vessel and the trub is discharged from the bottom. It is sometimes the case that copper finings are added to the wort in this vessel. Only the supernatant wort is fermented to beer. It is desirable, therefore, that any trub formed be as compact as possible in order to maximise yield of fermentable wort.

After trub removal, the hot wort is cooled prior to fermentation. Upon cooling, a second precipitation occurs, known as the "cold break".

Although this second break is carried forward to the fermentation vessel, it is desirable that the aggregates are large, settle well to a compact layer at the bottom of the fermentation vessel and that the supernatant wort be bright. If these criteria are met, less work upon the final beer, either by cask fining or filtration, is required.

Traditionally, copper finings were derived from seaweeds, known as Irish Moss. Seaweeds from Indonesia and the Philippines such as Euchema Cottonii have largely replaced Irish Moss as they possess a higher proportion of the active compound. It is generally thought that the active component responsible for the fining process is the linear sulfated polysaccharide carrageenan, notably Kappacarrageenan. Kappa-carrageenan contains D-galactose and 3,6-anhydro-D-galactose (1.4 to 1 ratio) and is approximately 25% esterified as the sulfate.

Carrageenans are not the only materials which have been used for wort clarification. One other such material is silica sol.

Silica sols are colloidal solutions of silica (Silicon Dioxide) in water and are commercially available in concentrations from 10-60 % W/W. The silica takes the form of compact, non-crosslinked beads which are hydroxylated upon their surface. The size of the beads is adjusted by the manufacturing process to produce beads varying in size from 2-100 ym. The size of the particles is reflected by the specific surface area which is quoted in m2 per gramme. Typical surface areas are available from 50 to 600 m2/g. A suitable food grade silica sol is BAYKISOL 30, from Bayer. The silica sol may be modified by the addition of aluminium compounds.

Silica sols have been used in wort clarification agents in both hot and cold worts. Typically between 10 and 100 g (as Sio2) per hl of wort is added to vigorously agitated wort, as described in DE-A-2208022 and DE-A-3308743. The silica is claimed to react with the proteinaceous material in the wort in a similar manner to carrageenan and forms a trub in the same way.

Given that both carrageenan and silica sol react upon proteinaceous matter in the wort, we have now surprisingly found that when used in combination much improved clarity is obtained compared to the use of the materials separately.

What is also surprising is that the increase in 'cold' wort clarity is not accompanied by a very large increase in the volume of bottoms generally associated with overaddition. Moreover, the quantity of both types of copper finings are reduced in combination to produce better results, indicative of a synergistic effect.

According to the present invention, there is provided a process for the clarification of a beverage brew comprising adding to the brew wort in a hot or cooled state a mixture of a linear sulfated polysaccharide and silica sol. The linear sulfated polysaccharide is preferably carrageenan, most preferably Kappa-carrageenan, but may also be a synthetic material.

Preferably, the polysaccharide and silica sol are added at a wort temperature of below 1000C, most preferably between 600C to 1000C.

The ratio of linear sulfated polysaccharide to silica sol (as Six2) may vary from 1:10 to 5:1, calculated by weight, preferably from 1:4 to 1:1.

The combined level of addition may vary from 10 to 500 ppm, preferably from 50 to 150 ppm, most preferably from 60 to 100 ppm.

EXAMPLES The following examples are commercially prepared worts treated with conventional ; carrageenan based copper finings, with silica sol alone and with carrageenan and silica sol combination, compared against an unfined control. The worts were selected to give a range of end product types, specific gravities and pH values.

The data elements are split into two groups: the first two elements express characteristics of the hot break, namely formation of the floc particles and the clarity of the supernatant wort.

The flocculation may be described as follows: A - Large readily formed flocs which settle rapidly; B - Small flocs which form readily although settle slowly; C - Little or no floc formation.

Clarity is expressed on a scale from A to D by visual inspection, A being a bright wort and D a cloudy wort.

The cold break characteristics are expressed by the final three data elements. The cold break flocculation is described as follows: A - Flocs form readily during cooling; B - Flocs form shortly after cooling; C - Flocs form after 24hrs or not at all.

The level of settled particles following the cold break is expressed as a percent of the wort volume.

Clarity for cold break is judged visually using the same scale as for the hot break.

Example 1 Brewery conditioned ale wort brewed to SG 1048, pH 4.7 Treatment Hot Break Cold Break Floc Clarity Floc %Bottoms Clarity None C D C 2 D Carrageenan (30) B D B 3 C Silica Sol (150) A B C 2 D Combination (20) + (75) B B B 6 A Figures in brackets indicate dose rate in parts per million. In combination the first figure refers to the carrageenan level and the second the level of SiO2, both in ppm.

In the hot break it is desirable that the flocs form quickly and form a compact trub with a clear supernatant.

Although silica alone performs this function it affords poor cold break clarity and floc formation. Clearly in combination at reduced rates a satisfactory hot break is obtained with good cold break performance.

Example 2 Lager Wort brewed to SG 1060, pH 5.4 Treatment Hot Break Cold Break Floc Clarity Floc %Bottoms Clarity None C B B 3 D Carrageenan (30) B C A 10 B Silica Sol (150) C B B 2 D Combination (20) + (75) A B A 14 A In combination, better cold break performance is achieved at lower treatment levels than the materials used singly.

Although a slight increase in % bottoms is observed the improved hot break performance justifies the increased volumes of bottoms by producing clearer wort.

Example 3 Bottle conditioned ale wort brewed to SG 1076, pH 5.0 Treatment Hot Break ; Cold Break Floc Clarity Floc %Bottoms Clarity None B D C 2 D Carrageenan Only (40) A C A 6 C Silica Sol Only (60) A B C 2 D Combination (30) + (30) A A A 8 A Improvement to both hot and cold breaks are observed in this high gravity wort which is generally difficult to clear in production. Similar observations are made in Example 4.

Example 4 Cask Conditioned Ale Wort brewed to SG 1052, pH 4.8 Treatment Hot Break Cold Break Floc Clarity Floc %Bottoms Clarity None C C C 2 D Carrageenan Only (30) A C A 19 B Silica Sol Only (60) A B C 2 C Combination (20) + (60) A B A 6 A In Example 4, the facility to reduce carrageenan levels by the co-addition of silica sol imparts a dramatic reduction in volume of bottoms.

Benefits to the fermented product were observed by microscopic examination of the fermented but unprocessed product.

The level of fine particles was recorded for beers produced from worts treated with carrageenan alone, silica sol alone and both materials in combination.

Beer A No Treatment Count particles > 10ym = 0.12 x 106/ml particles < 10y but > 2y = 0.07 x 106/ml particles < 2 y = 11.35 x 106/ml Carrageenan Treatment only particles > 10y = 0.10 x 106/ml particles < 10y but > 2y = 0.20 x 106/ml particles < 2y = 1.33 x 106/ml Silica Sol only particles > 10y = 0.04 x 106/ml particles < 10 but > 2 = 0.05 x 106/ml particles < 2y = 1.23 x 106/ml Carageenan and Silica Sol in combination particles > 10y = 0.03 x 106/ml particles < 10y but > 2 = 0.14 x 106/ml particles < 2 = 0.18 x 106/ml In the case where the carrageenan and silica sol were used the same reduction in dose rates was applied as in Examples 1-4.

The counts were performed on unfiltered/unfined beer. The untreated wort produces a beer with a high level of very fine particles of less than 2 ym. The wort which was treated with either carrageenan or silica sol gives a reasonable performance with many fine particles removed.

However, the combination of these fining agents produces a dramatic further reduction in fine particles. It is these very fine particles (less than 2 tcm) which are responsible for filter blockage and haze formation. The same trend is observed in Example B.

Beer B Untreated particles > 10 ym = 0.03 particles 2-10 ym = 0.14 particles < 2 ym = 6.90 Carrageenan only particles > 10 Fm = 0.03 particles 2-10 zm = 0.10 particles < 2 zm = 0.59 Silica Sol only particles > 10 zm = 0.08 particles 2-10 m = 0.16 particles < 2 ym = 2.55 Carrageenan and Silica Sol in combination particles > 10 ym = 0.01 particles 2-10 ym = 0.02 particles < 2 ym = 0.23 Therefore, the process of clarification of wort using a combination of silica sol and linear sulfated polysaccharide gives a much improved performance in the clarification of wort. The resulting wort clarity is carried forward to produce a beer with a low fine particle count which facilitates ease of fining and/or filtration.

Worts treated with this fining system generally have compact rapidly settling sediments, in particular in the hot break.

Claims (6)

1. A process for the clarification of a beverage brew comprising adding to the brew wort a mixture of a linear sulphated polysaccharide and silica sol.

2. A process as claimed in Claim 1, wherein the ratio of linear sulphated polysaccharide to silica sol (as SiO2) ranges from 1:10 to 5:1, calculated by weight.

3. A process as claimed in Claim 1, wherein the ratio of linear sulphated polysaccharide to silica sol (as Sio2) ranges from 1:4 to 1:1, calculated by weight.

4. A process as claimed in any one of the preceding Claims, wherein the combined level of addition of the polysaccharide and silica sol ranges from 10 to 500 ppm.

5. A process as claimed in any one of the preceding Claims, wherein the polysaccharide and silica sol are added to the wort at a wort temperature of below 1050C.

6. The use in clarification of wort of a combination of silica sol and linear sulphated polysaccharide.