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Optimization of Technological Processes for Gluten-Free Beer Production Zsuzsanna Kiss, Beata Vecseri-Hegyes, Gabriella Kun-Farkas, Á. Hoschke
Corvinus University of Budapest,Dep. of Brewing and Distilling Hungary
[email protected], [email protected], [email protected],[email protected]
1. Introduction
In Hungary intensive research is being done regarding the production of food suitable for coeliacs, but these – so far – have not covered beer production, even though adult coeliacs, who cannot consume this alcoholic drink due to the hordein content of barley, would demand its presence on the retail market. The solution is to find suitable raw materials that are guaranteed to be free of this protein fraction, as well as to elaborate and optimize a technology by the application of which chance of gluten contamination can be eliminated, and a product with acceptable flavour and quality may be done.
Coeliac disease is a genetically determined autoimmune disorder that affects the whole body. It causes damages in the epithelium of the small intestine due to which malabsorption occurs. In Europe and in Hungary as well it has an incidence of 1% in the population. Currently there is no licensed, inland product on the market. Since 2007 gluten-free beer is available from Austria and Italy on a very high price (600-1000 Hungarian Forint per bottle) through two Hungarian distributors. The first restaurant-pub where foreign-made gluten-free beer is served was opened in Pécs (South Hungary).
2. Alternative cereals for gluten-free beer production
In Hungary the following raw materials are available for the production of gluten-free beer: sorghum, millet, buckwheat and maybe amaranth. These cereals/pseudo-cereals contain no gluten (or less than 20 ppm of it); their grain might be suitable to make malt, and wort.
Common buckwheat (Fagopyrum esculentum L. Moench) is traditionally used for pasta, blended bread and other types of flour. Many positive physiological effects are associated with buckwheat. Due to the presence of soluble and insoluble fibres, antioxidants, high values of micro-, and macroelements, as well as the absence of glutenin-like proteins buckwheat is considered a grain which can be used for preventative nutrition.
Red and white millet (Panicum miliaceum L.) is well adapted to low rainfall, high temperatures and, in comparison to barley, to many different soil conditions. Millet starch contains 28% amylose and 72% amylopectin, almost similar than barley, and they have well malting property. Millet’s starch granules of the corneous endosperm are angular, whereas the ones located in the floury area are spherical, their size ranges from 3–21 µm. Though the range of protein content in millet varies significantly, the values appear to lie most frequently in a narrow range of 11.3 to 12.7%. Millet is well adapted to low rainfall, high temperatures and, in comparison to barley and wheat, to many different soil conditions (PELEMBE at al., 2002; ZARNKOW et al., 2007).
Sorghum (Sorghum bicolor L. Moench) is a cereal with remarkable genetic variability, having an important advantage over temperate grains because it can yield crops under harsh environmental conditions. Starch characteristics of sorghum plus the tendency to gelatinize more rapidly than regular endosperm types, make waxy sorghums more attractive as potential sources of industrial brewing material. Among the different varieties of sorghum, there are those with waxy endosperm that contain more than 95% amylopectin and a relatively weak protein matrix. These sorghums are more susceptible to hydrolysis by amylolytic and proteolytic enzymes. (OBETA et al., 2000; GOODE et al., 2002, POSO-INSFRAN et al, 2004).
3. Aim to work
In the course of our work we aimed to develop a product from gluten-free raw materials (millet, sorghum and buckwheat) that is similar to beer made of barley malt but is consumable by coeliacs. Our measurements were started by qualification of cereal/pseudo-cereal grains. Next malts were made of them with different steeping, germination and kilning parameters, and their most important quality characteristics were determined. Qualification of grains were done by grading, determination of thousand-kernel and hectoliter weight, and protein content, while malts were examined with congress mashing, Hartong mashing and lauter test, as well. Gelatinization point of the starch found in grains and malts were determined by Brabender amyloviscograph which helped to set the temperature of β-amylase rest in future mashings.
4. Materials
All of the cereals and pseudo-cereals were grown in Hungary and harvested in 2009. Samples of two millet varieties, the white one, Fertődi 2 and the red one, GKT Piroska were used, furthermore the buckwheat variety called Hajnalka and the sorghum was Alföldi 1 variety. All of them were received from Wheat Reserch Institute of Szeged. The reference spring barley seed was Jubilant.
5. Qualification of grains
As a beginning of our work qualification of cereal/pseudo-cereal grains was done according to examinations created for barley specification. Tested grains were compared to barley grains based on moisture content, grading, hectolitre weight, protein content and germinating capacity, since these values affect most the process of malting and mashing, where high starch (70-75%) and low protein contents (10-12%) are required. Germinating capacity of sorghum turned out to be the weakest; the other grains reached the 95% requirement level.
Results of mechanical tests reflected well the differences in the morphology and size of grains. In case of millets and sorghum values are higher than that of barley, because grains can settle tightly next to each other due to their homogeneous distribution and symmetrical round shape. On the other hand grain of buckwheat is irregular, and its polygonal seed is larger than barley. Hectolitre weight of buckwheat is lower because more gaps are formed in the measuring cup due to the pyramidal shape of seeds.
Table 1. Quantification of gluten-free basic material
6. Examination of cereals starch 6.1. Gelatinization point
Fig. 1. Gelatinization point of buckwheat, millets (red and white) and sorghum.
A: Amylogram of buckwheat’s starch (gelatinization point:67 ˚C; B: Amylogram of millet’s starch (gelatinization point:78 ˚C;
C: Amylogram of sorghum’s starch (gelatinization point:85 ˚C). Temperature:
Brabender Unit:
Barley seed principal properties
Requirement
(%) Controllbarley
Red millet
White millet
Sorghum
Buckwheat
Moisture content % 14.5 suitable suitable suitable suitable suitable Germinating capacity % 95 suitable suitable suitable suitable suitable Protein content (Kjeldahl) (% dry weight). 11.5 10.8 13.2 12.0 14.64 13.4
Clearing % 98 96 99 99 85 98 Hectoliter weight kg/hl 65 66 74.5 69.1 65.7 54.5 Thousand kernel weight (g) 38-40 39 7.5 6.4 23.2 35.9 Mix %: 2 0 2 2 6 2 Glassy kernels % <2 0.8 0.8 0 1.2 2.4 Grading: sieve 2.5 mm,remaining seeds % 75 73 12 11 37 54
Sieve 2.2 mm remainingseed 4 2 87 88 46 2
Starch granules have to be digested in order to reach adequate level of degradation, so amylases can break down glycoside bonds.
Gelatinization point of millets (red and white), buckwheat and sorghum was 78°C, 67°C and 85°C, respectively, which are all higher than that of barley (63°C). This affects enzymatic processes to a great extent during mashing, because barley malt gelatinizes at about 52-57°C, thus when β-amylase rest is reached the enzyme meets an already gelatinized starch. But in case of the tested malts gelatinization point is above the optimal range of the enzyme (62-65°C), so temperature of β-amylase rest should be chosen with great care. An optimal temperature has to be found at which most of the starch can gelatinize, but amylolitic enzymes are not inactivated from high temperature. In the course of mashings iodine tests always showed blue colour because of the large amount of residual limit dextrin.
6.2. Determination amylose and amylopectin rate:
It is highly important to know the rate of amylose and amylopectin to adjust mashing processes, since viscosity of the mash and water-absorbing capacity of grist depend on this. Amylose is a linear polymer made up of α-D-glucose units that has weak water-absorbing capacity and responsible for retrogradation. On the hand, amylopectin, which contains α-1,6 branches beside α-1,4 bonds, hydrates well.
Amylose and amylopectin content of barley was approached best by values of buckwheat. Data shown in case of sorghum and red millet are higher, while white millet has the highest amylase content.
Table 2 Amylose and amylopectin contains of starch Sample Amylose (%) Amylopectin (%)
Barley 19 81Red millet 24 76
White millet 28 72 Sorghum 23 77
Buckwheat 16 84
7. Malting optimization
After specification of the grains malts were made with different parameters (time, extent of aeration, temperature) by steeping, germination and kilning (4 types of settings), and their main nutritional values were determined.
Table 3. Different malting process parameters Process L1.
(Laboratory 1.) L2.
(Laboratory 2.)L3.
(Laboratory 3.)Ind.
Industrial malting Steeping 20 °C water
12 h Overflow by
water
25 °C water 16 h
Aeration and Overflow by
water
25 °C water 18 h
Aeration and Overflow by
water
10 °C water 12 h
Aeration and Overflow by water
Germination 96 h 20 °C
90 h 15 °C
84 h 15°C
96 h 15 °C
Kilning 40 °C 24 h
45 °C 36 h
50 °C 48 h
40 °C 48 h
Malts made with the above mentioned methods (Table 3.) were subjected to Congress and Hartong mashings, and filtration test, as well. (These are standards procedures)
The results from the analysis of small scale mashing experiment with fine grist are shown Figs 2. and Table 4. The best values are for L3 approach. Extract requirement is 80–83%. All worts had very low extract levels, almost the half part of the barley malt, because of the higher gelatinization temperature, which caused unsuitable degradation of starch.
Fig 2. Extract contain of congress worts. L1; L2; L3; Ind. laboratory and industrial malting profiles
Table 4. Qualification of congress wort (L.3)
Congress Wort
pH Colour (EBC)
Filtering time(Min)
Time of saccharification
FAN (mgl-1)
Hartong-number
Requirement 5.7-5.9 2.5-4 15-20 25 150-180 5.5-10 Red millet 4.8 5 25 iodine positive 132 2.8
White millet 4.8 4 26 iodine positive 134 2.4 Sorghum 5.2 5 30 iodine positive 126 1.2
Buckwheat 5.4 7 25 iodine positive 138 2.2
Malting process that proved to be the most suitable for brewing requirements (high extract content, good lautering characteristics, high FAN content) has the following parameters: steeping with 25°C water for 18 hours with aeration in every 5 hours; germination at 15°C for 84 hours; kilning at 50°C for 48 hours.
8. Mashing optimization
Optimization of mashing was continued with malts that were made with the previously mentioned parameters. Mashing programs were written for all raw materials on our laboratory scale mashing equipment (4 types of settings, 3 infusion and a decoction technologies, Duration and temperature of protein and enzyme rests of mashings were set (Fig.3.) The difference is that in decoction mashing part of the mash is boiled in a separate kettle. The boiled part is added back to the mash to achieve the required temperature rise. The effect of the boil on the final beer is stronger, and it is important for achieving the characteristic malty taste.
Fig 3. Mashing processes.
Extract content of worts were measured, as well as their carbohydrate composition was determined by HPLC, α-amylase activity by the Phadebas test, and free amino nitrogen (FAN) content by the ninhydrin method.
Carbohydrate composition of regular all malt worts is characterized by the decreasing amount of the following sugars: maltose, maltotriose, glucose and fructose, in this order. In case of alternative cereals due to defective starch degradation β-amylase cannot break off as much maltose as in regular wort, but α-amylase can hydrolyse at 72 and 78 °C as well. This results a peculiar carbohydrate composition in which there are less maltose and more glucose. The wort is also characterized by the presence of high amount of residual maltodextrins and higher polymerization degree oligosaccharides. (based on HPLC analysis)
Fig. 4. Extract value (Plato%). C1….C2….C3….C4 mashing programs
Table 5. Nutritive value in the C4 mashing process (decoction) Wort (C4 optimal process) Extract value pH Colour
(EBC) Filtrating time
(min) FAN mgl-1
Control 12.2 5.9 10 40 202
Red millet 10.2 5.2 12 48 183
White millet 10.3 5.3 11 51 177
Shorgum 9.8 6.0 13 52 165
Buckwheat 11.6 5.3 14 47 198
Based on the measured parameters optimal mashing (Fig. 4. and Table 5.) was the following: 1:4 grist to water rate, using the 2nd mashing procedure as decoction mashing. One third of the cereal malt grist was boiled and transferred back to the thick mash helping the complete gelatinization of starch.
9. Fermentation of the worts
The fermentation of the worts were carried out in ferment flasks for five days, during this time we followed up the changes of pH values, extract and alcohol content. Increasing scale we produced beer in the pilot plant brewery.Finally we did sensory examination; the white millet beer received the best qualification. Buckwheat beer has a specific taste, just like chesnut and sunflower seed.
10. Conclusions As result of our work it can be concluded that the tested buckwheat, millet and sorghum,
furthermore malts made of them are suitable for application in brewing. The quality and quantity of their components meet requirements of yeast and an undisturbed fermentation. Since our investigation have proved that the nutritive value and brewing technological value of malts made of gluten-free cereals fall behind that of regular barley malt, it is advisable to use gluten-free adjuncts (invert sugar syrup, agave syrup, maize grits) and industrial enzyme preparations to increase extract content of wort.
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