SK153897A3 - Method for malting barley and improved malt thus obtained - Google Patents

Abstract

Method of barley malting consists of the phase of soaking, phase of germination and the phase of drying on the kiln. To reach small contents of nitrosodimethylamine (NDMA) in the malt after the drying on the kiln, excluding addition of sulphur during drying, the barley is during the soaking acidified to pH in the range 3.5 to 4.6 during at least one sub-stage of soaking. The integral part of the used technique is lowering of dimethylamine (DMA) in green malt, what reduces later production of nitrosamines in the malt. The malt prepared by said method contains 81 - 82 % of the extract, 4 % to 5 % of soluble proteins and has viscosity in the range 1.4 - 1.5 mPas, homogeneity of maturity > 72 %, contents of NDMA < 1 % and contents of soluble beta-glucans < 200 mg.

Description

Barley malting process and malt upgraded in this way

Technical field

The invention relates to a process for malting barley, i. a process consisting of a soaking stage, a germination stage and a kiln drying stage to achieve a low nitrosodimethylamine (NDMA) content.

BACKGROUND OF THE INVENTION

During the 1980s, brewers found in beer the presence of NDMA, a substance believed to be carcinogenic and mutagenic in humans. NDMA present in malt appears to be formed by the reaction of secondary and tertiary amines synthesized in barley during malting with the forms of nitrogen oxides (Ν0 _χ ) present in ambient air.

According to the cited authors, the largest precursors of NDMA are various types of amines.

T. WAINWRIGHT et al. in 1986, after numerous earlier work in a review article The chemistry of nitrosamine formation: relevance to malting and brewing, published in JOURNAL INST. BREW., Jan-febr. 1986, vol. 92, p. 61 assumes that the largest precursor of NDMA is hordenine and other secondary amines such as dimethylamine (DMA), sarcosine and gramin.

In 1985, published by MM MANGINO and RS SCANLAN under the title Nitrosation of the Alkanoids Hordenine and Gramine, Potential Precursors of N-Nitrosodimethylamine in Barley Malt in JOURNAL AGRIC. FOOD CHEM., 1985, Vol. 33, p. 705, clearly show the important role of gramin in barley in the phenomena of NDMA formation due to its great ability to nitrosate Ν0 _χ agents from air.

However, several authors report that the main precursor of NDMA in malt is dimethylamine (DMA), a secondary amine synthesized in barley roots during malting. The authors of the works published in 1981 by S.SAKUMA et al. in an article entitled Formation of N-nitrosodimethylamine during malt kilning, published in REPORTS RES. LAB. KIRIN BREWERY CO, 1981, Vol. 24, p. 20, report that there is a direct relationship between the amount of NDMA that is formed in malt and the amount of DMA from green malt and from NO _in air. Prior to a recent LJ YOO in a 1992 article entitled Precursors of Nitrosodimethylamine in Malted Barley. Determination of Dimethylamine published in JOURNAL AGRIC. FOOD CHEM., Vol. 40, p. 2224, confirms, based on the amounts of amines measured in the malt and the formation of NDMA after nitrosation, that DMA is the major precursor of NDMA and that its concentration in green malt allows the amount of NDMA potentially formed in kiln drying to be determined. Simultaneously in this article and in a follow-up article by B. POOCHAROEN et al., Entitled Precursors of Nitrosodimethylamine in Malted Barley. Determination of Hordenine and Gramine published by JOURNAL AGRIC. FOOD CHEM., Vol. 40, p. 2220, some of these authors strongly question the role of hordenine and gramin in forming NDMA in malt, which, according to recent data, suggests that the main precursor of NDMA is dimethylamine (DMA) formed in roots during germination of barley.

The currently widely used process for reducing NDMA content is the addition of sulfur in kiln drying as well as the use of low-NO ₂ burners or indirectly burners; various options are explained in an article by W. FLAD, entitled Minimizing nitrosamine formation during malt kilning, which was published in the November issue of BRAUWELT INTERNATIONAL in 1989.

However, such a process, in addition to satisfying in all cases, the fact that some of the industrial malt groups treated in this way still contain unacceptable doses of NDMA, is also unreliable, since the use of sulfur causes sulfur dioxide emissions during its combustion. The use of sulfur in the malting plant should be re-discussed in the short term due to environmental standards.

In the prior art, there is no industrially applicable method that avoids the use of sulfur and which results in low NDMA content without significant disadvantages in terms of the quality of the malt obtained and / or industrial use as such and / or efficiency.

Several methods have been proposed which use an additive compound, typically an acid after germination and immediately before drying in the kiln or during drying.

Article by William J. OLSON entitled Control of Malt N-Nitrosodimethylamine in Direct Kilning without Use of Sulfur Oxides published in MBAA TECHNICAL QUARTERLY, Vol. 19, no. 2, 1982 (pp. 63-67) contemplates adding phosphoric acid and sugar (dextrose or fructose) prior to kiln drying, resulting in NDMA contents that remain of the order of 2-3 µg / kg, with the addition of H ₂ PO ₃ alone gives malt with an NDMA content of 20 to 30 Mg / kg, and the sugar additive gives malt with an NDMA content of 5 to 8Ag / kg. This method leads to variable results, as reported by WJW LLOYDA and SJ HUTCHINGSA, entitled Suppression of NDMA Formation in Malt, published as a report by EBC Congress 1983 (pp. 55-62). Finally, the addition of phosphoric acid prior to kiln drying releases an unpleasant odor during drying, which makes industrial use of the process difficult.

Another method of acidification immediately prior to kiln drying is described in W. A. HARDWICK et al. under the title N-Nitrosodimethylamine in Malt Beverages - The Anticipatory Action by the Brewing Industry,

Toxicology and Pharmacology 2 (p

Inc., 1982. It consists in acidifying the grain surface to a pH of the order of 2.5 (page 54) so as to reduce the amount of NDMA. The phenomenon used consists in the freezing of hordenin, one of the potential precursors of NDMA, which, under these conditions, in its proton form is incapable of, or hardly capable of forming, NDMA in the presence of _{χ χ} . This technique did not seem to lead to industrial applications due to the reasons given in PA BROOKESA article The Effects of Nitrosodimethylamine published in Regulators 38-66), Academic Press

Palliatives on Mált Properties ”and published in JOURNAL of

INST. BREW., 1982, Vol. 88, p. 256-260, namely due to considerable handling and safety problems that would result in industrial scale use.

Another known means for reducing the amount of hordenin is to slow germination.

Such retardation can be achieved, according to the older method, by adding ammonium persulfate or NO ₂ after soaking and before germination or acidification by soaking to limit germination development or by selecting conditions (humidity, temperature, germination time) also to limit germination development.

The addition of ammonium persulphate or bromate during malting is reflected in the article by T. WAINWRIGHTA and D. D. O'FARRELL under the title Ammonium Persulphate in Malting: Control of NDMA and Increased Yield of Malt Extract at JOURNAL of INST. BREW., May-June 1986, Vol. 92, p. 232-238. This process, which has not been used on an industrial scale, requires the addition of gibberellic acid.

The use of steep water acidification to reduce germ growth is known from the following three articles by T. WAINWRIGHTA:

Nitrosodimethylamine: formation and palliative measures, published in INST Journal. BREW., 1981, Vol. 87, p. 264-265

N-Nitrosodimethylamine Precursors in Malt p. 71-80 (cited)

Nitrosamines in Malt and Beer, published by JOURNAL INST. BREW (1986) Vol. 92, p. 73 to 80.

It follows from these articles that any treatment, in particular suitable acidification during steeping, which limits the growth of the germ, reduces the amount of hordenine, a potential precursor of NDMA, mainly produced in this substance by a factor of about 10 and consequently the amount of NDMA formed in the finished malt.

But the last of these three articles (Nitrosamines in

Mált and Beer) states (p. 76, vol. 1, § 3 and 4) that all adjustments that may be considered to reduce the development of germ have negative effects on the quality of malt and are not directly applicable on an industrial scale.

For documentation purposes, it should be noted that non-industrially used methods using germ inactivation were proposed in the following two articles:

G. H. PALMER et al. Combined acidulation and gibberellic acid treatment in the accelarated malting of abraded barley published in J. Ins. Brew, Vol. 78, (1972) p. 81-83;

D. CRABB and G. M. PALMER The Production and Brewing Value of Malt made without Embryo Growth, published in ASBC Proceedings, 1972, p. 36 to 38.

These articles do not address the NDMA problem because, due to their earlier publication date, the problems caused by NDMA have not been identified. Their aim is to destroy the germ so that it does not develop roots and germs that would lead to loss of yield. The method envisages the addition of gibberellic acid. Abrasive barley should be used as the pericarp is impermeable to gibberellic acid.

The first article exemplifies the addition of H ₂ SO ₄ to the abrasive barley at 0.006N for the first steep and 0.0IN for the second steep as well as gibberellic acid (0.5 to 0.1 ppm) at the end of each steep. This results in the inactivation of the germ, reduction in the size of the roots (more than 70%), increase in the amount of soluble proteins, stimulation of the aleurone layer and increase in the amount of yield because the germ and its roots do not grow.

The second article relates to the destruction of the germ of abrasive barley with acid (not specified) to 0.02% with the addition of gibberellic acid to replace the acid that could be formed during normal germination.

These processes, which require a phase of abrasion of barley, an addition of gibberellic acid and which, moreover, lead to an increase

- 6 amounts of soluble proteins are also not suitable for industrial use.

French patent FR-1 360 637 (STAUFFER CHEMICAL COMPANY) relates to a malting process which provides malt with a more vivid and attractive color, allowing reduced development of roots during germination. It uses acidic steeping in a typical ratio of 1 liter of water per 100 grams of barley, the initial pH of steeping varies between 1.7 and 2.4. Such volume ratios between the soaking water and the amount of barley result in the pH of the soaking water being long equal to the initial pH. Since the barley remains at a low pH (42.3) for a very long time, this results in a delay in germination, which is associated with the aforementioned disadvantages.

It follows from the foregoing that there is currently no known process, applicable on an industrial scale without major or minor disadvantages, which would make it possible to obtain malt with a low NDMA content without adding sulfur during kiln drying.

SUMMARY OF THE INVENTION

The present invention is intended to solve this problem and therefore relates to a process applicable on an industrial scale and in particular to obtain malt with low NDMA content.

The basic idea of the invention is that it is possible to control acidification during steeping so that germination is not at all or only slightly altered, acting on a mechanism which results in small amounts of NDMA after drying in the kiln without affecting the malt or industrial use properties or reducing efficiency .

The process according to the invention is characterized in that the steeping stage comprises at least one acidic steeping sub-stage, which is carried out at a pH which after stabilization is in the range of 3.5 to 4.6 at ambient temperature, the ratio between the steeping water volume and the amount of barley being chosen so that the activity of the grain during germination is not substantially altered under otherwise identical circumstances. This makes it possible to take into account the dampening effect of barley.

The germination of barley is only affected by its pH values

- 7 little or not at all, while eg. A pH of 3 after stabilization would result in a significant modification of the germination and hence the quality of the malt. The malt obtained according to the present invention has a low NDMA content, e.g. less than 2 µg / kg and preferably less than ljug / kg.

According to a preferred embodiment, said stabilized pH is between 3.8 to 4.6, preferably equal to 4.5. The results obtained according to the invention are practically the same, e.g. for a pH of 3.5 to 4.5 and it is nevertheless desirable to work with the highest value which corresponds to the addition of the smallest amount of acid with the same volume of steeping water.

The acid used may be hydrochloric acid and / or phosphoric acid.

Said ratio between the steep water volume and the amount of barley is preferably between 0.8 1 to 1.2 L per kg of barley and preferably equal to about 1 L of steep water per kg of barley.

The at least one soak sub-stage is preferably between 4 and 6 hours in length.

In all cases, a decrease in soluble proteins is observed (reduction of the Kolbach index), but in the case of phosphoric acid, the advantage is also a significant decrease in the mash viscosity, which causes substantially a decrease in the malt-soluble glucan content. It can be observed that if the phosphoric acid is used cold during steeping, there is no odor problem and handling difficulties which have been raised above in the case of phosphoric acid addition during kiln drying.

The acid may be added to the soaking water during each of the soaking sub-stages.

According to a preferred variant, the soaking stage comprises three sub-stages and the acid is added to the soaking water during the first and second of these sub-stages.

The invention also relates to malt obtained with considerable germination stimulation, characterized in that it has a yield of between 81% and 82% of dry matter (S), a soluble protein content of between 4 and 5%, a viscosity of between 1.4 and 1.5 mPas, > 72%, NDMA content <10θ and optionally soluble β-glucans content of 4 200 mg.

Other features and advantages of the invention will become more apparent from the description that follows, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows two major hypotheses of NDMA formation in malt, published in the literature, and at the same time NDMA formation from DMA formed during germination and from DMA formed by successive nitrosation of hordenine and nitrosohordenine during kiln drying.

Fig. 2 shows in a comparative manner the development of the pH during steeping according to French patent 1 360 637 and according to the invention.

Fig. 3 illustrates in a comparative manner the filterability of the test malts and the comparative sample according to TESTS 8 and 9 and TEST II.

Tables 1 and 2 represent the results of Tests I below.

Tables 3 and 4 represent the results of TEST II below. Table 4 shows the significant effect of stimulation in acid germination germination on malt quality.

Table 5 presents the results of TEST II below.

DETAILED DESCRIPTION OF THE INVENTION!

The invention has been applied to several series of experiments carried out in a micro-malt and on an industrial scale.

TEST I: COMPARISON OF HCl / H ₃ PO ₄

Barley varieties

Three brewing varieties were tested under micro-malting conditions. In all cases they were spring varieties Printemps

ALEXIS, VODKA and NOMAD).

Micro-sweetening procedure Dipping

Stored barley at 13 ° C is subjected to three successive soaking, interrupted by two cycles of wind- nia grains. first soaking 6 hours Low: 14 ° C first ventilation 14 hours Deň: 18 ° C second soaking 5 hours Low: 14 ° C second ventilation 13 hours Deň: 18 ° C third soaking 2 hours Low: 14 ° C In acid soak tests it is added hydrochloric acid (HCl) and acid phosphoric (H ₃ PO ₄ ) for the first two Macan: - HCl test (37%) pH 4.5 after stabilization - HCl test (37%) pH 3.5 after stabilization - Test H ₃ PO ₄ (85%) pH 4.5 after stabilization - Test H ₃ PO ₄ (85%) pH 3.5 after stabilization Soaking is done in ratio of approximately 1 1 steep water on kilogram of barley. germination This stage that takes 96 hours can be divided into three different stages * Phase 1 14 hours Deň: 18 ° C Phase 2 2 hours Deň: 18 ° C Phase 3 80 hours Low: 14 ° C Wood drying Sprouted barley with drying in the micro-malt temperature. Phase 1 3 Hours 68 ° C

2. phase 2 hours 65 ° C 3. phase 2 hours 68 ° C 4. phase 2 hours 73 ° C 5. phase 1 lesson 78 C 6. phase 2 hours 80 C 7th phase 6 hours 83 C

After drying in the kiln and before storing the malt, the roots are removed from the grain by mechanical impact.

Industrial kiln drying

Section. ALEXIS green malt varieties were harvested and dried in micromalt industrial scale without the combustion of sulfur (S0 ₂₎ in order to promote the formation of NDMA precursors present in the green barley.

The green barley is dried by direct heating with a low content of Ν0 _χ on two round shelves.

The first stage is carried out on the upper shelf of the kiln for 20 hours. The initial temperature of 55 ° C is increased to 68-70 θ during this cycle, resulting in a reduction in grain moisture from 42% to 10%.

The second stage is done on the bottom shelf. The stage consists of 3 phases. Gradual temperature rise for 12 hours to 75 ° C, stop heating at 80 ° C for 4 hours, then cooling the grain for 4 hours. During this second stage the grain moisture suddenly drops from 10 to 4%.

Malt analysis

Classic parameters

The main malt quality criteria (yield, viscosity, Kolbach index, diastatic power, pH, soluble / 3-glucan) were measured by the methods described in Analytica-EBC. The dried malts were then analyzed under micro-malting conditions.

Dosage of nitrosodimethylamine (NDMA)

The NDMA contents were measured on malts dried in an industrial kiln and after the roots were separated.

NDMA was obtained by extracting 15 g of malt in 100 ml of distilled water at 50 ° C for one hour with gentle stirring. After extraction with dichloromethane in a Chemelut tube, the yield is concentrated to 0.5 ml with dichloromethane (DCM), and 10 µL is injected into a CPG / TEA (Thermal Energy Analyzer) system.

The NDMA content is calculated compared to the calibration performed on a malt sample containing increasing amounts of NDMA.

Nitrosodipropylamine (NDPA) is added as an internal standard for analysis.

THE RESULTS

NDMA content in malt (Table 1)

Regardless of the acid used (HCl or H ₃ PO ₄ ) and acidity, the NDMA contents generated at the time of drying the green malts (ALEXIS) on the kiln are lower than the NDMA contents of the untreated comparative sample. NDMA values in finished malt are lower by a factor of more than 2.

Soluble proteins (Table 2)

The soluble protein content (Kolbach index) in the experiments is lower than the values of the reference sample irrespective of the variety of the barley examined, the pH and the acid used.

Soluble β-glucan contents (Table 2)

The acidification of the steeping water causes a decrease in the soluble malt glucan. This phenomenon is particularly significant when H ₃ PO ₄ is used, which allows the reduction of 15 to 50% soluble β-glucans depending on the variety.

Viscosity (Table 2)

The decrease in viscosity is significant in all cases using phosphoric acid.

- 12 mash pH (Table 2)

The acidification during malting results in a small drop in pH (0.2 0.1 pH) of the mash produced from malt.

Diastatic power. (Table 2)

Diastatic cardinality is influenced by the type of acid and acidity, without being able to be regulated by general regulations, as this phenomenon is variable depending on the variety.

The other malt quality criteria analyzed remain largely unchanged.

CONCLUSION

This study shows that the reduction of NDMA formation in malt by acidification of steeping water is not limited to the use of hydrochloric acid (HCl). The use of phosphoric acid (H ₃ PO ₄ ) in steeping allows a reduction in the equivalent content of NDMA formed in the finished malt.

On the other hand, a stronger acidification (stabilized pH equals 3.5) does not provide advantages compared to acidification consisting in regulating the dipping water to stabilized pH 4.5.

Taking into account the other malt quality factors, the positive impact of the use of H ₃ PO ₄ or HCl in steeping on the overall malt quality is evident from our study. First of all, we observe a decrease in soluble protein content (breeding index). Second, in these tests is a malt viscosity. The pH values of mash and cardinality are also influenced by malt (Collapsing decrease of soluble β-glucan values of diastatic acidification of steeping water.

The above statements make it possible to consider such germination to obtain soluble protein contents (Kolbach index) identical to the reference sample. This could lead to an increase in the yield of malt allowing higher yield values in the brewhouse. In this case the other malt parameters would remain unchanged.

TABLE, 1Α 1

Samples Contents of NDMA malt 10 ⁹ Comparative sample 1.8 test HCI. pH 4.5 0.7 HCI. pH 3.5 0.8 H ₃ PO ₄ . pH 4.5 0.7 H ₃ PO ₄ . pH 3.5 0.8

TABLE 2

Variety parameters units Comparative sample HCl pH 4.5 HCl pH 3.5 H3PO4 pH 4.5 H3PO4 pH 3.5 ALEXIS humidity % 4.5 4.4 4.3 4.2 4.2 yield % MS 81.1 81.1 81.6 81.4 81.6 Proteiny celkove % MS 11.7 12 11.9 12.3 11.7 Soluble proteins % 4.6 4.1 4 4.3 4.2 Kolbach index % 39.3 34.2 33.6 35 35.9 viscosity m Pa.s 1.63 n n 1.49 1.53 Soluble Zi-glucans mg / 1 357 358 333 249 n pH diastatic 5.89 5.69 5.82 5.75 5.81 cardinality (D.M.) WK 308 297 286 350 286 NOMÁD humidity % 4.4 4 4.4 4 4.1 yield % MS 82.5 82.5 82.4 83 82.7 Proteiny celkove % MS 9.8 9.9 10 9.8 9.9 Soluble proteins % 3.9 3.6 3.6 3.7 3.8 Kolbach index % 39.8 36.4 36 37.8 38.4 viscosity m Pa.s 1.69 n n 1.61 1.65 Soluble / 3-glucans mg / 1 366 378 328 318 n PH diastatic 6.01 5.8 5.9 5.88 5.9 cardinality (D.M.) WK 140 96 97 96 82 VODKA humidity % 4.5 4.4 4.8 4.2 4.3 yield % MS 81.4 81.6 81.8 81.8 81.9 Proteiny celkove % MS 10.4 10.6 10.5 11 10.6 Soluble proteins % 4.4 3.6 3.7 3.6 3.9 Kolbach index % 42.3 34 35.2 32.7 36.8 viscosity m Pa.s 1.61 1.61 1.55 1.51 1.59 Soluble / 3-glucans mg / 1 405 380 230 192 n PH diastatic 5.96 5.85 5.89 5.86 5.85 cardinality (D.M.) WK 286 200 176 261 197

n - not determined

TEST II

Barley varieties

Four breeding barley varieties (TESTS 1 to 5) in the industrial range (200 tonnes of malt) were tested. Two are spring varieties (PRISMA and ALEXIS); two of the varieties are winter, (CLARINE and PLAISANT).

Malting procedure

maceration

Barley stored at 13 ° C is exposed to three consecutive soaks interrupted by grain ventilation cycles.

To 240 tons of barley is added 250 m ^ of water heated to 12 ° C. After six hours, the water from the first soaking is drained and the grain is ventilated for 11 hours at 20 [deg.] C. with air. At this stage, the grain moisture is between 26 and 28%.

The second soaking is carried out with the same volume of water for three hours, followed by a ventilation cycle of 8 hours at 16 ° C. At this stage the grain moisture is 35-37%.

The last soaking is immersion under water for two hours, followed by 3-4 hours of ventilation at 16 ° C.

In the last stage of the steeping the grains reach the humidity of the order of 40 - 42%.

The hydrochloric acid for testing (acid soaking) is pumped from the storage tank and mixed with the water supplying the soaking pot. ι,

germination

This stage is carried out for 5 days in circular compartments stacked in a vertical malting tower-type device and the grains are turned every eight hours to homogenize the germination.

At the start of germination, the soaked barley is moistened to achieve 43% moisture in the grain. The supply air temperature is controlled at 15 ° C.

Wood drying

The germinated barley (green malt) is transported from the germinating shelter to the kiln, where the green malt is dried by direct heating with a low content of Ν0 _χ on two circular shelves.

The first stage is done on the upper shelf of the kiln for 20 hours. The initial temperature of 55 ° C during this cycle is raised to 68-70 ° C, which has the effect of reducing grain moisture from 42% to 10%.

The second stage is done on the bottom shelf. The stage consists of three phases. Gradual temperature rise over 12 hours up to 75 ° C, stop heating at 80 ° C for 4 hours, then grain cooling phase by venting for 4 hours. During this second stage the moisture, grains will drop from 10 to 4%.

In the case of comparative samples which were run in parallel with each test, 75 kg of sulfur was burnt during kiln drying.

After drying in the kiln and before storing the malt, the roots are separated from the grain by mechanical impact. NDMA determination is performed after root separation.

Determination of nitrosodimethylamines

NDMA are obtained by extracting 15 g of malt in 100 ml of distilled water at 50 ° C for one hour with gentle stirring. After extraction with dichloromethane in a Chemelut tube, the yield is concentrated to 0.5 mL with DCM, and 10 µL is injected into a CPG / TEA (Thermal Energy Analyzer) system.

The NDMA content is calculated compared to the calibration performed on a malt sample containing increasing amounts of NDMA.

For analysis, NDPA is added as an internal standard.

THE RESULTS

The observations made in the micro-malt house (TEST I) are also valid for industrial use (200 t). The use of acid in steeping water makes it possible to obtain malt with a low content of nitrosamines of the same quality as the malt of the comparative sample, treated with sulfur, see Tab. Third

This was verified in five industrial trials with different barley qualities (winter / spring).

The application of different doses to different steeping shows that the use of acid in two different steeping is sufficient. By volume, it can be considered that approximately 500 L of acid added to the soaking water makes it possible to achieve the target.

With these volumes of acid and with about 1 l of soaking water per kilogram of barley, the pH of the soaking water after homogenization and the pH equilibrium is between 3.8 to 4.1 for the first soaking and between 3.8 to 4.6 for the second soaking.

The low-acid test (TEST 4 of Table 3) shows the need for a minimum amount of sulfur-free steeping acid for kiln drying. With such a dose of acid, the pH of the first and second soaks are in equilibrium of 5.1 and 4.8.

In parallel to the nitrosamine criterion, other malt quality criteria were observed. The values of some of them differ between the test and the reference sample (see Table 3).

First, the amount of sulfur dioxide is very small in the malts from the trials compared to the malt of the reference sample. Of course, this is associated with the fact that sulfur was not used in the kiln drying for the tests.

Secondly, the β-glucanase activity level is always greater than or equal to 400 IRVU for the tests, while for some comparative samples the order of 300 IRVU. These figures give an idea that acid stimulates the formation of hydrolases when classical storage conditions would not allow grain to fully demonstrate its potential.

At the same time, the assays in the assays help to reduce the Kolbach index, which is manifested by a low amount of soluble proteins.

Finally, in certain cases it helps to reduce the viscosity of the malt from the trials.

The other malt quality criteria remain overall

- 17 unchanged.

To confirm the sharp decrease in soluble protein content from the tests during these industrial verifications, we wanted to verify in TEST II whether the soluble protein content could be restored by greatly stimulating germination of the test.

For this reason, we conducted an experiment (TESTS 6 to 9 compiled in Table 4) with two choices. Option 1 (TESTS 6 and 7) consists of adding Gibberellic acid (30 mg / tonne) to the germination test. Option 2 (TESTS 8 and 9) consists in extending the period of five hours of the last soak aeration phase during the test. In the latter case (option 2) we observed malt properties at four and five days of germination. In both options, the amount of acid added corresponds to the amount used for Test 3 (400 and 150 L). The results are shown in Tab. 4th

The results of these additional tests confirm what has been said previously, namely, a significant increase in the yield of malt during the recovery of the soluble protein value by a significant phase of germination. This increase is ranked among the stages of the yield step of the test.

There is also a more noticeable decrease in viscosity than that observed in previous tests. This difference in viscosity is associated with better degradation of cell wall components, which results in increased cytolytic activity. For example, the malt soluble β-glucan contents of the assays are reduced by exhibiting higher endocellulase and glucanase activities in these malts than in the malts of the comparative samples.

This property has a significant effect on the quality of mash filtration in fermentation barr, described by GRANDCLERC, J. et al., 1988, in the Simplification of the Brassin Filtration TEPRAL, description and measurement, published in the French journal BIOS n ° 19, p. . 88-92. When comparing the 50/50 mixture of IRANIS test malts from TESTs 8 and 9 with the 50/50 malt mixture of the comparative samples of TESTs 8 and 9, a distinct difference in filtration behavior is observed. During the first 300 seconds of the test, stimulating 0.4 to 1.3 fig. 3, (PHASE I) is the gravity filtration and at the end of the test,

T = 300 s, filtration is performed at a pressure of 1 bar. Fig. 3 shows this fact showing a marked improvement in the filtration rate in the case of the test mixture mainly in Phase II compared to the malt mixture of the comparative samples.

At the same time, a better homogeneity of the maturation of the malt can be observed in all cases. Finally, the qualitative properties of malt associated with this type of malting are very significant in the observation of malts formed after 4 days of germination (TEST 8). The use of acidic steeping makes it possible, after four days of germination, to produce malt of the same quality as that produced in five days under standard malting conditions.

On the other hand, the physiological changes associated with acidic steeping make it possible to limit grain breathing, which leads to an improvement in malting efficiency by approximately one point (%).

CONCLUSION

The object of the study has been achieved - the use of acid in soaking makes it possible, on an industrial scale, to limit the formation of nitrosamines in malting without sulfur in kiln drying.

The malts produced under these conditions are the same in quality with in all cases a lower amount of sulfur dioxide with a constant content and high β-glucanase activity.

In some cases, these malts are also characterized by a lower Kolbach index and lower viscosity.

In tests for the recovery of soluble protein content with significant stimulation of germination, we found, in comparison with the comparative sample, that in parallel to mastering NDMA, accepting such conditions would allow a significant increase in malt yield and a large decrease in soluble β-glucans and mash viscosity. These observations of soluble protein content, which are identical to those measured on the comparative sample, suggest that the method of claimed malting not only allows for the management of the content produced by NDMA, but also the production of malt of generally better quality.

Effect of the ratio between the volume of steeping water and the volume of processed barley

Fig. 2 shows the change in the pH curve during the first six hours of soaking. The tests STAUFFER A and STAUFER B correspond to the extreme conditions of patent FR 1 360 637 (page 2, left column), namely soaking water containing 0.1% acid for test A and 1% acid for test Have 10 volumes of water per one volume of barley, (ie liter of steeping water per 100 g of barley). The test according to the invention corresponds to a dipping water containing 0.2% of acid, i. 400 liters of acid per 200 tonnes of test water corresponding to 200 tonnes of grain.

The pH values recorded during the soaking are shown in FIG. 2 and correspond to the following table:

T (h) STAUFFER A STAUFFER B AN EXAM COMPARATIVE SAMPLE 0.25 2.3 1.3 2.67 7.4 0.5 2.28 1.3 3.15 7.45 0.75 2.35 1.31 3.4 7.45 1 2.37 1.23 3.6 7.5 1.5 , 2.39 1.23 3.72 7.4 2 2.4 1.24 3.8 7.5 2.5 2.4 1.25 3.85 7.45 3 2.4 1.23 3.88 7.45 3.5 2.42 1.23 3.92 7.5 4 2.41 1.25 3.95 7.45 4.5 2.42 1.26 3.96 7.4 5 2.44 1.22 3.98 7.4 6 2.45 1.22 4.05 7.4

In the STAUFFER A and STAUFFER B tests, it is water with the addition of acid that affects its pH. During the first six hours of soaking, the pH remains once below 2.5 and then below 1.3. In the TEPRAL assay, the initial pH is 2.67, but is about 3.5 at the end of one hour. At the beginning of six hours, the final value was 4.05. Thus, at the water volume / weight ratio of the selected grain per test, there is a significant barley-inhibiting effect which makes it impossible to avoid that the grain is not held for too long at too low a pH. In this way, interruption of the physiological activity of the grain during germination is avoided. The pH changes only slightly during most of the soaking sub-stage.

Table 3: Impact of acidic steeping on overall malt quality

parameters TEST 1 PRISMA TEST 2 ALEXIS TEST 3 ALEXIS TEST 4 CLARINE TEST 5 PLAISANT

OLUTION E T E T E T E T E T Vol.Hcl VI 1 250 0 350 0 400 0 250 0 400 0 V2 1 250 0 170 0 150 0 125 0 150 0 V3 1 250 0 0 0 0 0 0 0 0 0 analysis malt yield % MS 81.4 81.3 82.5 83.1 82.1 82.9 80.3 79.6 80.2 79.8 Kolbe % 37.8 40.2 34.7 38.6 37.2 38.3 30.3 30.9 37.2 43.4 protein % 4.2 4.3 3.4 3.6 3.5 3.6 3.3 3.4 4.1 4.9 soluble Hartong 45 % 38.0 33.0 36.5 34.0 35.0 38.0 28.5 26.0 34.0 41.0 diastatic WK 220 200 200 190 250 250 180 190 330 350 mightiness viscosity mPas 1.46 1.46 1.59 1.65 1.51 1.58 1.58 1.60 1.51 1.52 NDMA ppb 0.5 0.5 0.5 0.8 0.9 0.5 1.7 0.8 1.4 1.2 (10- ³ ) SO2 PPm (IO ' ⁶ ) 7.0 27.0 6.0 10,0 3.0 22.0 3.0 7.0 2.0 32.0 Soluble β-glucans mg / 1 44 85 80 45 140 160 493 550 130 140 / 3-glucanase iRVU 480 300 400 330 420 400 400 300 440 430

E - Test

T - Comparative sample

Table 4:

Impact of significant germination stimulation on malt quality after acid steeping

• Parameters TEST 6 TEST 7 TEST 8 TEST 9 PRISMA PRISMA Irani Irani Malting conditions Gib +30 Gib +30 4 days 5 days

units E T E T E T E T analysis malt yield % MS 80.9 80,4 80.8 80,4 80,4 79.9 81.9 80.6 homogeneity % 72 65 75 65 84 57.0 84 77 protein soluble % 4.6 4.4 4.3 4.4 4.9 4.9 5.0 5.0 Hartong 45 % 38.1 35.8 36.1 35.8 43.2 42.2 46.1 42.9 diastatic power WK 270 260 230 260 300 290 290 310 viscosity m Pas 1.50 1.59 1.49 1.59 1.46 1.52 1.46 1.50 NDMA ppb (10 ³ ) 1.6 0.9 1.2 0.9 0.2 0.2 0.1 0.2 soluble / 3-glucans mg / 1 195 240 190 240 100 180 70 130 β-glucanase U / kg n n n n 357 286 411 355 endocellulase mU / g n n n n 499 332. 591 415

E - Test

T - Comparative sample

- 23 TEST III: MECHANISM OF THE EFFECT OF ACID FOR THE NDMA CONTENT

Barley varieties

Samples of germinated barley were taken at the end of the germination phase and before drying on kiln (green malt) in the case of industrial test TEST 3, tab. 3 (ALEXIS) and in case of micro-sweetening of VODKA and NOMADS, tab. 2. In each case, the green malt of the reference sample, untreated and the acidic steeping malt, were harvested.

Malting procedures

The conditions for malting these samples are summarized in the description of Tests I and II described above.

Analysis of green malts

Several potential green malt NDMA precursors were analyzed:

hordenin and gramin by P.T.

Hordenine INST. BREV methods published in 1981 by T. WAINWRIGHT in an article entitled is the precursor of NDMA in malt, in JOURNAL vol. 87, p. 260th

sarcosine is extracted under similar conditions to hordenine, esterified with fluorinitrobenzene (FNNB) and analyzed by HPLC

- dimethylamine (DMA) was extracted with methanol, derivatized with fluorinitrobenzene (FDNB) and analyzed by HPLC according to a method published in August 1991 in VEREIN DEUTSCHER INGENIEURE under the title Determination of aliphatic amines by HPLC.

The green malt content of NDMA was determined in accordance with the method described in TEST I. In addition, the visual examination of green malt was made with an estimate of the effect of acid on the growth of leaf roots and germs, substances that are predominantly involved in the formation of amines, NDMA precursors.

- 24 ’

THE RESULTS

Concentrations of secondary amines (DMA, sarcosine) and tertiary (hordenine, gramin) measured in green malt collected prior to kiln drying are expressed in parts per billion ppb on a dry weight basis and are shown in Tab. 5th

The results show that gramin and sarcosine are in very small amounts in green malt and that only hordenine and dimethylamine are present in measurable amounts. In the case of industrial malt, the concentrations of the two amines are two to ten times higher for hordenine and DMA compared to the mean values of the two malt analyzed from the malt.

If we look at the green malt hordenin concentration, we can see that the amount of hordenine produced during germination is 50-100% lower in the sample from the acid test compared to the comparative sample for the malt from the micro-malt, and is formed at the same level in the sample and a sample from the acid malt test for industrial malt (ALEXIS).

In the case of DMA, the malt values from the malt and industrial malt are more consistent with each other than in the previous case. In all cases, the concentration of the acidic dipping test sample DMA is lower by an order of magnitude of 4 relative to the reference sample. In the case of the NOMADE test, the measured samples show that the amount of DMA green malt from the acid soak test is 10 times lower than that measured in the reference sample.

The use of acid in steeping has no significant effect on the amount of NDMA formed during germination, nor on the size of roots and germs formed during grain germination.

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CONCLUSION

This study clearly shows the role of the acid used in steeping on the amount of NDMA precursors present in the grain at the end of germination.

The amine values measured in this study show that the steep acid additive significantly reduces and reproduces the amount of DMA present in green malt.

The lower availability of this secondary amine in green malt, which is considered to be one of the major precursors of NDMA, therefore logically leads to a reduction in NDMA formation during roz0 _χ induced nitrosation during kiln drying, allowing sulfur elimination during this last stage of malting while keeping standards. required for NDMA.

The effect of acid on hordenine content in green malt is less significant and reproducible from one test to another, suggesting that reducing the NDMA content by acidifying the soaking water is essentially associated with a reduction in green malt DMA in this malting process.

This mechanism of acid action differs from that associated with a decrease in the growth of substances (germ, roots) and the amount of hordenin cited by WAINWRIGHT et al. in Nitrosamines in malt and beer, in JOURNAL INST. BREW., 1986, Vol. 92, p. 76; the addition of acid to the soaking carried out according to our conditions has no significant effect on the size, roots and seeds of the leaves developed during malting or on the amount of hordenin formed.

At the same time, additional malting tests designed to recover protein contents lower than those of the tests allow the conclusion that the acidification of the grain during steeping causes physiological phenomena leading to malt of higher quality than that of the reference sample. The use of steeping acid in conjunction with considerable grain stimulation during germination makes it possible, on the one hand, to produce malt with a high yield and low viscosity, while managing the content of soluble proteins produced, and on the other hand, applying these malting conditions.

- 27 to produce the same quality in four days of germination of malt as is achieved in five days of germination under standard conditions.

Finally, the use of this method and the physiological phenomena it causes brings about an increase in efficiency in the malt house.

Claims (13)

PATENT CLAIMS 1. A process for malting barley, comprising a steeping, germination and kiln drying stage, characterized in that the steeping stage consists of at least one acidic steeping sub-stage, carried out at a pH between 3.5 and 4.6 after stabilization, wherein the ratio between the steeping water volume and the amount of barley is selected such that the grain activity during germination is not appreciably changed. 2. A method of malting comprising 3.8 to 4.6. The barley of claim 1, wherein said stabilized pH is between The barley malting process according to claim 2, characterized in that it comprises two acidic steeping sub-stages and wherein said stabilized pH is between 3.8 to 4.1 during the first sub-stage and 3.8 to 4.6 during the second sub-stage. Barley malting process according to claims 1 to 3, characterized in that at least one acidic steeping sub-stage is carried out with a ratio of 0.8 to 1.2 liters of steeping water per kg of barley. The barley malting process according to claim 4, wherein said ratio is about one liter of steeping water per kg of barley. Barley malting process according to any one of the preceding claims, characterized in that the at least one steeping sub-stage lasts 4 to 6 hours. Barley malting process according to any of the preceding claims, characterized in that the acid is added to the steeping water during each of said steeping sub-stages. Barley malting process according to one of claims 1 to 6, characterized in that the steeping step consists of three sub-stages and that the acid is added to the steeping water during the first and second of these sub-stages. Barley malting process according to any one of the preceding claims, characterized in that said acidification is carried out with hydrochloric acid. Barley malting process according to one of claims 1 to 8, characterized in that said acidification is carried out with phosphoric acid. Barley malting process according to any one of the preceding claims, characterized in that the germination stage is stimulated compared to standard germination to recover the soluble protein content to a level approximately equal to that obtained from the same barley variety without acidic steeping and exposed mentioned standard germination. 12. Malt having: - yield between 81 and 82% dry matter - soluble protein content between 4 and 5% a viscosity between 1.4 and 1.5 mPas - aging homogeneity> 72% - NDMA content <10 ^- ^ Malt according to claim 12, characterized in that it has a soluble glucan content of less than 200 mg / l.