FR2717494A1 - Use of Geotrichum candidum in the prodn. of malt from barley - Google Patents

Abstract

Use of microorganisms of the family Geotrichum candidum in the process to convert barley into malt, to control the development of flora which can contaminate and colonise the grain, is new.

Description

 The invention relates to the application of a given microorganism in the process of processing barley into malt for the control of the development of the microflora able to contaminate and colonize the grain.

 The present invention will find application in the field of malting and, therefore, to brewers-maltors.

 It should be noted that barley, even before undergoing the various processing and processing operations at a malting unit, is naturally contaminated by many micro-organisms.

thus, barley is the natural host of a large and diverse flora that is composed. mainly bacteria, yeasts and filamentous fungi. In fact, this flora contaminates and colonizes the barley grain both in the fields and during storage. The nature and number of these microorganisms depend, of course, on culture conditions and climate, as well as the duration and storage conditions.

 The various analyzes carried out on these micro-organisms from the fields made it possible to list around a hundred or so species.

 Tou.efois. the most common molds are ALTERNARIA, CLASDOSPORIUM and FUSARIUM.

 It has also been observed that in the case of late harvest or when it is carried out in wet weather, the barley grains show considerable contamination by FUSARIUNI. As for the flora that contaminates and colonizes the barley grains during storage, so before malting, it is composed of filamentous xerophilous fungi. Here again, the study of these filamentous fungi made it possible to highlight that the predominant species are ASPERGILLUS and PENICILLIU;

 In the end, the problem lies in the fact that the various operations of transforming the barley into malt are carried out under conditions that favor the development of the microflora previously present on the barley. Effectively. we find malting conditions, especially in terms of humidity, temperature, nutrients or in terms of residence time in different reactors, which ultimately allow bacteria and yeast to to multiply in a scale ranging from 102 to 104 without counting a significant development of molds.

In this connection, it is advisable to recall the different stages of the malting process. Specifically, after preparation of the grain, it undergoes a tempering peration lasting about forty hours, in order to achieve a contribution of: 35 to 45 o humidity. Then follows the germination for a period of about six days at a temperature of about 16 '. After that we proceed to the kilning which consists of drying the grain at different temperature levels, it evolves between 50 'and 80'
Celsius approx. It follows the degerming and storage of malt finally obtained.

 This uncontrolled development of the microflora is a disadvantage in that it influences the quality of the malt and, ultimately, the resulting beer. In fact, it is at the origin of a production, and of germination. Moreover, it results in the production of undesirable enzymes such as lipases, oxidases, proteases, etc.

Some of these superabundant microorganisms also cause undesirable flavors. The beer finally obtained can, thus, present a taste of musty or earth or oxidized.

 Generally. in the field of the brewery. there is a fear of the phenomenon of spraying which, as its name indicates, consists in the fact that the sour spurts out of the bottle at the moment of opening, because of the instability of the carbon dioxide. In fact, it is specific microorganisms that are at the origin. It is therefore advisable to avoid their presence or at least that their quantity does not exceed a given threshold.

Now, the only way to achieve certain results in this way is to avoid the significant development of the microflora and, therefore, the precursors to the spraying, produced especially by USARlUM.

 To this it can be added that the presence of certain microorganisms such as bacteria of the type PEDIOCOCCGS has consequences on the filtration rate of the mash and leads to a rapid clogging of the filters.

 However. the major disadvantage encountered through the extensive development of molds, consists of a considerable increase in the risk of mycotoxin formation knowing that toxicogenic molds are naturally present on barley.

 In fact, despite the aforementioned drawbacks, this development of the microflora is hardly controlled in malting. The fault lies in the lack of effective means for this control.

 Thus, only a disinfection operation is performed at the time of quenching. this by the addition of bleach or milk of lime. While the addition of such disinfectants has little influence on the microflora, it is nonetheless a risk for some malting operations.

In particular, in case of exceeding specific doses, these disinfectants represent a risk for the germination of barley grain and false taste in beer.

 Finally, the present invention aims to remedy all of these disadvantages by avoiding the development, more particularly, of the undesirable microflora, this through the seeding of a specific microorganism that has been selected because of the conclusive results. that it helps to get.

 So. The invention relates to the application of a microorganism of the family Geotrichus Candidum in the process of converting barley into malt for the control of the development of the flora able to contaminate and colonize the grain. .

 In addition, according to the invention, selected strains of GEOTRICHUM CA.X-DIDI; 3I are seeded during malting, either in the form of a pure culture or in the form of a mixed culture in association with one or more other microorganisms. .

 According to the invention, the seeding of GEOTRICHUM CANDIDUM is carried out in proportions of between 105 and 109 colony-forming units (CFU) per kilogram of barley, so as to obtain the desired result, namely the control of the development of the microflora of barley.

 The advantages obtained by virtue of this invention consist, essentially, in that the GEOTRICHUM CANDIDUM has an inhibitory effect on unwanted flora such as USARIUM, PENICILLIUM, ASPERGILLUS, besides it makes it possible to inhibit the production of secondary metabolites of undesirable flora, such as mycotoxins and gutting precursors.

 It should be noted, moreover, that this improvement in the sanitary state of the malt is accompanied by qualitative contributions, since we obtain, through this seeding of GEOTRICHUM CANDIDUM, a reduction of the fatty acids of the mutant. are often responsible for problems of false taste in beer, such as the taste of oxidized, and poor behavior of the foam. In addition, the inhibition by GEOTRICHUM CANDIDUM of certain flora responsible for the synthesis of polysaccharides leads to an improvement from the point of view of the kinetics of filtration.

 Finally, by the use of certain strains of GEOTRICHUM CANDIDUM it is possible to promote the development of lactic acid bacteria which are able to enhance the inhibitory effect of unwanted flora and improve the quality of the malt by a natural lowering of the pH .

 Other objects and advantages of the present invention will become apparent from the following description describing the seeding methods of GEOTRICHUM C.A1N-DIDUNI.

The understanding of this description will be facilitated by reference to the attached drawing and in which
- Figure 1 shows the main stages of the malting; moreover, arrows represented the steps during which seeding of selected microorganisms can be carried out.
FIG. 9 shows the evolution of the lipase activity during malting according to whether or not controlled seeding of GEOTRICHUM CA.NDIDliNI:
FIG. 3 is a diagram illustrating the kinematics of filtration according to whether or not there is seeding of GEOTRICHUM CANDIDUM
The present invention aims to intervene in the malting process to improve the health and quality of malt finally obtained.

FIG. 1 schematically illustrates the six steps I, II, III, IV,
V, VI I which define this malting process. Thus, after preparation of the grain corresponding to the first stage I, the barley undergoes a quenching operation which consists of immersing the barley in the water in order to increase its moisture content so that it reaches 35 to 45%. . Note that during this quenching operation, the water is renewed one or more times, to ensure a washing action and oxygenation of the grain.

 After this second stage II, the barley thus moistened, goes to stage III which is that of germination. It follows the kilning (step IV) which consists of drying the grain by subjecting it to temperature levels between o0 'Celsius and 80 Celsius and respecting, at each level, drying times determined.

 Then comes step V which consists of degerming. The resulting malt is then stored which constitutes the last stage VI of this malting process.

 It is easy to understand that the supply of moisture, the residence times and the temperatures to which barley is subjected during these different stages constitute favorable conditions for the development of the microflora present on the grain before malting.

 The present invention aims to prevent the development of particularly undesirable microflora by seeding a microorganism particularly well suited for this purpose. In fact, depending on the microorganism that. in the context of the application concerned, preseit ?. the desired results, comes from the family of GEOTRICHUM CANDIDUM.

 In this regard, in Figure I are marked by arrows 7 to 12, the moments during the malting process where this seeding can take place.

 So. GEOTRICHUM CANDIDUM can be seeded before the quenching operation. However. because of the washing action that may have this step II on the barley grain, it may be preferred to carry out this seeding, during this quenching operation, but during the last sub-water. that is to say during the last cycle of water renewal.

 This seeding can also take place during the transport of the barley between the quenching unit and the germination unit. Note that this is not a problem, since it is usually provided in the malting units and at this stage of the process of spraying on the barley grain germination activators.

 Finally, and as shown in FIG. 1, this seeding can take place, also, during germination, during the transfer towards the kilning or even when the grain is being dried.

 The advantage of early seeding is that the development of the microflora is controlled from the outset.

 Experiments have shown that seeding in amounts of 10 to 10 colony forming units (CFU) per kilogram of barley provides convincing results. In this regard, this seeding can be carried out in one or more times during the steps mentioned above. In addition, GEOTRICHUM CANDIDUM may be inoculated as a pure culture or as a mixed culture, that is, in combination with other microorganisms, such as lactic acid bacteria. Finally, an alternating seeding of pure culture of GEOTRICHUM CANDIDUM or mixed culture, then culture other than GEOTRICHUM CANDIDUM, is also a possible solution.

 it should be observed, in this connection, that a mixed or alternating seeding allows. while ensuring the sanitary quality of the malt by strict control of the development of microorganisms, to improve other properties as well. this can be expressed as an improvement in the yield of extract or inhibition of undesirable enzymes, such as oxidases or on the contrary the production of interesting enzymes, such as cellulases. One can also seek to modify the malt flavor by associating with GEOTRICHUM CANDIDUNI or by alternating seeding with GEOTRICHUAI CANDIDUM, a specific microorganism to obtain the desired result.

Table I below illustrates the advantages of the present invention.

<Tb>

MOLD <SEP> BARLEY <SEP> FUSARIEE <SEP> MALT <SEP> MALT
<tb><SEP>"WITNESS"<SEP>"GEOTRICHUM"<SEP>
<tb><SEP>%<SEP> OF <SEP> GRAINS <SEP> CONTAMINATED
<tb> ALTERNARIA <SEP> 20 <SEP> 5 <SEP> 0
<tb> ASPERGILLUS <SEP> 20 <SEP> 15 <SEP> 0
<tb><SEP> 100 <SEP> 40 <SEP> 5
<tb> GEOTiCHUM <SEP> 0 <SEP> 0 <SEP> 100
<Tb>
Thus, in this table I are reported the percentages of grains contaminated by the molds most commonly encountered in this field including ALTERNARIA, ASPERGILLUS, FUSARIUM, PENICILLIUM and
GEOTRICHUM, this according to the fact that the measurements are carried out on fusarium barley, on malt control that is to say having undergone no seeding and finally on malt "GEOTRICHUM" that is to say of the malt from a malting process during which GEOTRICHUM was seeding
CANDIDUM. The results are, of course, glaring and revealing since, in the "GEOTRICHUM" malt, only 5% of grains are contaminated with rUSARlUM and PENICILLIUM, these figures being compared to the control malt in which 40% of grains contaminated with FUSARIUM and about 10% by PENICILIUM.

 As for the following table II, its purpose is to show the inhibitory effect of GEOTRICHUM CANDIDUM on the production of mycotoxin during the maitage.

More precisely. this demonstration is carried out through the determination of ZEARALENON at the level of the fusarium barley, the control malt, that is to say having undergone no treatment and. finally, malt "GEOTRICHUM".

<Tb>

<SEP> BARLEY <SEP> MALT <SEP> MALT
<tb><SEP> FUSARIEE <SEP> WITNESS <SEP>"GEOTRICHUM"<SEP>
<tb> ZERALENONE <SEP> 3 <SEP> 100 <SEP> 3
<tb><SEP> ssgRg <SEP>
<Tb>
The advantages deriving from the invention also appear in the. a-ees diagram illustrated in Figure 2 showing the evolution of iipasic activity during malting according to whether there is or not
seeding of GEOTRICHUM CANDIDUM. At the level of this diagram are represented, as abscissa. the steps of the malting process, while on the ordinate we find the total lipase activity in the grain in nanomoles per second per gram of dry matter. Thus, there is a discrepancy, particularly at the green malt stage, between the curve T corresponding to the malt control that is to say untreated and the curves Al, A2 and A3 corresponding to situations where there is seeding of different strains of GEOTRICHUM CANDIDUM called AI, A2 and A3.

Thus, it is clear that the seeding of selected strains of
GEOTRICHUM CANDIDUM really makes it possible to control the evolution of the microflora at the level of the barley grain and that one obtains the desired health arnilions. to know
- Inhibition of unwanted flora FUSARIUM, PENICLLIUM, ASPERGILLUS
- Inhibition of secondary metabolite production of unwanted flora. mycotoxin and precursor of giclage
- increased development of lactic acid bacteria which can enhance the inhibitory effect of unwanted flora and improve the quality of the malt by a natural lowering of the pH.

In fact, the results of the invention are all the more interesting that this health improvement is accompanied by major qualitative contributions such as
- the reduction of fatty acids in the must which are often the cause of problems of false taste in beer, such as the taste of oxidized or poor behavior of the foam
better filtration of the mash by inhibiting certain flora responsible for the synthesis of polysaccharides.

 The improvement obtained in terms of filtration is illustrated in the diagram of Figure 3 showing the filtration kinetics determined by a method called "TEPRAL BRASSIN". Thus, in this diagram we find, on the abscissa, the time in minutes, while on the ordinate, the amount of must filtered in grams is reported. The curve T, corresponding to the control malt, having undergone no treatment, lies well below the GI curves. G2 and G3 corresponding to malts having been seeded by different strains of GEOTRICHUM CANDIDUM G1, G2, G3.

 It is also surprising to note that these advantages deriving from the invention are obtained without consequence, nor on the process of manufacturing the beer. nor on the beer that results. More specifically, no significant variation in the process has been observed. In addition, beer obtained from GEOTRICHUM CANDIDUM-treated malt is organoleptically similar to untreated malt beer. The aromatic profile is identical and in triangular tasting there is hardly any difference.

 Consequently, the application of GEOTRICHUM CANDIDUM to the malt according to the invention leads to a clear progress in the field under consideration.

 Although the invention has been described with respect to a particular embodiment, it is understood that it is in no way limited and that various modifications of shapes, materials and combinations thereof can be made. various elements without departing from the scope and spirit of the invention.

Claims (7)

claims  1. Application of a micro-organism of the GEOTRICHUM CANDIDIJM family in the process of transformation of barley into malt for the control of the development of the flora able to contaminate and colonize the grain. GEOTRICHUM CANDIDUM.  2. Application according to claim 1, characterized in that the microorganism is composed of one or more selected strains of  3. Application according to any one of the preceding claims, characterized in that the microorganism is inoculated during malting, either in pure culture form, or in the form of mixed culture in combination with one or more other microorganisms. organizations.  4. Application according to any one of the preceding claims, characterized in that the seeding is carried out in amounts of the order of 10 to 10 colony forming units (CFU) per kilogram of barley.  5. Application according to any one of the preceding claims, characterized in that the seeding of the microorganism is carried out in one or more times during one or more of the following steps. preparation of the grain, during quenching of the grain, at the time of its transfer between the quenching stage and the germination stage, during germination, after germination and before kilning, during kilning.  6. Application according to any one of the preceding claims, characterized in that the microorganism is inoculated several times, either in pure culture form, or in the form of mixed culture, alternately with another microorganism.  7. Application according to any one of the preceding claims, characterized in that the microorganism is inoculated alternately or is combined in the form of mixed culture with lactic acid bacteria.