Drying and gas or vapor contact with solids – Process – With nondrying treating of material
Reexamination Certificate
2000-07-03
2002-09-17
Walberg, Teresa (Department: 3742)
Drying and gas or vapor contact with solids
Process
With nondrying treating of material
C034S267000
Reexamination Certificate
active
06449872
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method of treating cereal kernels (seeds) to decrease their mould content. The invention also relates to the treated cereal kernels, cereal kernel products made of them and to their use in malting, brewing, food and feed industry. The invention further relates to apparatuses for treating cereal kernels to decrease their mould content. More specifically, the method of the invention allows the mould content of the cereal kernels to be decreased without interfering with the germinability of the kernels. This is important particularly in the malting process of the kernels.
BACKGROUND OF THE INVENTION
Moulds can be found everywhere in nature, e.g. in the soil and in the air, from where they spread to growing grain. Although moulds thus belong to the natural flora of grain, their wide occurrence is harmful because they may reduce the quality of grain and malt made thereof. For example, moulds can produce various mycotoxins detrimental to health. In addition, they may e.g. decrease the germinability of a kernel and the growth of germs, which is not only harmful for seed grain but also for malting of grain. It has also been shown that the beer brewed from heavily contaminated grain and malt tends to gush, which is a big problem for the brewing industry. Gushing is apparently due to metabolites produced by Fusarium and other moulds, which metabolites survive the process of brewing.
Kernels are exposed to moulds as soon as they are sown in the soil. The growth of mould is influenced by many factors, particularly moisture, temperature and time. Other significant factors are the supply of nutrients and oxygen and the competition between micro-organisms. Growing grain is predominated by so-called field fungi, the most common of which are Alternaria, Aureobasidium, Cladosporium, Epicoccum, Fusarium, Cochliobolus, Drechslera and Pyrenophora. Some of the field fungi are plant pathogens, the most harmful of which are
Fusarium graminearum
and
F. culmorum
. Also
Cochliobolus sativus
and Fusarium ssp. cause plant diseases and may be very harmful for the malting process. Humid weather during ear maturation and harvesting in particular presents favourable conditions for the growth of Fusarium moulds.
After harvest the grain should be dried rapidly to prevent the moulds from further reproduction. Field fungi cannot reproduce themselves in grain dried in an appropriate manner (approximately 12-13% moisture content) but they remain alive and reproduce themselves again, if they are exposed to humid conditions. Poorly stored grain is dominated by so-called storage fungi, i.e. Aspergillus and Penicillium, which survive in low moisture contents. Also storage fungi reduce the quality of grain and incur health risks both to those treating contaminated grain and to those consuming it.
When grain is malted, the moisture of the grain is increased again to 45-50% and the supply of oxygen is ensured, whereby the kernel starts germinating. The prevailing conditions during the process of malting are, however, not only suitable for the germination but also for the growth of moulds. A large amount of moulds is harmful for the process.
Malting aims at effecting physical, chemical and biochemical changes in the kernel. The malting process comprises three main stages: steeping, germination and kilning. First the cleaned and sieved grain is steeped in water to achieve the adequate moisture content. When the kernels have a sufficient moisture content, they are germinated at 13-16° C. generally at least five days. This way, “green malt” is produced. Actual malt is produced by drying green malt under controlled conditions in which the temperature is slowly raised from about 45° C. to about 85° C., whereby the moisture content decreases approximately to four per cent. After drying, rootlets are eliminated, and they can be used as animal feed. Malt can also be processed into a malt extract for the food industry, for example.
Already at the stage of steeping during malting, the mould content of grain may rise, and it rises further at the stage of germination, Normal kilning of the malt does not substantially decrease the mould content of the kernels either.
Malt is mainly used for brewing beer, but also for the production of distilled spirits. Brewing comprises wort production, main and secondary fermentations and post-treatment. First the malt is milled, stirred into water and heated. During this “mashing”, the enzymes activated in the malting degrade the starch of the kernel into fermentable sugars. The produced wort is clarified, yeast is added, the mixture is fermented and a post-treatment is performed.
Many moulds are known to produce toxic compounds, i.e. mycotoxins, which may prejudice animal and human health. They may also harm malting and brewing. Thus, if there are a lot of moulds in the grain, the probability of mycotoxins is also higher. The most examined mycotoxins growing in grain originate from Fusarium,
Cochliobolus sativus
, Aspergillus and Penicillium moulds.
Several species of Fusarium moulds are not only pathogens of cereals but also potential sources of various mycotoxins. Particularly important mycotoxins are trichothecenes, zearalenone (ZEN) and its derivatives, fumonisins, moniliformin, fusarochromanones and fusaric acid. More than 100 different trichothecenes have been identified and characterized. Most attention has focused on Type A trichothecenes, including T-2 toxin, neosolaniol (NEO) and diacetoxyscirpenol (DAS) and on Type B trichothecenes, comprising deoxynivalenol (DON, i.e. vomitoxin) and its acetyl derivatives (3-ADON and 15-ADON), nivalenol (NIV) and fusarenon X. Fusarium mycotoxins and the factors affecting them are presented in J. P. F. D'Mello and A. M. C. Macdonald: Some Factors Affecting the Production of Fusarium Mycotoxins, p. 35-44, in:.
J. P. F. D'Mello: Mycotoxins in Cereals: An Emerging Problem
?, Handbook for fourth SAC Conference October 1996, Edinburgh.
In the chapter “Mycotoxins in Malting and Brewing” of the above-mentioned work, B. Flanigan (p. 45-55) discusses the effects of mycotoxins on the malting and brewing industry. It is stated therein e.g. that the harmful effect of
Cochliobolus sativus
and Fusarium ssp. moulds on germinability is attributed at least in part to their production of mycotoxins, or other phytotoxic metabolites. Trichothecenes produced by Fusarium ssp. are inhibitory to the protein synthesis and thus reduce the production of alpha-amylase important for malting. Also the alpha-amino nitrogen concentrations in the wort decrease. Fusarium moulds may produce DON and zearalenone during malting. Grain and malt may also be contaminated with toxins produced by
Penicillium verrucosum
or
Aspergillus clavatus
causing allergic lung disease. T-2 toxin and other potent trichothecenes may retard fermentation, but although DON may be present in the wort, it has little effect on fermentation. Mycotoxins are not found in distilled spirits, but DON, nivalenol, fumonisins, aflatoxins, ochratoxin A and some other mycotoxins have been found in beer, but in low concentrations. Gushing of beer seems to correlate with zearalenone or DON. The health risk to humans from consuming mycotoxin contaminated beer is still uncertain, but the toxic effect of mycotoxins on farm stock fed on contaminated malting and brewing by-products is undisputed. For example, DON has been found in high concentrations in rootlets used as animal feed, and aflatoxins, zearalenones and ochratoxin A have been found in the mash waste.
Various solutions have been suggested to the problems relating to moulds in grain and malt. It is naturally worth aiming to dry the grain immediately after harvesting and to store it in dry. The growth of moulds can be retarded already in the field by spraying mould pesticides. Various cereals with a genotype resistant to e.g. Fusarium diseases have also been developed. Attempts have been made to reduce harmful effects of moulds in malting and brewing e.g. by supplying microbicidal substances, such
Olkku Juhani
Peltola Petri
Räsänen Esa
Reinikainen Pekka
Tuokkuri Veli-Matti
Fastovsky L
LP-Tutkimuskeskus Oy
Walberg Teresa
Young & Thompson
LandOfFree
Method and apparatus for treating cereal kernels, treated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for treating cereal kernels, treated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for treating cereal kernels, treated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2893687