Hello phytosan and thank you for your question,
I cannot give you a definitive answer to part 'C'of your question and
so I am posting this as a comment, however I'm 95% sure that my answer
is correct. Maybe another researcher can find a source for the
ammount of kGy to deactivate the enzymes in oats.
In answer to the first part of your question:
"a) what excactly is desactivation (is it prevention of germination, is
it desactivation of encymatic processes or something else all
together)"
The answer is:
Deactivation is the deactivation of enzymes in the oats, this has the
effect of prolonging shelf life and stops the oats from going rancid.
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In answer to the second part of your question:
"b) how is it done conventionally?"
The answer is:
Moist heat above 190°F is used for several minutes in order to
deactivate the enzymes.
=================================================================
To the third part of your question:
"c) is there research information available with respect to using
ionizing irradiation as a replacement process. If so, what are doses
(Gray) that are required to achieve desactivation?"
There was no information that I could find! I suspect that this is
because the ammount of radiation permitted is just 1 kGy for oats. I
think that the dosage required would be much higher to deactivate the
enzymes. For example I have seen information stating that up to 10
kGy can be used to deactivate "dry enzymes" My reasoning behind this
is that microorganisms are destroyed by radiation more easily than
enzymes, therefore if the maximum ammount of kGy permitted for oats is
1 (and remember this is to prevent insect infestation) Then the
ammount of kGy required to kill enzymes in the oats must be higher
than 1 kGy, which is not permitted by law.
See below for further details:
=================================================================
"Microorganisms are destroyed by radiation more easily than enzymes
which lead to food deterioration"
http://www.fcs.uga.edu/pubs/current/FDNS-E-3.html
"Heat treatment, which is routinely used in oat processing,
deactivates lipolytic enzymes and extends the shelf life of a final
product. In the same time during such processing a characteristic
?toasted? flavour develops. Oat grains are often infested with the
Fusarium moulds, which may leave spores and produce mycotoxins. Kiln
drying, which is commercially used in oat processing has the ability
to deactivate the enzymes involved in the formation of rancidity.
However, this method is not capable of eliminating the heat resistant
Fusarium spores."
http://www.ageng.ndsu.nodak.edu/asae/rrv/RRV03-0017.pdf
"The activity of these enzymes is proportional to the amount of
available water present and, therefore, to the water activity as seen
in Figure 1. They are most readily destroyed by moist heat above
190°F for several minutes. Dry heat is much less effective at
deactivating these enzymes in cereal systems.
In most biological systems, peroxidase requires much more heat to
destroy than lipases, lipoxygenases or any of the other enzymes that
may be present. It would follow then that if the peroxidase has been
destroyed, the other enzymes have also been deactivated.
Cereals can be checked for proper enzyme deactivation by using a
simple colorimetric procedure based on the peroxidase oxidation of a
phenolic dye (2, 6-dichloroindophenol), which has been reduced to its
leuco form by ascorbic acid. During the reoxidation, a blue color is
formed which can be used to measure peroxidase activity. This test is
an adaptation of an old U.S. Army Quartermaster Corps method used to
ensure the proper blanching of vegetables"
http://www.medlabs.com/Newsletters/Food%20Product%20Shelf%20Life%2020030615.doc
"In 1986, the United States Food and Drug Administration (FDA)
approved irradiation of spices and seasonings up to 30 kGy to reduce
microorganisms and insects."
"while a maximum of 1 kGy can be applied to grains, such as wheat and oats, to ."
http://www.aces.edu/pubs/docs/H/HE-0727/
Very best regards
THX1138
Search strategy included:
enzymes kGy oats
://www.google.com/search?q=enzymes+kGy+oats&hl=pt&lr=&ie=UTF-8&oe=UTF-8&as_qdr=all&start=10&sa=N |
