[Note: After asking about the subject of this post, Erich, the next day,
essentially answered his own question in a second post that I have combined with
this one, below it, after which I make some comments. --Paul]

Greetings:

It occurred to me this morning that when you say cooked buckwheat,
(http://morelife.org/personal/health/dietregmore.html) there is no
temperature given for a minimum so as to inactivate the trypsin
inhibitors present in the uncooked buckwheat.

After milling the unhulled buckwheat essentially into a powder, I add
some rye flakes a few dried fruits pieces and some non-fat milk and
microwave it till it thickens. I would not say that is temperature is
anywhere near 212 F. It is usually about 160-170 F. Does it need to be
much higher and how long would it have to remain at that temperature
to inactivate the trypsin inhibitors? I hope I am not being too picky
here, but I am concerned that I may not be getting the mixture hot
enough for long enough to take care of this problem.

How do you determine if this is hot enough to inactivate the trypsin
inhibitors?

It would be very easy for me to take the temperature of the mixture
with an instant read thermometer, so what would you suggest as a
minimum temperature and for how long at that temperature?

Thanks,
Erich Brueschke

------------------------

After asking about how long to cook buckwheat to deactivate the
trypsin inhibitors, I ran across the following information that seems
to conclude that the trypsin inhibitors are very heat stable and may
not be inactivated even with heating.

http://foodallergens.ifr.ac.uk/biochemical.lasso?selected_food=12&allergenID=94
The above link is to an allergen information site that lists the
trypsin inhibitors in buckwheat to be similar to that found in potatoes.

It is stated there that: "The inhibitors function after heating,
exposure to organic solvents and low pH during extractions. Thus they
are either very stable or else can easily refold. They would be
expected to survive cooking."

I say a few other references to the stability of the trypsin
inhibitors, but only the above was one that came right out and stated
its stability to heat. A lot of the other references are in Russian
and not available to me.

http://www.specialcrops.mb.ca/BuckwheatProductionMarketResearch/buckwkwheatpromo\
tionbrochure.doc
The link above is to a microsoft word document that lays out all the
information in a succent way:

"Despite the balanced amino acid composition, the buckwheat protein
digestibility in humans and in animals is relatively low (Farrell,
1978; Javornik et al, 1981), because of anti-nutritional factors
present in common buckwheat, including protease inhibitors (such as
trypsin inhibitors) and tannins (Ikeda et al 1986, 1991). Trypsin
inhibitors in buckwheat seeds are resistant to thermal processing at
elevated temperatures and to acidic conditions (Ikeda et al, 1986,
199l). Germination of buckwheat seeds significantly reduces the
activity of proteases inhibitors, so seedlings and young buckwheat
plants as a food source show improved digestibility and utilization of
proteins (Kreft, 1983)."

Farrell, D.L. (1978). A nutritional evaluation of buckwheat (Fagopyrum
esculantum). Anim. Feed Sci. Technol. 3:95-108. (No PMID available)

Javornik, B., Eggum, B.O. and Kreft, I. (1981) Studies on protein
fractions and protein quality of buckwheat. Genetika 13:115-118. (No
PMID available)

Ikeda, K. (2002) Buckwheat:composition, chemistry and processing.
Advances in Food and Nutrition Research 44:395-434. (PMID: 11885141)

Ikeda, K., Arai, R. and Kreft, I. (1998). A molecular basis for the
textural characteristics of buckwheat products. In: Advances in
Buckwheat Research, Eds. C. Campbell and R. (No PMID available)

Kreft, I. (1983) Buckwheat breeding perspectives. In: Buckwheat
Research. Eds: T. Nagatomo and T. Adachi, Kuroda-Toshado Printing,
Miyazaki, pp. 3-12. (No PMID available)

Kreft, I., Skrabanja, V., Ikeda, S., Ikeda, K. and Bonafaccioa, G.
(1998)) Buckwheat nutritional value and technological properties. In:
Alternative Getreiderohstoffe-Technologie und ErnahrungischeBedeutung.
Universitat fur Bodenkultur, Vienna, pp.44-51. (No PMID available)

Kreft, S., Knapp, M. and Kreft, I. (1999) Extraction of rutin from
buckwheat seeds and determination by capillary electrophoresis. J.
Agric. Food Chem. 47:4649-4652. (PMID: 10552865)

Erich Brueschke

[My research suggests that trypsin inhibitors are ubiquitous in seeds, nuts,
beans, legumes and tubers (see PMID: 9972064). They have various inhibition
strengths with respect to protein digestion and any combination of
cooking/heating/drying/pressure deactivates them somewhat, but never completely.
All that one can do is try one's best to deactivate those in foods where they
are most concentrated. Beans are certainly a concentrated source and should
always be presoaked and cooked. I have not been able to find out the strength of
inhibitors in buckwheat relative to soy, for example, but my guess is that it is
strong enough that buckwheat is best to be cooked so that its inhibitors are
deactivated at least to some extent.

With respect to food allergies, the major way in which trypsin inhibition would
affect them would be if the digestive system is faulty in allowing whole
proteins or large fragments to be absorbed intact. A healthy and normally
functioning digestive system will simply not absorb the protein that is not
broken down. --Paul]

[Up until this past winter I was making our hot cereals in separate bowls in the
microwave, cooking at 100% power for 3 to 4 minutes for each. The initially thin
gruel did actually boil - sometimes over the sides if I filled the bowl too
much. I am now using a double boiler because that's easiest when preparing 2
servings (which I always do), keeps the cereal moist and prevents burning on the
bottom. The cooking time is from 20 to 30 minutes, depending on what combination
of grains I have used (I judge by appearance of grains - soft - and taste). I am
assuming that the cereal temperature is very near that of the boiling temp of
water, 212F. I'll try to remember the next time I cook hot cereal to put in the
confectionary thermometer to verify. **Kitty]