EFFECT OF MICROWAVE AND v· IRRADIATION ON SOME ANTINUTRITIONAL FACTORS IN SOME LEGUME SEEDS

The effect of microwave heating and y- irradiation treatment are investigated
on oligosaccharides, trypsin inhibitor, phytic a~'d' polyphenols and saponin content of
two varieties of two Egyptian legume seeds so bean and kidney bean.
Sucrose constituted 3.76 and 1.94° for dried soybean and kidney been
seeds, respectively. The stachyose levels vari d from 0.97% for soybean to 1.65% for
kidney bean. Soybean seeds contained 0.75to of raffinose versus 0.95% in kidney
bean seeds.
Thermal heating for 80 sec of pre-soaked seeds (for 12 hr) produced a sharp
reducUon in raffinose by 94.67% and staChyot by 92.78% in soybean and 94.74 and
56.36% in kidney bean, respectively. It is not d that the same treatment decreased
the sucrose content by 70.21% in soybean an 58.76% in kidney bean.
On irradiation treatment of soya and idney bean seeds followed by soaking
for 6 hr, sucrose content was reduced by 51.86 and 35.57% at 2.5 KGy, and 56.91
and 38.66% at 5.5 KGy of its amount in raw seeds, respectively.
Quantitative measurement indicated that phytic acid was ranged from 3.68
mg/g soybean to 3.25 mg/g kidney bean (defatted meal). All processing decreased
phytic acid content in both legume seeds and such decrease increases as soaking
and microwave heating period increases.
The maximum decrease in phytic acid was about 70% in soybean and 60%
in kidney bean seeds when the soaked seeds exposure to microwave heating for 160
sec. Irradiation at a dose of 7.5 KGy followed by soaking for 12hr resulted in a
decrease in p hytic a cid level ins oybean and kidney bean seeds only by 53.8 and
74.77%, respectively.
Trypsin inhibitor activity (TlA) was decreased with increasing microwave-
heating period in all treatments. After exposure the presoaked seeds (12 hr) to
microwave heating for 160 sec, about 61.80% and 60.25% of the TIA was destroyed
in soya and kidney beans respectively. Microwave heating for 160 sec of pre-soaked
soya and Kidney bean seeds for 1hr destroyed TIA by 27.8 and 29.5%, respectively.
Whereas, TIA degradation in pre-soaked seeds for 6hr was 55.4 and 41.45%.
Soaking of irradiated (at 7.5 KGy) soya and kidney bean seeds for 12 hr was found to
remove, about 49.8% and 60% of TIA, respectively as compared to the levels in the
raw flour, while in other treatments, considerable amounts of trypsin inhibitors 'Nell still
found.
The obtained results showed a rapid increase in polyphenols con lent as a
result of microwave treatment for 160 sec of soaked seeds for 6hr 10 reach 27.91 %
and 33.33% of ils amount in raw seeds of soya bean and kidney beans, respectively.
Soaking for 12hr followed by microwave heating for 160 sec showed the highest
increase of tannins (34.88%) in soybean and (45.33%) in kidney bean. While,
irradiation at dose 7.5 KGy accompanied by soaking for 12hr raised Ihe content of
polyphenols content in soybean and kidney beans by 1.4 and 1.7-fold, respectively.
The results showed that eight olive green to purple (mauve) spots have been
detected in raw soybean seeds. The spots corresponding to glycosides with R, values
of 0.06, 0.19. 0.25 and 0.44 were having high intensity. On the other hand, the