i THERMAL PROCESSING EFFECTS ON TOTAL ... - McGill University

In lentils, the phytic acid content varies from 6.2 to 8.8 g kg -1 dwb, while tannin
levels in raw seeds average about 4.7 g kg -1 dwb (Wang and Hatcher, 2008). Phytic acid,
major phosphorus storage constitutes 1-3% and they occupy high content in whole grains,
legumes. According to Fred-lund et al., (2006), phytate, phosphorus storage in plants and
its salts occurs as a mineral complex, which is insoluble at the physiological pH of the
intestine.
2.4.1 Trypsin Inhibitors:
In legume seeds, trypsin inhibitors (TI) are both proteinanceous and non-
proteinanceous in nature (Dave Oomah et al., 2011). Only proteinanceous TI has been
extensively studied in the literature. Trypsin inhibitors are present in variety of foods, and
especially in comestible legumes. Plant proteinase inhibitors vary in size from 4 to 60
kDa molecular weight (Ryan, 1981). Bowman–Birk inhibitor (BBI) proteins are double-
headed serine protease inhibitors which have a molecular mass of 7-8 kDa in dicot seeds
and but vary substantially in size and inhibitory sites in monocots (Ragg, Galbusera et al.,
2006).
Birk, (1994) reported that the mechanism of TI‘s anti-nutritional effects, though
not clearly understood, probably occurred through a mechanism of feedback inhibition
which controls the pancreatic secretions, according to the level of trypsin in the small
intestine at any given time. When TI‘s react with the enzyme trypsin, the enzyme level
falls below the critical threshold value, and the pancreas is then induced to produce more
of the enzyme, thus leading to pancreatic hyperactivity, which can cause hypertrophy and,
hyperplasia of the pancreas. The hormone cholecystokinin (CCK) is believed to act as a
mediating agent between the pancreas and trypsin. Thus TIs interfere with protein
digestibility, by binding to trypsin in the small intestine to form insoluble complexes.
Therefore inactivating a TI is accompanied by an increase in nutritive value of protein.
Generally, raw legumes contain higher levels of anti-nutritional factors than
processed forms, hence processing plays a major role before incorporating them into food
or animal diets (Hajós and Osagie, 2004). Table 2.1 illustrates the level of trypsin
inhibitor activity in different legumes (Elkowicz and Sosulski, 1982). It is well
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