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

include compounds such as phytate, polyphenols, enzyme inhibitors (trypsin,
chymotrypsin, and α-amylase) and haemagglutinins. Reduction of these anti-nutrients
was significantly greater when these legumes cooked by autoclave at 121º C or 128ºC,
compared to other traditional processes (ur-Rehman and Shah, 2005). Additionally, when
various lentil cultivars‘ flour was digested with pepsin and pancreatin, the in-vitro protein
digestibility was reduced from 77.1%-88.0% by the process of normal cooking (Sulieman,
Mashair, 2008).
Phytic acid is considered an antinutritional compound given its ability to bind
essential dietary minerals as well as proteins and starch, and to consequently reduce their
bioavailability in humans (Philippi, 2003). The toxic effects of lectins are due to their
ability to bind to specific receptor sites on the surface of intestinal epithelial cells, which
causes an interference with the absorption of nutrients across the intestinal wall. Bound
lectins also impair the transfer of amino acids, leading to a decrease in protein
digestibility (Adsule et al., 1989).
2.5.2 Effects of thermal processing on protein digestibility
Cooking, soaking, roasting, boiling, germination and other conventional cooking
methods are applied to lentils in order to inactivate the antinutritional compounds and to
improve of protein digestibility.
Monsoon and Yusuf, (2002), found that non-soaked lentil seeds after dry heating
or autoclave treatments which caused reduction in trypsin inhibitor activity, tannins and
phytic acid and increased tannin/catechins ratio without causing any significant changes
in in-vitro protein digestibility of lentils. On the other hand, soaking of lentil seeds
followed by traditional or autoclave cooking process, has been found to significant by
decrease phytic acid and tannin content, and improve in-vitro and in-vivo protein
digestibility (Savage and Scott, 1989; Zia-ur-Rehman and Shah, 2005). Paraná et al.,
(2000) reported that microwave treatment caused a significant reduction in trypsin
inhibitor activity and hæmaglutinins of raw and soaked lentils. All the above forms of
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