digestibility by formation of phytic–protein complexes, and depress absorption of
nutrients due to damage to the pyloric caeca region of the intestine (Francis et al.
2001). However, dietary phytates aid in lowering cholesterol level and also prevent
cancer (Steer and Gibson 2002). Also, phytates help in reducing lipid peroxidation
and are, thus, considered to be natural antioxidants (Serna-Saldivar et al. 2017).
Sesame seeds are reported to be a rich source of phytates (5.18%) as compared to
soybean meal (1%) and soybean protein (1.5%) (De Boland et al. 1975). Toma et al.
(1979) reported 4.7, 5.2, 4.7, and 5.1% phytin content in whole, dehusked, roasted
dehusked, and roasted sesame seeds, respectively. Makinde and Akinoso (2013)
reported 30 mg/100 g phytate in dehusked white cultivar and 25.07 mg/100 g in
black cultivar of sesame seeds. The authors also observed that the high content of
phytic acid and oxalic acid in sesame seed hinders the use of sesame protein as food.
12.5.2 Oxalates
Oxalic acid salts of calcium and magnesium are insoluble crystals and are not
absorbed in the human body (Leeson and Summers 2001). Massey et al. (2001)
reported that after absorption from diet, oxalate cannot be metabolized and is
excreted by the kidney into urine, where it binds to calcium forming an insoluble
salt that may precipitate to form kidney stones. Sesame seed contains 2.2% oxalic
acid, and processing methods like pearling, soaking, steaming, oil expelling, and
drying treatments aid in reducing the oxalate content of the seeds. Further, the
authors reported that the combination of 20 min pearling, 15 min soaking, 15 min
steaming at 100 kPa steam pressure, and drying at 50
C reduced the oxalate content
to a marked extent (0.43%) and, thus, can increase the functionality of the sesame
seed protein to be used as a protein supplement (Manikantan et al. 2015).
12.5.3 Tannins
Tannin, a phenolic derivative of flavones, forms complexes with protein and reduces
bioavailability of amino acids in the human body (Lampart-Szczapa et al. 2003) and
is the chief ANF present in sesame meal (Mukhopadhyay and Bandyopadhyay
2003). Sesame seed was reported to contain 5.62 mg/100 g tannin, whereas it was
also observed that cooking for 10, 20, and 30 min and toasting for 5, 10, and 15 min
led to a marked decrease to 3.96, 1.54, and 0.49 mg/100 g and 2.19, 1.83, and
1.81 mg/100 g, respectively. The authors concluded from their study that moist heat
treatment can be an appropriate method to reduce tannin content in sesame (Jimoh
et al. 2011).
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L. Sharma et al.
nutrients due to damage to the pyloric caeca region of the intestine (Francis et al.
2001). However, dietary phytates aid in lowering cholesterol level and also prevent
cancer (Steer and Gibson 2002). Also, phytates help in reducing lipid peroxidation
and are, thus, considered to be natural antioxidants (Serna-Saldivar et al. 2017).
Sesame seeds are reported to be a rich source of phytates (5.18%) as compared to
soybean meal (1%) and soybean protein (1.5%) (De Boland et al. 1975). Toma et al.
(1979) reported 4.7, 5.2, 4.7, and 5.1% phytin content in whole, dehusked, roasted
dehusked, and roasted sesame seeds, respectively. Makinde and Akinoso (2013)
reported 30 mg/100 g phytate in dehusked white cultivar and 25.07 mg/100 g in
black cultivar of sesame seeds. The authors also observed that the high content of
phytic acid and oxalic acid in sesame seed hinders the use of sesame protein as food.
12.5.2 Oxalates
Oxalic acid salts of calcium and magnesium are insoluble crystals and are not
absorbed in the human body (Leeson and Summers 2001). Massey et al. (2001)
reported that after absorption from diet, oxalate cannot be metabolized and is
excreted by the kidney into urine, where it binds to calcium forming an insoluble
salt that may precipitate to form kidney stones. Sesame seed contains 2.2% oxalic
acid, and processing methods like pearling, soaking, steaming, oil expelling, and
drying treatments aid in reducing the oxalate content of the seeds. Further, the
authors reported that the combination of 20 min pearling, 15 min soaking, 15 min
steaming at 100 kPa steam pressure, and drying at 50
C reduced the oxalate content
to a marked extent (0.43%) and, thus, can increase the functionality of the sesame
seed protein to be used as a protein supplement (Manikantan et al. 2015).
12.5.3 Tannins
Tannin, a phenolic derivative of flavones, forms complexes with protein and reduces
bioavailability of amino acids in the human body (Lampart-Szczapa et al. 2003) and
is the chief ANF present in sesame meal (Mukhopadhyay and Bandyopadhyay
2003). Sesame seed was reported to contain 5.62 mg/100 g tannin, whereas it was
also observed that cooking for 10, 20, and 30 min and toasting for 5, 10, and 15 min
led to a marked decrease to 3.96, 1.54, and 0.49 mg/100 g and 2.19, 1.83, and
1.81 mg/100 g, respectively. The authors concluded from their study that moist heat
treatment can be an appropriate method to reduce tannin content in sesame (Jimoh
et al. 2011).
312
L. Sharma et al.