Nutritional composition and angiotensin-converting enzyme inhibitory activity of blue lupin (Lupinus angustifolius L.)
Angiotensin-converting enzyme (ACE) plays a dominant role in blood pressure regulating system. Synthetic ACE inhibitor is designed as an antihypertensive drug to restrict ACE activity. However, the usage of synthetic drug may cause several adverse effects. Hence, a natural food protein with ACE i...
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| Format: | Thesis |
| Language: | English |
| Published: |
2017
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/79334/1/FPSK%28m%29%202019%2014%20ir.pdf |
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| Summary: | Angiotensin-converting enzyme (ACE) plays a dominant role in blood pressure
regulating system. Synthetic ACE inhibitor is designed as an antihypertensive drug to
restrict ACE activity. However, the usage of synthetic drug may cause several adverse
effects. Hence, a natural food protein with ACE inhibitory activity may be promising as
a safer alternative to the synthetic drug. Blue lupin (Lupinus angustifolius) is one of the
legumes that rich in protein. It has the potential to be a good source of ACE inhibitory
peptides. However, blue lupin is usually served as an animal feed and consumption by
human is rare. Therefore, this study was carried out to investigate the nutritional,
protein and amino acid composition of blue lupin flour, and to evaluate the ACE
inhibitory activity of its protein hydrolysates. The results revealed that the lupin flour
was abundant in protein (43.3 g/100 g) and dietary fibre (33.5 g/100 g). According to
the Osborne classification, plant storage protein was characterised into four categories
based on their solubility in different solvents. Results from sequential Osborne
extraction procedure showed that lupin protein comprised of 46% salt-soluble globulin,
27% water-soluble albumin, 18% alkaline-soluble glutelin and 7% alcohol-soluble
prolamin fractions. Furthermore, lupin protein was rich in lysine but limiting in
methionine. In this study, Alcalase and Flavourzyme were used to hydrolyse the lupin
protein isolate for different hydrolysis times (4, 10 and 16 h). Gel electrophoresis
analysis demonstrated that protein hydrolysis catalysed by Alcalase was more effective
compared with Flavourzyme as evidenced by the lower molecular weight peptides
presented in the hydrolysates prepared using Alcalase. The ACE inhibitory activity of
hydrolysates was determined using an in vitro method. Hydrolysates prepared using
Alcalase exhibited higher ACE inhibitory activities compared with those prepared
using Flavourzyme, showing IC50 values ranging from 0.10 to 0.21 mg/mL. However,
there was no significant difference in IC50 values between the hydrolysates prepared
using Alcalase for 4, 10 and 16 h of hydrolysis times. The results suggested that
globulin was the major contributing protein fraction on ACE inhibitory effect in lupin
protein. In addition, the information obtained in this study is important to reveal the
nutritional values and health benefits of blue lupin protein and to recognise the lupin protein hydrolysates as nutraceuticals or functional foods. The lupin protein
hydrolysates with potent ACE inhibitory activities can be incorporated into the daily
diet to prevent hypertension. They can also be consumed by hypertensive patients to
reduce the dosage of antihypertensive drugs needed, thereby lowering the risk of side
effects. |
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