Session: General Poster:

Hypertension is a controllable risk factor of cardiovascular diseases and angiotensin-converting enzyme (ACE) is a central component of the renin–angiotensin system (RAS) which controls blood pressure. Most of the antihypertensive drugs are ACE-inhibitors which are effective but often cause many side effects. Some food protein-derived hydrolysates/peptides showed significant antihypertensive activity without side effects. Limited studies show that regular consumption of peanuts reduces blood pressure and total/cause-specific mortality. This study evaluated the in vitro allergenicity and ACE-inhibitory activity of peanut protein hydrolysates (PPH) produced by proteolytic hydrolysis of partially defatted peanut flours. Partially defatted light- and dark-roasted peanut flours with about 50% protein were hydrolyzed with Alcalase for different time. The peanut flour suspensions incubated without Alcalase were used as controls. Samples were taken every 2 hours to inactivate the enzyme. After centrifugation, the supernatants (PPH) were collected and total protein concentrations were determined. The PPH was then tested for IgE-binding, a key indicator of allergenicity, by Western Blot using pooled plasma from 6 peanut allergic patients. The ACE-inhibitory activity of PPH was determined using ACE from rabbit lung. Western blot shows that Alcalase hydrolysis significantly reduced IgE-binding of peanut flour, although the residual of Ara h 6 and proteins/peptides 5-15 kDa remained IgE-binding. The fractions of PPH smaller than 5kDa did not bind to the IgE antibody from peanut allergic patients. Alcalase hydrolysis resulted in PPH with significant ACE-inhibitory activity depending on hydrolysis time and protein concentration. The fraction smaller than 5 kDa exhibited higher ACE-inhibitory activity than crude PPH. The ACE-inhibitory activity of dark-roasted PPH was slightly higher than that of light-roasted PPH at same concentration. Higher ACE-inhibitory activity indicates greater antihypertensive potential. Thus, peanut flour could be an inexpensive and available protein source for producing anti-hypertensive ingredient.