Abstract
Among various food sources, milk proteins remain the major vector for functional peptides endowed with several biological activities. Particularly, the proteolytic activity of lactic acid bacteria during milk fermentation has been one of the most followed strategies to produce bioactive peptides. In the present study, the exploration of the activity of several starter cultures, at different fermentation times, was firstly investigated by reversed phase-high performance liquid chromatography. Among the tested strains, Lactobacillus helveticus showed a higher proteolytic activity and it was submitted to further investigations by changing the fermentation substrate (skim milk, brain heart infusion, peptone water) as well as the extraction strategy (trichloroacetic acid vs. glass beads). The chromatographic analyses and the in vitro antioxidant and antihypertensive assays highlighted considerable differences for L. helveticus hydrolysates from different substrates, while a negligible impact by the two extraction protocols emerged. Furthermore, nano-high pressure liquid chromatography coupled with a high resolution mass spectrometry analyzer allowed the preliminary discrimination of fractions from fermented skim milk, likely responsible for the found activity. The obtained results suggest the possibility of varying the fermentation parameters in order to maximize the functional effects of the bioactive peptides.
Highlights
The role of proteins in food has gained increasing acknowledgement. Beyond their purely nutritional role, bioactive peptides (BPs) encrypted in dietary protein sequences are emerging as an important tool for the treatment of various diseases [1,2]
The release of the active form of BPs from the sequence of the parent protein could mainly follow three processes, namely, (i) the hydrolysis by gastrointestinal digestive enzymes, (ii) the hydrolysis by proteolytic microorganisms, or (iii) the action of proteolytic enzymes derived from microorganisms or plants [3]
Once split from their precursors, BPs contribute to the modulation of different body functions exerting, inter alia, antioxidant, digestive, immunomodulatory, hypotensive, antithrombotic, antibacterial, and opiate-like properties
Summary
(ii) the hydrolysis by proteolytic microorganisms (during fermentation), or (iii) the action of proteolytic enzymes derived from microorganisms or plants [3] Once split from their precursors, BPs contribute to the modulation of different body functions exerting, inter alia, antioxidant, digestive, immunomodulatory, hypotensive, antithrombotic, antibacterial, and opiate-like properties. Such potential health benefits justify the emerging employment of BPs and protein hydrolysates as valuable sources for physiological functioning and human well-being promotion [1,2,3]
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