Physicochemical, antioxidant, calcium binding, and angiotensin converting enzyme inhibitory properties of hydrolyzed tomato seed proteins

Abstract

The objective of this was to determine the impact of enzymatic hydrolysis on the multifunctionality of tomato seed protein hydrolysates (TSPH) and their physicochemical properties. The enzymatic hydrolysis was performed using alcalase and two factors response surface methodology. The best conditions were 131.4 min and 3% enzyme/substrate (E/S) for antioxidant activity; 174.5 min and 2.93% E/S for angiotensin‐converting enzyme (ACE) inhibition; and 66.79 min and 2.27% E/S for the calcium binding. Antioxidant and ACE hydrolysates were characterized by higher solubility, zeta potential, and thermal stability while properties of the calcium binding hydrolysate were only minimally affected by the enzymatic hydrolysis. Gel electrophoresis showed that molecular weights of polypeptides in the calcium binding TSPH were higher compared to those in ACE and antioxidant TSPHs. This was due to the low degree of hydrolysis of the calcium binding hydrolysate. Practical applications Nowadays, different protein sources are used to produce protein hydrolysates containing bioactive peptides that can help alleviate oxidation of foods, oxidative stress, and chronic conditions (e.g., hypertension, diabetes, cardiovascular disorder). Hydrolyzed proteins also have the potential to increase mineral absorption through the formation of mineral‐binding complexes. Biological activities of proteins and peptides from tomato processing byproduct (i.e., pomace) have received until now little attention. The determination of physicochemical properties and biological activities of the hydrolyzed proteins has application in the formulation of value‐added food products for the reduction of oxidative stress and risks of developing chronic diseases. In addition, there will be a reduction of pomace waste generated by the tomato processing industry.

Extraction and Characterization of Antioxidant Peptides from Fruit Residues

“…Alcalase (the commercial name of subtilisin Carlsberg endopeptidase) is the most used enzyme for obtaining antioxidant peptides. This is not surprising, because Alcalase is a very cost effective food-grade protease with a low specificity that enables the release of a wide range of short peptides [43]. Trypsin, conversely, is a highly selective protease and has not been very effective in antioxidant peptide releasing [90].…”

“…Molecular weights between 0.5 and 1.5 kDa are also a common feature within antioxidant peptides [22]. Antioxidant peptides have been obtained from rapeseed residues (Brassica napus) [23,24], peels of pomegranate (Punica granatum) [3,25] and mango (Mangifera indica) [26], and seeds of apricot (Prunus armeniaca) [11,27], peach (Prunus persica L.) [11,16,28,29], bottle gourd (Lagenaria sciceraria) [30][31][32], cherry (Prunus cerasus L.) [11,33], olive (Olea europaea) [11,16,17,34], plum (Prunus domestica L.) [11,14,29,35], tomato (Solanum lycopersicum) [21,[36][37][38][39][40][41][42][43], wax gourd (Benincasa hispida) [44], jujube (Ziziphus jujube) [45,46], muskmelon (Cucumis melo) [47], watermelon (Citrullus lanatus) [32,[48][49][50][51][52][53], papaya (Carica papaya)…”

“…Incubation temperatures of 40-50 • C have been employed to promote protein solubilization. This strategy has been used in the extraction of proteins from the seeds of tomato, jujube, watermelon, Chinese cherry, African breadfruit, and pumpkin, as well as in pumpkin oil cake [21,37,[41][42][43]45,48,50,52,[55][56][57][58][59][60][61][62]. Despite the popularity and industrial applicability of this procedure, its selectivity and extraction yield, in general, are very low.…”

“…Antioxidant peptides have been obtained from rapeseed residues ( Brassica napus ) [ 23 , 24 ], peels of pomegranate ( Punica granatum ) [ 3 , 25 ] and mango ( Mangifera indica ) [ 26 ], and seeds of apricot ( Prunus armeniaca ) [ 11 , 27 ], peach ( Prunus persica L .) [ 11 , 16 , 28 , 29 ], bottle gourd ( Lagenaria sciceraria ) [ 30 , 31 , 32 ], cherry ( Prunus cerasus L. ) [ 11 , 33 ], olive ( Olea europaea ) [ 11 , 16 , 17 , 34 ], plum (Prunus domestica L. ) [ 11 , 14 , 29 , 35 ], tomato ( Solanum lycopersicum ) [ 21 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ], wax gourd ( Benincasa hispida ) [ 44 ], jujube ( Ziziphus jujube ) [ 45 , 46 ], muskmelon ( Cucumis melo ) [ 47 ], watermelon ( Citrullus lanatus ) [ 32 , 48 , 49 , 50 , 51 , 52 , 53 ], papaya ( Carica papaya ) [ 54 ], Chinese cherry ( Prunus pseudocerasus ) [ 55 ], African breadfruit ( Treculia Africana ) [ 56 ], pumpkin ( Cuburbita ...…”

“…Typically, a preliminary extraction with hexane is the selected procedure. Sometimes, there is also a sieving step before the extraction to obtain a more homogeneous material [ 21 , 43 , 45 , 46 , 47 ]. Then, the extraction of proteins is performed.…”