Lipase-catalyzed acidolysis of fish liver oil with dihydroxyphenylacetic acid in organic solvent media

Lipase-catalyzed acidolysis reaction of fish liver oil with dihydroxyphenylacetic acid (DHPA) was investigated in terms of enzyme specificity as well as the effects of enzyme concentration, molar substrate ratio and organic solvent mixture on the bioconversion yield. The highest bioconversion yield of 83% was obtained when Novozym 435 was used as biocatalyst in a hexane:2-butanone mixture of 75:25 (v/v) at a fish liver oil to DHPA substrate molar ratio of 4:1; however, lower bioconversion yield (15%) was obtained when Lipozyme IM 20 was used. The bioconversion yield of phenolic monoacylglycerols (MAGs) increased from 11 to 70% when the ratio of the hexane/2-butanone reaction medium was changed from 85:15 to 75:25 (v/v), whereas that of phenolic diacylglycerols (DAGs) remained relatively unchanged (13–16%). The results also showed that the acidolysis reaction resulted in an increase of C_20:5 ω-3 and C_22:6 ω-3 proportions from 11.5 and 20.2% in the original fish liver oil to 22.6–27.1 and 22.8–23.1% in the phenolic lipids, respectively. The radical scavenging ability of phenolic lipids was determined to be about half-time lower than that of α-tocopherol.     

Glycation of lysozyme with galactose,galactooligosaccharides and potato galactan through the Maillard reaction and optimization of the production of prebiotic glycoproteins

The production of glycated lysozyme (LZM), with galactose, galactooligosaccharides (GOSs) and potato galactan through the Maillard reaction, was investigated. The percent blocked lysine, estimated from the furosine content, reached a maximum value of 11.2% for LZM:galactan conjugates after 1 day incubation at a a_w of 0.65. A maximum percent blocked lysine of 7.0 and 13.5% were obtained for LZM:galactose/GOS conjugates at a lower a_w of 0.45 after 3 and 7 days, respectively. However, the low percent blocked lysine and the high protein aggregation index of LZM:galactose/GOS conjugates at a_w 0.79 and 0.65 revealed the prevalence of the degradation of the Amadori compounds and the protein cross-linking. Mass spectrometry of LZM conjugates revealed the formation of different glycoforms. Glycated LZMs containing up to seven galactose moieties were formed; while only mono- and diglycated LZMs with GOSs were detected. 2–3 mol of galactan were conjugated to 1 mol of LZM. Response surface methodology, based on a 5-level and 3-factor central composite design, revealed that molar ratio and temperature were the most significant variables for the glycation of LZM with GOSs. The optimal conditions leading to a high percent blocked lysine (16.11%) with a low protein aggregation index (0.11) were identified: temperature of 49.5 °C, LZM:GOS molar ratio of 1:9 and a_w of 0.65. To the best of our knowledge, this is the first study on the optimization of LZM glycation with GOSs.     

Enzymatic generation of peptides from potato proteins by selected proteases and characterization of their structural properties

The use of low grade starting material for the generation of peptides with bioactivity properties is of interest. The proteins from the potato starch industry byproduct is a promising source, as several health benefits may be associated with their hydrolysates. The efficiency of selected proteases (Novo Pro‐D, Alcalase, Flavourzyme, and Papain), exhibiting different substrate specificities and cleavage action modes, to hydrolyze potato protein isolate (patatin and protease inhibitors) was investigated. Novo Pro‐D resulted in the lowest degree of hydrolysis, whereas Alcalase, Flavourzyme, and Papain exhibited a high catalytic efficiency for the hydrolysis of potato proteins. The degree of hydrolysis behaved in a concentration dependent manner. However, the end‐product profile (peptides and free amino acids) was dependent not only on the protease specificity, its cleavage action mode (endo/exo) and the availability of the intermediate substrates but also on the contribution of the protease inhibitors to the reaction kinetics through their inhibitory effects. Indeed, the dependence of the exo‐activity on the catalytic efficiency of the endo‐action of protease was shown to be significant. Papain generated more unique peptide sequences with homology assessment matching several potato proteins when compared with Flavourzyme. This can be attributed to the high exo‐peptidase activity of Flavourzyme resulting in the generation of shorter peptides which were difficult to match. Flavourzyme produced more peptides originated from patatin fraction, whereas Papain resulted in the release of more peptides corresponding to the protease inhibitor fractions. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:420–429, 2016     

Enzymatic synthesis of structured phenolic lipids by incorporation of selected phenolic acids into triolein

The synthesis of structured phenolic lipids by lipase-catalyzed transesterification of selected phenolic acids, including p-hydroxyphenyl acetic, p-coumaric, sinapic, ferulic and 3,4-dihydroxybenzoic acids, with triolein was investigated. The highest enzymatic activity (248 nmol esterified phenolic acid/g solid enzyme/min) and bioconversion (62%) was obtained for the transesterification of p-hydroxyphenyl acetic acid with triolein. In addition, the transesterification of p-coumaric with triolein resulted in a higher enzymatic activity (87 nmol esterified phenolic acid/g solid enzyme/min) and bioconversion (46%) than those obtained for the transesterfication of ferulic and sinapic acids. The results also showed that using p-hydroxyphenyl acetic, p-coumaric and ferulic acids as substrate, the maximum bioconversion of phenolic monoacylglycerols was close to that of phenolic diacylglycerols. Although p-coumaric acid had very low radical scavenging activity (2%) compared to that of ferulic acid (62%), the p-coumaroylated lipids demonstrated a higher scavenging potency (16%) than that of the feruloylated one (10%).     

Lipase-catalyzed biosynthesis of cinnamoylated lipids in a selected organic solvent medium

Biosynthesis of cinnamoylated lipids through the lipase-catalyzed transesterification reaction of cinnamic acid with triolein was investigated in organic solvent media. Electrospray ionization-mass spectroscopy (ESI-MS) structural analysis of the reaction mixture revealed the formation of two major end products, monoleyl-1(3)-cinnamate and dioleyl-2-cinnamate. Decreasing the molar ratio of cinnamic acid to triolein from 1:1 to 1:4.5 resulted in an increase in the maximum bioconversion yield of cinnamoylated lipids from 19 to 42%, which remained constant at a lower ratio of 1:6. However, an excess of triolein appeared to have a more beneficial effect on the formation of dioleyl-2-cinnamate than monoleyl-1(3)-cinnamate, leading to different end product compositions at ratios of substrates. With cinnamic acid to triolein ratios of 1:4.5 and 1:6.0, an increase in the bioconversion yield of cinnamoylated lipids to 55% was achieved by adding 2.2 mgmL(-1) silica gel to the reaction mixture. Radical scavenging activity of cinnamoylated lipids, with 50% of radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, was found to be higher than that of its corresponding phenolic acid.     

Lipase-catalyzed synthesis of phenolic lipids from fish liver oil and dihydrocaffeic acid

The enzymatic synthesis of phenolic lipids by lipase-catalyzed transesterification of dihydrocaffeic acid (DHCA) with fish liver oil was investigated in a selected organic solvent medium. These synthesized phenolic lipids have potential use as nutraceutical products. Using a molar ratio of 1:8 DHCA to fish liver oil in hexane:2-butanone mixtures of 75:25 and 85:15 (v/v), the lipase-catalyzed reaction resulted in maximum conversion of 55.8 and 65.4%, respectively. The maximum conversion of phenolic monoacylglycerols in hexane:2-butanone mixture of 75:25 and 85:15 (v/v) was 40.3 and 37.7%, respectively; using the same solvent mixtures, the conversions of the phenolic diacylglycerol were 15.8 and 36.8%, respectively. Hexane:2-butanone mixture of 75:25 (v/v) was, therefore, the best organic solvent mixture for the production of phenolic monoacylglycerols, while that of 85:15 (v/v) was best for the production of phenolic diacylglycerols. The phenolic lipids produced from the fish liver oil and DHCA demonstrated antioxidant property as indicated by its free radical scavenging capacity.     

Enzymatic synthesis of structured phenolic lipids by incorporation of selected phenolic acids into triolein

The synthesis of structured phenolic lipids by lipase-catalyzed transesterification of selected phenolic acids, including p-hydroxyphenyl acetic, p-coumaric, sinapic, ferulic and 3,4-dihydroxybenzoic acids, with triolein was investigated. The highest enzymatic activity (248?nmol esterified phenolic acid/g solid enzyme/min) and bioconversion (62%) was obtained for the transesterification of p-hydroxyphenyl acetic acid with triolein. In addition, the transesterification of p-coumaric with triolein resulted in a higher enzymatic activity (87?nmol esterified phenolic acid/g solid enzyme/min) and bioconversion (46%) than those obtained for the transesterfication of ferulic and sinapic acids. The results also showed that using p-hydroxyphenyl acetic, p-coumaric and ferulic acids as substrate, the maximum bioconversion of phenolic monoacylglycerols was close to that of phenolic diacylglycerols. Although p-coumaric acid had very low radical scavenging activity (2%) compared to that of ferulic acid (62%), the p-coumaroylated lipids demonstrated a higher scavenging potency (16%) than that of the feruloylated one (10%).     

Biophysical,Rheological, and Functional Properties of Complex of Sodium Caseinate and Olive Leaf Aqueous Polyphenolic Extract Obtained Using Ultrasound-Assisted Extraction

Food Biophysics - This study demonstrated the use of ultrasound-assisted extraction to render aqueous extract polyphenolic compounds from olive leaves. Sodium caseinate-olive leaf extract complexes...     

Immobilization of epoxide hydrolase from Aspergillus niger onto DEAE-cellulose: enzymatic properties and application for the enantioselective resolution of a racemic epoxide

Recombinant epoxide hydrolase (EH) from Aspergillus niger can be a very promising tool for the resolution of various racemic epoxides by enantioselective hydrolysis. The enzyme was successfully immobilized by ionic adsorption onto DEAE-cellulose (99% yield, 70% of retention activity). The temperature for maximal activity (40 °C) and the activation energy (38.8 kJ/mol) were similar for both the immobilized and free EHs, whereas the optimal pH was about one unit less for the immobilized enzyme. Thermal stability was also affected by immobilization; the immobilized enzyme appeared to be slightly less stable than the free one. However, a gram-scale resolution of racemic para-chlorostyrene oxide (pCSO) was successfully carried out in a repeated batch reactor, operated for seven cycles. Furthermore, using a very high substrate concentration of 2 M (306 g/L), i.e. biphasic conditions, the resolution of 3 g of pCSO was also achieved in a repeated batch reactor using approximately 300 mg of immobilized EH, corresponding to less than 3 mg of the enzymatic powder.     

Lipase-catalyzed transesterification of dihydrocaffeic acid with flaxseed oil for the synthesis of phenolic lipids

Lipase-catalyzed transesterification reaction of dihydrocaffeic acid (DHCA) with flaxseed oil in organic solvent media was investigated. Using equal molar concentration of DHCA and flaxseed oil, only phenolic monoacylglycerols were obtained with a transesterification yield (TY) of 18.9%. A 1:4 DHCA to flaxseed oil ratio resulted in the production of both phenolic mono and diacylglycerols, with TY of 39.6 and 27.8%, respectively. On the other hand, when 1:8 ratio of DHCA to flaxseed oil was used, the TY of phenolic diacylglycerols (46.0%) was higher than that of the phenolic monoacylglycerols (33.3%). The TY of phenolic diacylglycerols increased from 25.1 to 55.8%, when the ratio of the hexane/2-butanone reaction medium was changed from 65:35 to 85:25 (v/v); however, the TY of phenolic monoacylglycerols decreased slightly from 34.0 to 31.8%. The relative proportion of the C(18:3)n-3 was higher in the phenolic mono and diacylglycerols, 64.9 and 59.5%, respectively, as compared to the original flaxseed oil, 53.1%. The radical scavenging ability of phenolic lipids was significant; however, it was about half than that of alpha-tocopherol.