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Nanoencapsulation of hydrophobic nutraceuticals with food ingredients has become one of topical research subjects in food science and pharmaceutical fields. To fabricate food protein-based nano-architectures as nanovehicles is one of effective strategies or approaches to improve water solubility, stability, bioavailability and bioactivities of poorly soluble or hydrophobic nutraceuticals. Milk proteins or their components exhibit a great potential to assemble or co-assemble with other components into a variety of nano-architectures (e.g., nano-micelles, nanocomplexes, nanogels, or nanoparticles) as potential nanovehicles for encapsulation and delivery of nutraceuticals. This article provides a comprehensive review about the state-of-art knowledge in utilizing milk proteins to assemble or co-assemble into a variety of nano-architectures as promising encapsulation and delivery nano-systems for hydrophobic nutraceuticals. First, a brief summary about composition, structure and physicochemical properties of milk proteins, especially caseins (or casein micelles) and whey proteins, is presented. Then, the disassembly and reassembly behavior of caseins or whey proteins into nano-architectures is critically reviewed. For caseins, casein micelles can be dissociated and further re-associated into novel micelles, through pH- or high hydrostatic pressure-mediated disassembly and reassembly strategy, or can be directly formed from caseinates through a reassembly process. In contrast, the assembly of whey protein into nano-architectures usually needs a structural unfolding and subsequent aggregation process, which can be induced by heating, enzymatic hydrolysis, high hydrostatic pressure and ethanol treatments. Third, the co-assembly of milk proteins with other components into nano-architectures is also summarized. Last, the potential and effectiveness of assembled milk protein nano-architectures, including reassembled casein micelles, thermally induced whey protein nano-aggregates, α-lactalbumin nanotubes or nanospheres, co-assembled milk protein-polysaccharide nanocomplexes or nanoparticles, as nanovehicles for nutraceuticals (especially those hydrophobic) are comprehensively reviewed. Due to the fact that milk proteins are an important part of diets for human nutrition and health, the review is of crucial importance not only for the development of novel milk protein-based functional foods enriched with hydrophobic nutraceuticals, but also for providing the newest knowledge in the utilization of food protein assembly behavior in the nanoencapsulation of nutraceuticals.

Use of protein-based nanovehicles has been well recognized to be one of the most effective strategies to improve water dispersibility, stability and bioavailability of nutraceuticals or bioactive ingredients. Thanks to their health-benefiting effects and unique assembly behavior, soy proteins seem to be the perfect food proteins for fabricating nanovehicles in this regard. This review presents the state-of-art knowledge about the assembly of soy proteins into nano-architectures, e. g., nanoparticles, nanocomplexes or nanogels, induced by different physicochemical strategies and approaches. The strategies to trigger the assembly of soy proteins into a variety of nano-architectures are highlighted and critically reviewed. Such strategies include heating, enzymatic hydrolysis, pH shift, urea or ethanol treatment, reduction, and static high pressure treatment. The self-assembly behavior of soy proteins (native or denatured) is also reviewed. Besides the assembly of proteins alone, soy proteins can co-assemble with polysaccharides to form versatile nano-architectures, through different processes, e.g., heating or ultrasonication. Finally, recent progress in the development of assembled soy protein nano-architectures as nanovehicles for hydrophobic nutraceuticals is briefly summarized. With the fast increasing health awareness for natural and safe functional foods, this review is of crucial relevance for providing an important strategy to develop a kind of novel soy protein-based functional foods with dual-function health effects from soy proteins and nutraceuticals.

In the work, we report a kind of novel highly transparent oil-in-water (O/W) HIPE gels stabilized solely by c-phycocyanin (CPC; an important biliprotein pigment), with a great potential to act as outstanding containers for heat or UV labile lipophilic bioactives. The CPC was solubilized in 6 M urea solution containing 40 wt% glycerol, in order to achieve the improved emulsification performance of the protein, as well as the transparency of the resultant HIPE gels through the refractive index (RI) matching between the aqueous and dispersed oil (dodacane) phases. Using 6 M urea containing 40 wt% glycerol as the aqueous phase, the transparent HIPE gels could be formed at the CPC concentration (c) as low as 0.1 wt%, and oil fractions in the range 0.6–0.86. In the protein-poor regime, e.g., c

Summary Biodegradable food packaging promises a more sustainable future. Poly(lactic acid) (PLA) is a promising alternative for petroleum-derived polymers. However, PLA films suffer from poor barrier properties compared with petroleum-derived ones. To address this issue, we designed bilayer and sandwich-architectured trilayer films based on PLA and gliadin. We reported firstly the direct formation of PLA–gliadin bilayer/trilayer films without surface modification on PLA film. The films were compact and uniform, and double/triple layers were combined firmly, preventing delamination. This strategy enhanced mechanical resistance, ductility and moisture barrier of gliadin films and concomitantly enhanced the oxygen barrier for PLA films. Thymol loadings endowed bilayer/trilayer films with antimicrobial activity and antioxidant activity. The antimicrobial activity of the films depended on film types, and gliadin layer presented larger inhibition zone than PLA layer, hinting that the films possessed directional releasing role. This study opens a promising route to fabricate bilayer/trilayer architecture helping to create synergism of the biopolymers.

A softer natural Pickering nanostabilizer, S-ovalbumin (S-OVA) was reported in this work, based on our previous researches about soft globular protein nanoparticles. Compared with native OVA, S-OVA has higher surface hydrophobicity, greater conformational flexibility and thinner tightly-bond water layer, which make it be unfolded more highly at the oil-water interface. However, S-OVA also possesses higher zeta-potential and thicker closely-surrounding water layer, offering it stronger electrostatic repulsion and steric hindrance between molecules and increased intramolecular cohesion. The improvements guarantee S-OVA undisintegrated particle structure and independent state on the interface and high refolding off the interface. The more flexible interior and firmer exterior together endow a higher softness to S-OVA. The HIPPE gels solely stabilized by S-OVA were fabricated using one-step shearing. These HIPPE gels own steady network structure mainly supported by bridging flocculation, strong self-supporting ability and moldability. The high storage stability and ability to inhibiting lipid oxidization provide the HIPPE gels an enormous potential in encapsulating and protecting volatile, easily-oxidized or dangerous organic liquids, during the storage and transportation. The attractive temperature responsiveness offers a high convenience to re-obtaining the organic liquids. And a re-encapsulation can be easily achieved via a re-shearing. The heat-enhanced gel intensity and moldability mean the HIPPE gels can be applied to produce dualistic gels or porous scaffolds with latent applications. These findings are helpful to explore more new Pickering stabilizers from the nature and extend the applications of HIPPEs in highly-demanded and high-tech industries.

There is increasing interest in the development of Coenzyme Q10 (CoQ10) ingredients appropriate for functional food formulations, due to its potential health effects. The present work reported that food proteins including milk and soy proteins can effectively perform as vehicles to remarkably improve water dispersibility, stability and even bioaccessibility of CoQ10. The improvement was mainly due to the formation of protein-CoQ10 complexes, through hydrophobic interactions. The formation of complexes with CoQ10 distinctly changed the physicochemical properties of food protein particles that seemed to be more favorable for their colloidal stability. The complexation remarkably improved the stability against UV exposure or in vitro digestion, and bioaccessibility of CoQ10. In contrast, milk proteins (sodium caseinate and whey protein concentrate) were more appropriate to perform as vehicles for improved bioaccessibility of CoQ10 than soy protein isolate. The findings provide an effective strategy to improve the delivery and bioaccessibility of CoQ10 for the formulation of functional foods enriched with CoQ10.

In this work, we report on highly transparent and stable high internal phase emulsions (HIPEs) stabilized by protein in general and globular proteins in particular using a refractive index (RI)-matching technique. Sucrose (50 wt.%) was added in the aqueous phase to match the RI of the oil phase (dodecane). In the presence of 50 wt.% sucrose, gel-like HIPEs (oil fraction of 0.75) could be stabilized by bovine serum albumin (BSA - a representative globular protein) at a concentration in the aqueous phase as low as 0.3 wt.%. In addition to achieving high transparency, the presence of 50 wt.% sucrose remarkably improved the emulsification performance of BSA and facilitated the formation of HIPE gels. The improvements were largely associated with high surface coverage via the formation of bridging droplets. The presence of 50 wt.% sucrose transformed BSA into a soft nanoparticle with high structural integrity that could resist the adsorption-induced structural disruption at the interface. The RI-matching strategy to fabricate transparent HIPE gels could be applied to other proteins. The findings are of interest for providing a facile strategy to fabricate biocompatible and highly transparent HIPE gels with great potential in the food, healthcare and light-induced catalysis fields.

In this paper we reported that pea protein isolate (PPI) at pH 3.0 exhibits a novel Pickering stabilization for oil-in-water emulsions. At pH 3.0, most of the proteins in PPI were present in the nanoparticle form, with the hydrodynamic diameter of 134–165 nm depending on the concentration (c; 0.25–3.0 g/100 mL). For the emulsions formed at a specific oil fraction of 0.2, increasing the c from 0.25 to 3.0 g/100 mL resulted in a considerable reduction in the emulsion size, while their creaming stability progressively increased, and especially at c values higher than 2 g/100 mL, no creaming occurred even after storage of 20 days. Confocal laser scanning microscopy observations showed that increasing the c resulted in a progressive increase in extent of droplet flocculation, and at higher c values, a network consisting of flocculated droplets could be formed. The emulsions formed at c values above 1.0 g/100 mL exhibited extraordinary stability against coalescence. The flocculated droplet network formation was closely associated with the increased amount of adsorbed proteins at the interface. The results suggest that pea proteins exhibit a good potential to act as a kind of Pickering stabilizers for oil-in-water emulsions at acidic pHs.

The spray-drying microencapsulation properties of protein isolates from three selected Phaseolus legumes (kidney, red and mung beans; KPI, RPI and MPI), at a specific concentration (6 g/100 mL) and oil/protein ratio (1:1, w/w) were compared with soy protein isolate (SPI). The oil retention efficiency (RE), redispersion and dissolution behavior, as well as microstructure of the spray-dried powders were characterized. The influence of storage at 75% relative humidity for 7 days on these characteristics was also evaluated. The results indicated that the microencapsulation properties (except RE in the KPI case) of the three protein isolates were considerably poorer than SPI, though their emulsifying ability was even superior. The microencapsulating properties of these protein isolates were largely associated with their interfacial properties, especially the interfacial protein concentration. Among the three protein isolates, the spray-dried powders with KPI exhibited highest RE but least redispersion and/or dissolution behavior. The storage resulted in a severe loss of RE and ability to be redispersed and/or dissoluted, with much higher extent observed for the KPI powder. These results suggest that appropriate modifications, especially in interfacial properties, should be conducted on these proteins to warrant their application as wall materials in spray-drying microencapsulation.

A novel process to efficiently form soy protein isolate (SPI)-stabilized emulsion gels, induced by microbial transglutaminase (MTGase) was reported, with the enzyme added before the emulsification (instead of after the emulsification in the conventional case). The rheological behavior and microstructure of the formed emulsion gels (at a constant protein concentration of 6 g/100 mL and oil fractions (o) of 0.2–0.6) were characterized using dynamic oscillatory measurement and confocal laser scanning microscope. The gel stiffness of the formed gels with the novel process progressively increased with increasing enzyme concentration (1.0–5.0 U/g), or with the o increasing from 0.2 to 0.6. Interestingly, the gel stiffness at a given o with the novel process was considerably greater than that with the conventional process, though the enzyme concentration was less (e.g., 1.0 vs 20 U/g). Furthermore, a pre-incubation (15–60 min) of the proteins with the enzyme (before the emulsification) greatly improved the gelation. The analyses of droplet size and amount of entrapped proteins within the gel matrix indicated that during the initial gel network, the bridging flocculation of oil droplets played a prominent role, but the full development of the gel stiffness mainly depended on the inter-droplet covalent cross-linking.

The work reports the influence of stirring (with intermittent or continuous modes) during incubation on the rheological properties, water-holding capacity (WHC) and microstructure of soy protein isolate (SPI)-stabilized emulsion gels, induced by microbial transglutaminase (MTGase), at a constant protein concentration (6 g/100 mL) and three oil fractions (0.2, 0.4 and 0.6). The results indicated that the stirring simultaneously during incubation with the enzyme greatly facilitated the gel network formation and increased stiffness of the formed emulsion gels. The improvement of gel stiffness and WHC for the stirred-type gels was much better with the intermittent than continuous mode. The differences in rheological properties and WHC between different emulsion gels were basically consistent with the differences in their microstructure. Interestingly, the pattern of interaction forces involved in the gel network varied between unstirred and stirred gels, and even between the two stirring modes. The results suggest that the application of shearing could greatly improve the enzyme-induced gelation of protein-stabilized emulsions, and produce stirred-type emulsion gels with better water-holding and rheological properties, within a much shorter periods (relative to enzyme-set gels).

Summary The aim of this investigation was to explore the pH-induced conformational changes of phaseolin using differential scanning calorimetry (DSC), fluorescence and circular dichroism (CD) spectra. The surface charges at the varying pH and ionic strength were also determined to probe the possible relationship between the surface charges of phaseolin and its conformation. The ζ-potential of phaseolin decreased from 27.9 mV at pH 3.0 to –44 mV at pH 9.4, and the isoelectric point (iep) occurred at pH 4.21, which were comparable with the theoretical estimations derived from amino acid composition and pK values. The iep of phaseolin was independent of ionic strength, while the magnitude of ζ-potential decreased as the ionic strength increased. The near-UV CD, DSC and fluorescence spectra analyses indicated highly acidic and alkaline pH conditions induced the loss of tertiary conformation of phaseolin. The far-UV CD spectra analysis confirmed pH-shift led to the decreases in ordered secondary structure compositions. The present results suggested the loss of secondary and/or tertiary conformation of phaseolin as a result of the varying pattern in electrostatic interactions as pH shifted from 7.0 to acidic or alkalic pH.

Summary The effect of pHs and heating on the protein–polysaccharide complexation between the 0.5 wt% soy globulin (7S or 11S) and 0.1 wt% chitosan was studied. Electrophoretic and light scattering techniques were used to examine the electrical charge and aggregation of the individual biopolymers and complexes. At pH 3.0–6.5, 7S (or 11S) globulin in the presence of chitosan had significantly higher ζ-potentials and lower particles size than 7S (or 11S) globulin alone did (e.g. 600–6000 nm at pH 5.5), indicating the formation of complexes. After heating 7S (or 11S)–chitosan mixtures had higher positive value of ζ-potential. 7S (or 11S)–chitosan mixtures exhibited a significant increase in positive value of ζ-potential and stability after heating at lower pH values (pH 3.3 instead of pH 4.5). Compared with other mixtures, at pH 2.5–6.0, the most remarkable decrease in aggregation was obtained for 11S–chitosan mixtures after heating at pH 3.3.

Steady shear and dynamic oscillatory measurements were used to investigate the effect of concentration, ionic strength and thermal treatment on rheological properties of soybean β-conglycinin in aqueous dispersions. SDS-PAGE and Differential Scanning Calorimetry (DSC) showed that β-conglycinin exhibited partial denaturation and formation of aggregates during isolation. Under steady shear flow, strong shear-thinning behavior was observed with increasing shear rate from 0.001 to 1200 s−1. A dispersion of β-conglycinin (≥5% w/v, without applying thermal treatment) exhibited gel-like dynamic mechanical spectra at 20°C. This suggested that β-conglycinin in aqueous dispersions showed rheological properties of typical weak gel-like (entanglement) or semi diluted polymeric solution. Weak gel network of β-conglycinin was susceptible to ionic strength, suggesting that electrostatic forces play an important role in the formation of weak gel network. These properties of β-conglycinin have practical significance for t...

This study aimed at establishing an effective preparative isolation method of soy β-conglycinin constituent subunits and characterizing some of their physicochemical properties and their heat-induced aggregation. These subunits were isolated in relatively large amounts and in high purity by dissociating β-conglycinin in 6 M urea and using a combination of DEAE-Sepharose fast flow column chromatography and immobilized metal ion affinity chromatography (IMAC). At a pH deviating from isoelectric point (pI), zeta potentials of α′ and α subunits were much larger than that of β subunit, while in the latter case, the hydrophobic groups were more buried within the proteins. Dynamic light scattering analysis indicated that the extent of heat-induced aggregation of β subunit was much higher than that of α′ and α subunits, and the aggregation was also more affected by the increase in ionic strength. Atomic force microscopy analysis indicated that more ordered and stranded aggregates were formed for α′ and α subunits. These results confirm a close relationship between physicochemical properties and heat-induced aggregation of β-conglycinin subunits.

A simple two step precipitation method was used to investigate the effect of MgCl 2 instead of CaCl 2 on fractionation of soybean glycinin and β-conglycinin. Compositional and physicochemical properties of the resulting protein fractions were characterised. The optimised procedure, in terms of protein yield, purity, phytate content and physicochemical properties, was obtained when the addition of 5 mM MgCl 2 was used. After application of 5 mM MgCl 2 , the phytate content of the glycinin-rich and β-conglycinin-rich fractions was about 0.4% and 1.3%, respectively, but the addition of 5 mM CaCl 2 increased the phytate content of the glycinin-rich fraction to 1.25% and decreased that of β-conglycinin-rich fraction to 0.67%. Low phytate protein product was suitable for use in infant formula and acidic food. The solubility of the glycinin-rich fractions with MgCl 2 was significantly higher than that with CaCl 2 at pH < 4.5. Application of MgCl 2 improved thermal stability of the β-conglycinin-rich fraction.

The mechanical, hydrophobic and thermal properties of cast films of vicilin-rich protein isolates from three Phaseolus legumes were investigated and compared to that of soy protein isolate (SPI). The influence of heat curing at 85 °C on the properties of these films was characterized. The films of vicilin-rich protein isolates exhibited much less mechanical strength (TS) and elongation at break (EB) and similar film surface hydrophobicity, as compared with those of the SPI film. The heating remarkably improved the TS of these films, and the extent of the improvement much higher than that of the SPI film, while the EB was only slightly affected. The thermal properties of these protein isolate films were variable, and much distinctly affected by the heating of the films, to a various extent, depending on the type of protein isolates. Protein solubility analyses indicated strengthened hydrogen and hydrophobic bondings of these films by the heating. The results suggest that those vicilin-rich protein isolates have good potential to form cast films with mechanical strength comparable to that of SPI film.

The effects of succinylation and acetylation on some functional, structural properties and in vitro trypsin digestibility of hemp protein isolate (HPI) were investigated. The extent of acylation gradually increased from 0 to 60―70%, with the anhydride-to-protein ratio increasing from 0 to 1.0 g g ―1 . Size exclusion chromatography showed that succinylation led to formation of more soluble protein aggregate than acetylation, especially at anhydride levels higher than 0.1 g g ―1 . Succinylation led to gradual increase in protein solubility (PS) from 30 to 85―90%, while in the acetylation case, the PS was improved only at low anhydride levels, increasing from 30 to about 50% with anhydride-to-protein ratio increasing from 0 to 0.2 g g ―1 . At neutral pH, the emulsifying activity indexes (EAI) of HPI was 22.1 m 2 g ―1 , and the EAI linearly and significantly increased with the extent of acylation. The EAIs of succinylated and acetylated HPI (1.0 g g ―1 ) were 119.0 and 54.4 m 2 g ―1 , respectively. Differential scanning calorimetry (DSC) and intrinsic fluorescence spectrum analyses indicated gradual structural unfolding of proteins, or exposure of hydrophobic clusters to the solvent, especially at higher anhydride levels. Additionally, the in vitro trypsin digestibility was significantly improved by the succinylation. The results indicated that the chemical acylation treatment (especially succinylation) could be applied to modify some selected functional properties of hemp proteins, especially PS and emulsifying ability.

The aggregation and structural properties of soy protein isolate (SPI), induced by high pressure (HP) treatment at 200–600 MPa were investigated by size-exclusion chromatography combined with multi-angle laser scattering (SEC-MALLS) and fourier transform infrared (FTIR) spectroscopy. HP treatment at lower pressure level (e.g., 200 MPa) resulted in formation of marked insoluble aggregate of SPI, while the treatment at higher pressure level (e.g., 600 MPa) led to transformation of insoluble aggregate to soluble one. The soluble aggregate formed at 400 or 600 MPa had much less mean molecular weight (MW) (about 5.2 × 10 6 g/mol) than that at 200 MPa (about 1.6 × 10 7 g/mol), and was also much more homogenous in MW distribution. FTIR analyses confirmed changes in secondary and tertiary structures, induced by HP treatment. These results can provide direct evidence or explanation for HP-induced modification of soy proteins.

The thermal denaturation and gelation properties of vicilin-rich protein isolates from red bean, red kidney bean and mung beans (further denoted as RPI, KPI and MPI) were investigated by differential scanning calorimetry (DSC) and dynamic oscillatory measurements. The relation between the properties of these proteins to their free sulphydryl (SH)/disulfide bond (SS) contents was also evaluated. DSC analyses showed that many DSC characteristics of major endothermic peak (corresponding to vicilin component), including its denaturation temperature ( T d ), enthalpy changes (Δ H ) and width at half-peak height (Δ T 1/2 ), significantly varied with the type of protein isolates. Furthermore, the heat-induced gelation, including onset of gelation and the development of mechanical moduli, was also dependent on the type of protein isolates. The thermal denaturation of these proteins was nearly unaffected by the presence of reducing agent dithiothreitol (DTT), while the presence of DTT weakened the gel formation. The T d of vicilin components and the mechanical moduli of corresponding formed gels were positively related to their SS contents. Additionally, the formed gels were thermo-irreversible, and heat pretreatment (carried out at temperatures higher than or close to the T d of these vicilins) could improve the gel network formation. These results confirm that vicilin-rich protein isolates from various legumes show different patterns of thermal denaturation and gelation, and these properties are to a great extent related to their SH and/or SS contents.

The influence of thermal pretreatment of raw soymilk on the gel hardness and microstructure of tofu, induced by microbial transglutaminase (MTGase), was investigated in this paper. Modulated differential scanning calorimetry analysis showed that individual proteins in soymilk were to a various extent denatured by different thermal pretreatments. The viscosity of the soymilk and the gel hardness of MTGase-induced tofu were more highly related with the heating rate (up to 90 °C) than the mode of heating. At any enzyme concentration of MTGase, the tofus prepared from soymilk heated at 75 °C for 10 or 30 min showed highest gel hardness among all tested ones (P⩽0.05). Scanning electron microscopy analysis indicated that the microstructure of the tofu from soymilk heated at 75 °C for 30 min had a unique coral-like structure, much more continuous and homogenous than that from soymilk at 95 °C for 5 min. These results confirmed that the appropriate heat pretreatment (e.g. in the present, at 75 °C for 10–30 min) remarkably improved the gel strength of tofu by means of MTGase, and strengthened the tofu gel structure.

Microbial transglutaminase (MTGase) has been shown to effectively induce soymilk with a certain level of solid content to form filled tofu. The gel formation of this kind of tofu and the influence of reaction parameters on the properties of formed tofu were investigated by dynamic oscillatory and/or large-strain rheological measurements. The gelation process and the development of the mechanical moduli (especially the storage modulus, G′ ) of this kind of tofu were highly dependent upon the incubation temperature. Textural property analysis (TPA) results showed that many TPA parameters of this kind of tofu, including gel hardness, gumminess, springiness and cohesiveness, were also affected by the applied enzyme amount, the pH of soymilk and the presence of NaCl, especially for gel hardness. In addition, the additional heating and cooling treatment could significantly improve the gel strength of tofu, induced by MTGase at lower temperatures (e.g. 25 and 37 °C). These results suggested that a new kind of tofu with good quality could be produced using the enzymatic cross-linking technique, by the combination with the thermal treatment.

The influence of microbial transglutaminase (MTGase) treatment in the presence and absence of dithiothreitol (DTT) on the thermal stability of β-lactoglobulin (β-LG) was investigated using size-exclusion chromatography (SEC) combined with on-line multiangle laser light scattering (MALLS) and UV detection. SEC–MALLS–UV analyses showed that moderate MTGase treatment (up to 6 or 9 h) led to the decline in thermal stability of β-LG, while excess treatment (e.g. 23 h) resulted in remarkable increase, irrespective of whether the reducing agent DTT was present or not. The modulation in thermal stability may be attributed to the partial unfolding of protein molecules and the subsequent re-arrangement of conformation.

Hemp protein hydrolysates with various yields of trichloroacetic acid (TCA)-soluble peptides (Ysp) and surface hydrophobicity (Ho) were obtained by Neutrase® hydrolysis from hemp protein isolate (HPI). The peptide profiles, amino acid composition and antioxidant activities (DPPH radical scavenging ability, reducing power and Fe2+ chelating ability) of the hydrolysates, obtained at 60–240 min, were evaluated. Higher DPPH radical scavenging (IC50, 2.3–2.4 mg/mL) and Fe2+ chelating (IC50, 1.7–1.8 mg/mL) abilities were observed for the hydrolysates with Ysp in the range of 28–30 and 18–28 %, respectively, while the high reducing power was only observed for the hydrolysate with Ysp of 18 %. The DPPH radical scavenging and Fe2+ chelating abilities were closely correlated with the peptide profiles and Ho of the hydrolysates. The peptide profiles of the hydrolysates with higher hydrophobic amino acids exhibited higher DPPH radical scavenging and Fe2+ chelating abilities., Hidrolizom izolata proteina pomoću enzima Neutrase® dobiveni su hidrolizati proteina konoplje s različitim prinosom peptida topljivih u trikloroctenoj kiselini (Ysp) i hidrofobnošću površine (Ho). Ispitan je peptidni profil, sastav aminokiselina i antioksidativna aktivnost (sposobnost uklanjanja DPPH radikala, reducirajuća snaga i sposobnost stvaranja helata Fe2+) hidrolizata dobivenih nakon 60-240 min. Uočena je veća sposobnost hidrolizata s Ysp=28-30 % da uklone DPPH radikale (IC50; 2,3-2,4 mg/mL), te veća mogućnost stvaranja helata Fe2+ s hidrolizatima vrijednosti Ysp=18-28 % (IC50; 1,7-1,8 mg/mL). Velika je reducirajuća snaga samo u hidrolizata s Ysp=18 %. Sposobnost uklanjanja DPPH radikala i stvaranja helata Fe2+ povezana je s peptidnim profilom i hidrofobnošću površine hidrolizata (Ho). Hidrolizati s većim udjelom hidrofobnih aminokiselina pokazali su bolju sposobnost uklanjanja DPPH radikala i stvaranja helata Fe2.

The objective of this work was to investigate the effect of microbial transglutaminase (MTGase) treatment on the properties and microstructures of soy protein isolate (SPI) films cast with 0.6 plasticizer per SPI (gg(-1)) of glycerol, sorbitol and 1:1 mixture of glycerol and sorbitol, respectively. Tensile strength (TS), elongation at break (EB), water vapor transmission rate (WVTR) or water vapor permeability (WVP), moisture content (MC), total soluble matter (TSM), lipid barrier property and surface hydrophobicity of control and MTGase-treated films were evaluated after conditioning film specimens at 25 degrees C and 50% relative humidity (RH) for 48 h. The treatment by 4 units per SPI (Ug(-1)) of MTGase increased the TS and surface hydrophobicity by 10-20% and 17-56%, respectively, and simultaneously significantly (Por =0.05) decreased the E, MC and transparency. The WVTR or TSM of SPI films seemed to be not significantly affected by enzymatic treatment (P0.05). The MTGase treatment also slowed down the moisture loss rate of film-forming solutions with various plasticizers during the drying process, which was consistent with the increase of surface hydrophobicity of SPI films. Microstructural analyses indicated that the MTGase-treated films of SPI had a rougher surface and more homogeneous or compact cross-section compared to the controls. These results suggested that the MTGase treatment of film-forming solutions of SPI prior to casting could greatly modify the properties and microstructures of SPI films.