In vitro digestibility and antioxidant activity of plant protein isolate and milk protein concentrate blends

The replacement of animal with plant proteins in human diets has been increasing in recent years. The impact of blending milk protein concentrate (MPC) with protein isolates from soy (SPI), rice (RPI) and pea (PPI) on the in vitro digestibility and antioxidant activity of the resultant blends was investigated. Different plant protein–MPC blends (i.e., SPI–MPC (25:75), RPI–MPC (50:50) and PPI–MPC (25:75)) were analyzed. The lowest protein digestibility corrected amino acid score (PDCAAS) was associated with RPI (0.70), while the blends had PDCAAS values above 1.00 demonstrating the high digestibility of the proteins in the blends studied. An in vitro simulated gastrointestinal digestion was carried out on the samples. The degree of hydrolysis and gel permeation high performance liquid chromatography profiles showed that the SPI–MPC blend was more extensively digested in the gastric phase compared with the two other blends, while the PPI–MPC and RPI–MPC blends were mainly digested during the intestinal phase. The SPI–MPC digested blend had the highest 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity having a half maximal effective concentration (EC50) of 0.10 ± 0.01 mg/mL. The findings show that blends of plant protein with MPC had higher in vitro digestibility and antioxidant activity compared to the individual plant protein isolates

Physicochemical properties and water interactions of milk protein concentrate with two different levels of undenatured whey protein

Two bovine milk protein concentrate (MPC85) samples containing 85% protein were produced using different heat treatments. The physicochemical and water absorption properties (i.e., the solubility, wettability, water holding capacity (WHC) and particle size on reconstitution) of these two MPC85 samples with two different levels of undenatured whey protein (WP, i.e., MPC85S1 and MPC85S2) were investigated. The undenatured WP level in MPC85S1 and MPC85S2 was 16.6 and 6.0 g/100 g total protein, respectively. The calcium ion activity of MPC85S1 and MPC85S2 was 2.93 and 2.64 mmol/L, respectively (p < 0.05). The surface elemental profile, as determined using X-ray photoelectron spectroscopy, showed that protein (84%) and lipid (16%) were the dominant macromolecules on the surface of both MPC85 powder particles. Scanning electron microscopy analysis showed that MPC85S1 powder particles were relatively spherical while MPC85S2 particles appeared agglomerated. Particle size analysis of 5% aqueous suspensions showed a broader size distribution for MPC85S1 compared to MPC85S2. The cold solubility of the samples rehydrated at 4 ◦C after 192 h storage at 4 ◦C was higher for MPC85S1 than MPC85S2, while on increasing the temperature of rehydration from 4◦ to 75 ◦C the solubility increased for both MPC85 samples. A lower contact angle, and thus higher wettability was observed for MPC85S2 in comparison to MPC85S1. While the MPC85 samples studied herein had similar gross composition, major differences in the level of heat induced WP denaturation (~2.5 times) and a 10% difference in ionic calcium content existed. Consequently differences in the ionic calcium and more importantly the differences in the interactions between casein and native/denatured WP are considered to have resulted in altered physico-chemical properties and thereby different aqueous phase interactions

Contribution of whey protein denaturation to the in vitro digestibility, biological activity and peptide profile of milk protein concentrate

The impact of whey protein (WP) denaturation on the in vitro digestibility and biological activity of milk protein  concentrate-85 (MPC85) was investigated. MPC85S1 and MPC85S2 having undenatured WP levels equal to 16.6  and 6.0 g/100 g overall protein, respectively, had similar in vitro protein digestibility corrected amino acid scores  equal to 1.14. The samples were subjected to in vitro simulated gastrointestinal digestion while sampling was  performed every 30 min during gastric (GD) followed by intestinal (GID) digestion. Liquid chromatography–mass  spectroscopy showed that MPC85S1-GD, MPC85S2-GD, MPC85S1-GID and MPC85S2-GID had 50, 38, 47 and 66  unique peptides, respectively. The degree of hydrolysis, molecular mass distribution, dipeptidyl peptidase-IV  inhibition, oxygen radical absorbance capacity and 2,2′ -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)  radical scavenging activity of the digests were compared. Overall, the results showed higher digestibility and  bioactivities for low-denatured MPC85 compared to high-denatured MPC85 upon GD, however, following GID,  both samples were digested to a similar extent.  </p

Generation of hydrolysates from rice bran proteins using a combined ultrasonication-Alcalase hydrolysis treatment

Hydrolysis of rice bran protein (RBP) using a physical-enzymatic combined method (ultrasound-Alcalase) was carried out. The RBP was extracted using an ultrasound-aided alkaline extraction method and then the extract was hydrolysed. Furthermore, ultrasounication was used prior to Alcalase hydrolysis (pH 8.5, 10 min, 55 ◦C). Two variables were considered to operate the ultrasonication: power (50, 100 and 150 w) and duration of the treatment (10, 25 and 40 min). The results showed that the degree of hydrolysis (DH%) was increased with increasing the power and the duration. The highest DH (27.35 ± 0.45%) was associated with the hydrolysates obtained by ultrasonication (150 w, 40 min)-Alcalase combined treatment. The optimal condition for the ultrasonication was found at 50 w-10 min, where the bioactive peptides (BAPs) had the highest 2,2-diphenyl-1- picrylhydrazyl free radical (DPPH• ) scavenging activity (86.55 ± 1.17%) and lipase inhibitory activity (57.57 ± 0.91%). The hydrolysates obtained at the optimized condition were studied in terms of physicochemical and structural properties. The mass distribution of the materials was studied using the high performance liquid chromatography (HPLC) showing a lower molecular weight proteins and peptides for all generated hydrolysates compared to non-hydrolysed samples. The results were in agreement with the results of DH analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Ultrasonication enhanced the effect of enzyme hydrolysis by affecting the structure of the proteins. This was confirmed by the structural investigation using fourier-transform infrared spectroscopy and ultraviolet–visible spectrophotometry. Using ultrasound in different conditions prior to enzymatic hydrolysis influenced in the biological properties of the BAPs generated from RBP

Semi-continuous production of xanthan in biofilm reactor using Xanthomonas campestris

Semi-continuous production of xanthan gum using self-immobilized Xanthomonas campestris cells in biofilm reactors was studied. Fermentation was carried out using two different designs of biofilm reactor equipped with a) stainless-steel support (SSS) and b) polyethylene support (PES). Fermentation was performed in three cycles with refreshing the media at the beginning of each: cycle 1, 0− 27 h; cycle 2, 27− 54 h; and cycle 3, 54–78.5 h. Results showed that the glucose consumption and the pH reduction in the PES biofilm reactor was faster compared to the SSS biofilm reactor. Scanning electron microscopy showed that the SSS was capable to immobilize more cells during the growth of X. campestris. The maximum concentration of xanthan gum in the SSS biofilm reactor obtained after 27 h (3.47 ± 0.71 g/L), while the maximum concentration of xanthan in the PES biofilm reactor obtained after 78.5 h (3.21 ± 0.68 g/L). Thermal stability analysis of xanthan using differential scanning calorimetry showed the presence of two fractures attributed to dehydration and degradation of polymer. The thermogram represented both endothermal and exothermal behaviour of xanthan polymer. Furthermore, the functional groups and molecular structure of the xanthan produced in this study was evaluated using Fourier transform infrared spectrometry and also proton nuclear magnetic resonance. in addition, the surface tension of (0.2 %, w/v) xanthan gum solution was in a range of 52.16–56.5 mN/m. Rheological analysis of xanthan showed that the G′ values were higher than the G′′ in all frequencies demonstrating a relatively high elasticity of the produced xanthan gum

Application of in silico approaches for the generation of milk protein-derived bioactive peptides

Milk protein derived peptides have numerous well-documented bioactive properties. The conventional approach for the generation, identification and validation of bioactive peptides (BAPs) has involved (i) protein hydrolysis, (ii) bioactivity screening and (iii) validation in vivo. The low potency (in comparison to conventional drugs), susceptibility to breakdown during gastrointestinal transit and low intestinal permeability are key challenges in the development of highly bioactive food protein hydrolysates/peptides. However, the generation of potent and effective health enhancing hydrolysates/peptides can benefit from a range of in silico techniques including the application of structure bioactivity relationship modelling (e.g., quantitative structure activity relationship (QSAR) modelling), molecular docking and design of experiments (DOE) approaches to optimise BAP production and identification. Some examples of how these approaches have been employed in BAP discovery and generation will be outlined

Production of synbiotic ice-cream using Lactobacillus casei/Lactobacillus plantarum and fructooligosaccharides

Production of synbiotic ice creams formulated with fructooligosaccharides was performed in this study. Fermentation of ice cream mix was carried out using Lactobacillus casei and Lactobacillus plantarum. Fermented samples had lower pH and higher acidity than unfermented samples. The highest viability of probiotics during storage was associated with synbiotic ice creams, demonstrating a beneficial role of fructooligosaccharides for the growth of lactic acid bacteria (LAB). The highest degree of hydrolysis (DH) (9%–12%) and the highest 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity (75%–78%) was associated with synbiotic ice creams. The results showed that melting postponed, and the apparent viscosity (μapp) was increased for the ice creams formulated with fructooligosaccharides. The maximum μapp (~2 Pa∙s) and the highest gumminess (9,528.70 gf) and cohesiveness (0.32) were associated with the synbiotic ice cream having L. casei. Sensory analysis showed that the fermented ice creams had lower overall acceptability than the unfermented ice creams due to the high acidity as a consequence of LAB growth. Novelty impact statement A comparison between Lactobacillus plantarum and L. casei for the development of synbiotic ice creams showed that the ice cream fermented by L. casei had a higher apparent viscosity, gumminess, and cohesiveness. Addition of fructooligosaccharides to the ice cream mix inoculated with lactic acid bacteria reduced the adverse effect of LAB on the sensory properties. The incorporation of fructooligosaccharides and LAB resulted in the development of synbiotic ice creams with improved tehchno‐functional properties and higher antioxidant activity compared to the control ice cream