Physicochemical characteristics and antioxidant stability of spray-dried soy peptide fractions.

The direct addition of health-promoting peptides to food products is limited due to their physicochemical instability and bitter taste as well as their bio-functionality may be influenced by MW. In this study, SPI hydrolysate (SPIH) was Alcalase-prepared, size-fractionated (<10, 10-30, and 30-100 kD), and the amino acid composition of peptide fractions determined. The physicochemical properties, morphology, and antioxidant stability of the fractions were also investigated after spray-drying encapsulation in maltodextrin-WPC carrier. The two low MW peptide fractions (especially, PF < 10) were more active than intact SPI, SPIH, and high MW peptide fraction in scavenging free radicals and chelating transition metal ions. As compared to the particles containing SPIH, those containing the smallest peptide fraction (PF < 10) had higher solubility and hygroscopicity, lower production yield and wettability, and more wrinkles, indentations and surface roughness. The highest antioxidant stability during spray-drying was observed for the two low MW peptide fractions, which examined by scavenging of free radicals of DPPH (88%), ABTS (97%), OH (93%) and NO (80%), chelating of iron (88%) and copper (87-90%) ions, reducing power (93%), and total antioxidant activity (90%). This finding reflects more structural and biological stability of the low MW fractions to shear stress and dehydration during spray-drying, as compared with SPIH. The spray-drying encapsulated soy peptide fractions may be used as nutraceuticals for the development of functional foods.

Modification of Whey Proteins by Sonication and Hydrolysis for the Emulsification and Spray Drying Encapsulation of Grape Seed Oil.

In this study, whey protein concentrate (WPC) was sonicated or partially hydrolyzed by Alcalase, then examined as an emulsifier and carrier for the emulsification and spray drying of grape seed oil (GSO)-in-water emulsions. The modification treatments increased the free amino acid content and antioxidant activity (against DPPH and ABTS free radicals), as well as, the solubility, emulsifying, and foaming activities of WPC. The modified WPC-stabilized emulsions had smaller, more homogeneous droplets and a higher zeta potential as compared to intact WPC. The corresponding spray-dried powders also showed improved encapsulation efficiency, oxidative stability, reconstitution ability, flowability, solubility, and hygroscopicity. The morphology of particles obtained from the primary WPC (matrix type, irregular with surface pores) and modified WPC (reservoir type, wrinkled with surface indentations), as well as the oxidative stability of the GSO were influenced by the functional characteristics and antioxidant activity of the carriers. Changes in the secondary structures and amide regions of WPC, as well as the embedding of GSO in its matrix, were deduced from FTIR spectra after modifications. Partial enzymolysis had better results than ultrasonication; hence, the WPC hydrolysates are recommended as emulsifiers, carriers, and antioxidants for the delivery and protection of bioactive compounds.

Optimization of whey protein isolate-quince seed mucilage complex coacervation.

In this study, the complex coacervation of whey protein isolate (WPI) and quince seed mucilage (QSM) was studied as a function of pH (7.0-2.0), biopolymers concentration (0.05, 0.1 and 0.5%) and WPI:QSM ratio (10:90 to 90:10), according to protolytic titration, electrical conductivity (EC) and turbidity analyses. The solution containing 0.5% biopolymers with WPI:QSM ratio of 70:30 resulted in maximum complex coacervation at the pHopt 4.0. With increasing WPI:QSM ratio, the peaks of pH-turbidity curves shifted to higher pH values, and with increasing biopolymers concentration, the optimum WPI:QSM ratio and pH shifted to higher values. The EC of biopolymers solutions (concentration 0.5%) increased by decreasing pH and WPI:QSM ratio. The aforementioned optimum condition resulted coacervates with maximum particles size (16.22 µm) and minimum ζ-potential (-5.1 mV), which were observed as densely agglomerated macro-complexes with highest coacervation yield (80.67%). The X-ray analysis showed that coacervates retain the amorphous structure of individual biopolymers. These coacervates may be useful for encapsulation and delivery of (bio-) active compounds.

Stability of astaxanthin-loaded nanostructured lipid carriers in beverage systems.

BACKGROUND: Nanostructured lipid carriers (NLCs) offer many potential benefits for incorporating lipophilic molecules into clear to opaque food systems. This study examined the stability of astaxanthin-loaded NLCs (Ax-NLCs) in model (solutions with 0 or 12% sucrose; pH 3, 7), semi-actual (whey) and actual (non-alcoholic beer) beverages during 30-60 days storage at 6 or 20 °C. RESULTS: Ax-NLCs (Z-average size: 94 nm), containing α-tocopherol and EDTA as antioxidants, were stabilised with Tween 80 and lecithin, and mixed with the aforementioned beverages at the volume ratio of 3:97. The presence of sucrose, improved the physical stability of Ax-NLCs in acidic model beverage. No astaxanthin loss and particle size growth were observed for Ax-NLCs-added whey. Carbonation and/or thermal pasteurisation of NLCs-added beer led to a major increase in its particles size and astaxanthin loss. Stability of Ax-NLCs in non-pasteurised CO2 -free beer improved at low storage temperature. The organoleptic quality of NLCs-added beers was still acceptable. CONCLUSION: These results indicate that NLCs containing hydrophobic nutraceuticals have potential to be used for functional beverages/foods development. © 2017 Society of Chemical Industry.

Stability of astaxanthin-loaded nanostructured lipid carriers as affected by pH, ionic strength, heat treatment, simulated gastric juice and freeze-thawing.

Nanostructured lipid carriers (NLCs) offer many potential benefits for incorporating lipophilic molecules into clear/opaque food systems. In this study, the influence of pH, ionic strength, thermal treatment, simulated gastric juice (SGJ), and freeze-thawing on the stability of astaxanthin-loaded NLCs (Ax-NLCs) was examined. Ax-NLCs (containing α-tocopherol and ethylenediaminetetraacetic acid as antioxidants) were stabilized with Tween 80 and lecithin (Z-average size: 94 nm), and studied for the above mentioned purpose. The size of Ax-NLCs increased at low pH values (≤5), high NaCl concentrations (≥50 mM), and slightly at SGJ, mainly because of decreasing the ζ-potential. Moreover, thermal treatment at 80/90 °C led to an increase in Ax-NLCs size. Glycerol was found as an appropriate cryoprotectant for preventing aggregation of Ax-NLCs during freeze-thawing. pH, ionic strength, heat and SGJ had no drastic effects on the chemical stability of astaxanthin in NLCs. These results have valuable implications for the utilization of food-grade NLCs.

Rheological and physical properties of yogurt enriched with phytosterol during storage.

Phytosterols enriched products are innovative types of functional foods, in which dairy products, like low fat yogurt are ideal vehicles for this functional component. In this study, phytosterol dispersions were prepared using an oil/water (O/W) emulsion. The emulsion was added to yogurt milk. pH, titratable acidity (TA), syneresis, firmness and apparent viscosity of enriched yogurt were determined during storage. Moreover, phytosterols distribution in different parts of enriched yogurt was studied. Results indicated that in enriched yogurt, apparent viscosity and syneresis were lower and firmness was higher compared to the control. Addition of phytosterol to the yogurt had significant effect on acidity. Distribution of phytosterols in different parts of one sample was not uniform. Sensory results showed that there was no significant difference between enriched and control on texture, appearance, flavor and overall acceptance.