Optimization of emulsification conditions with rice bran concentrates for the preliminary formulation of potential vegan dressings and their characterization.

A fraction of rice bran (RB), generated during the brown rice polishing, is utilized to extract oil, resulting in defatted RB (DRB). The aim of this study was to optimize the emulsification conditions to enhance the value of this byproduct by formulating potential vegan dressings and characterizing them. Enzymatic hydrolysis of the starch present in DRB yields the DRB concentrate (DRBC). A central composite design was applied and the results were analyzed using response surface methodology to select optimal conditions for an oil-in-water emulsion formula. Two formulations were chosen: one corresponds to the optimal conditions, with 26.5% of oil and 73.5% of DRBC dispersion (eoptimal), and the other one with 21.7% of oil and 78.3% of dispersion (eED8). The eoptimal formulation exhibited significantly lower mean De Brouckere diameter (D4,3) value and higher viscosity when compared with eED8. For both emulsions, the particle size distribution and D4,3 remained unchanged during storage, whereas viscosity decreased, and backscattering (BS) increased. Initially, both emulsions exhibited solid viscoelastic behavior, which was partially lost during quiescent storage. The increase in BS was attributed to particle disaggregation, ultimately leading to the aforementioned change in rheological behavior. In conclusion, although the designed emulsions underwent microstructural changes, they were stable against gravitational separation. To improve stability during quiescent storage, it is suggested to incorporate a thickening agent. Hence, it is propose to procced with the development of a vegan dressing based on the eoptimal emulsion, as it exhibits superior physicochemical properties.

Emulsifying properties of defatted rice bran concentrates enriched in fiber and proteins.

BACKGROUND: Rice bran (RB), a by-product of the rice milling industry, constitutes around 10% of the total weight of rough rice. The interest in the use of RB is centered on its nutritional quality, its low cost, and its extensive worldwide production. As RB is commonly used for oil extraction, the defatted rice bran (DRB) is obtained as a second by-product. The aim of this work was to obtain a defatted rice bran concentrate (DRBC), enriched in protein and fiber, from defatted rice bran flour (DRBF) and to determine its physicochemical and emulsifying properties. RESULTS: To obtain the DRBC, the starch was efficiently hydrolyzed (> 98%) with α-amylase and amyloglucosidase, with a concomitant increase in the proportions of crude protein (from 154.7 to 274.3 g kg-1 ) and total dietary fiber (from 276.1 to 492.3 g kg-1 ). Defatted rice bran concentrate exhibited a loss of protein solubility and increased surface hydrophobicity compared with DRBF. Defatted rice-bran concentrate dispersions with and without previous ultrasound treatment were prepared. The sonication led to an increase in the apparent viscosity. Emulsions were prepared with dispersions with and without previous ultrasound treatment and showed high stability in quiescent conditions over 28 days. However, the emulsions prepared with dispersions treated with ultrasound resulted in lower D4,3 values and higher elastic and viscous moduli. CONCLUSION: The rice bran concentrate can be used to obtain stable oil-in-water (O/W) emulsions, including both soluble and insoluble fractions, in acidic and neutral conditions. These innovative findings thus contribute to increasing the added value of this important by-product of the rice-milling industry. © 2019 Society of Chemical Industry.

Adsorption of chia proteins at interfaces: Kinetics of foam and emulsion formation and destabilization.

Chia proteins were extracted by solubilisation at pH 10 or 12 and precipitated at pH 4.5. Isolates were named as CPI10 and CPI12, according to their extraction pH, 10 or 12, respectively. The surface properties of both isolates were studied at neutral conditions. Foams were formed by air bubbling and both the formation and destabilization processes were analysed by conductimetry. The extraction pH significantly affected the interfacial properties of chia proteins. The higher surface hydrophobicity in CPI10 led to more flexible proteins with improved foaming properties. Foams formed by CPI10 were more stable than those by CPI12 due to the formation of a thicker interfacial film, which meant a greater ability to retard liquid drainage. Freshly-made coarse emulsions stabilized with CPI12 showed a lower mean droplet size and a significantly lower degree of overall destabilization than those stabilized with CPI10. None of the two emulsions showed flocculating effect.

Functional properties of amaranth, quinoa and chia proteins and the biological activities of their hydrolyzates.

Amaranth, quinoa and chia are non-conventional sources of proteins whose interest has increased in recent years due to their excellent nutritional value. Vegetable proteins can be used as food ingredients to replace animal proteins in human diet. The present article provides a comprehensive analysis of amaranth, quinoa and chia proteins and focuses on their solubility, superficial, gelling and textural properties as well as on the biological activities of enzymatic hydrolyzates.

Amaranth, quinoa and chia protein isolates: Physicochemical and structural properties.

An increasing use of vegetable protein is required to support the production of protein-rich foods which can replace animal proteins in the human diet. Amaranth, chia and quinoa seeds contain proteins which have biological and functional properties that provide nutritional benefits due to their reasonably well-balanced aminoacid content. This review analyses these vegetable proteins and focuses on recent research on protein classification and isolation as well as structural characterization by means of fluorescence spectroscopy, surface hydrophobicity and differential scanning calorimetry. Isolation procedures have a profound influence on the structural properties of the proteins and, therefore, on their in vitro digestibility. The present article provides a comprehensive overview of the properties and characterization of these proteins.

Physicochemical study of mixed systems composed by bovine caseinate and the galactomannan from Gleditsia amorphoides.

Model systems formed by sodium caseinate (NaCAS) and espina corona gum (ECG) were studied. There was no evidence of attractive interactions between NaCAS and ECG macromolecules. Aqueous mixtures of NaCAS and ECG phase-separate segregatively over a wide range of concentrations. According to the images obtained by confocal laser scanning microscopy, NaCAS particles form larger protein aggregates when ECG is present in the system. An increase in the hydrodynamic diameter of NaCAS particles, as a result of ECG addition, was also observed by light scattering in diluted systems. A depletion-flocculation phenomenon, in which ECG is excluded from NaCAS surface, is proposed to occur in the concentrated mixed systems, resulting in NaCAS aggregation. ECG raises the viscosity of NaCAS dispersions without affecting the Newtonian flow behaviour of NaCAS. These results contribute to improve the knowledge of a barely-studied hydrocolloid which may be useful in the development of innovative food systems.