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This paper aim to evaluate the ultrafiltration (UF) process for constituents recovery from whey. Sequences of factorial designs were performed by varying temperature (5 to 40°C) and pressure (1 to 3 bar), to maximize the proteins concentration using membrane of 100kDa in dead end system. Based on the best result new experiments were performed with membrane of 50kDa and 10kDa. With the membrane of 50 the protein retention was about 3 times higher than the membrane of 100kDa. The concentrated obtained by UF membrane of 10kDa, 10°C and 2 bar in laboratory scale showed a mean protein retention of 80 %, greater protein solubility, emulsion stability and the identification of β-lactoglobulins (18.3 kDa) and α-lactalbumin fractions (14.2kDa). Therefore, the use of membrane of 100 and 50kDa are became a industrially recommendable alternatives to concentration of whey proteins, and/or as a previous step to the fractionation of whey constituents using membrane ≤10kDa, aiming at future applications in different areas (food, pharmaceutical, chemical, etc.).

Highlights  Chia proteins were isolated from defatted milled seeds at pH 10 (CPI10) or 12 (CPI12)  The interfacial behavior of these isolates was related to their extraction conditions  Foams from CPI10 were more stable due to the formation of a thicker interfacial film  CPI10 showed a greater ability to retard liquid drainage  CPI12 showed better emulsifying properties whereas poorer foaming properties

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 -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 D 4,3 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 andinsoluble 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. Surface hydrophobicity (H 0 )Aromatic surface hydrophobicity was determined on a soluble protein fraction of samples prepared as detailed above, following the approach described by Fernández-Fernández et al., 31 based on J Sci Food Agric 2020; 100: 1336-1343

Soybean glycinin [11S] was modified by an acidic pH treatment to improve its emulsifying properties. Glycinin was obtained by isoelectric precipitation (11Sn) and then treated with acid (11St). The oil-water interfacial tension and rheology were measured. The rate constants of adsorption (k a ) and rearrangement (k r ) of proteins at the interface and the dilational (E), elastic (E d ), and viscous modulus (E v ) of the protein interfacial film were determined. Particle size distribution (PSD), interfacial protein concentration (Γ), and the creaming destabilization rate constants k s (for the smaller droplets) and k l (for the larger droplets) were analyzed in oil-in-water emulsions (25% v/v of oil and 75% v/v of 1 mg/mL protein solution in 10 mM sodium phosphate buffers, pH 7.0 and 2.5, respectively).Compared to the native protein, the acid treatment caused irreversible denaturation of 11S and significantly increased Г, k a , E, E d , and E v (P ≤ 0.05), resulting in a greater rate of protein adsorption to the interface and a stronger interfacial film. PSD showed a bimodal distribution with peaks above and below 4 μm. Smaller droplets moved toward smaller diameters for 11St. It also showed lower values of creaming destabilization constants k s (d ≤ 4 μm) and k l (d ≥ 4 μm) than 11Sn. In conclusion, acid treatment of 11S enhances the creaming stability of its emulsions by improving the interfacial properties and reducing the droplet size.