Ulva green macroalgae or sea lettuce are rich sources of protein with nutritional benefits that promote health as a future plant-based functional ingredient in the food industry. Alkaline pretreatment improved ultrasonic-assisted protein extraction from Ulva rigida biomass. Parameters affecting ultrasonic-assisted extraction of protein were type of solvent, biomass-solvent ratio, biomass preparation and extraction cycle. In vitro digestibility was evaluated from oven- and freeze-dried biomass. Results showed highest concentration and extraction yield of protein from U. rigida using alkaline rather than acid and distilled water. A high biomass–solvent ratio at 1:10 or 0.1 g mL−1 increased protein extraction. Higher alkaline concentration increased protein extraction. Highest protein extractability was 8.5% dry matter from freeze-dried U. rigida biomass, with highest protein extraction and antioxidant activity from extraction of U. rigida macroalgae at high alkaline concentrations. U. rigida macroalgae oven-dried biomass presented suitable human digestibility. Efficient pretreatment of U. rigida maximized protein hydrolysate and bioactive peptide production for wide-ranging applications.

No abstract

BACKGROUND Polysaccharides may enhance/inhibit lipid digestibility of oil‐in‐water (O/W) emulsions because of their emulsifying and/or stabilizing ability and can also affect the formation, stability, and viscosity of emulsions. Tamarind seed gum (TSG) was used as the sole emulsifier/stabilizer to stabilize an O/W emulsion prepared using high‐speed homogenization. We investigated the effects of various TSG concentrations (50–150 g kg−1) on the lipid digestibility, rheological properties, and stability of O/W emulsions during in vitro gastrointestinal digestion. RESULTS A low concentration (50 g kg−1) and a high concentration (150 g kg−1) of TSG reduced lipid digestibility by about 33% and 45%, respectively, compared to the control sample (without TSG). However, the emulsion containing the intermediate TSG concentration at 100 g kg−1 was the most efficient in the inhibition of lipid digestion, reducing lipid digestibility by about 70% compared to that of the control sample. The stability of emulsion tended to enhance as the concentration of TSG increased. The size of oil droplets before passing through the intestinal phase and the viscosity of the intestinal digested system may be important factors for enhancing/inhibiting lipid digestibility of emulsions. The destabilization of the emulsion during digestion was not clearly detected by rheological analysis because rheological characteristics (e.g. flow behavior index) were mainly driven by TSG. CONCLUSIONS The addition of TSG in O/W emulsions inhibited lipid digestibility. TSG at a concentration of 100 g kg−1 was the most efficient in the inhibition of lipid digestibility, suggesting that TSG is an attractive alternative ingredient for control of lipid digestibility of emulsion foods. © 2020 Society of Chemical Industry

Summary Water‐soluble soybean polysaccharide (SSPS) is a naturally occurring emulsifier. SSPS was used as the sole emulsifier to stabilize an oil‐in‐water (O/W) emulsion. The effects were investigated of different SSPS concentrations (3–20% (w/w)) on the lipid digestibility, rheological properties and stability of O/W emulsions during in vitro digestion model. The droplet size of the emulsions tended to increase during the oral phase because the emulsions were unstable and droplets coalesced, except with a SSPS concentration of 20% (w/w). The presence of SSPS markedly reduced the free fatty acid (FFA) content after its stabilized O/W emulsion passed through in vitro gastrointestinal digestion. The amount of FFA significantly decreased as the concentration of SSPS increased due to SSPS stabilization film on oil droplet surface and high viscous system. SSPS may be an attractive alternative ingredient to control the lipid digestibility of emulsions for various food products.

In the context of food waste valorization, the purpose of this study is to demonstrate the complete valorization of soybean residue (okara) through supercritical carbon dioxide extraction (SCE). Okara oil (OKO) was separated from full-fat powder (FFP) using SCE with and without ethanol (EtOH) as a cosolvent. The kinetics of extraction, chemical composition, and physicochemical, functional, and health-promoting properties of OKO and defatted powder (DFP) were determined. The process yielded 18.5% oil after 450 min. The soluble dietary fiber and protein of the DFP increased significantly; its water and oil absorption capacities increased despite the decrease in swelling capacity corresponding to particle size reduction. The OKO was rich in linoleic and oleic acids, with a ratio of ω6-to-ω3 fatty acids = 9.53, and EtOH increased its phenolic content (0.45 mg GAE/g), aglycone content (239.6 μg/g), and antioxidant capacity (0.195 mg TE/g). The DFP paste showed gel-like consistency and shear-thinning flow behavior, whereas the OKO showed characteristic transition of the product and affected lubrication at contact zones. Both fractions showed potential as food ingredients based on their nutritional and functional properties, as well as the capability of modifying the microstructure of a model food system.