The aim of this work was to obtain, by water extraction, antioxidant dietary fiber from orange juice byproducts. Extractions were performed to orange pomace powder (OPP) varying temperature (55, 65, 75°C) and time (30, 45, 60 min). Two fractions (sediment and supernatant) were obtained from the water extractions and extractable polyphenolic content, antioxidant capacity, total carotenoid content (TCC), and bioaccessibility were determined. Results showed that at 75°C and 45 min the best combination of antioxidant capacity for both fractions is obtained. Under this condition, the sediment is a potential source of antioxidant dietary fiber. Supernatant is rich in bioaccessible polyphenols, associated to soluble fiber as majority component of dietary fiber. Moreover, the water extraction increased the bioaccessibility of polyphenols and carotenoids contained in the OPP. Therefore, both fractions are a potential source of functional food ingredients and orange juice byproducts were entirely revalued. Practical applications The present study suggests an extraction method for orange juice byproducts. Following the principles of green extraction, the technique proposed consists of a water extraction (free of solvents), does not produce waste and is of easy industrial application. As a result, two potential food ingredients with different functional and technological properties are obtained. Therefore, orange juice byproducts are completely revalued and a solution for the management of these byproducts is presented. In addition, the two functional ingredients obtained in this study are a step in the right direction for the development of new functional food formulations.

This study aimed to determine the effect of the extrusion process on the nutritional and bioactive profiles of brewer’s spent grain (BSG), contributing to nutrition security by applying a circular economy concept. Response surface methodology was used to optimize the effect extrusion parameters (moisture content, screw speed, and barrel temperature ) had on BSG’s soluble dietary fiber, free glucose, and overall antioxidant capacity. Proximate composition analyses, amino acid profile, extractable polyphenolic content, and antioxidant capacity of BSG and brewer’s spent grain extruded under optimal conditions (BSGE) were carried out. Food safety was analyzed by their microbiological quality, gluten, and acrylamide content. Optimal extrusion conditions were 15.8% of moisture content, 164.3 revolutions per min and 122.5 °C. BSGE presented 61% more soluble dietary fiber than BSG, lower digestible starch, 0.546% of free glucose, and protein quality parameters mostly like those reported for egg, soy, and milk. Despite this, BSG’s overall antioxidant capacity was not improved after thermomechanical processing; BSGE had significantly higher extractable polyphenolic content in its alkali extracts, which were determined qualitatively by high-performance liquid chromatography quadrupole time-of-flight assay in its hydro-alcoholic acid extracts. Furthermore, although it is not gluten free, BSGE is a safe food ingredient with acceptable microbiological quality and no acrylamide.

This study aimed to evaluate the effect of the extrusion process on the bioaccessibility of brewers’ spent grain (BSG) nutrients (carbohydrates and proteins) and non-nutrients (bioactive compounds). BSG and extruded BSG (EBSG) were digested in vitro simulating human oral-gastro-intestinal digestion and colonic fermentation. The duodenal bioaccessibility of glucose, amino acids and phenolic compounds was analyzed. The fermentability of the dietary fiber was assessed by analysis of short-chain fatty acids. Additionally, assessment of the bioaccessibility of phenolic compounds after colonic fermentation was undertaken. The antioxidant, anti-inflammatory and antidiabetic properties of the bioaccessible compounds were studied. Extrusion caused no change in the digestibility of gluten and glucose bioaccessibility (p > 0.05). Moreover, the bioaccessibility of amino acids and phenolic compounds significantly increased (p < 0.05) due to extrusion. However, higher short-chain fatty acid content was formed in colonic fermentation of BSG (p < 0.05) compared to EBSG. The latter inhibited intracellular ROS formation in IEC-6 cells and showed anti-inflammatory properties in RAW264.7 cells. With respect to antidiabetic properties, glucose absorption was lower, and the inhibition of carbohydrases higher (p < 0.05), in the presence of EBSG compared to BSG. The effects of EBSG and BSG digests on glucose transporters were not significantly different (p > 0.05). In conclusion, extrusion positively affected the nutritional value and health-promoting properties of BSG.

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Background and objectives: Full fat rice bran is a highly nutritional by-product of white rice production underutilized at present, with 90% of it being employed as a cheap feedstock. This study aimed to apply a water-and-citric-acid extraction method as a green technique to obtain a protein concentrate from rice bran. Extractions were carried out through a heat treatment, varying time and temperature, and optimized using response surface methodology based on protein purity, followed by citric acid (50% w/w) precipitation. Co-products obtained after the procedure were also characterized to determine their functional properties. Findings: Increasing temperature and time yielded higher protein purity, so 75 °C for 90 min was applied. Under these conditions, the protein concentrate contained 69.5% of protein, the supernatant had 60.6% of soluble carbohydrates, and their corresponding bioaccessible fraction had better antioxidant capacity than that of the bran. Finally, the sediment was similar in composition and functional properties to rice bran, which means high dietary fiber content. Conclusions: A protein concentrate, hypoallergenic and with high nutritional value, and two other functional fractions could be obtained through this environmentally friendly method. Significance and novelty: This technique could help meet the demand of proteins throughout the world.