Value-added processCo-products Fruit pomace Supercritical fluid extrusion Cheese whey a b s t r a c t Food industry co-products, fruit pomace and liquid whey, were converted into shelf-stable, puffed products by using low-shear, low-temperature supercritical fluid extrusion. Coproducts were utilized as a source of dietary fiber, phytochemicals, and milk nutrients in extruded products. Liquid whey was concentrated and pumped directly into extruder barrel in lieu of water while processing cereal formulations fortified with finely ground fruit pomace. The resulting extruded products were very light in weight with 0.21-0.35 g/cm 3 density and contain14 g dietary fiber, 93 mg gallic acid equivalent polyphenols, and 652 mg vitamin C equivalent antioxidants in 100 g products. The natural fruit color is retained in the final product, indicating the preservation of color pigments and the associated bioactive compounds. About 84% of the total phenolics and 74% of the antioxidants of apple pomace were preserved in the final extrudates. The utilization of the agro-industry waste streams offers effective preservation and utilization of the nutritionally attractive byproducts as a source of functional ingredients in extruded products while adding value to the industrial waste streams.

Summary Prebiotic soluble fibre (fructooligosaccharides)‐incorporated whey protein crisps were produced by low‐shear supercritical fluid extrusion (SCFX), which utilises supercritical CO2 as an expansion agent instead of steam. Protein crisps with desirable qualities were obtained with a formulation containing 8% prebiotic fibre and 60% whey protein concentrate (WPC‐80), which gave the final product with a protein content of 49.6% (w/w). A maximum of 70% WPC‐80 and 8% prebiotic fibre could be incorporated to produce expanded protein crisps; however, increasing WPC‐80 from 50% to 70% decreased the end‐product expansion ratio from 3.1 to 1.2 and increased the product hardness and piece density from 1.3 to 2.8 kN and 0.63 to 0.75 g mL−1, respectively. Addition of 8% prebiotic fibre did not affect the textural qualities of final products. The process produced an expanded protein matrix with unique internal microstructure of uniformly distributed closed cells. Amino acid analysis indicated that 90% of the total lysine and 92% of the total essential amino acids were retained after SCFX processing and oven‐drying, indicating the preservation of protein nutritional quality during the process.