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Brewers' spent grain (BSG) is the primary by-product of beer production, and its potential use in food products is largely dependent on its processing, given its moisture content of up to 80%. This study aimed to evaluate the effects of physical separation with ultrasound application on the color, total phenolic content (TPC), antioxidant activity, proximate composition, total dietary fibers, and particle size distribution of BSG powders. Wet BSG (W) was subjected to two processes: one without ultrasound (A) and one with ultrasound (B). Both processes included pressing, convective air-drying, sieving, fraction separation (A1 and B1 as coarse with particles ≥ 2.36 mm; A2 and B2 as fine with particles < 2.36 mm), and milling. The total color difference compared to W increased through both processes, ranging from 1.1 (B1 vs. A1) to 5.7 (B1 vs. A2). There was no significant difference in TPC, but process B powders, particularly B2, showed lower antioxidant activity against ABTS•+, likely due to the release of antioxidant compounds into the liquid fraction during pressing after ultrasound treatment. Nonetheless, process B powders exhibited a higher content of soluble dietary fibers. In conclusion, ultrasound application shows potential for further extraction of soluble fibers. However, process A might be more practical for industrial and craft brewers. Further studies on the use of the resulting BSG powders as food ingredients are recommended.

The recent COVID-19 pandemic resulted in major postharvest losses because most fresh produce could not be sold. Drying is an important thermal-based food preservation method which could have prolonged the shelf-life of these produce, but most drying technologies are costly, and cannot be afforded by small-time farmers. From this context, we were interested in evaluating the drying of Moringa oleifera leaves (MOL) using a low-cost self-built prototype convective-air dryer (CAD), alongside conventional drying methods for its antioxidant properties, microbial load and phytoconstituents. Results showed total polyphenol content was the highest (p < 0.05) in our CAD samples, and it retained among the highest total flavonoid content, total antioxidant capacity, total alkaloid content and DPPH radical scavenging activity. Furthermore, methanolic CAD extract presented lower coliform and yeast and mold count than the aqueous CAD extract. We also briefly explored MOL as a sanitizer where the microbial load of the methanolic extract was comparable (p > 0.05) with several commercial non-alcoholic sanitizers, indicating its commercialization potential as a bio-friendly sanitizer. Finally, using GC-MS, we are the first to report (best of our knowledge) on the presence of caprolactam, an important bio-medical field compound, in the CAD sample's aqueous extract., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s).)