Articles

C-phycocyanin (C-PC) is a high-value pigment–protein in <i>Spirulina</i> biomass whose thermolability makes it vulnerable to degradation during post-harvest drying, yet freeze-drying—the gold-standard preservation method—remains prohibitively energy-intensive for large-scale production. This study investigated whether controlled-humidity air drying can preserve C-PC content and its antioxidant functionality in dried biomass comparably to freeze-drying. Wet <i>Spirulina</i> biomass (25 g fresh weight) was dried under nine factorial combinations of temperature (25, 40, and 60°C) and relative humidity (20, 30, and 40%) using a temperature–humidity chamber, with freeze-drying (FD) as the reference. C-PC was extracted, quantified spectrophotometrically along with allophycocyanin and chlorophyll, and its purity index (A<SUB>620</SUB>/A<SUB>280</SUB>) and antioxidant activity (DPPH radical scavenging, IC<SUB>50</SUB>, and ascorbic acid equivalent antioxidant capacity) were determined. Statistical analyses included one-way ANOVA with Tukey's post-hoc test and partial Pearson correlation. Air drying at 25°C yielded C-PC contents of 184.39 - 194.72 mg g<SUP>-1</SUP> DW (98 - 104% of the FD reference, 188.11 mg g<SUP>-1</SUP> DW) with food-grade purity indices of 0.95 - 1.00, whereas drying at 40°C and 60°C reduced C-PC to 76 - 85% and 58 - 63% of the FD value, respectively. Partial correlation analysis identified temperature as the dominant determinant of C-PC loss (Pearson <i>r</i> = -0.90 to -1.00), while relative humidity exerted a secondary, modulatory influence. The 25°C air-dried C-PC retained 86 - 87% of the antioxidant capacity of a commercial C-PC reference standard, approaching the 94% retention achieved by freeze-drying. These findings demonstrate that controlled-humidity air drying at 25°C and 20 - 30% relative humidity effectively preserves both C-PC yield and bioactivity at levels comparable to freeze-drying, offering a potential scalable and low-cost drying alternative for the <i>Spirulina</i> nutraceutical industry

Background</b>: The study of phenolic compounds and their potential to contribute to health is a major interest in research. This work was to determine phenolic compound contents as well as antioxidant properties of roasted maize-peanut snack product with and without spices. <b>Methods</b>: HPLC was used to determine the phenolic composition of the maize flours, peanut flour and their composite snacks with and without spices. Total phenolic content (TPC), total flavonoid content (TFC), tannin content (TC) and radical scavenging activity (measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis (3- ethylbenzothiazoline-6-sulphonicacid) (ABTS) and hydrogen peroxide radical scavenging assays was also used. <b>Results:</b> TPC of the extract of roasted maize flour, roasted peanut flour and composite roasted maize-peanut flour ranged from 48.93 to 178.31 mg GAE/100 g, while the TFC was 3.18–25.94 mg CE/100 g and TC (0.22 – 0.73 mg CE/g). The dominant phenolic acid was protocatechuic acid ranged from 13.73 to 1643.54 µg/g. Among the flavonoids, quercetin and catechin were dominant. The extracts of the free soluble fraction exhibited 23.88 – 81.52 %, 49.59 – 85.17 % and 0.58 -5.13 µmol AAE/g of DPPH, hydrogen peroxide and ABTS radical scavenging abilities respectively. <b>Conclusion:</b> Maize–peanut product showed potential ability in contributing to alleviating radical induced oxidative stress.