OPTIMIZATION OF SOLID-STATE FERMENTATION PARAMETERS FOR MAXIMIZING BIOACTIVE COMPOUND YIELD AND ENZYME PRODUCTION USING Cucurbita moschata D. SEEDS AS SUBSTRATE

Pumpkin seeds are consumed in certain regions of the world, but in many cases, they are discarded during processing. The study aimed to explore the use of pumpkin seeds from Cucurbita moschata D. as a solid-state substrate for producing antioxidant compounds and enzymes. For this, Aspergillus tubingensis LBA02 was cultivated under varying conditions (Initial moisture: 45–75%, temperature: 23–37°C) for 48 and 72 hours, guided by a CCRD 2² experimental design. Responses measured included: Total Phenolic Content (TPC), antioxidant properties (ABTS, DPPH and FRAP), enzyme production (α-amylase, endo-β-1,4-glucanase, protease and lipase), and soluble protein content. TPC varied significantly (p<0.05) among the different assays, with the central point (60% of moisture and 30°C) showing the highest value at 72h (4.43 mg gallic acid equivalent per gram of fermented peels – mg GAE/g). Antioxidant activity measured by ABTS and DPPH methods increased over the fermentation period, particularly in assay 2 (70.6% of moisture and 25°C) and at the central point (60% of moisture and 30°C); for the FRAP method, reduced activity was detected. The enzymes production also showed significant (p<0.05) variation between the assays from experimental design and increased at 72h of fermentation, with assay 2 (70.6% of moisture and 25°C) yielding the following values: 88.98 U/g for α-amylase; 5.70 U/g for endo-β-1,4-glucanase; 96.37 U/g for protease; 8.24 U/g for lipase. Regarding soluble protein content, assay 1 (49.4% of moisture and 25°C) exhibited the highest protein content at 48h of fermentation (3.91 mg/mL), and at 72h, the fermentation performed at central point conditions increased to 4.18 mg/mL. These results suggested that moisture levels from 70.6% and incubation temperatures between 25 and 30°C may result in greater simultaneous production of antioxidant compounds and hydrolytic enzymes by solid state fermentation using pumpkin peels and Aspergillus tubingensis.