Cellulase and β-glucosidase activity of crude enzyme extracted from fresh and expired soybean tempeh

Enzymes are protein biomolecules that act as catalysts, including cellulase and β-glucosidase with extensive applications. Thus, this work aimed to contrast the activity of both enzymes from tempeh fermented by Rhizopus microsporus at 2 and 7 days of incubation.

Incubated tempeh was tested for quality evaluation. The crude extracts of cellulase and β-glucosidase were obtained by extracting tempeh with a cold phosphate buffer solution. The presence of the R. microsporus was examined through microscopic identification, and molecular identification using PCR amplification. Cellulase activity was determined using 3.5-dinitrosalicylic acid (DNS) reagent, whereas β-glucosidase activity was evaluated by measuring the release of p-nitrophenol from p-nitrophenyl-β-D-glucopyranoside (p-NPG).

The protein content and water content increase with the length of fermentation time. Microscopic identification and molecular identification confirmed the presence of R. microsporus. The highest cellulase activity was found in fresh tempeh (2-day incubation) at 0.0911 U/mL at pH 7, while the highest β-glucosidase activity was found in expired tempeh (7-day incubation) at 0.0042 U/mL at pH 5.

These findings indicate that the standard quality contributed to the differences in the enzymatic profile of tempeh incubated for 2 and 7 days.