Determination of Moisture, Ash, Protein, Polyphenolic, Flavonoids, and Amino Acid Contents and Antioxidant Capacity of Dried Mekai (Pycnarrhena tumefacta Miers) Leaf as Potential Herbal Flavor Enhancers

Abstract

Mekai leaf (Pycnarrhena tumefacta Miers) is used by the Dayaks tribe as a glutamic acid substitute to enhance the umami flavor of traditional foods. A dried mekai leaf is applied directly to the pan during cooking. Mekai contains glutamate, but its amino acids and other properties such as antioxidant capacity and phenolic-related substances have not been quantified. This study aims to determine the moisture, ash, protein, polyphenolic, flavonoids, amino acid content, and the antioxidant capacity of Mekai, leaves were dried in the sun, gas, and electric ovens at various temperatures and times. The moisture content of dried Mekai leaves was 6.95-9.30% (w/w). The ash and protein contents of dried Mekai leaves were 4.22-5.47 % and 15.7-20.6 % (w/w), respectively. The optimal moisture and ash content conditions were obtained after 3.5 hours of electric oven drying at 60 °C. Different drying methods had no discernible effect on protein content; excepted for electric oven drying at 60 °C for 3.5 hours, which results in protein content of 16.90.0 percent (w/w). Sundried Mekai had the lowest TPC value, whereas samples dried in an electric oven had a higher TPC value than samples dried in a gas oven. Both electric and gas oven drying at 60 °C for 2.5 hours resulted in significantly higher levels of flavonoids and antioxidant activity than other drying conditions in the same group. Mekai leaves were identified by the presence of arginine, glutamate, aspartic acids, and leucine. After sun drying, arginine, leucine, and isoleucine concentrations increased more than other amino acids.