Antimicrobial activities and total yield of potential natural preservatives extracted using different solvents

Traditionally, natural preservatives are added to the palm saps to avoid spontaneous fermentation. Three selected plants have been used, namely chengal wood chips (Neobalanocarpus heimii), mangosteen rind (Garcinia mangostana Linn.), and guava leaves (Psidium guajava Linn.). The present study aims to estimate the total yield of potential natural preservatives extracted using different solvents and investigate their antimicrobial activity. Chengal wood chips, mangosteen rind, and guava leaves were extracted with methanol, ethanol, and water by the hot maceration technique. The total yield for each extract (methanol, ethanol, and water) of chengal wood chips is 17.5 %, 14.04 %, and 16.46 %, respectively. The total yield for methanol, ethanol, and water extracts of mangosteen rinds is 22.58 %, 17.76 %, and 20.10 %, respectively. Besides, the total yield for methanol, ethanol, and water extracts of guava leaves are 16.64 %, 15.20 %, and 16.12%, respectively. The result has indicated that the best solvent to obtain the highest yield of extracts is the methanol solvent. Antimicrobial test of the potential natural preservatives was performed against Escherichia coli, Streptococcus aureus, and Candida albicans. Based on the results, none of the chengal and guava extracts can inhibit E. coli growth with 100 mg/mL concentration. Only mangosteen rind water extract can inhibit the E. coli growth with a 12.0±2 mm inhibition zone. For S. aureus inhibition, chengal wood chips extracts (methanol; 17±1.00 mm; ethanol, 17±0.00 mm; water, 17.33±0.58 mm) give the best inhibition zone slight difference between the solvents. The result for S. aureus inhibition is followed by mangosteen rind extracts (methanol, 11.79±0.29 mm; ethanol, 10.5±0.50 mm; water; 11±1.00 mm) and guava leaves extract (methanol, 12±0 mm; ethanol, 11.33±0.58 mm; water, 10±0 mm). For C. albicans inhibition, none of the extracts has shown antimicrobial activity. In conclusion, the results have indicated that different extracts have had different antimicrobial activity against the selected microbes due to the different active compounds in the extracts.