Enzymatic Glycerolysis of Palm Kernel Olein-Stearin Blend for Monolaurin Synthesis as an Emulsifier and Antibacterial

Abstract

Monolaurin is a monoacylglycerol, which can act as an emulsifier and antibacterial. Palm kernel oil is a monolaurin raw material that can be fractionated into palm kernel olein (PKOo) and palm kernel stearin (PKS). Therefore, this study prepares monolaurin through enzymatic glycerolysis of the PKOo-PKS blend. The effects of enzyme concentration, molar ratio of oil to glycerol, solvent to oil ratio, and reaction temperature on the products of glycerolysis were investigated. The best conditions were selected for further production, purification, and characterization of the monolaurin. The results showed that the best glycerolysis condition was obtained with an enzyme concentration of 10% w/w, an oil–glycerol molar ratio of 1:4, a solvent–oil ratio of 2:1 v/w, and a glycerolysis temperature of 40 °C with a stirring speed of 600 rpm based on the monoacylglycerol (MAG) concentration. The identification of the sample with FTIR and NMR indicated that the purified glycerolysis product is the monolaurin. The thermal analysis showed a large endothermic peak with a melting point of 35.56 °C. The purified monolaurin has a HLB value of 5.92, and an emulsion capacity and stability of 93.66 ± 1.85% and 89.54 ± 3.36%, respectively. The minimum inhibitory concentration (MIC) of the monolaurin for Escherichia coli FNCC 0091 and Staphylococcus aureus FNCC 0047 were at 500 ppm, and 100 ppm for Bacillus subtilis FNCC 0060.

Glycerolysis of palm kernel oil catalized by MgO on mono and diglyceride composition and their antibacterial activity

“…This may be because the glycerolysis products contained monolaurin, which is more effective against gram-positive bacteria like B. subtilis. Meanwhile, E. coli is less sensitive against monolaurin as monolaurin has a limited effect on inhibiting the growth of gram-negative bacteria [1,11,23].…”

“…To achieve the desired yield of glycerolysis product, these parameters need to be optimized. Ngatirah et al [11] found that he antibacterial activity of monolaurin with aquadest solvents highlights a slightest inhibitory concentration of 500 ppm for E. coli FNCC 0091 and S. aureus FNCC 0047 and 100 ppm for B. subtilis FNCC 0060. Monolaurin also affect of spore germination.…”

“…Monolaurin also affect of spore germination. Ngatirah et al [12] found that spores of Bacillus subtilis FNCC 0060 in supplement broth with monolaurin of 100-1,000 ppm deferred germination for up to seven days of brooding.…”

“…One of the raw materials for monolaurin is from Palm Kernel Oil (PKO) [9][10][11][12]. Indonesia is known as one of the largest palm oil producing countries in the world, with land area in 2018 reaching 14 million hectares and palm kernel oil production reaching 8,5 million tons [13][14][15][16][17].…”

“…However, the majority of PKO in Indonesia is exported in the form of crude oil. Therefore, to support the development of downstream industries, there is an opportunity to develop palm kernel oil as a raw material for monolaurin (emulsifier) [9][10][11][12]. The emulsifiers that are widely used in industry are mono and diglycerides [19].…”