No abstract

Food preservatives are commonly used to guarantee the safety and quality of food. Naturally-derived preservatives are preferred by the consumers as chemical preservatives are associated with adverse side effects. The application of naringenin as a food preservative is restricted due to its high volatility, albeit known for its good efficacy in inhibiting microbial growth on food. Thus, this study aimed to synthesis and characterise naringenin-grafted PVA (Na/PVA) nanoparticles as potential meat preservative. The nano-size of naringenin was characterised by transmission electron microscopy. Finally, the antibacterial efficiency of Na/PVA nanoparticles substance was evaluated on disc diffusion assay, broth microdilution assay and using fresh beef as food model. The naringenin nanoparticles appeared in globule and smooth structure, with an average size of less than 200 nm. In total, 11.08% of naringenin nanoparticles was successfully encapsulated into PVA nanoparticles. Based on Fourier transform infrared spectra, naringenin was successfully encapsulated into PVA nanoparticles. The release of naringenin from Na/PVA nanoparticles was slow and gradual, with an initial burst release effect observed. The property was ideal for application in food model. It gained a plateau at 48 h. The Na/PVA nanoparticles depicted its antibacterial efficiency on all the test foodborne bacteria, except E. coli. It was represented by the presence of inhibition zones, which were ranged from 10 mm to 14 mm. The activity was concentration-dependent, and a higher concentration of nanoparticles was needed to kill the test bacteria. The meat coated with Na/PVA nanoparticles displayed a 100% reduction in bacterial load, where no bacterial growth was detected at the sample throughout the incubation period. The coating of nanoparticles also improved the organoleptic property of fresh beef, by maintain the meat colour. The developed nanoparticles can be potentially used nano-preservative to maintain the microbiological quality of fresh beef.

No abstract

Deep Eutectic Solvent (DES) are eutectic mixes of hydrogen bond acceptors (HBA) and donors (HBD) with melting points significantly lower than their constituents. Choline chloride (ChCl) and glycerol were chosen as HBA and HBD because they are simple to prepare, have low toxicity, are biodegradable, and are environmentally friendly. As a result, the study aims to determine the feasibility of extracting lignin from oil palm fronds (OPF) and empty fruit bunches (EFB) using DES. The molar ratios of DESs were investigated to determine their effect on OPF solubility and lignin yield. The reaction is carried out at a solid loading ratio of 1:10, 150°C, and 6 hours. Because the DES medium induces homogeneous swelling and breakdown of small fibre fragments but not dissolution, both OPF and EFB are insoluble in DES. Small fragment disintegration suggests rapid dissolution, which will be easily dissolved in the DESs. The lignin yield and solubility of EFB and OPF in DESs are significantly reduced when the molar concentration of glycerol is increased. The highest lignin yields, 27.6% (EFB) and 16.1% (OPF) were obtained with a ChCl/glycerol molar ratio of 1:3. The comparatively low lignin yield achieved for both OPF and EFB is ascribed to the poor hydrogen bonding between the chloride ion and the hydroxyl group of the DES due to the low acidity of the DES. Despite this, lignin is extracted successfully due to the presence of chloride ions in ChCl, which target β-O-4 bonds and successfully cleave the ether bonds present in the lignin-carbohydrate linkage.