Effect of Excess Air Levels on PAHs Content in Smoke During Charcoal Combustion in Grilling Process

Charcoal grilling may lead to carcinogenic PAHs contamination of grilled food from incomplete combustion of charcoal. The objective of this study was to determine the effect of complete combustion of charcoal on PAHs content in smoke during the grilling process. Firstly, proximate and ultimate compositions of the charcoal were determined to identify the amount of air required for combustion according to stoichiometry. Different excess air levels consisting of stoichiometric air, 60, 100 and 150% excess air during combustion of charcoal on 16 PAHs released in smoke were studied. Moreover, CO and CO2 concentrations were measured. The use of excess air decreased the emission factor of CO and increased the emission factor of CO2. The 16 PAHs contents in smoke produced from charcoal combusted with stoichiometric air, 60, 100 and 150% excess air were 73.62, 51.78, 27.68 and 19.23 μg/kg dry charcoal, respectively. The use of excess air during charcoal combustion resulted in significantly lower PAHs contents in the smoke. Therefore, the use of excess air during charcoal grilling is one way to reduce the risk of PAHs contamination in grilled food

Effect of Oscillating Magnetic Field on Freezing Rate, Phase Transition Time and Supercooling of Deionized Water

Due to a growing interest toward quality improvement of frozen foods, many advanced technologies have been combined with conventional freezing system to expedite rate of freezing and reduce ice crystal formation. This research aimed to investigate the effect of oscillating magnetic field (OMF) in the range of 0 to 12 mT (50 Hz) on freezing rate, phase transition time and supercooling of deionized water during freezing in an air blast freezer at –10°C. The sample was placed between two magnetic cores where an oscillating magnetic field (OMF) was generated and the temperature profile was recorded by a data logger at 1-minute interval. The magnetic field strength was varied at 0, 4, 8, and 12 mT. It was found that there was no significant difference in the freezing rate and phase transition time when different OMF strengths were applied (p > 0.05). Interestingly, the probability of supercooling occurrence increased when the OMF was applied; without OMF only 16% of the experiment exhibited supercooling phenomenon where 33% was detected when OMF in the range of 4–12 mT was applied. However, the probability of supercooling occurrence was independent of the OMF strength

Effect of lignin removal on the properties of coconut coir fiber/wheat gluten biocomposite

UMR IATE AXE 2; Contact: [email protected] effect of fiber lignin content on biocomposite properties was investigated. Coconut fiber was treated with 0.7% sodium chlorite to selectively decrease amounts of lignin. The fiber lignin content was then reduced from 42 to 21 wt.%. The composition and mechanical properties of the individual modified fibers were characterized. Gluten-based materials reinforced with modified fibers were prepared by compression molding. Then, the mechanical properties, water sensibility, matrix glass transition and infrared spectra of biocomposites prepared with fibers containing various amounts of lignin were evaluated. This study showed that the addition of coconut coir fiber significantly improved properties of wheat gluten biomaterials. In addition, the variation of lignin content in the fibers, in the investigated range, had no significant effect neither on matrix deplasticization nor fiber/matrix adhesion, suggesting that a partial lignin removal is not an efficient way to improve the properties of natural fiber/plasticized protein biocomposite

Characterization of Defatted Rice Bran Properties for Biocomposite Production

Commercial defatted rice bran (DRB) was characterized to produce biocomposite. DRB extracted protein plasticized with glycerol presented viscoelastic properties. The whole DRB with different amount and type of plasticizers was extruded into pellets. All extrudates presented pseudoplastic behavior as determined by capillary rheometer. Power-law index (n) and flow behavior consistency (K) of all DRB extrudates were respectively in a range of 0.30-0.32 and 1.2-3.8 x 10(4) which is closed to agro-polymer due to a modification of DRB structure after extrusion process. In addition, extrusion process promoted protein aggregation. However, no significant effect of plasticizer type and content on DRB protein aggregation for a given temperature processing was observed. The effect of plasticizer content on tensile properties presented the same trend as viscosity results. Extrudate that had a high viscosity presented high mechanical properties

Valorization of industrial by-products through bioplastic production: defatted rice bran and kraft lignin utilization

The objective of this study was to develop a bioplastic from industrial by-products. Commercial defatted rice bran (DRB) was extruded with 0-30% kraft lignin (KL) as a filler and 30% glycerol as a plasticizer. Firstly, the effect of extrusion temperature on the plasticized DRB's processability was determined. Increasing the die extrusion temperature from 100 degrees C to 150 degrees C improved the extrudability by decreasing the die pressure and motor current. Subsequently, the effect of KL on plasticized DRB was studied. The addition of 10-30% KL improved DRB processability. The addition of 30% KL markedly lowered the die pressure in comparison to using a 150 degrees C extrusion temperature. Moreover, KL addition decreased DRB viscosity determined by a capillary rheometer. These results were coherent with a decreased storage modulus in a rubber state and an increased tan d height determined by a dynamic mechanical thermal analyzer (DMA). However, n values of DRB with 10-30% KL could not be explained by a simple mixing rule. This may be attributed to the interaction between DRB and KL, as shown by Fourier transform infrared (FTIR) spectra. KL addition increased Young's modulus and the glass transition temperature (T-g) of plasticized DRB. Therefore, blending DRB with KL is an effective way to improve polymer flowability at the processing temperature and mechanical properties at ambient temperature

Extrusion Processing of Wheat Gluten Bioplastic: Effect of the Addition of Kraft Lignin

Plasticized wheat gluten (WG) was extruded with 0-50 wt% Kraft lignin (KL) contents using a co-rotating twin screw extruder with circular die. The objective of this study was to evaluate the effect of KL on the extrusion processing, and on the resulting properties of those new materials. The addition of either 30 or 50 wt% KL which is a radical scavenger allowed increasing the extrusion die temperature from 80 to 110 A degrees C. Moreover, the addition of 10-50 wt% KL contents improved the processability of WG in extrusion: it decreased both die pressure and residence time for all studied feed rates and screw speeds. The addition of KL induced a protein depolymerization and the association between KL and WG as evidenced by the co-elution of KL and WG in SE-HPLC. Moreover, the addition of 10-30 wt% KL improved mechanical properties and reduced the water absorption of WG-based material

Effect of Overfilled Solvent and Storage Time of Subcritical Extraction of Jasminum sambac on Yield, Antioxidant Activity, Antimicrobial Activity and Tentative Volatile Compounds

Essential oil from Jasminum sambac flowers has demonstrated the potential of antioxidant and antimicrobial properties. However, jasmine flowers contain only a small amount of essential oil; therefore, subcritical fluid extraction (SFE) with HFC-134a, one of the effective extraction methods for flower extraction, was performed in this study. The percentage of overfilled solvent and storage time of the flowers were varied during the extraction. Antioxidant potential, antimicrobial potential and tentative volatile compounds were investigated in this study to observe the quality of the essential oil. It was discovered that a greater amount of overfilled solvent resulted in thicker essential oil and a longer storage time resulted in a lower amount of total oil yield. It could be seen that almost all extraction conditions did not have any significant difference in antioxidant and antimicrobial potential. The essential oil contained primary compounds such as indole, 9-tricosene, α-farnesene, muurolene, and benzyl alcohol. This study led to the conclusion that the amount of overfilled solvent from SFE affected the thickness of jasmine essential oil and its tentative volatile compounds. The longer storage time caused the significantly lower essential oil yield, but changing the extraction conditions had no significant effect on antioxidant or antimicrobial potential