Suwit Siriwattanayotin

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

Abstract 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°C to 150°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°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 δ 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 (Tg) 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.

Reduction of the polycyclic aromatic hydrocarbon (PAH) content of charcoal smoke during grilling by charcoal preparation using high carbonisation and a preheating step

ABSTRACT Charcoal-grilling may lead to contamination of food with carcinogenic polycyclic aromatic hydrocarbons (PAHs) during the grilling process. The objective of this work was to determine the effect of charcoal preparation on 16 USEPA priority PAHs in the smoke produced during the grilling process. Firstly, mangrove charcoal was prepared at carbonisation temperatures of 500, 750 and 1000°C. The charcoal were then preheated by burning at 650°C. This preheating step is usually used to prepare hot charcoal for the grilling process in the food industry. In this study, charcoal was preheated at different burning times at 5, 20 min and 5 h, at which time partial and whole charcoal glowed, and charcoal was completely burnt, respectively. Finally, PAHs in the smoke were collected and determined by GC/MS. The result showed that charcoal prepared at a carbonisation temperature of 500°C had higher levels of PAHs released into the smoke. In contrast, charcoal produced at 750 and 1000°C had lower PAHs released for all burning times. In addition, PAHs released for 5, 20 min and 5 h of burning time were about 19.9, 1.2 and 0.7 µg g−1 dry charcoal for charcoal produced at 500°C, and about 0.9–1.4, 0.8–1.2 and 0.15–0.3 µg g−1 dry charcoal for charcoal produced at 750 and 1000°C, respectively. Therefore, this research suggests that food grilled using charcoal carbonised at a high temperature of about 750°C presents a lower risk of PAH contamination. In addition, in the preheating step, whole charcoal should fully glow in order to reduce the PAH content in charcoal before grilling.

Reduction of the Phosphate Soaking Time Required for Shrimp Products Using Pulsed Vacuum Condition

ABSTRACT Pulsed vacuum (PV) was used to reduce the phosphate soaking time for raw and cooked shrimp, without reducing its quality. The shrimp was soaked in a phosphate solution under cycles of vacuum pressure (15 kPa, 7 min) and atmospheric (ATM) pressure (101 kPa, 3 min). PV-soaked shrimp reached stable absorption faster than ATM-soaked shrimp. At equilibrium absorption, no differences in moisture or phosphate contents were observed between PV- and ATM-soaked shrimp. After cooking, PV-soaked and ATM-soaked shrimp showed no differences in product yield or texture. Therefore, PV soaking reduces soaking time but does not affect the yield of cooked shrimp, increasing production capacity. Moreover, this study suggests that to maximize the yield of raw-soaked shrimp, shrimp should be soaked until the moisture content reaches equilibrium. In contrast, cooked shrimp should be soaked until the phosphate content stabilizes, to produce the highest yield with the lowest soaking time.