Heat induced formation of free radicals in wheat flour

Changes of lipids in noodle dough and dried noodles during industrial processing

This study investigated the changes of lipids during the industrial preparation of noodle dough and dried noodles, including the hydration, sheeting, and drying processes. The results showed that industrial processing markedly influenced the stability of lipids during the preparation of dried noodles. The contents of total free fatty acids, polyunsaturated fatty acids, and free lipids were reduced, while peroxide values increased during the hydration and sheeting processes, showing the instability of lipids. The increase in lipid oxidation may have been due to the activation of lipoxygenase. Although its activity declined by 45.7% in the hydration process compared to that of the native wheat flour (198.5 ± 20.4 U/g/min), the residue activity should have been high enough to oxidize lipids. Interestingly, lipase activity remained relatively stable. In addition, an obvious increase of carbon-centered free radicals was observed during the entire processing. In conclusion, the industrial processing, especially the hydration process, markedly changed the lipid profile and promoted lipid oxidation during the preparation of dried noodles. PRACTICAL APPLICATION: The present study showed the positive relationship between endogenous lipid degrading enzymes and the degradation of lipids and elucidated the role of industrial processing on lipid stability in noodle dough and dried noodles. The results of the present study will also help us to understand more about the sensory quality of dried noodles during preparation, as well as to develop high quality of wheat-based food products.

Effects of phenolic compounds from blueberry leaves on the thermal decomposition of trimethylamine oxide in squid extract

The effects of chlorogenic acid and quercetin-3-D-galactoside on the decomposition of trimethylamine oxide (TMAO) in squid extract and the main mechanism of inhibition of thermal decomposition were studied. The results indicated that chlorogenic acid and quercetin-3-D-galactoside could inhibit decomposition of TMAO in squid extract. The amount of TMAO was increased by 11.79 and 15.76% in squid extract treated with chlorogenic acid and quercetin-3-D-galactoside from 0 and 2.5 g/L, respectively. The contents of trimethylamine (TMA), dimethylamine (DMA), and formaldehyde (FA) were significantly decreased with increasing contents of chlorogenic acid and quercetin-3-D-galactoside. There were many free radicals in squid extract at high temperatures; however, the free radical signals were weakened after the addition of chlorogenic acid and quercetin-3-D-galactoside therein. This implied that chlorogenic acid and quercetin-3-D-galactoside could inhibit the thermal decomposition of TMAO in squid extract, which was associated with the scavenging of their free radicals. This result provides a theoretical basis for the development and utilization of blueberry leaf extract as an efficient FA inhibitor for aquatic products.

Synthesis of clay-cellulose biocomposite for the removal of toxic metal ions from aqueous medium

Clay-cellulose biocomposite (CCB) was synthesized in the present study. Spin and pressure-induced heating was applied to aggregate exfoliated clay tubules and cellulose using polyethylene glycol as an intermediate. The synthesized CCB was modified in the presence of NaOH at high temperature to obtain negative surface charge on the adsorbent. Physico-chemical properties of CCB were evaluated using different characterization techniques including Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) spectroscopy. The efficiency of the synthesized biocomposite for Pb(II) and Cd(II) removal from water was studied via laboratory scale experiments. The adsorption kinetics of Pb(II) and Cd(II) onto CCB was well described by the pseudo-second-order kinetic model. The maximum Langmuir adsorption capacity of CCB was found to be 389.78 and 115.96 mg g^-1 for Pb(II) and Cd(II), respectively. Fixed-bed column studies were conducted for the adsorption system to compare the adsorption performance of CCB in continuous mode.

Rice protein radicals: growth and stability under microwave treatment

Carbon-centred radicals are revealed in the microwave treated rice protein samples. The change of protein structure in a microwave field is often presumed to be caused by free radicals.