Factors affecting the concentration of acrylamide during deep‐fat frying of potatoes

The paper describes the effect of different factors influencing the concentration of acrylamide in deep‐fat fried potato products. In French fries the amount of acrylamide increased with the temperature as well as the frying time, especially at temperatures higher than 175 °C. The increase of acrylamide with the time followed a linear function, whereas a non‐linear relationship was given with the temperature of frying. As a result, a reduction of the processing temperature led to lower concentrations of acrylamide in the product. Both, oil type and silicon oil as antifoaming agents had no significant influence upon the acrylamide concentration in the food. The variety of potatoes had a strong effect on the acrylamide concentration in potato crisps and French fries. The investigation showed a significant correlation (r = 0.73) between the concentration of acrylamide and reducing sugars in raw potatoes, and no significant correlation with the asparagine concentration. The storage temperature of the raw material had an effect on the acrylamide concentration in the product. Lowering of the storage temperature from 8 to 4 °C resulted in an increase of the concentration of reducing sugars in the raw material, which led to a higher potential of acrylamide formation in the products. The experiments showed that the acrylamide concentration of French fries depended on the surface‐to‐volume ratio (SVR).     

Utilization of high‐oleic rapeseed oil for deep‐fat frying of French fries compared to other commonly used edible oils

Changes in chemical, physical and sensory parameters of high‐oleic rapeseed oil (HORO) (NATREON?) during 72 h of deep‐fat frying of potatoes were compared with those of commonly used frying oils, palm olein (PO), high‐oleic sunflower oil (HOSO) and partially hydrogenated rapeseed oil (PHRO). In addition to the sensory evaluation of the oils and the potatoes, the content of polar compounds, oligomer triacylglycerols and free fatty acids, the oxidative stability by Rancimat, the smoke point and the anisidine value were determined. French fries obtained with HORO, PO and HOSO were still suitable for human consumption after 66 h of deep‐fat frying, while French fries fried in PHRO were inedible after 30 h. During the frying period, none of the oils exceeded the limit for the amount of polar compounds, oligomer triacylglycerols and free fatty acids recommended by the German Society of Fat Science (DGF) as criteria for rejection of used frying oils. After 72 h, the smoke point of all oils was below 150 °C, and the amount of tocopherols was reduced to 5 mg/100 g for PHRO and 15 mg/100 g for HORO and HOSO. Remarkable was the decrease of the oxidative stability of HOSO measured by Rancimat. During frying, the oxidative stability of this oil was reduced from 32 h for the fresh oil to below 1 h after 72 h of frying. Only HORO showed still an oxidative stability of more than 2 h. From the results, it can be concluded that the use of HORO for deep‐fat frying is comparable to other commonly used oils.     

Effects of frying on the trans‐fatty acid formation in soybean oils

To evaluate the effects of repeated deep‐frying on the trans‐fatty acid (TFA) formation in soybean oils, simultaneous frying experiments were carried out. French fries were prepared using three different types of soybean oil (pressed soybean oil, PSBO; first‐grade solvent extracted soybean oil, FG‐SESBO; and third‐grade solvent extracted soybean oil, TG‐SESBO). French fries were fried intermittently at 180–185°C for a total frying time of 32 h and at an interval time of 30 min. It was found that the initial amount of total TFAs was 0.29 g/100 g, 0.31 g/100 g, and 0.90 g/100 g in PSBO, TG‐SESBO, and FG‐SESBO, respectively. Before the frying started, the C18:1,t‐9, trans‐linoleic acid (TLA), trans‐linolenic acid (TLNA), and total TFA content of the PSBO and TG‐SESBO were significantly lower than in the FG‐SESBO (p<0.05). However, in the frying oil samples, the final concentration of total TFA in the PSBO, TG‐SESBO, and FG‐SESBO were 1.79 ± 0.17 g/100 g, 1.12 ± 0.10 g/100 g, and 1.70 ± 0.07 g/100 g, which was 6.17‐, 3.61‐, and 1.89‐fold higher that in fresh oil, respectively. The highest increasing slopes of C18:1,t‐9, TLA, TLNA, and total TFA were observed in the PSBO. Practical applications : A high intake of TFAs has been shown to lead to an increased risk of coronary heart disease. Plant oils, particularly soybean oil, have been widely used in the food industry in China. Frying is one of the most common methods to cook food. The formation of TFAs during frying has been shown to be closely related to the temperature and duration of the frying process. However, the effects of frying on the formation of TFAs in different soybean oils have not been well studied. In the present study, we demonstrated that increasing the number of frying cycles can cause an intensive increase in the concentration of TFAs in different types of soybean oil, but especially in PSBO.     

Application of polyhedral oligomeric silsesquioxane to the stabilization and performance enhancement of poly(4‐methyl‐2‐pentyne) nanocomposite membranes for natural gas conditioning

The application of octatrimethylsiloxy polyhedral oligomeric silsesquioxane (POSS) nanoparticles was investigated in the fabrication of novel reverse‐selective poly(4‐methyl‐2‐pentyne) (PMP) nanocomposite membranes for the separation of heavier hydrocarbons from methane. Generally, PMP and PMP–fumed silica (FS) nanocomposite membranes suffer severe physical aging with approximately 40% permeation flux reduction over 120 days. A straightforward strategy was introduced to suppress the physical aging of PMP and also to improve the thermal stability without compromising the selectivities and permeabilities through the incorporation of a functionalized POSS–FS binary filler system. Fourier transform infrared spectroscopy and scanning electron microscopy proved productive interactions between the fillers and polymer, with a fair compatibility between them. Thermogravimetric analysis confirmed that the thermal stability of the neat PMP was enhanced by the incorporation of the fillers into the nanocomposites. The addition of POSS and FS led to improved operational performance, such as in the permeability and selectivity, over the neat PMP. The permeation stabilities of the PMP–POSS and PMP–FS–POSS nanocomposite membranes were clearly improved over a long time (120 days). The permeation data indicated that the PMP–3 wt % POSS–20 wt % FS nanocomposite membrane is promising for C₃H₈/N₂ and C₃H₈/CH₄ separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45158.     

A novel microencapsulation of neem (Azadirachta Indica A. Juss.) seed oil (NSO) in polyelectrolyte complex of κ‐carrageenan and chitosan

Microcapsules containing neem (Azadirachta Indica A. Juss.) seed oil (NSO) were prepared by encapsulation of natural liquid pesticide NSO in a polyelectrolyte complex of κ‐carrageenan and chitosan. The optimum ratio between carrageenan and chitosan to form a stable polyelectrolyte complex was found as 1 : 0.36. The microencapsulation method for NSO loading was also optimized. SEM study demonstrated that the surface of the microcapsules became more irregular as oil loading increased. The release rates of NSO were studied by varying the percentage of oil loading, concentration of cross‐linking agent, and polymer concentration. Fourier transform infrared spectroscopy (FTIR) study confirmed the complex formation between κ‐carrageenan and chitosan. Differential scanning calorimetry (DSC) and FTIR study indicated the absence of any significant interaction between polyelectrolyte complex of κ‐carrageenan ‐chitosan and NSO. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A novel polymer chemodosimeter for the detection of mercury ions: Synthesis and fluorescence “turn‐on” responses of fluorene‐based conjugated polymer with reactive pendent N,N‐diethyl‐2‐(4‐phenoxy)‐thioacetamide

A novel conjugating polyfluorene bearing N,N‐diethyl‐2‐(4‐phenoxy)‐thioacetamide as side chain was designed for the detection of Hg(II) ions. It was synthesized through postfunctionalization of acetamide‐based polyfluorene derivative. Upon the addition of Hg(II) ions, the thioacetamide groups of this polymer side chains were specifically reacted with Hg(II) ions, leading to this chemodosimeter with higher selectivity for Hg(II) over other metal ions tested under the same conditions. In addition, on the basis of the effect of fluorescent signal amplifications originated from electron transmission along the backbone, this designed conjugated polyfluorene with pendent reactive thioacetamide reached ultra high sensitivity for the detection of mercury ions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Reactions and polymerization of hexa‐[3‐tert‐butyl‐4‐ hydroxyphenoxy]cyclotriphosphazene: A new method for the preparation of soluble cyclomatrix phosphazene polymers

Novel cyclomatrix phosphazene‐containing polyester polymers were synthesized through the reaction of a polyhydroxylated cyclotriphosphazene and a bifunctional acid chloride. To demonstrate the chemistry of the free hydroxyl of hexa‐[3‐tert‐butyl‐4‐hydroxyphenoxy]cyclotriphosphazene, nucleophilic displacement reactions were performed with both acetic anhydride and alkyl chlorides. This work compares favorably to literature data for the chemistry of hexa‐[4‐hydroxyphenoxy]cyclotriphosphazene, whose hydroxyl is not hindered by an adjacent substituent. The hindered site of hexa‐[3‐tert‐butyl‐4‐hydroxyphenoxy]cyclotriphosphazene was found to react with bidentate acid chlorides to yield new high polymers. The phosphazene‐containing polyesters were observed to have good solubility in polar organic solvents. Characterization of these new materials was performed using dilute solution laser light scattering techniques, thermal analysis, and NMR spectroscopy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 242–251, 2001     

Evidence for the Formation of an Enamine Species during Aldol and Michael‐type Addition Reactions Promiscuously Catalyzed by 4‐Oxalocrotonate Tautomerase

The enzyme 4‐oxalocrotonate tautomerase (4‐OT), which has a catalytic N‐terminal proline residue (Pro1), can promiscuously catalyze various carbon–carbon bond‐forming reactions, including aldol condensation of acetaldehyde with benzaldehyde to yield cinnamaldehyde, and Michael‐type addition of acetaldehyde to a wide variety of nitroalkenes to yield valuable γ‐nitroaldehydes. To gain insight into how 4‐OT catalyzes these unnatural reactions, we carried out exchange studies in D₂O, and X‐ray crystallography studies. The former established that H–D exchange within acetaldehyde is catalyzed by 4‐OT and that the Pro1 residue is crucial for this activity. The latter showed that Pro1 of 4‐OT had reacted with acetaldehyde to give an enamine species. These results provide evidence of the mechanism of the 4‐OT‐catalyzed aldol and Michael‐type addition reactions in which acetaldehyde is activated for nucleophilic addition by Pro1‐dependent formation of an enamine intermediate.     

1‐Butyl‐3‐methylimidazolium Tetrafluoroborate ([Bmim]BF4) Ionic Liquid: A Novel and Recyclable Reaction Medium for the Synthesis of vic‐Diamines

Aziridines undergo ring opening smoothly with various arylamines in 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF₄) or 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([bmim]PF₆) ionic liquids under mild and neutral conditions to afford the corresponding vicinal‐diamines in excellent yields with high regioselectivity. The recovered activated ionic liquids are recycled for four to five runs with no loss of activity.     

Effect of the mass ratio of Fe3O4/PAA on separation properties and the extractive amount of Fe3O4 during the formation of Fe3O4‐PES ultrafiltration membranes

A series of Fe₃O₄‐PES ultrafiltration membranes with different mass ratios of Fe₃O₄ and PAA were prepared from suspensions, using the phase inversion process. The suspensions consisted of polyether sulfone (PES), dimethyl formamide, polyacrylic acid (PAA), and ferrosoferric oxide (Fe₃O₄). The separation properties of ultrafiltration membranes with different Fe₃O₄/PAA mass ratio were investigated by a cross‐flow experimental system. The Fe₃O₄/PAA mass ratio had little effect on the rejection of membranes to BSA. However, the pure water flux had a slight decline and then rised rapidly with the increase of Fe₃O₄/PAA mass ratio. An interesting phenomenon observed was that the Fe₃O₄ particles could diffuse into the nonsolvent bath during the formation of membrane, and the amount of Fe₃O₄ extracted into the nonsolvent bath nearly kept a constant mass ratio to PAA, even if the Fe₃O₄/PAA proportion was changed. The reasons of this interesting phenomenon were investigated. This result indicates that modified inorganic fillers may be used as the pore‐forming agent to prepare the porous membranes like the template leaching method. At the same time, this method does not use any strong acid or base. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013