Efficient synthesis of benzophenone derivatives in Lewis acid ionic liquids

Benzophenone and its derivatives were prepared via Friedel–Crafts acylation reactions using ionic liquids (ILs) of BmimCl–FeCl₃, BmimCl–AlCl₃ and BmimCl–ZnCl₂ as dual catalyst–solvent. Among them, BmimCl–FeCl₃ showed much higher catalytic activity than that observed for the other two ILs, and in conventional organic solvents. In these reaction systems, good to excellent yields (up to 97%) of acylation products were obtained in a short reaction time. This method features high yield, a simple product isolation procedure, ILs reusability and reduced waste discharge, thus rendering this catalytic system both efficient and environmentally friendly.     

Experimental investigation of free single jet impingement using Al2O3-water nanofluid

Four volume fractions Al₂O₃-water nanofluids (0.5%, 1%, 1.5% and 2%) are introduced into free single jet impingement experiment as working fluids. The Reynolds numbers, impact angles and nozzle-to-plate distances (H/D) are variable for investigating the heat transfer performance. As to get observation of flow characteristics in nanofluid, heat transferring performance would be studied in this case. Experimental results show that there is a relationship between convective heat transferring coefficient and nanoparticles suspendability within base fluid. Convective heat transfer coefficient is proportional to the extent of nanoparticles concentration, Reynolds number while it decreases with the increasing angle of impacting. In addition, considering the influence of the suspended nanoparticles and the condition of impinging jet, a heat transfer correlation has been proposed combining the influence of the suspended nanoparticles and the condition of impinging jet.     

基于低场核磁共振技术检测秋刀鱼腌干制过程 水分状态变化

目的探讨腌干处理对秋刀鱼水分状态的影响,为秋刀鱼的高值化加工提供参考。方法秋刀鱼进行"三去"(去头、去尾、去内脏)处理,采用10%食盐溶液(料液比1:2)进行腌制,选取腌制2 h的样品进行40℃热风干燥,检测样品的水分含量、盐含量以及水分活度,利用低场核磁共振技术(low-field nuclear magnetic resonance,LF-NMR)测定腌干过程样品的水分存在状态。结果秋刀鱼样品腌干过程中均存在结合水、不易流动水和自由水3种状态水分。腌制10 h过程中样品的水分活度未低于0.90的细菌生长临界值。结合水比例呈现先增大后减小的变化趋势,自由水比例相对降低,不易流动水比例增大,表明腌制处理使得部分结合水与自由水转化为不易流动水。随干制时间的延长,样品的水分含量和水分活度均显著降低(P0.05),结合水变化较小,不易流动水比例呈降低趋势,表明干制处理一方面使得秋刀鱼组织内不易流动水流失,另一方面使其部分转移成其他相态的水。同时,核磁共振成像灰度图和伪彩图深色区域面积逐渐增大,表明干制过程伴随油脂的溢出。结论腌制和干制处理降低了秋刀鱼鱼肉的水分活度,同时改变了水分存在状态。核磁共振成像灰度图和伪彩图表明干制处理改变了秋刀鱼样品的油水平衡。     

Inhibition of haemoglobin-mediated lipid oxidation in washed cod muscle and cod protein isolates by Fucus vesiculosus extract and fractions

The effects of Fucus vesiculosus extract and fractions towards haemoglobin- (Hb-) catalysed lipid oxidation in washed cod muscle system and cod protein isolates during ice storage were examined. The extract and fractions were characterised in terms of total phlorotannin content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferrous ion-chelating ability and reducing power. Progression of oxidation was followed by determining rancid odour, thiobarbituric acid reactive substances (TBARS), redness and volatile oxidation compounds by gas chromatography (GC). In both washed cod muscle and protein isolates, phlorotannin-enriched ethyl acetate (EtOAc) fraction showed higher inhibitory effect than crude 80% ethanol (EtOH) extract. The addition of oligomeric phlorotannin-rich subfraction (LH-2) separated by Sephadex LH-20 chromatography, completely inhibited the initiation of lipid peroxidation in both systems throughout the entire study period (8 days). Its effectiveness at 300 mg/kg level was comparable to that of 100 mg/kg propyl gallate (PG), a highly effective synthetic antioxidant in muscle foods. Although polymeric phlorotannin-rich subfraction (LH-5) had similar level of TPC and chemical antioxidant activities as oligomeric subfraction LH-2, it was far less efficient in model systems. These results suggest that other factors rather than the intrinsic reactivity toward radicals could be responsible for the inhibitory effect of phlorotannins on lipid oxidation in fish muscle. This study highlights the great potential of oligomeric phlorotannins as novel natural antioxidants in fish and fish products.     

Tracer experiments in fixed beds: effects of flow maldistribution on the estimation of transport kinetic parameters

A systematic study of liquid phase axial dispersion was conducted in glass columns (inner diameters, 1 cm and 1.6 cm), packed randomly with granular sand, by varying the fluid flow rate, particle size and bed height. Pulse and step response techniques, with KCl as an inert tracer, were used. The resultant data, covering the Reynolds number range from 1 to 50, are presented as plots of the Peclet number based on particle diameter against Reynolds number.Inert tracer experiments were also carried out in a column (inner diameter, 1.6 cm) packed with activated carbon granules, using different particle sizes, fluid flow rates and bed heights, in order to estimate the effective intraparticle diffusivity. We show that flow maldistribution produces pulse response curves with sharp, narrow peaks which, when compared with theoretical curves, result in small intraparticle diffusivities.We illustrate how the outer-phase transfer function can be obtained from the overall transfer function of the activated carbon bed and we compare it with the transfer function obtained directly using impermeable particles similar to the activated carbon granules.     

热塑挤压蒸煮处理对鱼肉蛋白质消化率的影响

采用胃蛋白酶-胰酶复合处理法对几种热加工处理的鱼肉制品进行蛋白质体外消化率的测定,从蛋白质消化率角度,将热塑挤压蒸煮处理与3种传统热加工处理进行比较,了解几种热加工处理对鱼肉蛋白质营养价值的影响。研究结果发现,热塑挤压蒸煮处理方法比3种传统热加工处理方法更能提高鱼肉蛋白质的消化率,进而表明热塑挤压蒸煮处理方法比3种传统热加工处理方法有利于提高鱼肉蛋白质的营养价值。     

Changes in appearance and natural microflora on iceberg lettuce treated in warm,chlorinated water and then stored at refrigeration temperature

The objective of this study was to determine the effect of warm, chlorinated water on the survival and subsequent growth of naturally occurring microorganisms and visual quality of fresh-cut iceberg lettuce. After dipping cut lettuce leaves in water containing 20 mg l⁻¹free chlorine for 90 s at 50°C, samples were stored at 5 or 15°C for up to 18 or 7 days, respectively. Populations of aerobic mesophiles, psychrotrophs, Enterobacteriaceae, lactic acid bacteria, and yeasts and molds were determined. The visual appearance and development of brown discoloration were monitored. Treatment of lettuce in warm (50°C) chlorinated water delayed browning of lettuce. Shelf life of lettuce stored at 5°C, as determined by subjective evaluation of color and general appearance, was about 5 days longer than that of lettuce stored at 15°C. Treatment in warm (50°) water, with or without 20 mg l⁻¹chlorine, and in chlorinated water at 20°C significantly (α= 0·05) reduced the initial population of mesophilic aerobic microflora by 1·73–1·96 log₁₀cfu g⁻¹. Populations increased, regardless of treatment, as storage time at 5°C and 15°C increased. The same trends were observed in populations of psychrotrophs and Enterobacteriaceae. Yeast populations increased slightly in lettuce stored at 5°C but were consistently about 3 logs lower than mesophilic aerobes. Populations of molds and lactic acid bacteria were less than 2 log₁₀cfu g⁻¹throughout storage at 5 or 15°C. Results suggest that heat (50°C) treatment may have delayed browning and reduced initial populations of some groups of micro-organisms naturally occurring on iceberg lettuce, but enhanced microbial growth during subsequent storage.     

Enzyme-enhanced extraction of antioxidant ingredients from red algae Palmaria palmata

The effect of various protease and carbohydrase treatments on the extraction of polyphenols and other antioxidant ingredients from the red algae Palmaria palmata (dulse) was investigated. In addition, the relative contribution of different fractions to the overall antioxidant capacity of the hydrolysate was evaluated. Considerable differences were observed both in total phenolic content (TPC) and antioxidant activities of the hydrolysates evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorbance capacity (ORAC) and ferrous ion-chelating ability assays. All the proteases tested had significant enhancing effect on the extraction of polyphenols and other active components compared to carbohydrases and cold water extraction (control). The Umamizyme extract had the highest TPC and consequently exhibited the strongest scavenging capacity against DPPH and peroxyl radicals. Further fractionation of the Umamizyme extract revealed that the crude polyphenol fraction possessed the highest peroxyl radical scavenging activity, whereas the crude polysaccharide fraction was more effective for chelating ferrous ions. The data from this study suggest the potential of protease treatment to improve value-added utilization of dulse extracts as antioxidants in functional foods and nutraceuticals.     

Distribution of Ca,P and Mg and casein micelle mineralisation in donkey milk from the second to ninth month of lactation

Ca, P and Mg content and distribution between soluble and colloidal phases of donkey milk (DM) were investigated in 62 individual milk samples collected from 9 Ragusano donkeys followed from the second to the ninth month of lactation. Ca (69%) and P (64%) were mainly associated with casein, while Mg was largely found in the soluble form (69%). Only 25% of the colloidal P was present as phosphorylated residues of caseins (casein-P). The colloidal contents of Ca, casein-P, inorganic P (as a constituent of the colloidal calcium phosphate; CCP) and Mg were 1.84, 1.30, 0.45 and 0.15 mmol g casein⁻¹, respectively, revealing a high level of mineralisation of DM casein micelle. The colloidal Ca to colloidal inorganic-P ratio was 1.51, suggesting that most colloidal Ca was in the form of CCP. All parameters were affected by the period of lactation, except casein level in milk and its level of phosphorylation.     

解冻方式对冷冻秋刀鱼品质影响

目的为了探究适宜冷冻秋刀鱼的解冻方法,比较流水解冻、静水解冻、室温空气解冻和低温空气解冻对秋刀鱼鱼肉品质的影响。方法采用智能温度芯片系统对秋刀鱼解冻过程温度变化进行测定,以感官评分、解冻损失率、蒸煮损失率、硬度值、TVB-N值、肌原纤维蛋白含量、活性巯基含量、TBARS值为指标评定秋刀鱼解冻后的品质,并对肌肉组织结构进行观察。结果4种解冻方式将冻结秋刀鱼完全解冻耗时依次为低温空气解冻>室温空气解冻>静水解冻>流水解冻;低温空气解冻对应的解冻损失率和蒸煮损失率最低,而静水解冻和室温空气解冻之间解冻损失率和蒸煮损失率均无显著差异(P>0.05);低温空气解冻的硬度值显著高于其他解冻方式(P<0.05);4种解冻方式对应的TVB-N值和肌原纤维蛋白含量无显著差异(P>0.05),而低温空气解冻对应的活性巯基含量最低;流水解冻和静水解冻对应的TBARS值较高,低温空气解冻可有效延缓脂肪氧化;从肌肉组织结构看,秋刀鱼经低温空气解冻后肌肉纤维紧密、空隙小,而室温空气解冻造成秋刀鱼肌纤维变得松散并出现了轻微断裂现象。结论 从品质保持效果和经济效能考虑,低温空气解冻适宜作为实际生产中秋刀鱼的解冻方式。