Development of an on-line molecularly imprinted chemiluminescence sensor for determination of trace olaquindox in chick feeds

BACKGROUND: Olaquindox, as one of the antimicrobial growth accelerants, is usually used in livestock production to improve feed efficiency. Due to health concerns over possible carcinogenic, mutagenic and photoallergenic effects of olaquindox on animals, the development of simple, rapid and sensitive analytical method for determination of olaquindox is crucial and necessary. RESULTS: In this study, a surface molecularly imprinted polymer was prepared by a molecular imprinting technique in combination with a sol‐gel process using activated silica gel as a support material. This imprinted material exhibited with good recognition and selective ability, and fast adsorption‐desorption dynamics toward olaquindox. Using it as the recognition element, a new on‐line molecularly imprinted solid phase extraction coupled with chemiluminescence sensor for the determination of olaquindox was developed. The factors affecting preconcentration of the analytes and sensitivity of the method were all investigated. Under the optimal condition, the linear range of the calibration graph was between 2 × 10^?8 and 1 × 10^?6 g mL^?1, and the detection limit of this method was 7 × 10^?9 g mL^?1. The blank chick feed samples spiked with olaquindox at 0.3, 0.9 and 1.5 µg g^?1 levels were extracted and determined by this presented method with recoveries ranging from 87% to 94%. This method was validated by high‐performance liquid chromatography and the results correlated well with those obtained by both methods. Moreover, this method was quantitatively analysed with two contaminated chick feed samples. CONCLUSION: This study will provide a sensitive and fast method for the monitoring of olaquindox residues in foods. Copyright © 2012 Society of Chemical Industry     

Preparation and Application of a Molecular Imprinting Matrix Solid Phase Dispersion Extraction for the Determination of Olaquindox in Chicken by High Performance Liquid Chromatography

In this paper, a new method was established to extract olaquindox in chicken by matrix solid phase dispersion extraction using the molecularly imprinted polymers as solid phase materials. The polymers were prepared using olaquindox as the template, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linking agent. The imprinted material was characterized by static and kinetic adsorption experiments. The results showed that it had good recognition, selective ability, and fast adsorption–desorption dynamics for olaquindox. The prepared material was used as solid phase materials of matrix solid phase dispersion to enrich the olaquindox and then determined by high performance liquid chromatography. Under the optimized conditions, the range of recovery spiked with olaquindox at 1.0 and 2.0 μg?g^?1 levels was between 85.3 and 93.2 %.     

A sensitivity-improved enzyme-linked immunosorbent assay for fenvalerate: a new approach for hapten synthesis and application to tea samples

BACKGROUND: Fenvalerate has been widely used for the control of many common pests, but residues of this pesticide have been found in some agricultural crops. China is a large exporter of tea products; thus monitoring of pesticide residues in tea products has become increasingly important. In this study, a method of competitive direct enzyme‐linked immunosorbent assay (CD‐ELISA) for the rapid detection of fenvalerate in tea sample was developed. RESULTS: A polyclonal antibody against fenvalerate (FEN) was produced by the hapten with the characteristic moiety of fenvalerate. After acidification, the hapten was synthesized from 2‐(4‐chloro‐phenyl)‐3‐methyl‐butyric acid and aminocaproic acid methyl ester. The CD‐ELISA method developed has a high sensitivity of detection: 9 µg L^?1 for IC₅₀ and 0.5 µg L^?1 for IC₁₅. Fenvalerate was treated with 0.5 mmol L^?1 NaOH–methanol solution to improve its solubility by isomerization. In the tea sample, the detection limit of fenvalerate was 0.16 mg L^?1. A recovery rate of 76.67–91.43% was obtained from spiked tea. The reliability of the CD‐ELISA method is better in comparison with the gas chromatographic method (R² = 0.9968). CONCLUSION: In this study, a simple and efficient immunoassay method was developed. It is preferable for the rapid determination of fenvalerate residues in tea samples. Copyright © 2011 Society of Chemical Industry     

Determination of olaquindox,carbadox and cyadox in animal feeds by ultra-performance liquid chromatography tandem mass spectrometry

Olaquindox, carbadox, and cyadox are chemically synthesised antibacterial and growth-promoting agents for animals. At high doses they may exert mutagenicity and hepatic and adrenal toxicities in animals. Regrettably, these substances are frequently abused or misused when added into animal feeds. Thus, developing a sensitive and reliable method for simultaneous determination of olaquindox, carbadox, and cyadox in different kinds of animal feeds is crucially important for food safety monitoring. In this paper we optimised instrumental conditions, extraction solvents, solid phase extraction cartridges, and pH of the loading solvents on the Oasis HLB cartridge. Under the optimal conditions, mean recoveries ranged from 74.1 to 111%, and intra-day and inter-day variations were lower than 14.6% and 10.8%, respectively. The limits of quantification for olaquindox, carbadox, and cyadox were 0.05 mg kg^?1, 0.10 mg kg^?1, and 0.025 mg kg^?1, respectively. The proposed method uses ultra-performance liquid chromatography tandem mass spectrometry and is sensitive and reliable for the simultaneous determination of olaquindox, carbadox, and cyadox in three kinds of animal feeds (specifically, mixed feed, concentrated feed, and additive premixed feed). This method has good precision, high sensitivity, and good reproducibility, and thus it can be used for convenient and accurate determination of olaquindox, carbadox, and cyadox in different kinds of animal feeds.     

Molecularly Imprinted Nanosilica Solid-Phase Extraction for Bisphenol A in Fish Samples

This paper reports a method using molecularly imprinted nanosilica as the solid-phase extraction sorbent to extract bisphenol A (BPA) from fish samples. The selective extraction efficiency of BPA from its structure-analogous by molecularly imprinted solid-phase extraction (MISPE) was compared with commercial C18 SPE column. The reproducibility of MISPE and optimal flow rate of sample were studied. There was a linear correlation in the concentration range of 0.7–114.1 μg l^?1 of BPA (r?=?0.997). The limit of detection (LOD) based on three times ratio of signal to noise was 0.11 μg l^?1. Under optimal conditions, the proposed method was applied to the analysis of BPA in fish samples. The amount of BPA in bream was 4.00 μg kg^?1, and both concentrations of BPA in crucian and weever were below the LOD. The recoveries of BPA standard solution spiked with fish samples were in the range of 92.56–102.3 % with the relative standard deviation less than 10 %.     

Simultaneous determination of five quinoxaline-1,4-dioxides in animal feeds using an immunochromatographic strip

An immunochromatographic (ICG) strip was developed for the simultaneous quantitative determination of five quinoxaline-1,4-dioxides in animal feed. For this purpose, polyclonal antibodies (PcAb) with group-specific quinoxaline-1,4-dioxides were conjugated to colloidal gold particles as the detection reagent for ICG strips to test for quinoxaline-1,4-dioxides. This method achieved semi-quantitative detection of quinoxaline-1,4-dioxides within 5–10 min. The visual lower detection limits of the strip for quinocetone, cyadox, carbadox, mequindox and olaquindox were 10, 15, 15, 20 and 20 ng ml^?1, respectively. Using an ICG strip reader, the 50% inhibitions (IC₅₀ values) were calculated to be 9.1, 13.5, 16.6, 20.2 and 21.3 ng ml^?1 for quinocetone, cyadox, carbadox, mequindox and olaquindox, respectively. When used to analyse samples of animal feed, acceptable recovery rates of 77.5–99.5% and coefficients of variation (CVs) of 4.3–10.7% were obtained. Levels measured with the ICG strip for 10 spiked samples were confirmed by HPLC with a high correlation coefficient of 0.9965 (n = 10). In conclusion, the method was rapid and accurate for simultaneous determination of five quinoxaline-1,4-dioxides antibiotics in animal feed.     

Preparative separation and purification of phenolic compounds from Canarium album L. by macroporous resins

BACKGROUND: Canarium album L. (also called Chinese olive) is a traditional medicine material in China, and phenolic compounds from C. album possess great pharmacological activities. To obtain high‐purity phenolics from C. album, a crude extract of C. album phenolics was prepared by ethanol extraction. The use of macroporous resins for further separation and purification of phenolics in the extract was studied. RESULTS: Through static adsorption and desorption tests, AB‐8 resin was chosen for the separation of phenolics because of its higher adsorption capacity and desorption ratio than other resins. Then, dynamic adsorption and desorption experiments were carried out on an AB‐8 resin packed column to obtain optimal separation parameters. The highest adsorption capacity of AB‐8 was achieved when variables including initial concentration (C₀), feed flow rate and feed volume were 10 mg mL^?1, 2 mL min^?1 and 9 bed volumes (BV), respectively, and saturated resin was first washed with 5 BV of water to remove impurities, then a purified product containing more than 85% of C. album phenolics was obtained by desorbing the resin with 2.5 BV of 70% (v/v) aqueous ethanol at flow rate of 1 mL min^?1, and the recovery of phenolics was up to 75%. In addition, five phenolic compounds in the product were identified as gallic acid, ellagic acid, corilagin, hyperin and kaempferol‐3‐glucopyranoside by UV and LC–ESI–MS analysis. CONCLUSION: The results in this study could provide scientific references for the large‐scale production of phenolics from C. album. Copyright © 2007 Society of Chemical Industry     

Rapid Screening of Quinoxaline Antimicrobial Growth Promoters and Their Metabolites in Swine Liver by Indirect Competitive Enzyme-Linked Immunosorbent Assay

Quinoxaline feed additives are antimicrobial growth promoters (AGPs); use three of them is permitted, and two of them are illegally used. It results in residue of quinoxaline AGPs and their metabolites in edible animal tissues, which are potentially harmful to human health. In order to effectively monitor the multiple residues of them in swine liver, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was developed based on polyclone antibody preparation. Protein conjugates were synthesized and immune to New Zealand white rabbit according to designed schemes. The effective antiserum with 50 % inhibiting concentration (IC₅₀) value of 1.34 μg?L^?1 was obtained. A new synthesized quinoxaline with similar chemical structure to olaquindox but longer spacer arm was used as coating antigen. Cross-reactivity of other four quinoxaline AGPs and their eight metabolites was tested; seven of them have cross-reactivity over 10 %, with IC₅₀ of 0.10–2.50 μg?L^?1. At the spike level of 1 to 100 μg?kg^?1 in swine liver, the recoveries of all compounds ranged from 80.14 % to 96.90 %, with the inter-day variation coefficient (CV) of 5.67–13.82 % and the intra-assay CV of 6.22–14.19 %. The limit of detection ranged from 0.03?±?0.002 to 0.79?±?0.05 μg?L^?1. Positive samples were determined by the ic-ELISA method and successfully confirmed by liquid chromatography-tandem mass spectrometry. The proposed ELISA is feasible for screening quinoxaline AGPs and their metabolites in swine liver.     

Highly Selective Determination of Chrysoidine in Foods Through a Surface Molecularly Imprinted Sol–Gel Polymer Solid-Phase Extraction Coupled with HPLC

A highly selective determination method for chrysoidine, an industrial azoic dye banned in foods, was developed through a novel molecularly imprinted polymer (MIP) online solid-phase extraction coupled with high-performance liquid chromatography. The MIP was firstly synthesized by a surface molecular imprinting technique in combination with a sol–gel process and characterized by FT-IR and adsorption experiments. The MIP exhibited high selectivity and high adsorption capacity for chrysoidine and offered a fast kinetics for the adsorption and desorption of chrysoidine. A number of parameters, including the pH of loading solution, the sample loading flow rates, and eluting time of analyte, were carefully optimized to improve the extraction efficiency. Under the optimal experimental conditions, for a 50-mL sample solution, the enrichment factor was 279 and the detection limit (S/N?=?3) was 6 ng L^?1. The linear plots with r ²?>?0.99 were achieved over a range of 0.04–40 μg L^?1, and the peak area precision (relative standard deviation) for nine parallel determinations was below 6.32 %. This method was employed for quantitative determination of chrysoidine in oil bean curd, yellow croaker, and paprika with satisfactory recoveries (89.3–97.6 %).     

Molecularly imprinted solid phase extraction coupled to high-performance liquid chromatography for determination of trace dichlorvos residues in vegetables

In this paper, we prepared a highly selective imprinted polymer by a room temperature ionic liquid-mediated bulk polymerization technique, using dichlorvos as the template, methacrylic acid as the functional monomers, and trimethylolpropane trimethacrylate as the cross-linker. This functionalized material was characterized by FT-IR, static and kinetic adsorption experiments, and the results showed that this imprinted sorbent exhibited good recognition and selective ability, and offered fast kinetics for the adsorption and desorption of dichlorvos. Using the prepared material as a solid phase extraction sorbent, a novel sample pre-treatment technique that can be coupled to high-performance liquid chromatography (HPLC) had been developed for determination of trace dichlorvos residues in foods. Under the selected experimental condition, the detection limit (S/N = 3) of dichlorvos was 94.8 ng L⁻¹, and the peak area precision (RSD) for five replicate detections of 10 μg L⁻¹ dichlorvos was 4.41%. The blank samples of cucumber and lettuce spiked with dichlorvos at 0.005 and 0.02 μg g⁻¹ levels were determined with recoveries ranging from 82.1% to 94.0%.     

The determination of olaquindox in pig feeds by high-performance liquid chromatography

A simple, rapid method, based on high performance liquid chromatography, h.p.l.c., is described for the determination of olaquindox in pig feeds. The drug is extracted from the feed by use of a methanol-water mixture, an aliquot is injected on to the h.p.l.c.-column and quantified by u.v.-detection. The method has been tested on feeds and premixes containing olaquindox between 1–400 mg kg^?1.     

Simultaneous lactic acid and xylitol production from vine trimming wastes

Hemicellulosic hydrolyzates from vineshoot trimmings obtained by dilute sulfuric acid hydrolysis were evaluated for xylitol production by Debaryomyces hansenii NRRL Y‐7426. Bioconversion was not efficient, however, since a mixture of products (mainly ethanol) was achieved. Taking into account that hexoses (such as glucose or mannose) can inhibit xylose metabolism by repression and inactivation of the xylose transport system or catabolic enzymes and that these hemicellulosic hydrolyzates are characterized by a high glucose concentration, a novel technology was developed, sequentially transforming glucose into lactic acid by Lactobacillus rhamnosus followed by fermentation of xylose into xylitol by Debaryomyces hansenii after L. rhamnosus removal by microfiltration. Optimal conditions were achieved using detoxified concentrated hemicellulosic hydrolyzates, after CaCO₃ addition in both stages of fermentation and using nitrogen purges after sampling in order to reduce the oxygen dissolved. Under these conditions 31.5 g lactic acid L^?1 (Q_LA = 1.312 g L^?1 h^?1 and Y_LA/S = 0.93 g g^?1) and 27.5 g xylitol L^?1 (Q_Xylitol = 0.458 g L^?1 h^?1 and Y_Xylitol/S = 0.53 g g^?1) were produced. Finally, lactic acid was selectively recovered using the resin Amberlite IRA 400 (0.0374 g of lactic acid g^?1 of dry resin), allowing a further recovery of xylitol by sequential stages of adsorption, concentration, ethanol precipitation, concentration and crystallization to obtain food‐grade xylitol according to a developed process. Copyright © 2007 Society of Chemical Industry     

Application of molecularly imprinted hydrogel for the preparation of lactose‐free milk

BACKGROUND: A variety of lactose imprinted hydrogels were prepared and their binding properties were studied in comparison with blank non‐imprinted hydrogel. Methacrylamide and ethylene glycol dimethacrylate were used as functional monomer and cross‐linker, respectively. Dimethylsulfoxide was also applied as polymerisation solvent. RESULTS: Different template/monomer ratios were studied and the optimised imprinted hydrogel (MIP₂), with a lactose/methacrylamide ratio of 1:8, was selected in a rebinding test. In Scatchard analysis of MIP₂‐lactose interactions, the dissociation constant and maximum binding sites were 0.33 mmol L^?1 and 67.76 µmol g^?1 hydrogel, respectively. The selectivity of MIP₂ for lactose in aqueous media was also evaluated in comparison with different mono‐ and disaccharides. The data showed that the affinity of MIP₂ for lactose is significantly higher than other saccharides. The imprinted hydrogel was finally used as a sorbent for separation of lactose from milk. CONCLUSIONS: The results indicated that MIP₂, as an optimised imprinted hydrogel, can effectively bind lactose and decrease its concentration in milk. Copyright © 2012 Society of Chemical Industry     

The effect of glyphosate on digestion and horizontal gene transfer during in vitro ruminal fermentation of genetically modified canola

BACKGROUND: The impact of glyphosate on ruminal fermentation, selective pressure on ruminal bacteria and horizontal transfer of the gene encoding 5‐enolpyruvylshikimate‐3‐phosphate synthase (epsps) to ruminal bacteria was studied using batch culture with glyphosate‐tolerant (Roundup Ready^®) canola meal as substrate. RESULTS: A glyphosate concentration × time interaction (P < 0.05) occurred when glyphosate (0–100 mmol L^?1) was included in in vitro ruminal incubations with a diet containing 150 g kg^?1 Roundup Ready^® canola meal (Experiment 1). Glyphosate at 50 and 100 mmol L^?1 inhibited fermentation. In Experiment 2, epsps fragments were detected in plant debris for up to 16 h of incubation using primer sets that amplified three fragments (62, 108 and 300 bp) of DNA spanning the transgenic construct. Persistence was affected by fragment size but not by glyphosate concentration (0, 10 or 60 mmol L^?1). Extensive polymerase chain reaction assays provided no evidence of acquisition of epsps by feed‐ or fluid‐associated bacteria during fermentation. A glyphosate concentration × time interaction (P < 0.05) was observed for all fermentation parameters measured, and glyphosate caused a general inhibition of fermentation. CONCLUSION: The presence of glyphosate did not increase selective pressure for gene transfer of DNA encoding glyphosate resistance from Roundup Ready^® canola meal to ruminal bacteria. Copyright © 2007 Society of Chemical Industry     

Integral utilisation of barley husk for the production of food additives

A new and effective chemical–biotechnological process for the global utilisation of barley husk (obtained from the spent grains in the brewing process) is reported. With the proposed process the three main components of the lignocellulosic residue (cellulose, hemicellulose and lignin) are utilised. A first treatment with sulfuric acid (pre‐hydrolysis) allowed the solubilisation of hemicelluloses to give xylose and glucose‐containing liquors (suitable to make fermentation media for the continuous lactic acid (LA) production with L. pentosus) and a solid phase containing cellulose and lignin. In this set of experiments, a maximum volumetric productivity (Q_P) = 2.077 g L^?1 h^?1 and product yield (Y_P/S) = 0.62 g g^?1 were obtained for a dilution rate of 0.01 h^?1. The solid residues from pre‐hydrolysis were treated with NaOH in order to increase their cellulase digestibility, and dissolve the lignin content. The cellulose residue was used as substrates for lactic acid production by simultaneous saccharification and fermentation (SSF) in media containing Trichoderma reesei cellulases and Lactobacillus rhamnosus cells using the complete MRS broth or a cheaper medium. In both cases similar LA concentrations and volumetric productivities were achieved (P = 73.4–71.0 g L^?1 and Q_P = 1.28–1.25 g L^?1 h^?1, respectively), where P is LA concentration. The lignin solution obtained after the alkaline treatment was extracted with ethyl acetate in order to obtain the phenolic components. The extract obtained at pH 3 showed three times more antioxidant activity than the one extracted at pH 12.8, with an EC₅₀ of 1.396 g L^?1 for pH 3 and 4.604 g L^?1 for pH 12.8. The best extracts showed twice antioxidant activity than BHT. Copyright © 2007 Society of Chemical Industry     

Mutation of Acetobacter pasteurianus by UV irradiation under acidic stress for high‐acidity vinegar fermentation

To obtain a mutant with higher vinegar production, a wild‐type industrial strain Acetobacter pasteurianus CICIM B7003 was pretreated in 50 g L^?1 acetic acid for 1 h and cultured for 12 h without adding any acetic acid; then, the enriched cells were mutated by UV under acidic stress (60 g L^?1 acetic acid). Using this method, A. pasteurianus CICIM B7003‐02, a mutant exhibiting best performance, was obtained. Notably, after repeated experiments, it was confirmed that B7003‐02 accumulated 103.81 ± 1.17 g L^?1 acetic acid within 160‐h batch cultivation in Erlenmeyer flasks, which was 49.2% higher than that of the wild type. Repeated batch fermentations with A. pasteurianus B7003‐02 were carried out for several runs in a Frings 8‐L acetator, and high‐acidity vinegars (90 ± 0.39 g L^?1) were produced. This work reveals the potential value for improvement in industrial vinegar production.     

Rapid determination of Alternaria mycotoxins in tomato samples by pressurised liquid extraction coupled to liquid chromatography with fluorescence detection

ABSTRACT

A sensitive and reliable method using pressurised liquid extraction (PLE) followed by molecularly imprinted solid phase extraction (MISPE) and high performance liquid chromatography with fluorescence detection (HPLC–FLD) has been developed for the analysis of alternariol (AOH) and alternariol monomethyl ether (AME) in tomato samples. Influence of several extraction parameters that affect PLE efficiency were evaluated for the simultaneous extraction of both mycotoxins in the selected samples. AOH and AME were optimally extracted using MeOH/water (25:75, v/v) at 70°C as solvent, a pressure of 1000 psi and a single extraction cycle. The resulting PLE extracts were pre-concentrated by molecularly imprinted solid phase extraction (MISPE) cartridges followed of analysis by HPLC with fluorescence detection (λ_exc = 258, λ_em = 440 nm). The proposed method was applied to the analysis of AOH and AME in fortified tomato samples (20–72 µg· kg–1) with recoveries of 84–97% (RSD < 8%, n = 6) for AOH and 67–91% (RSD < 13%, n = 6) for AME. The detection limit for AOH and AME were 7 and 15 µg· kg^–1, respectively. The ensuing PLE–MISPE–HPLC–FLD method was validated for the analysis of both mycotoxins in tomato samples in accordance with European Commission Decision 2002/657/EC.     

莠去津分子印迹聚合物微球的制备及其吸附性能与在食品检测中的应用

以莠去津为模板分子,甲基丙烯酸（methacrylic acid,MAA）为功能单体,乙腈为致孔剂,采用沉淀聚合法制备莠去津分子印迹聚合物微球（molecularly imprinted polymer microspheres,MIPMs）。对MIPMs制备工艺进行优化,当莠去津与MAA物质的量比1∶4、乙腈用量50 mL、聚合温度60 ℃时,MIPMs的吸附效果最好。通过吸附实验考察MIPMs对目标物的吸附性能,并结合Scatchard分析可知MIPMs对莠去津存在两类吸附位点,且最大表观结合量为282.69 μmol/g。以MIPMs作为固相萃取材料,制备分子印迹固相萃取（molecularly imprinted solid phase extraction,MISPE）柱,用于样品前处理,并建立莠去津-MISPE-高效液相色谱法测定食品中4 种三嗪类农药（西玛津、莠灭净、莠去津、扑草净）残留的方法。结果表明,MISPE柱对4 种三嗪类农药具有特异选择性,4 种农药的线性相关系数为0.999 1～0.999 7,检出限为0.5～5 ng/mL,平均回收率在86.2%～95.7%之间,相对标准偏差为1.98%～4.51%（n=5）。该方法能够简单、准确、高选择性地检测食品中三嗪类农药残留。     

In vitro culture of Pandanus amaryllifolius and enhancement of 2‐acetyl‐1‐pyrroline,the major flavouring compound of aromatic rice,by precursor feeding of L‐proline

Shoots, plantlets and semi‐differentiated callus (SDC) cultures of Pandanus amaryllifolius capable of producing high levels of basmati rice flavour were established in vitro using Murashige and Skoog nutrient medium. A total of 10% of the initial explants responded to produce shoot cultures in the presence of benzylamino purine (BAP) (0.5 mg L^?1) and glutamine (100 mg L^?1). Leaf explants and basal portions of shoots produced SDC whereas elongated in vitro shoots could be continuously multiplied, using BAP (1.5 mg L^?1) and kinetin (Kn) (1.0 mg L^?1), and rooted in half‐strength medium for ex vitro cultivation leading to a process of micropropagation. Steam‐distillation extraction (SDE) followed by gas chromatography‐mass spectrometry (GC‐MS) analysis of various cultured organs and spent liquid medium used for SDC revealed the presence of 2‐acetyl‐1‐pyrroline (2‐AP) to various extents. This 2‐AP compound has been identified as the major flavouring compound of scented basmati and other scented rice varieties. 2‐AP was found to be highest, on a fresh weight basis, in SDC (19.7 mg kg^?1) on the 40th day, whereas in vitro roots, shoots and field leaves (of one‐year‐old plant) had lower levels of 15, 6.8 and 14 mg kg^?1, respectively. Further enhancement of 2‐AP in SDC using precursor was possible by feeding into medium 1 mmol L^?1 of L ‐proline where a highest level of 21.67 ppm of 2‐AP accumulated on the seventh day whereas a higher level of 2 mmol L^?1 of L ‐proline suppressed 2‐AP levels. The present report is the first on the tissue culture studies of P. amaryllifolius where continuous production of plantlets as well as synthesis of high levels of 2‐AP has been documented. Copyright © 2005 Society of Chemical Industry     

Physicochemical and microbiological description of Caxiri – a cassava and corn alcoholic beverage

Caxiri is a fermented alcoholic beverage made from cassava, corn and sweet potatoes by indigenous people in Brazil. Saccharomyces cerevisiae Rhodotorula mucilaginosa, Lactobacillus fermentum, Bacillus subtilis and L. helveticus were the main microbial species detected. Maltose was the main carbohydrate found (19.12 g L^?1), and lactic acid (15.09 g L^?1) and ethanol (92.16 g L^?1) were also found in high concentrations. Gas chromatography‐flame ionisation detector was used to identify thirteen volatile compounds. Among these volatiles, the higher concentrations were decanoic acid (123.04 μg L^?1) for the acids, diethyl malate (88.32 μg L^?1) for the esters, furfural (109.31 μg L^?1) for the aldehydes, 2‐phenylethanol (1022.76 μg L^?1) for the alcohols and 1,1‐diethoxyethane (226.24 μg L^?1) for the others. This study contributes to increasing knowledge of the microbiota present in the alcoholic fermentation produced from cassava, corn and sweet potatoes.