Detection of Corn Adulteration in Brazilian Coffee (Coffea arabica) by Tocopherol Profiling and Near-Infrared (NIR) Spectroscopy.

Coffee is a high-value commodity that is a target for adulteration, leading to loss of quality and causing significant loss to consumers. Therefore, there is significant interest in developing methods for detecting coffee adulteration and improving the sensitivity and accuracy of these methods. Corn and other lower value crops are potential adulterants, along with sticks and coffee husks. Fourteen pure Brazilian roasted, ground coffee bean samples were adulterated with 1-20% of roasted, ground corn and were analyzed for their tocopherol content and profile by HPLC. They were also analyzed by near-infrared (NIR) spectroscopy. Both proposed methods of detection of corn adulteration displayed a sensitivity of around 5%, thus representing simple and fast analytical methods for detecting adulteration at likely levels of contamination. Further studies should be conducted to verify the results with a much larger sample size and additional types of adulterants.

Composition and antifungal activity of the essential oil of the Brazilian Chenopodium ambrosioides L.

The antifungal activity of essential oil (EO) from the Brazilian epazote (Chenopodium ambrosioides L.) was evaluated by the poison food assay at concentrations of 0.3%, 0.1%, and 0.05% with eight postharvest deteriorating fungi (Aspergillus flavus, Aspergillus glaucus, Aspergillus niger, Aspergillus ochraceous, Colletotrichum gloesporioides, Colletotrichum musae, Fusarium oxysporum, and Fusarium semitectum). EO components were tentatively identified by Kováts retention indices (RIs) using gas chromatography and gas chromatography combined with mass spectrometry (GC-MS). Growth of all fungi was completely inhibited at 0.3% concentration, and by 90% to 100% at 0.1% concentration. The following 13 tentatively identified compounds (relative percent) accounted for 90.4% of the total volatile oil: alpha-terpinene (0.9), p-cymene (2.0), benzyl alcohol (0.3), p-cresol (0.3), p-mentha-1,3,8-triene (0.2), p-cimen-8-ol (0.6), alpha-terpineol (0.5), (Z)-ascaridole (61.4), piperitone (0.9), carvacrol (3.9), (E)-ascaridole (18.6), (E)-piperitol acetate (0.5), and (Z)-carvyl acetate (0.3). Autobiographic thin layer chromatography of the EO to separate the principal fungitoxic fraction yielded only one fraction that completely inhibited the growth of all test fungi at a concentration of 0.1%. This fraction was characterized by RIs and GC-MS presenting a composition (%) of p-cymene (25.4), (Z)-ascaridole (44.4), and (E)-ascaridole (30.2). The results suggest ascaridoles were the principal fungitoxic components of the EO.

Gamma-tocopherol as a marker of Brazilian coffee (Coffea arabica L.) adulteration by corn.

The adulteration of coffee with cereals, coffee twigs, etc. is apparently widespread in Brazil with corn being considered the most widely used. No adequate methods are available to detect such contamination in commercial coffee. A new method, based on high-performance liquid chromatography (HPLC) tocopherol determination was developed to detect coffee adulteration by corn. Percentages of alpha-, beta-, gamma-, and delta-tocopherol determined by HPLC in six coffee varieties were 29.0, 61.7, 3.3, and 6.0, respectively. Similar values were obtained in six popular coffee brands. The percentages of alpha-, gamma-, and delta-tocopherol in six corn samples were 3.6, 91.3, and 5.1, respectively. These differences could be applied to detect corn in a pure coffee sample intentionally contaminated with corn with the best result obtained with gamma-tocopherol. With this methodology, one coffee brand was apparently adulterated (8.9%), most likely with corn. Tocopherol fingerprinting offers the potential to detect adulteration.

Purification of the seven tetranortriterpenoids in neem (Azadirachta indica) seed by counter-current chromatography sequentially followed by isocratic preparative reversed-phase high-performance liquid chromatography.

Counter-current chromatography (CCC) sequentially followed by isocratic preparative reversed-phase high-performance liquid chromatography was used to isolate the seven bio-actives (azadirachtin A, azadirachtin B, azadirachtin H, desacetylnimbin, desacetylsalannin, nimbin and salannin) from the seed concentrate (NSC) of the neem tree (Azadirachta indica A. Juss). Reproducible, narrow polarity range, high purity fractions were obtained from repeated injections of the NSC (700 mg loadings/injection), on to a relatively small volume CCC coil (116 mL). The CCC biphasic solvent system chosen was hexane:butanol:methanol:water (1:0.9:1:0.9, v/v). A mass balance of injected material showed that 95+% were recovered.

Triacylglycerol composition of coffee beans (Coffea canephora P.) by reversed phase high-performance liquid chromatography and positive electrospray tandem mass spectroscopy.

The triacylglycerol (TAG) composition of coffee beans (Coffea canephora P.) was determined by reversed phase liquid chromatography-mass spectrometry and tandem mass spectrometry. The TAGs were separated on a Microsorb RP C-18 column in series with a Supelcosil RP C-18 column using isocratic elution with acetonitrile/2-propanol/hexane (v/v/v, 57:38:5) as the mobile phase at a flow rate of 1 mL/min for 100 min. Under these conditions, 13 TAGs were identified (elution order): trilinoleyl-glycerol (LLL, 11.76%), dilinolenoyl-palmitoyl-glycerol (PLnLn, 2.94%), dilinoleyl-oleyl-glycerol (OLL, 7.77%), dilinoleyl-palmitoyl-glycerol (PLL, 25.90%), dipalmitoyl-linolenoyl-glycerol (PPLn, 1.66%), dioleoyl-linoleyl-glycerol (OOL, 1.68%), dilinoleyl-stearyl-glycerol (SLL, 8.28%), palmitoyl-oleyl-linoleyl-glycerol (POL, 8.76%), dipalmitoyl-linoleyl-glycerol (PPL, 13.74%), dilinoleyl-arachidyl-glycerol (ALL, 3.51%), trioleoyl-glycerol (OOO, 2.33%), palmitoyl -linoleyl-stearyl -glycerol (PLS, 8.73%), and distearoyl-linolenonyl-glycerol (SSLn, 2.91%). The relative composition (%) was obtained directly from the data system with the photodiode array detector.

Location of double bonds in diene and triene acetates by partial reduction followed by methylthiolation.

Two random reduction procedures (NH2NH2/H2O2 and NH2NH2/O2) were compared and conditions optimized for the reduction of two synthetic pheromone compounds (9Z,11E)-9,11-tetradecadienyl acetate and (9Z,12E)-9,12-tetradecadienyl acetate on a 300 microg scale at 60 degrees C. The relative amounts of the four products (completely reduced acetate, unreacted diene acetate and two monoene acetates), characterized by gas chromatography (GC) from the reaction mixture, depended on the reaction conditions. The reduction was straightforward without any detectable undesired side products. The reaction yields were reproducible with both the reducing reagents. The optimized reduction conditions thus established were utilized to reduce seven synthetic compounds (four diene and three triene acetates) on a micro scale (5 microg). In all cases, expected compounds were identified by GC-MS. After reduction, two methods were used to locate the position of double bonds in the partially reduced compounds. In the first method, the products from the above seven compounds were isolated by extraction with hexane and reacted with dimethyl disulfide to give the DMDS adducts. In the second method ("one-pot"), the reduced compounds were not isolated but instead, the solvents were evaporated and the DMDS derivatives formed. In both cases, determination of the position of the double bonds was possible by GC-MS analyses. The complete procedure (reduction and DMDS derivative formation) could be carried out on a 100 ng scale. Although neither of the partial reduction methods offered significant advantages over the other, partial reduction with NH2NH2/H2O2 was more convenient and hence should be the method of choice, together with DMDS derivative formation to locate double bonds in pheromones. In addition, a new procedure is described using ND2ND2/H2O2 and DMDS derivative formation capable of distinguishing between the double bond positions in (Z)-9-tetradecenyl acetate and (9Z,12E)-9,12-tetradecadienyl acetate (1:1 mixture).

Identification (GC and GC-MS) of unsaturated acetates in Elasmopalpus lignosellus and their biological activity (GC-EAD and EAG).

Two insect colonies of Elasmopalpus lignosellus were reared in our laboratory, the first being initiated from pupae obtained from a cornfield in the region of Sete Lagoas, Minas Gerais and the second from a cornfield in the region of Goiânia, Goiás. From the two colonies, two extracts were prepared from the pheromone glands of virgin E. lignosellus females. The extract obtained from the first colony was designated as extract 1 while the extract obtained from the second colony was designated as extract 2. Extract 1 was analyzed by gas chromatography-mass spectrometry (GC-MS) with (Z)-9-hexadecenyl acetate [(Z)-9-HDA] and (Z)-11-hexadecenyl acetate [(Z)-11-HDA] being identified and confirmed by the formation of DMDS derivatives. In addition, a third acetate, which could be either (E)-8-hexadecenyl acetate [(E)-8-HDA] or (E)-9-hexadecenyl acetate [(E)-9-HDA] was detected by GC-MS. Extract 2 was analyzed by gas chromatography (GC) and gas chromatography-electroannetography (GC-EAD) revealing the presence of (Z)-11-HDA and (Z)-9-TDA. In addition, the same compounds elicited a response with the E. lignosellus male antenna obtained from the second insect colony. Electroantennography (EAG) screening with the male E. lignosellus antenna (obtained from the second insect colony) was conducted with the 23 possible tetradecenyl acetates (TDA) and 22 hexadecenyl acetates (HDA) as standards. Out of the 23 TDA isomers evaluated, only (Z)-9-TDA elicited a response and out of the 22 HDA [(Z) and (E) isomers gamma2 to delta13] evaluated only (Z)-11-HDA elicited a response. The acetate compositions of two extracts obtained from insects originating from the two states (Minas Gerais and Goiás) of Brazil were different from one another as well as from that obtained from insects in Tifton, GA, USA. The bioactivity data (GC-EAD) of the extract 2 differed from those reported for the Tifton, GA, USA population. These data suggest polymorphism in relation to the insect populations found in Brazil and in the USA. The possibility of the existence of an E. lignosellus sub-species cannot be ruled out.

Seletividade de extratos de nim (Azadirachta indica A. Juss.) ao ácaro predador Iphiseiodes zuluagai (Denmark & Muma) (Acari: Phytoseiidae) / Selectivity of neem extracts (Azadirachta indica A. Juss.) to the predatory Mite Iphiseiodes zuluagai (Denmark & Muma) (Acari: Phytoseiidae)

The relative toxicity of the leaf, seed and oil neem cake extracts of Azadirachta indica A. Juss (neem) to the predatory mite Iphiseiodes zuluagai (Denmark & Muma) (Acari: Phytoseiidae) was evaluated. To verify the relative toxicity of these extracts on the predatory mite, discriminatingconcentrations of the extracts were determined for adult females of the Oligonychus ilicis (McGregor) (Acari: Tetranychidae), through the method of concentration-mortality. Coffee leaf disks with 3.5 cm of the diameter were put floating on water and impregnated with dry residue of the extracts. Concentrations of neem extracts which caused mortality (99%) of O. ilicis, after 72h of exposition, were 277.4; 520.9 e 10.9 mg/ml for leaf, seed and oil neem cake, respectively. The discriminating concentration of extract ofoil neem cake for O. ilicis females was highly toxic to I. zuluagai; while extract of leaf and seed were selective to the predatory mite.

A toxicidade relativa dos extratos de folha, semente e óleo de torta de Azadirachta indica A. Juss (nim) ao ácaro predador Iphiseiodes zuluagai (Denmark & Muma) (Acari: Phytoseiidae) foi estudada em laboratório. Foram determinadas concentrações discriminatórias (CLs99) dos extratos de folha, semente e óleo de torta de nim para fêmeas adultas de Oligonychus ilicis (McGregor) (Acari:Tetranychidae), através de bioensaios de concentração-mortalidade. Arenas com 3,5 cm de diâmetro, confeccionadas com folhas de cafeeiro flutuando em água, foram impregnadas com resíduo seco dos extratos e usadas para se estimar a seletividade ao ácaro I. zuluagai. As concentrações dos extratos de nim que mataram 99% de O. ilicis, após 72h de exposição foram: 277,4; 520,9 e 10,9 mg/ml, para folha, semente e óleo de torta, respectivamente. A concentração discriminatória do extrato de óleo de torta de nim para fêmeas adultas de O. ilicis foi altamente tóxica ao ácaro I. zuluagai, as dos extratos de folha e de semente foram seletivos.

Determination of the triacylglycerol composition of coffee beans by reverse-phase high-performance liquid chromatography.

Reverse-phase HPLC with refractive index and light scattering detectors in isocratic and gradient elution modes, respectively, was applied for the separation of the major triacylglycerols (TAG) in coffee lipids. Twelve TAG species could be identified and determined using a linear gradient of acetonitrile in dichloromethane: dichloroethane. The quantitative evaluation was based on the relative area percentages derived directly from a data-station. The procedure was applied to determine the TAG composition of three types of coffee beans harvested in two coffee producing areas in Brazil and dried by two commonly used procedures. No significant differences in the TAG compositions due to the type, origin and drying procedure were found.

Comparison of GC and HPLC for the quantification of organic acids in coffee.

A GC and an HPLC method for the quantification of organic acids OAs in coffee have been compared. The GC procedure, employing trimethylsilyl derivatives, was found to be very tedious. The HPLC method, which employed an ion exchange column using a flow gradient of water containing 1% phosphoric acid and UV detection (210 nm), was found to be much simpler for the quantification of eight organic acids (oxalic, succinic, fumaric, malic, tartaric, citric, quinic and fumaric acids) in four representative coffee samples. The HPLC procedure was more convenient than that described in the literature since no pre-purification was required for quantification of the OAs.