The presented thesis deals with the monitoring sensory quality of processed cheese analogues, focusing mainly on the taste (flavour) and related content of volatile (aroma active) substances. Model samples of analogues were produced by a standard procedure at Tomas Bata University in Zlín. The experimental part was divided into two experiments, which differed in the composition of model samples of analogues. In the first experiment, the traditional fat (butter) was completely replaced by selected vegetable fats (palm, coconut, mixed), in the second experiment only a part (1% w/w - expressed on the total weight of the sample) of butter was replaced by vegetable oils (apricot, flax seed, currant, grape seed). Solid phase microextraction in conjunction with gas chromatography with flame ionization detection was used to determine volatiles. Methods based on valid international standards were used to evaluate the sensory quality of samples, focusing mainly on flavor, namely evaluation using scales (ISO 4121), profile test (EN ISO 13299) and ranking test (ISO 8587). The aim of the work was to assess the effect of the addition of various vegetable fats/oils on the above parameters, at the same time their changes were monitored during 6 months of storage (at 6 ° C). The results showed that the vegetable oil used affects both the sensory quality and the content and composition of volatile substances of analogues. Significant differences between samples were mainly in taste, aroma and overall acceptability. The decreasing overall acceptability of the samples can be expressed in experiment I by the order: product with butter coconut palm mixed fat; in the case of experiment II: product with butter apricot = flax = grape currant oil. Mixed fat, currant and grape seed oil proved to be unsuitable for the production of analogues, on the contrary, analogues with coconut fat and apricot oil were evaluated best. Based on the results of sensory analyses, it was shown that the samples maintain a good sensory quality min. for 3 months while maintaining a low storage temperature ( 6 ° C). An analogue with coconut fat, whose taste, aroma and acceptability were rated as very good, and apricot oil, whose taste, aroma and acceptability were even rated as excellent, could enrich the food offer on the market.

The aim of this master‘s thesis was to determine the aroma active compounds and monitor the sensory quality of apples. The theoretical part deals with the description, composition and properties of apples, information about the aroma compounds, their determination and possibilities for sensory evaluation of apples is also given. The gas chromatography method combined with the solid-phase microextraction, utilized for the specification of aroma compounds, is described. In the experimental part, the SPME-GC-FID method was applied on selected cultivars of apples specially cultivated against apple scab (Venturia inaequalis), i.e. 24 genotypes and Golden Delicious as the control variety. In total 60 various aroma compounds were identified, 22 alcohols, 12 aldehydes, 11 ketones, 10 esters and 5 organic acids. The number and concentration of compounds identified differed according to the cultivars. Sensory analysis was performed using category ordinal scales and the profile test.

Also aged bottles are safer to use than new bottles because their chemical leaching was found to be lower than that of new bottles. This study recommends the reassessment of the absence of international guidelines for acetaldehyde in water and foods. The study also recommends that the amount of acetaldehyde that can be added to soft drinks as flavouring agent should be below the specific migration limit (SML) for migration of acetaldehyde from PET bottle into bottle contents. This is essential since the SML was designed to ensure that exposure to acetaldehyde, as a result of intake of bottled water and soft drinks in PET bottles, is below the tolerable daily intake (TDI) for acetaldehyde. As antimony was reported to go beyond the safe limits in some Nigerian bottled water and soft drinks after 11 months of storage this study discourages the use of bottle contents stored for a very long time.

Neste trabalho prepararam-se ésteres de ácidos graxos por esterificação do ácido oléico e transesterificação do óleo de soja e do triéster oléico via catálise enzimática. Determinou-se a composição dos produtos obtidos por RMN 1H e CG-FID. Os padrões dos ésteres do ácido oléico via esterificação ácida foram preparados empregando ácido sulfúrico, os padrões dos ésteres do óleo de soja por transesterificação básica com hidróxido de sódio e o padrão do triéster oléico foi sintetizado utilizando ácido p-tolueno sulfônico como catalisador. A melhor enzima para essas reações foi determinada através de reações de esterificação do ácido oléico e transesterificação do óleo de soja com etanol na ausência de co-solventes, sendo que foi selecionada a lipase de Candida antarctica. A mesma enzima foi empregada nas esterificações enzimáticas do ácido oléico com diversos alcoóis (metanol, etanol, n-propanol e n-butanol), na transesterificação enzimática do óleo de soja e do triéster oléico com etanol. Em ambos os estudos, foram avaliados os fatores que influenciam as reações: quantidade de enzima; tempo de reação; água adicionada ao álcool e reuso do biocatalisador. Na esterificação enzimática do ácido oléico, o uso do etanol forneceu o melhor rendimento (96,5%) com 5,0% (m/m) de enzima em 24 horas de reação. Quando uma quantidade de 4,0% de água foi adicionada ao álcool, a reação utilizando metanol mostrou maior eficiência (98,5%) e os rendimentos com os outros alcoóis não foram alterados significativamente (acima de 90%). Também foi possível utilizar a enzima por até 10 ciclos sem perda de rendimento, com exceção do metanol, onde ocorreu um decréscimo acentuado de rendimentos nos ciclos seguintes. Na transesterificação enzimática do óleo de soja, os mesmos fatores foram avaliados e com 5,0% de enzima, após 24 horas, foi obtido um rendimento de 84,1% e com a adição de água o rendimento não foi significativamente alterado (83%). Na transesterificação, os métodos de quantificação por RMN 1H e CG-FID foram comparados sendo que uma maior diferença foi observada para as reações com baixos rendimentos por RMN 1H, porém em altos rendimentos a diferença entre os dois métodos não foi significativa. Monoglicerídeos e diglicerídeos foram quantificados por CG-FID e por RMN 1H onde foi possível calcular a razão dos produtos formados através de uma equação desenvolvida, sendo que a diferença entre esses tipos de análises foi pequena, de apenas 1,4%. A transesterificação enzimática do triéster oléico foi obtida em bom rendimento (90,4%) e uma pequena quantidade de mono- e diglicerídeos foi produzida. Em todas as reações de transesterificação, o glicerol não foi detectado após a lavagem dos produtos. A metodologia empregando a lipase de Candida antarctica mostrou-se eficiente para a produção de biodiesel a partir do óleo de soja e do ácido oléico com diferentes tipos de alcoóis. / In this work, it was prepared esters of the fatty acid by esterification of the oleic acid and transesterification of the soy oil through enzymatic catalysis. It was determined the composition of the products obtained by 1H NMR and GC-FID. The standards of esters of the oleic acid by acid esterification was prepared employing sulfuric acid, the standards of esters of the soy oil by alkaline transesterification with sodium hydroxide and the standard of the oleic triester was synthesized employing p-toluene sulfonic acid as catalyst. The best enzyme for those reactions was determined through reactions of esterification of the oleic acid and transesterification of the soy oil with ethanol and free co-solvents, and lipase from Candida antarctica was selected. The same enzyme was employed in the enzymatic esterifications of the oleic acid with various alcohols (methanol, ethanol, propanol and butanol), in the enzymatic transesterification of soy oil and the oleic triester with ethanol. In both studies, was assessed the factors that influence the reactions: amount of catalyst, reaction time, water added in the alcohol and the turnover of biocatalyst. In the enzymatic esterification of the oleic acid, the ethanol showed the better yield (96,5%) with 5,0% (m/m) of enzyme at 24 hours of reaction. When 4,0% of water was added to the alcohol, the methanol showed the high efficiency (98,5%) and the yield with another alcohols were not affected. It was also possible to use the enzyme for 10 cycles without lose yield, except for the methanol. In the enzymatic transesterification of the soy oil, the same factors were assessed using 5,0% of enzyme, after 24 hours, a yield of 84,1% was obtained and with the water addition the yield was not modified (83%). On the transesterification, 1H NMR and GC-FID were compared and a great difference was observed for low yields, but on high yields, the difference between methods was small. Monoglycerides and diglycerides were quantified by GC-FID and detected by 1H NMR, it was possible to calculate the ratio between them on the products formed through an equation developed and the difference for this type of analysis was small, only 1.4% . The enzymatic transesterification of the oleic triester was obtained with good yield (90,4%) and a small amount of the monoglycerides and diglycerides was produced. In all the transesterifications reactions, glycerol was not detected after washing mixture of products. The methodology employing Candida antarctica lipase was efficient for biodiesel production by soybean oil and oleic acid with different alcohols.

This paper reports the study of composition and variation of the chemical components of essential oils of Croton species of Sergipe emphasizing its importance chemotaxonomy. Essential oils from fresh aerial parts obtnained by hydrodistillation from samples of Croton blanchetianus (CB-GA), C. campestris (CC-AML), C. heliotropiifolius collected at different locations in the Sergipe (CH-SG1, CH-SG2, CH-GA, and CH-AML), C. pedicellatus (CP-SI), C. tetradenius (CT-SG) and seven other unidentified taxa, called CSP1-CPS7, were analyzed by GC-MS and GC-FID, such analysis revealed a highly variable chemical composition. It were identified 131 components by comparing the retention indices and mass spectra of compounds with literature data and NIST and Willey mass spectra libraries. With the chemical analysis of oil of Croton were established correlations between the taxa of C. heliotropiifolius, which can be differentiated by using their main chemical markers: (E)-caryophyllene and bicyclogermacrene. For comparative analysis of the chemical composition of essential oils of Croton species, chemometric tools as Principal Component Analysis (PCA) and hierarchic Cluster Analysis (HCA) was applied, by which it was possible to differentiate the components of the essential oil of aerial parts of Croton species grouped by class of compounds according to their biosynthetic origin (monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes, phenylpropanoids and derivatives of fatty acids). With this analysis it was possible to form three groups (I, II and III), corroborating the comparative analysis of chromatographic profiles. To our knowledge, this is the first report on the chemical composition of essential oils of C. pedicellatus and C. tetradenius. / Este trabalho relata o estudo da composição e variação dos componentes químicos do óleo essencial das espécies de Croton do estado de Sergipe dando ênfase a sua importância quimiotaxonômica. Os óleos essenciais das partes aéreas frescas obtidos por hidrodestilação das amostras de Croton blanchetianus (CB-GA), C. campestris (CC-AML), C. heliotropiifolius coletadas em diferentes localidades do Estado (CH-SG1, CH-SG2, CH-GA, CH-SI e CH-AML), C. pedicellatus (CP-SI), C. tetradenius (CT-SG) e outros sete táxons ainda não identificados denominados (CSP1-CPS7) foram analisados por CG-EM e CG-DIC revelando uma composição química bastante variável. Foram identificados 131 componentes, baseados nos índices de retenção e na comparação de seus espectros de massas com os da literatura e com as bibliotecas de espectros de massas Willey e NIST. Com a análise química dos óleos de Croton foram estabelecidas correlações entre os táxons de C. heliotropiifolius, os quais foram diferenciados dos demais mediante a utilização de seus marcadores químicos principais: (E)-cariofileno e biciclogermacreno. Para as análises comparativas da composição química dos óleos essenciais das espécies de Croton aplicaram-se ferramentas quimiométricas de Análise dos Componentes Principais (ACP) e Análise de Agrupamentos Herarquicos (AAH), pelas quais foi possível diferenciar os componentes do óleo essencial das partes aéreas das espécies de Croton agrupados por classe de compostos de acordo com sua origem biossintética (hidrocarbonetos monoterpênicos, monoterpenos oxigenados, hidrocarbonetos sesquiterpênicos, sesquiterpenos oxigenados, fenilpropanóides e derivados de ácidos graxos). Com essas análises foi possível a formação de três grupos (I, II e III), corroborando com as análises comparativas dos perfis cromatográficos. Ao nosso conhecimento, este é o primeiro relato sobre a composição química dos óleos essenciais de C. pedicellatus e C. tetradenius.

Neste trabalho prepararam-se ésteres de ácidos graxos por esterificação do ácido oléico e transesterificação do óleo de soja e do triéster oléico via catálise enzimática. Determinou-se a composição dos produtos obtidos por RMN 1H e CG-FID. Os padrões dos ésteres do ácido oléico via esterificação ácida foram preparados empregando ácido sulfúrico, os padrões dos ésteres do óleo de soja por transesterificação básica com hidróxido de sódio e o padrão do triéster oléico foi sintetizado utilizando ácido p-tolueno sulfônico como catalisador. A melhor enzima para essas reações foi determinada através de reações de esterificação do ácido oléico e transesterificação do óleo de soja com etanol na ausência de co-solventes, sendo que foi selecionada a lipase de Candida antarctica. A mesma enzima foi empregada nas esterificações enzimáticas do ácido oléico com diversos alcoóis (metanol, etanol, n-propanol e n-butanol), na transesterificação enzimática do óleo de soja e do triéster oléico com etanol. Em ambos os estudos, foram avaliados os fatores que influenciam as reações: quantidade de enzima; tempo de reação; água adicionada ao álcool e reuso do biocatalisador. Na esterificação enzimática do ácido oléico, o uso do etanol forneceu o melhor rendimento (96,5%) com 5,0% (m/m) de enzima em 24 horas de reação. Quando uma quantidade de 4,0% de água foi adicionada ao álcool, a reação utilizando metanol mostrou maior eficiência (98,5%) e os rendimentos com os outros alcoóis não foram alterados significativamente (acima de 90%). Também foi possível utilizar a enzima por até 10 ciclos sem perda de rendimento, com exceção do metanol, onde ocorreu um decréscimo acentuado de rendimentos nos ciclos seguintes. Na transesterificação enzimática do óleo de soja, os mesmos fatores foram avaliados e com 5,0% de enzima, após 24 horas, foi obtido um rendimento de 84,1% e com a adição de água o rendimento não foi significativamente alterado (83%). Na transesterificação, os métodos de quantificação por RMN 1H e CG-FID foram comparados sendo que uma maior diferença foi observada para as reações com baixos rendimentos por RMN 1H, porém em altos rendimentos a diferença entre os dois métodos não foi significativa. Monoglicerídeos e diglicerídeos foram quantificados por CG-FID e por RMN 1H onde foi possível calcular a razão dos produtos formados através de uma equação desenvolvida, sendo que a diferença entre esses tipos de análises foi pequena, de apenas 1,4%. A transesterificação enzimática do triéster oléico foi obtida em bom rendimento (90,4%) e uma pequena quantidade de mono- e diglicerídeos foi produzida. Em todas as reações de transesterificação, o glicerol não foi detectado após a lavagem dos produtos. A metodologia empregando a lipase de Candida antarctica mostrou-se eficiente para a produção de biodiesel a partir do óleo de soja e do ácido oléico com diferentes tipos de alcoóis. / In this work, it was prepared esters of the fatty acid by esterification of the oleic acid and transesterification of the soy oil through enzymatic catalysis. It was determined the composition of the products obtained by 1H NMR and GC-FID. The standards of esters of the oleic acid by acid esterification was prepared employing sulfuric acid, the standards of esters of the soy oil by alkaline transesterification with sodium hydroxide and the standard of the oleic triester was synthesized employing p-toluene sulfonic acid as catalyst. The best enzyme for those reactions was determined through reactions of esterification of the oleic acid and transesterification of the soy oil with ethanol and free co-solvents, and lipase from Candida antarctica was selected. The same enzyme was employed in the enzymatic esterifications of the oleic acid with various alcohols (methanol, ethanol, propanol and butanol), in the enzymatic transesterification of soy oil and the oleic triester with ethanol. In both studies, was assessed the factors that influence the reactions: amount of catalyst, reaction time, water added in the alcohol and the turnover of biocatalyst. In the enzymatic esterification of the oleic acid, the ethanol showed the better yield (96,5%) with 5,0% (m/m) of enzyme at 24 hours of reaction. When 4,0% of water was added to the alcohol, the methanol showed the high efficiency (98,5%) and the yield with another alcohols were not affected. It was also possible to use the enzyme for 10 cycles without lose yield, except for the methanol. In the enzymatic transesterification of the soy oil, the same factors were assessed using 5,0% of enzyme, after 24 hours, a yield of 84,1% was obtained and with the water addition the yield was not modified (83%). On the transesterification, 1H NMR and GC-FID were compared and a great difference was observed for low yields, but on high yields, the difference between methods was small. Monoglycerides and diglycerides were quantified by GC-FID and detected by 1H NMR, it was possible to calculate the ratio between them on the products formed through an equation developed and the difference for this type of analysis was small, only 1.4% . The enzymatic transesterification of the oleic triester was obtained with good yield (90,4%) and a small amount of the monoglycerides and diglycerides was produced. In all the transesterifications reactions, glycerol was not detected after washing mixture of products. The methodology employing Candida antarctica lipase was efficient for biodiesel production by soybean oil and oleic acid with different alcohols.

Táto diplomová práca je zameraná na nutričné zhodnotenie vybraných práškov hmyzu zo svrčkov domových, z lariev múčiara obyčajného a potemníka stajňového a jedného potravinového produktu na báze hmyzu, ktorý bol tiež vyvinutý ako jeden z cieľov tejto práce. Okrem základných nutričných analýz boli použité aj ICP-OES pre zistenie obsahu minerálov a GC-FID pre zistenie zloženia mastných kyselín. Tiež bol stanovený obsah hrubej bielkoviny pomocou CHNSO analyzátora a stanovený obsah EAA. Pomocou PCA analýzy sa úspešne podarilo rozlíšiť vzorky jednotlivých hmyzích práškov, ktoré potvrdili rozmanitosť jednotlivých druhov hmyzu a vďaka projekcii do roviny hlavných komponent je možné vidieť, v ktorých nutričných parametroch sa najviac líšia. Bola tiež vykonaná senzorická analýza novo vyvinutého produktu na báze hmyzu s prídavkom prášku z potemníka stajňového v porovnaní s konkurenčnými produktmu. Súčasťou práce je aj rozsiahly spotrebiteľský prieskum na vzorke 2 019 účastníkov, týkajúci sa vnímania entomofágie v Českej republike a na Slovensku, ktorý sa uskutočnil online.

The diploma thesis is confused to verify the applicability of selected physicochemical and spectroscopic methods for characterization of cyanobacteria, with special emphasis on possibilities of qualitative and quantitative analysis of polyhydroxyalkanoates (specifically polyhydroxybutyrate (PHB)) accumulated in cyanobacterial cells. The sample basis of the work was formed by cultures of cyanobacterial strains of Synechocystis sp. PCC 6803 and Synechocystis salina CCALA 192. The cultures were were cultivated in several ways to cover the widest possible range of physiological conditions and PHB contents, in particular using an autotrophic way of cultivation on shakers and multicultural culture method in a basic culture medium,and in media enriched with 2% salt (NaCl ) as well as mixotrophic culture media with different types of the carbon substrate. After few weeks of cultivation, cyanobacterial cultures were obtained and complexly analyzed by following techniques- cell suspensions were analyzed by flow cytometry and UV-VIS spectrometry (transmission and diffusion transmission mode), dry cell biomass was characterised by gas chromatography to obtain a exact amount of PHB, and then FT-IR spectrometry and thermogravimetric analysis. The work aimed to assess whether any of these methods can be a quick and affordable alternative to the determination of PHB content to the most commonly used method of gas chromatography, but also to assess what additional information about the physiological state of cyanobacterial cells can provide test methods. The highest correlation on PHB content was determined for the parameters determined by infrared spectroscopy, in which specific peaks from the characteristic wavelengths for polyhydroxybutyrate were important. Weak correlations on PHB content were achieved in thermogravimetric analysis and cytometry, using the hydrophobic fluorescent probe BODIPY 439/503, which bound to lipophilic parts of cells. In addition to the determination of PHB, it was possible to determine pigments present in cyanobacteria (such as chlorophyll, phycocyanin and carotenoids) by flow cytometry and UV-VIS diffusion transmission spectrometry. In the end, results from all used techniques were compared by PCA analysis to determine the similarity of all analyzed samples.

Polyethylene terephthalate (PET) is an excellent material for bottling water, beverages, edible oils and other liquids because it is light, tough and transparent. PET bottles are also extensively reused for storage of drinking water, beverages and other liquids and for solar disinfection of microbiologically unsafe drinking water in the tropics. In spite of the usefulness of PET bottles earlier works have reported leaching of antimony and acetaldehyde from the bottle matrix into the liquid contents. Both antimony trioxide and acetaldehyde belongs to Group 2B (possible carcinogens) in the International Agency for Research on Cancer (IARC) carcinogen classification. Additionally acetaldehyde associated with alcoholic beverages (derived from alcoholic beverage and formed endogenously) has recently been upgraded to IARC Group 1 carcinogen (carcinogenic to humans). The research aims to assess the pattern and extent of antimony and acetaldehyde migration from British and Nigerian polyethylene terephthalate bottles into bottle contents under typical use and reuse conditions. The research compares the assessed extents of migration with the current regulations to determine whether the maximum acceptable levels of antimony and acetaldehyde are being exceeded and whether current regulations might need to be reassessed. To achieve these goals the pattern and extent of PET bottle use and reuse in Britain and Nigeria were appraised through survey. The survey revealed that new bottles with contents are typically stored prior to use for periods ranging between one and 7 days, with Nigerians storing for longer periods than British respondents. However storage of up to one year was reported. The extent of bottle reuse was high and similar for the two countries. Nevertheless Nigerian respondents reuse bottles for longer periods than British respondents. The survey findings together with relevant literature were used to design laboratory experiments that assessed the extent of antimony and acetaldehyde migration from PET bottles into water/beverages. A total of 82 brands of bottled water and soft drinks in plastic and glass bottles and in cartons were collected. A few samples from Nigeria in plastic pouches were collected. Materials used in bottling including glass and plastic bottle materials, metal and plastic bottle cap materials and plastic cap lining materials were collected. All samples were collected in supermarkets and shops in Britain and Nigeria except drinking water from taps which was collected in Britain only. Some bottles were aged for the purpose of studying the impact of bottle aging on chemical migration. Other bottles were stored with their contents to study the impact of long term storage of bottle contents on chemical migration. Energy dispersive X-ray spectrometry (EDX) and Raman spectroscopy were used to characterise PET bottle material and other materials associated with water and soft drink bottling. Antimony and other trace metals in water and soft drinks were determined using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Antimony content of PET and other plastics was determined by microwave digestion and ICP-MS. Acetaldehyde content of water and soft drinks and PET were determined using headspace gas chromatography with flame ionisation detection (GC-FID). Accuracy and precision for determination of antimony and other trace elements in bottle materials and bottle contents were good as recoveries were around 100% and coefficients of variation were less than 15% for all analysis types. Accuracy and precision for determination of acetaldehyde in bottle materials and bottle contents were also good as recoveries were around 100% and coefficients of variation were less than 15% for all analysis types. Impact of long term storage, elevated temperatures, bottle thickness, carbonation, bottle aging and bottle size on migration of antimony and acetaldehyde were also assessed. All plastic bottle materials analysed were found to be PET. Bottle cap materials were either polyethylene or polypropylene. All plastic cap lining materials from Britain and some from Nigeria were found to be ethylene vinyl acetate/polypropylene copolymer. Plastic cap lining materials from some Nigerian soft drinks were identified as polyvinyl chloride. Glass bottle materials analysed were found to be soda-lime glass. Metal bottle caps were identified as tinplate, tin-free-steel coated with chromium or aluminium coated with chromium. The antimony concentration in 32 PET bottle materials from Britain and Nigeria were similar and ranged between 177 and 310 mg/kg with an average of 250±30 mg/kg. The concentration agrees well with the industry reported concentration of between 150 and 350 mg/kg. The concentration of residual acetaldehyde in 25 fresh PET bottle materials from Britain and Nigeria ranged between 0.95 and 12.52 µg/g. The average concentration in British and Nigerian soft drinks PET materials are 4.76 and 2.17µg/g respectively. Concentration of residual acetaldehyde was higher in soft drinks and still water PET materials than in sparkling water materials. The concentration of residual acetaldehyde decreases as the bottle wall material becomes older. Also the thinner the bottle walls the lower the concentration of residual acetaldehyde. Antimony concentration in 47 freshly purchased British bottled water and soft drinks ranged between 0.03 and 6.61µg/L with only one sample going above the EU acceptable limit. Concentrations of other trace elements measured were low except titanium which was detected at part per million levels in soft drinks. Lead content of a Nigerian soft drink in glass bottle stored for 2 months was above the EU acceptable limit for lead. At realistic temperatures of 40 and 60°C antimony concentration in the water remained below the EU acceptable limit even after 48 hours of exposure but the concentration exceeded the limit for most exposures at 80°C. Concentration of antimony in some Nigerian bottled water and soft drinks was above the EU limit after 11 months of storage at room temperature. Aged bottles leach lower amount of antimony than new bottles. Similarly larger bottles leach lower amount of antimony than smaller bottles. The average acetaldehyde concentrations found in British fruit juices, carbonated soft drinks, sparkling water and still water were 5113, 1458, 22 and 8 µg/L respectively. Acetaldehyde was not detected in water bottled in glass. The concentration of acetaldehyde in five fruit juice samples in PET bottles and carton was beyond the EU specific migration limit (SML) of 6mg/kg. Also the tolerable daily intake of acetaldehyde could be exceeded as a result of intake of some soft drinks and fruit juices. Acetaldehyde content in soft drinks increase with storage but the increase cannot be accounted for by the residual acetaldehyde in PET. Acetaldehyde was found to be outgassing from some bottles. It was also found to be capable of migrating from soft drinks into bottle wall. Without replenishment the concentration of acetaldehyde in solution decreases with time. The use of PVC cap lining in Nigeria as found in this study is a cause for concern as PVC is associated with health risk issues. The study recommends actions to ensure that antimony in fruit juices and other bottled products remain within the regulatory standard from bottling to consumption for the purpose of safeguarding the health of consumers. Glass used in bottling should be well scrutinized to ensure that it does not contain high levels of lead or other chemical substances that can cause harm to consumers through migration into contents. PET bottles can safely be used for solar water disinfection without the risk of antimony intake at concentrations above safe limits as water temperature achievable as the result of the technique doesn¿t go beyond 60°C. Also aged bottles are safer to use than new bottles because their chemical leaching was found to be lower than that of new bottles. This study recommends the reassessment of the absence of international guidelines for acetaldehyde in water and foods. The study also recommends that the amount of acetaldehyde that can be added to soft drinks as flavouring agent should be below the specific migration limit (SML) for migration of acetaldehyde from PET bottle into bottle contents. This is essential since the SML was designed to ensure that exposure to acetaldehyde, as a result of intake of bottled water and soft drinks in PET bottles, is below the tolerable daily intake (TDI) for acetaldehyde. As antimony was reported to go beyond the safe limits in some Nigerian bottled water and soft drinks after 11 months of storage this study discourages the use of bottle contents stored for a very long time. / Commonwealth Scholarship Commission in the United Kingdom

A tall tower flux measurement setup was established in metropolitan Houston, Texas, to measure trace gas fluxes from both anthropogenic and biogenic emission sources in the urban surface layer. We describe a new relaxed eddy accumulation system combined with a dual-channel gas chromatography - flame ionization detection used for volatile organic compound (VOC) flux measurements in the urban area, focusing on the results of selected anthropogenic VOCs, including benzene, toluene, ethylbenzene and xylenes (BTEX), and biogenic VOCs including isoprene and its oxidation products, methacrolein (MACR) and methyl vinyl ketone (MVK). We present diurnal variations of concentrations and fluxes of BTEX, and isoprene and its oxidation products during summer time (May 22 - July 22, 2008) and winter time (January 1 - February 28). The measured BTEX values exhibited diurnal cycles with a morning peak during weekdays related to rush-hour traffic and additional workday daytime flux maxima for toluene and xylenes in summer time. However, in winter time there was no additional workday daytime peaks due mainly to the different flux footprints between the two seasons. A comparison with different EPA National Emission Inventories (NEI) with our summer time flux data suggests potential underestimates in the NEI by a factor of 3 to 5. The mixing ratios and fluxes of isoprene, MACR and MVK were measured during the same time period in summer 2008. The presented results show that the isoprene was affected by both tail-pipe emission sources during the morning rush hours and biogenic emission sources in daytime. The observed daytime mixing ratios of isoprene were much lower than over forested areas, caused by a comparatively low density of isoprene emitters in the tower's footprint area. The average daytime isoprene flux agreed well with emission rates predicted by a temperature and light only emission model (Guenther et al., 1993). Our investigation of isoprene's oxidation products MACR and MVK showed that both anthropogenic and biogenic emission sources exist for MACR, while MVK was strongly dominated by a biogenic source, likely the isoprene oxidation between the emission and sampling points.