Variability of the phenolic profile of banana from Gran Canaria during maturation

[EN] The identification and quantification of phenolic compounds in bananas from Gran Canaria were carried out to examine changes in their profile during maturation. The phenolic composition of extracts derived from bananas was determined by using HPLC. The total phenolic contents were measured with Folin–Cicolteau`s phenol reagent. To quantify the total antioxidant capacity of banana extracts, we chose two methods commonly used: the percentage of inhibition of radical 1,1–diphenyl-2-picrylhydrazyl (DPPH) and the ferric reducing antioxidant power (FRAP assay). The antioxidant potential on banana extracts was found to increase during maturation in correlation whit the total phenol content.

Photocatalytic degradation of phenolic compounds with new TiO2 catalysts

[EN] New TiO2 catalysts have been synthesised by means of a sol–gel method in which aggregates have been selected before thermal treatment. Sieving and calcination temperature have been proved to be key factors in obtaining catalysts with greater photoactivity than that of Degussa P-25. These new catalysts have been characterized by means of transmission electron microscopy (TEM), BET surface area, diffuse reflectance spectroscopy (DRS), UV–vis spectroscopy, Fourier transformed infrared (FTIR) and X-ray diffraction (XRD). The different parameters studied were compared to those obtained from two commercial catalysts (Degussa P-25 and Hombikat-UV100). The photocatalytic efficiency of the new catalysts was evaluated by the degradation of various phenolic compounds using UV light (maximum around 365 nm, 9mW). The catalyst sieved and calcinated at 1023 K, ECT-1023t, showed phenol degradation rates 2.7 times higher than those of Degussa P-25. Also in the degradation of different phenolic compounds, this catalyst showed a higher activity than that of the commercial one. The high photoactivity of this new catalyst has been attributed to the different distribution of surface defects (determined from FTIR studies) and its increased capacity to yield H2O2

Application of chromatographic and spectroscopic techniques in the evaluation of the lipid fraction of animal products

Lipolysis and oxidation of lipids in foods are the major biochemical and chemical processes that cause food quality deterioration, leading to the characteristic, unpalatable odour and flavour called rancidity. In addition to unpalatability, rancidity may give rise to toxic levels of certain compounds like aldehydes, hydroperoxides, epoxides and cholesterol oxidation products. In this PhD study chromatographic and spectroscopic techniques were employed to determine the degree of rancidity in different animal products and its relationship with technological parameters like feeding fat sources, packaging, processing and storage conditions. To achieve this goal capillary gas chromatography (CGC) was employed not only to determine the fatty acids profile but also, after solid phase extraction, the amount of free fatty acids (FFA), diglycerides (DG), sterols (cholesterol and phytosterols) and cholesterol oxidation products (COPs). To determine hydroperoxides, primary products of oxidation and quantify secondary products UV/VIS absorbance spectroscopy was applied. Most of the foods analysed in this study were meat products. In actual fact, lipid oxidation is a major deterioration reaction in meat and meat products and results in adverse changes in the colour, flavour and texture of meat. The development of rancidity has long recognized as a serious problem during meat handling, storage and processing. On a dairy product, a vegetal cream, a study of lipid fraction and development of rancidity during storage was carried out to evaluate its shelf-life and some nutritional features life saturated/unsaturated fatty acids ratio and phytosterols content. Then, according to the interest that has been growing around functional food in the last years, a new electrophoretic method was optimized and compared with HPLC to check the quality of a beehive product like royal jelly. This manuscript reports the main results obtained in the five activities briefly summarized as follows: 1) comparison between HPLC and a new electrophoretic method in the evaluation of authenticity of royal jelly; 2) study of the lipid fraction of a vegetal cream under different storage conditions; 3) study of lipid oxidation in minced beef during storage under a modified atmosphere packaging, before and after cooking; 4) evaluation of the influence of dietary fat and processing on the lipid fraction of chicken patties; 5) study of the lipid fraction of typical Italian and Spanish pork dry sausages and cured hams.

Study of the antioxidant fraction in edible olive oils obtained from different technological systems and parameters

Questo lavoro di tesi è stato suddiviso in tre parti. L’argomento principale è stato lo “Studio della componente antiossidante di oli ottenuti da olive mediante l’utilizzo di diversi sistemi e parametri tecnologici”. E’ ben noto come la qualità ossidativa di un olio di oliva dipenda oltre che dalla sua composizione in acidi grassi, dalla presenza di composti caratterizzati da un elevata attività antiossidante, ovvero le sostanze fenoliche. I composti fenolici contribuiscono quindi in maniera preponderante alla shelf life dell’olio extravergine di oliva. Inoltre sono state riscontrate delle forti correlazione tra alcune di queste sostanze e gli attributi sensoriali positivi di amaro e piccante. E’ poi da sottolineare come il potere antiossidante dei composti fenolici degli oli vergini di oliva, sia stato negli ultimi anni oggetto di considerevole interesse, poiché correlato alla protezione da alcune patologie come ad esempio quelle vascolari, degenerative e tumorali. Il contenuto delle sostanze fenoliche negli oli di oliva dipende da diversi fattori: cultivar, metodo di coltivazione, grado di maturazione delle olive e ovviamente dalle operazioni tecnologiche poiché possono variare il quantitativo di questi composti estratto. Alla luce di quanto appena detto abbiamo valutato l’influenza dei fattori agronomici (metodi di agricoltura biologica, integrata e convenzionale) e tecnologici (riduzione della temperatura della materia prima, aggiunta di coadiuvanti in fase di frangitura e di gramolatura, confronto tra tre oli extravergini di oliva ottenuti mediante diversi sistemi tecnologici) sul contenuto in composti fenolici di oli edibili ottenuti da olive (paper 1-3-4). Oltre alle sostanze fenoliche, negli oli di oliva sono presenti altri composti caratterizzati da proprietà chimiche e nutrizionali, tra questi vi sono i fitosteroli, ovvero gli steroli tipici del mondo vegetale, che rappresentano la frazione dell’insaponificabile quantitativamente più importante dopo gli idrocarburi. La composizione quali-quantitativa degli steroli di un olio di oliva è una delle caratteristiche analitiche più importanti nella valutazione della sua genuinità; infatti la frazione sterolica è significativamente diversa in funzione dell’origine botanica e perciò viene utilizzata per distinguere tra di loro gli oli e le loro miscele. Il principale sterolo nell’olio di oliva è il β- sitosterolo, la presenza di questo composto in quantità inferiore al 90% è un indice approssimativo dell’aggiunta di un qualsiasi altro olio. Il β-sitosterolo è una sostanza importante dal punto di vista della salute, poiché si oppone all’assorbimento del colesterolo. Mentre in letteratura si trovano numerosi lavori relativi al potere antiossidante di una serie di composti presenti nell’olio vergine di oliva (i già citati polifenoli, ma anche carotenoidi e tocoferoli) e ricerche che dimostrano invece come altri composti possano promuovere l’ossidazione dei lipidi, per quanto riguarda il potere antiossidante degli steroli e dei 4- metilsteroli, vi sono ancora poche informazioni. Per questo è stata da noi valutata la composizione sterolica in oli extravergini di oliva ottenuti con diverse tecnologie di estrazione e l’influenza di questa sostanza sulla loro stabilità ossidativa (paper 2). E’ stato recentemente riportato in letteratura come lipidi cellulari evidenziati attraverso la spettroscopia di risonanza nucleare magnetica (NMR) rivestano una importanza strategica da un punto di vista funzionale e metabolico. Questi lipidi, da un lato un lato sono stati associati allo sviluppo di cellule neoplastiche maligne e alla morte cellulare, dall’altro sono risultati anche messaggeri di processi benigni quali l’attivazione e la proliferazione di un normale processo di crescita cellulare. Nell’ambito di questa ricerca è nata una collaborazione tra il Dipartimento di Biochimica “G. Moruzzi” ed il Dipartimento di Scienze degli Alimenti dell’Università di Bologna. Infatti, il gruppo di lipochimica del Dipartimento di Scienze degli Alimenti, a cui fa capo il Prof. Giovanni Lercker, da sempre si occupa dello studio delle frazioni lipidiche, mediante le principali tecniche cromatografiche. L’obiettivo di questa collaborazione è stato quello di caratterizzare la componente lipidica totale estratta dai tessuti renali umani sani e neoplastici, mediante l’utilizzo combinato di diverse tecniche analitiche: la risonanza magnetica nucleare (1H e 13C RMN), la cromatografia su strato sottile (TLC), la cromatografia liquida ad alta prestazione (HPLC) e la gas cromatografia (GC) (paper 5-6-7)

Technological processes study for high value health ingredients and foods production

This PhD thesis describes set up of technological models for obtaining high health value foods and ingredients that preserve the final product characteristics as well as enrich with nutritional components. In particular, the main object of my research has been Virgin Olive Oil (VOO) and its important antioxidant compounds which differentiate it from all other vegetables oils. It is well known how the qualitative and quantitative presence of phenolic molecules extracted from olives during oil production is fundamental for its oxidative and nutritional quality. For this purpose, agronomic and technological conditions of its production have been investigated. It has also been examined how this fraction can be better preserved during storage. Moreover, its relation with VOO sensorial characteristics and its interaction with a protein in emulsion foods have also been studied. Finally, an experimental work was carried out to determine the antioxidative and heat resistance properties of a new antioxidant (EVS-OL) when used for high temperature frying such as is typically employed for the preparation of french fries. Results of the scientific research have been submitted for a publication and some data has already been published in national and international scientific journals.

Determination of bioactive and potentially toxic compounds in food: raw material analysis and shelf life evaluation

"Bioactive compounds" are extranutritional constituents that typically occur in small quantities in food. They are being intensively studied to evaluate their effects on health. Bioactive compounds include both water soluble compounds, such as phenolics, and lipidic substances such as n-3 fatty acids, tocopherols and sterols. Phenolic compounds, tocopherols and sterols are present in all plants and have been studied extensively in cereals, nuts and oil. n-3 fatty acids are present in fish and all around the vegetable kingdom. The aim of the present work was the determination of bioactive and potentially toxic compounds in cereal based foods and nuts. The first section of this study was focused on the determination of bioactive compounds in cereals. Because of that the different forms of phytosterols were investigated in hexaploid and tetraploid wheats. Hexaploid cultivars were the best source of esterified sterols (40.7% and 37.3% of total sterols for Triticum aestivum and Triticum spelta, respectively). Significant amounts of free sterols (65.5% and 60.7% of total sterols for Triticum durum and Triticum dicoccon, respectively) were found in the tetraploid cultivars. Then, free and bound phenolic compounds were identified in barley flours. HPLCESI/ MSD analysis in negative and positive ion mode established that barley free flavan-3- ols and proanthocyanidins were four dimers and four trimers having (epi)catechin and/or (epi)gallocatechin (C and/or GC) subunits. Hydroxycinnamic acids and their derivatives were the main bound phenols in barley flours. The results obtained demonstrated that barley flours were rich in phenolic compounds that showed high antioxidant activity. The study also examined the relationships between phenolic compounds and lipid oxidation of bakery. To this purpose, the investigated barley flours were used in the bakery production. The formulated oven products presented an interesting content of phenolic compounds, but they were not able to contain the lipid oxidation. Furthermore, the influence of conventional packaging on lipid oxidation of pasta was evaluated in n-3 enriched spaghetti and egg spaghetti. The results proved that conventional packaging was not appropriated to preserve pasta from lipid oxidation; in fact, pasta that was exposed to light showed a high content of potentially toxic compounds derived from lipid oxidation (such as peroxide, oxidized fatty acids and COPs). In the second section, the content of sterols, phenolic compounds, n-3 fatty acids and tocopherols in walnuts were reported. Rapid analytical techniques were used to analyze the lipid fraction and to characterize phenolic compounds in walnuts. Total lipid chromatogram was used for the simultaneous determination of the profile of sterols and tocopherols. Linoleic and linolenic acids were the most representative n-6 and n-3 essential dietary fatty acids present in these nuts. Walnuts contained substantial amounts of γ- and δ-tocopherol, which explained their antioxidant properties. Sitosterol, Δ5-avenasterol and campesterol were the major free sterols found. Capillary electrophoresis coupled to DAD and microTOF was utilized to determine phenolic content of walnut. A new compound in walnut ((2E,4E)- 8-hydroxy-2,7-dimethyl-2,4-decadiene-1,10-dioic acid 6-O-β-D-glucopiranosyl ester, [M−H]− 403.161m/z) with a structure similar to glansreginins was also identified. Phenolic compounds corresponded to 14–28% of total polar compounds quantified. Aglycone and glycosylated ellagic acid represented the principal components and account for 64–75% of total phenols in walnuts. However, the sum of glansreginins A, B and ((2E,4E)-8-hydroxy- 2,7-dimethyl-2,4-decadiene-1,10-dioic acid 6-O-β-D-glucopiranosyl ester was in the range of 72–86% of total quantified compounds.

Control of peach phenolic compounds content

Phenolic compounds play a central role in peach fruit colour, flavour and health attributes. Phenolic profiles of several peaches and nectarines and most of the structural genes leading to the anthocyanin synthesis in peach fruit have been studied. Moreover, crosses of red and non-red peaches suggested that a major gene controls skin colour of the extreme phenotypes ‘highlighter’ and ‘full-red’. However, there is no data about either the ‘flavan-3-ols specific genes’ (ANR and LAR) or the regulation of the flavonoid metabolism in this crop. In the present study, we determined the concentration of phenolic compounds in the yellowfleshed nectarine Prunus persica cv. ‘Stark Red Gold’ during fruit growth and ripening. We examined the transcript levels of the main structural genes of the flavonoid pathway. Gene expression of the biosynthetic genes correlated well with the concentration of flavan-3-ols, which was very low at the beginning of fruit development, strongly increased at mid-development and finally decreased again during ripening. In contrast, the only gene transcript which correlated with anthocyanin concentration was PpUFGT, which was high at the beginning and end of fruit growth, remaining low during the other developmental stages. These patterns of gene expression could be explained by the involvement of different transcription factors, which up-regulate anthocyanin biosynthesis (PpMYB10 and PpbHLH3), or repress (PpMYBL2) the transcription of the structural genes. These transcription factors appeared to be involved also in the regulation of the lightinduced anthocyanin accumulation in ‘Stark Red Gold’ nectarines, suggesting that they play a critical role in the regulation of flavonoid biosynthesis in peaches and nectarines in response to both developmental and environmental stimuli. Phenolic profiles and expression patterns of the main flavonoid structural and regulatory genes were also determined for the extreme phenotypes denominated ‘highlighter’ and ‘full-red’ and hypotheses about the control of phenolic compounds content in these fruit are discussed.

Quali-quantitative study of the phenolic and polyphenolic compounds and their antioxidant capacity in vegetal matrix processed with different technologies

Food technologies today mean reducing agricultural food waste, improvement of food security, enhancement of food sensory properties, enlargement of food market and food economies. Food technologists must be high-skilled technicians with good scientific knowledge of food hygiene, food chemistry, industrial technologies and food engineering, sensory evaluation experience and analytical chemistry. Their role is to apply the modern vision of science in the field of human nutrition, rising up knowledge in food science. The present PhD project starts with the aim of studying and improving frozen fruits quality. Freezing process in very powerful in preserve initial raw material characteristics, but pre-treatment before the freezing process are necessary to improve quality, in particular to improve texture and enzymatic activity of frozen foods. Osmotic Dehydration (OD) and Vacuum Impregnation (VI), are useful techniques to modify fruits and vegetables composition and prepare them to freezing process. These techniques permit to introduce cryo-protective agent into the food matrices, without significant changes of the original structure, but cause a slight leaching of important intrinsic compounds. Phenolic and polyphenolic compounds for example in apples and nectarines treated with hypertonic solutions are slightly decreased, but the effect of concentration due to water removal driven out from the osmotic gradient, cause a final content of phenolic compounds similar to that of the raw material. In many experiment, a very important change in fruit composition regard the aroma profile. This occur in strawberries osmo-dehydrated under vacuum condition or under atmospheric pressure condition. The increment of some volatiles, probably due to fermentative metabolism induced by the osmotic stress of hypertonic treatment, induce a sensory profile modification of frozen fruits, that in some way result in a better acceptability of consumer, that prefer treated frozen fruits to untreated frozen fruits. Among different processes used, a very interesting result was obtained with the application of a osmotic pre-treatment driven out at refrigerated temperature for long time. The final quality of frozen strawberries was very high and a peculiar increment of phenolic profile was detected. This interesting phenomenon was probably due to induction of phenolic biological synthesis (for example as reaction to osmotic stress), or to hydrolysis of polymeric phenolic compounds. Aside this investigation in the cryo-stabilization and dehydrofreezing of fruits, deeper investigation in VI techniques were carried out, as studies of changes in vacuum impregnated prickly pear texture, and in use of VI and ultrasound (US) in aroma enrichment of fruit pieces. Moreover, to develop sensory evaluation tools and analytical chemistry determination (of volatiles and phenolic compounds), some researches were bring off and published in these fields. Specifically dealing with off-flavour development during storage of boiled potato, and capillary zonal electrophoresis (CZE) and high performance liquid chromatography (HPLC) determination of phenolic compounds.

Bioactive and toxic compounds in different foodstuffs: analytical techniques and sensory analysis

Foods that provide medical and health benefits or have a role in disease risk prevention are termed functional foods. The functionality of functional foods is derived from bioactive compounds that are extranutritional constituents present in small quantities in food. Bioactive components include a range of chemical compounds with varying structures such as carotenoids, flavonoids, plant sterols, omega-3 fatty acids (n-3), allyl and diallyl sulfides, indoles (benzopyrroles), and phenolic acids. The increasing consumer interest in natural bioactive compounds has brought about a rise in demand for these kinds of compounds and, in parallel, an increasing number of scientific studies have this type of substance as main topic. The principal aim of this PhD research project was the study of different bioactive and toxic compounds in several natural matrices. To achieve this goal, chromatographic, spectroscopic and sensorial analysis were performed. This manuscript reports the main results obtained in the six activities briefly summarized as follows: • SECTION I: the influence of conventional packaging on lipid oxidation of pasta was evaluated in egg spaghetti. • SECTION II: the effect of the storage at different temperatures of virgin olive oil was monitored by peroxide value, fatty acid activity, OSI test and sensory analysis. • SECTION III: the glucosinolate and phenolic content of 37 rocket salad accessions were evaluated, comparing Eruca sativa and Diplotaxis tenuifolia species. Sensory analysis and the influence of the phenolic and glucosinolate composition on sensory attributes of rocket salads has been also studied. • SECTION IV: ten buckwheat honeys were characterised on the basis of their pollen, physicochemical, phenolic and volatile composition. • SECTION V: the polyphenolic fraction, anthocyanins and other polar compounds, the antioxidant capacity and the anty-hyperlipemic action of the aqueous extract of Hibiscus sabdariffa were achieved. • SECTION VI: the optimization of a normal phase high pressure liquid chromatography–fluorescence detection method for the quantitation of flavanols and procyanidins in cocoa powder and chocolate samples was performed.

From Folke Medicine to Medicine Chemistry: Study, Using in Vitro and Cellular Assays, of Receptors Mechanism Involved in the Activities of Natural Compounds

My Doctorate Research has been focused on the evaluation of the pharmacological activity of a natural extract of chestnut wood (ENC) towards the cardiovascular and gastrointestinal system and on the identification of the active compounds. The ENC has been shown to contain more than 10% (w/w) of phenolic compounds, of which tannins as Vescalgin and Castalgin are the more representative. ENC cardiovascular effects have been investigated in guinea pig cardiac preparations; furthermore its activity has been evalueted in guinea pig aorta strips. ENC induced transient negative chronotropic effect in isolated spontaneously beating right atria and simultaneously positive inotropic effect in left atria driven at 1 Hz. Cardiac cholinergic receptors are not involved in the negative chronotropic effect and positive inotropic effects are not related to adrenergic receptors. In vascular smooth muscle, natural extract of chestnut did not significantly change the contraction induced by potassium (80 mM) or that induced by noradrenaline (1μM). In guinea pig ileum, ENC reduced the maximum response to carbachol in a concentrationdependent manner and behaved as a reversible non competitive antagonist. In guinea pig ileum, the antispasmodic activity of ENC showed a significant antispasmodic activity against a variety of different spasmogenic agents including histamine, KCl, BaCl2. In guinea pig proximal colon, stomach and jejunum, ENC reduced the maximum response to carbachol in a concentrationdependent manner and behaved as a reversible non competitive antagonist. ENC contracted gallbladder guinea pig in a reversible and concentration-dependent manner. This effect does not involve cholinergic and cholecystokinin receptors and it is reduced by nifedipine. ENC relaxed Oddi sphincter smooth muscle. The cholecystokinetic and Oddi sphincter relaxing activities occurred also in guinea pigs fed a lithogenic diet. The cholecystokinetic occurred also in human gallbladder. The Fractionation of the extract led to the identification of the active fraction.

Nuovi ingredienti funzionali per l'applicazione in campo alimentare

The Mediterranean diet is rich in healthy substances such as fibres, vitamins and phenols. Often these molecules are lost during food processing. Olive oil milling waste waters, brans, grape skins are some of the most relevant agri-food by-products in the Mediterranean countries. These wastes are still rich in extremely valuable molecules, such as phenolic antioxidants, that have several interesting health promoting properties. Using innovative environmental friendly technologies based in the rational use of enzymatic treatment is possible to obtain from agri-food by-products new ingredients containing antioxidants that can be used as functional ingredients in order to produce fortified foods. These foods, having health protecting/promoting properties, on top of the traditional nutritional properties, are attracting consumer’s attentions due to the increasing awareness on health protection through prevention. The use of these new ingredients in different food preparation was studied in order to evaluate the effects that the food processing might have on the antioxidant fraction, the effect of these ingredient on foods appearances as well as the impact in terms of taste and scent, crucial feature for the acceptability of the final product. Using these new ingredients was possible to produce antioxidant bred, pasta, cheese, cookies and ice-cream. These food products retains very well the antioxidant properties conferred by the added ingredients despite the very different treatments that were performed. The food obtained had a good palatability and in some cases the final product had also a good success on the market.

Massenspektrometrische Untersuchungen und Nachweise von organischen Hydroperoxiden und höhermolekularen Verbindungen im biogenen sekundären organischen Aerosol

Atmosphärische Aerosole beeinflussen den Strahlungshaushalt und damit das Klima der Erde. Dies geschieht sowohl direkt (Streuung und Absorption), als auch indirekt (Wolkenkondensationskeime). Das sekundäre organische Aerosol (SOA) bildet einen wichtigen Bestandteil des atmosphärischen Aerosols. Seine Bildung erfolgt durch Reaktionen von Kohlenwasserstoffen mit atmosphärischen Oxidationsmitteln (z.B. Ozon, OH-Radikalen). Eine Klasse dieser Kohlenwasserstoffe sind die Terpene. Sie werden in großen Mengen durch die Vegetation emittiert und gelten als wichtige Vorläufersubstanzen des biogenen SOAs. In den Reaktionen von Monoterpenen und Sesquiterpenen mit atmosphärischen Reaktionspartnern wird eine große Vielfalt an multifunktionellen Reaktionsprodukten gebildet, von denen bis heute nur ein Bruchteil identifiziert werden konnte. In der vorliegenden Arbeit soll im Speziellen die Bildung von organischen Peroxiden und oligomeren Verbindungen im biogenen SOA untersucht und Nachweise einzelner Moleküle erbracht werden.rnFür eine Identifizierung von organischen Peroxiden aus der Oxidation einzelner Monoterpene und Sesquiterpene mit Ozon wurden die Reaktionsprodukte direkt in eine bei Atmosphärendruck arbeitende chemische Ionisationsquelle überführt und massenspektrometrisch untersucht (online-APCI-MS). Hierdurch konnten organische Hydroperoxide in der Partikelphase nachgewiesen werden, welche sich durch eine signifikante Abspaltung von H2O2 im Tandem-Massenspektrum (MS/MS) auszeichneten. Des Weiteren sollte die Bildung von höhermolekularen Verbindungen („Dimere“) im SOA des α-Pinens untersucht werden. Hierfür wurden zunächst die Reaktionsprodukte des Cyclohexens, das als einfache Modellverbindung des α-Pinens dient, mittels online-APCI-MS und offline durch Flüssigkeitschromatographie und Elektrospray-Ionenfallenmassenspektrometrie (HPLC/ESI-MS) untersucht. Verschiedene Produkte der Cyclohexen-Ozonolyse konnten hierbei als Esterverbindungen identifiziert werden, wobei eigens synthetisierte Referenzsubstanzen für die Identifizierung verwendet wurden. In einem weiteren Experiment, indem gleichzeitig Cyclohexen und α-Pinen mit Ozon umgesetzt wurden, konnten ebenfalls eine Bildung von höhermolekularen Estern nachgewiesen werden. Es handelte sich hierbei um „Mischester“, deren Struktur aus Reaktionsprodukten der beiden VOC-Vorläufermoleküle aufgebaut war. Durch diese neuen Erkenntnisse, über die Bildung von Estern im SOA des Cyclohexens, wurden die Dimer-Bildung einer reinen α-Pinen/Ozon-Reaktion online und offline massenspektrometrisch untersucht. Hier stellten sich als Hauptprodukte die Verbindungen mit m/z 357 und m/z 367 ([M-H]--Ionen) heraus, welche zudem erstmals auf einem Filter einer Realprobe aus Hyytiälä, Finnland nachgewiesen werden konnten. Aufgrund ihrer Fragmentierung in MS/MS-Untersuchungen sowie den exakten Summenformeln aus FT-MS Messungen konnte für die Struktur der höhermolekularen Verbindung mit m/z 367 ebenfalls ein Ester und für m/z 357 ein Peroxyhemiacetal vorgeschlagen werden. Die vorgeschlagene Struktur der Verbindung m/z 367 konnte im Anschluss über eine Reaktion aus Hydroxypinonsäure mit Pinsäure bestätigt werden. Die Identifizierung der Esterverbindung des α-Pinen-SOA erfolgte ebenfalls mit Hilfe von LC-MSn-Messungen.rnDie bisher diskutierten Ergebnisse, sowie die meisten in der Literatur beschriebenen Studien befassen sich jedoch mit einzelnen Vorläuferverbindungen, im Gegensatz zu den komplexen SOA-Proben aus den Emissionen der Vegetation. Im Rahmen einer Messkampagne am Forschungszentrum Jülich erfolgte eine massenspektrometrische Charakterisierung (online-APCI-MS) des SOAs aus direkten VOC-Emissionen von Pflanzen. Durch einen Vergleich der Produktverteilung dieser erhalten online-Massenspektren mit denen aus den Reaktionen einzelner VOCs, konnten Aussagen über die in den Reaktionen umgesetzten VOCs gemacht werden. Es konnte gezeigt werden, dass in stressbedingten Situationen die untersuchten Exemplare der Betula pendula (Birke) hauptsächlich Sesquiterpene, Picea abies (Fichte) eher Monoterpene und Eucalyptus (Eukalyptus) sowohl Sesquiterpene als auch Monoterpene emittieren. Um die atmosphärischen Prozesse, die zur Bildung der Produkte im SOA führen vollständig zu verstehen, müssen jedoch noch weitere Anstrengungen unternommen werden.rn

Constraints on neutrino mass fraction using Redshift Space Distortions

Redshift Space Distortions (RSD) are an apparent anisotropy in the distribution of galaxies due to their peculiar motion. These features are imprinted in the correlation function of galaxies, which describes how these structures distribute around each other. RSD can be represented by a distortions parameter $\beta$, which is strictly related to the growth of cosmic structures. For this reason, measurements of RSD can be exploited to give constraints on the cosmological parameters, such us for example the neutrino mass. Neutrinos are neutral subatomic particles that come with three flavours, the electron, the muon and the tau neutrino. Their mass differences can be measured in the oscillation experiments. Information on the absolute scale of neutrino mass can come from cosmology, since neutrinos leave a characteristic imprint on the large scale structure of the universe. The aim of this thesis is to provide constraints on the accuracy with which neutrino mass can be estimated when expoiting measurements of RSD. In particular we want to describe how the error on the neutrino mass estimate depends on three fundamental parameters of a galaxy redshift survey: the density of the catalogue, the bias of the sample considered and the volume observed. In doing this we make use of the BASICC Simulation from which we extract a series of dark matter halo catalogues, characterized by different value of bias, density and volume. This mock data are analysed via a Markov Chain Monte Carlo procedure, in order to estimate the neutrino mass fraction, using the software package CosmoMC, which has been conveniently modified. In this way we are able to extract a fitting formula describing our measurements, which can be used to forecast the precision reachable in future surveys like Euclid, using this kind of observations.

Complementary mass spectrometric techniques for the characterization of the organic fraction in atmospheric aerosols

Aerosol particles are strongly related to climate, air quality, visibility and human health issues. They contribute the largest uncertainty in the assessment of the Earth´s radiative budget, directly by scattering or absorbing solar radiation or indirectly by nucleating cloud droplets. The influence of aerosol particles on cloud related climatic effects essentially depends upon their number concentration, size and chemical composition. A major part of submicron aerosol consists of secondary organic aerosol (SOA) that is formed in the atmosphere by the oxidation of volatile organic compounds. SOA can comprise a highly diverse spectrum of compounds that undergo continuous chemical transformations in the atmosphere.rnThe aim of this work was to obtain insights into the complexity of ambient SOA by the application of advanced mass spectrometric techniques. Therefore, an atmospheric pressure chemical ionization ion trap mass spectrometer (APCI-IT-MS) was applied in the field, facilitating the measurement of ions of the intact molecular organic species. Furthermore, the high measurement frequency provided insights into SOA composition and chemical transformation processes on a high temporal resolution. Within different comprehensive field campaigns, online measurements of particular biogenic organic acids were achieved by combining an online aerosol concentrator with the APCI-IT-MS. A holistic picture of the ambient organic aerosol was obtained through the co-located application of other complementary MS techniques, such as aerosol mass spectrometry (AMS) or filter sampling for the analysis by liquid chromatography / ultrahigh resolution mass spectrometry (LC/UHRMS).rnIn particular, during a summertime field study at the pristine boreal forest station in Hyytiälä, Finland, the partitioning of organic acids between gas and particle phase was quantified, based on the online APCI-IT-MS and AMS measurements. It was found that low volatile compounds reside to a large extent in the gas phase. This observation can be interpreted as a consequence of large aerosol equilibration timescales, which build up due to the continuous production of low volatile compounds in the gas phase and/or a semi-solid phase state of the ambient aerosol. Furthermore, in-situ structural informations of particular compounds were achieved by using the MS/MS mode of the ion trap. The comparison to MS/MS spectra from laboratory generated SOA of specific monoterpene precursors indicated that laboratory SOA barely depicts the complexity of ambient SOA. Moreover, it was shown that the mass spectra of the laboratory SOA more closely resemble the ambient gas phase composition, indicating that the oxidation state of the ambient organic compounds in the particle phase is underestimated by the comparison to laboratory ozonolysis. These observations suggest that the micro-scale processes, such as the chemistry of aerosol aging or the gas-to-particle partitioning, need to be better understood in order to predict SOA concentrations more reliably.rnDuring a field study at the Mt. Kleiner Feldberg, Germany, a slightly different aerosol concentrator / APCI-IT-MS setup made the online analysis of new particle formation possible. During a particular nucleation event, the online mass spectra indicated that organic compounds of approximately 300 Da are main constituents of the bulk aerosol during ambient new particle formation. Co-located filter analysis by LC/UHRMS analysis supported these findings and furthermore allowed to determine the molecular formulas of the involved organic compounds. The unambiguous identification of several oxidized C 15 compounds indicated that oxidation products of sesquiterpenes can be important compounds for the initial formation and subsequent growth of atmospheric nanoparticles.rnThe LC/UHRMS analysis furthermore revealed that considerable amounts of organosulfates and nitrooxy organosulfates were detected on the filter samples. Indeed, it was found that several nitrooxy organosulfate related APCI-IT-MS mass traces were simultaneously enhanced. Concurrent particle phase ion chromatography and AMS measurements indicated a strong bias between inorganic sulfate and total sulfate concentrations, supporting the assumption that substantial amounts of sulfate was bonded to organic molecules.rnFinally, the comprehensive chemical analysis of the aerosol composition was compared to the hygroscopicity parameter kappa, which was derived from cloud condensation nuclei (CCN) measurements. Simultaneously, organic aerosol aging was observed by the evolution of a ratio between a second and a first generation biogenic oxidation product. It was found that this aging proxy positively correlates with increasing hygroscopicity. Moreover, it was observed that the bonding of sulfate to organic molecules leads to a significant reduction of kappa, compared to an internal mixture of the same mass fractions of purely inorganic sulfate and organic molecules. Concluding, it has been shown within this thesis that the application of modern mass spectrometric techniques allows for detailed insights into chemical and physico-chemical processes of atmospheric aerosols.rn

The gas mass fraction and the dynamical state in x-ray luminous clusters of galaxies at low redshift

Gli ammassi di galassie sono le strutture gravitazionalmente legate con le più profonde buche di potenziale, pertanto è previsto che questi contengano una frazione di barioni non molto diversa da quella cosmologica. Con l’introduzione di modelli sempre più accurati di fisica barionica all’interno di simulazioni idrodinamiche è stato possibile predire la percentuale cosmica di barioni presente negli ammassi di galassie. Unendo questi modelli previsionali con misure della frazione di gas in ammassi e informazioni sulla densità di barioni dell’Universo si può ottenere una stima della densità di materia cosmica Ωm. L'obiettivo di questo lavoro di Tesi è la stima di Ωm a partire dalla frazione di gas osservata in questi sistemi. Questo lavoro era stato già fatto in precedenza, ma tenendo in considerazione solo gli ammassi più massivi e dinamicamente rilassati. Usando parametri che caratterizzano la morfologia della distribuzione di brillanza superficiale nei raggi X, abbiamo classificato i nostri oggetti come rilassati o disturbati, laddove presentassero evidenze di recenti attività di interazione. Abbiamo dunque valutato l’impatto degli oggetti disturbati sulla stima del parametro cosmologico Ωm, computando il Chi2 tra la frazione di massa barionica nell’Universo e quella da noi ricavata. Infine abbiamo investigato una relazione tra il valore della frazione di gas degli ammassi rilassati e quello dei disturbati, in modo da correggere quindi questi ultimi, riportandoli nei dintorni del valore medio per i rilassati e usarli per ampliare il campione e porre un vincolo più stringente su Ωm. Anche con il limitato campione a nostra disposizione, è stato possibile porre un vincolo più stretto su Ωm, utilizzando un maggior numero di oggetti e riducendo così l’errore statistico.