A indústria de processamento de citrinos gera grandes quantidades de resíduos, cujo reaproveitamento para a produção de subprodutos, como o óleo essencial (OE) de laranja, pode mitigar impactos ambientais. Este OE, extraído da casca da laranja, apresenta propriedades antimicrobianas, sendo uma alternativa sustentável e económica comparativamente a outros óleos essenciais. Este estudo teve como objetivo avaliar o potencial antimicrobiano do OE de laranja (Citrus sinensis) numa coleção de oito bactérias com importância em segurança alimentar, bem como explorar sua viabilidade para aplicação na indústria alimentar. A composição química do OE foi caracterizada por cromatografia gasosa acoplada à espectrometria de massa (GC-MS), encontrando um percentual de 69% de D-Limoneno. Além disso, foi realizada a caracterização do perfil de virulência das estirpes bacterianas que incluiram bactérias Gram-positivas (Staphylococcus aureus ATCC 25923, Listeria monocytogenes CECT 935 e Listeria monocytogenes isolada de suíno) e Gram negativas (Escherichia coli ATCC 25922, Salmonella enterica subsp. enterica CECT 443, CECT 722, 104 e CECT 7162). A atividade antimicrobiana do OE foi avaliada pelo método modificado de difusão em disco. Para as estirpes suscetíveis, foi aplicado o método de microdiluição em microplaca para determinação da Concentração Mínima Inibitória (CMI) e da Concentração Mínima Bactericida (CMB), bem como para determinação da curva da multiplicação bacteriana durante 24 horas de exposição ao OE. Os resultados demonstraram que o OE apresentou maior atividade antimicrobiana contra bactérias Gram-positivas, com halos de inibição observados para S. aureus e L. monocytogenes. Entre as bactérias Gram-negativas, apenas S. enterica subsp. enterica CECT 443 foi suscetível ao OE. As CMIs obtidas foram de 8 µL/mL (S. aureus ATCC 25923), 125 µL/mL (L. monocytogenes CECT 935 e isolado de suíno) e 63 µL/mL (S. enterica subsp. enterica CECT 443). As CMBs indicaram ação bactericida do OE, sendo de 125 µL/mL para todas as estirpes testadas. A curva de multiplicação bacteriana confirmou a capacidade do OE de inibir a multiplicação das estirpes suscetíveis ao longo do período avaliado. Os resultados reforçam o potencial do OE de laranja como um conservante natural eficaz, especialmente contra bactérias Gram-positivas, sugerindo a sua aplicação na indústria alimentar para aumentar a segurança microbiológica dos produtos. Contudo, estudos adicionais são necessários para validar sua eficácia em condições reais de processamento e armazenamento alimentar

The composition of the essential oil from Lantana camara L. (Verbenaceae) obtained by hydrodistillation of the aerial parts was examined by GC, GC/MS, and 13C-NMR. The GC analysis showed that carvone is the most abundant monoterpene 75.9%, together with limonene 16.9%, accounting for 92.8% of the oil. The major components were also tested by 13C-NMR analysis of the essential oil. The L. camara oil was assayed against several microorganisms, showing moderate antibacterial activity against the human pathogen Staphylococcus aureus (MIC  200  μg/ml). High antioxidant activity evaluated by the Trolox equivalent antioxidant capacity assay (TEAC) was found (29.0  mmol Trolox/kg) and relative low anti-inflammatory activity due to its weak ability for inhibiting lipoxygenase (IC50  =   81.5  μg/ml).

The scope of molybdenum carbonyl precatalysts has been expanded to include [Mo(CO)3(1-mim)3] (1) (1-mim = 1-methylimidazole) for application in epoxidation and sulfoxidation processes, using relatively ecofriendly and industrially used oxidants. The mechanisms of conversion of 1 to active species were investigated by systematically combining catalytic and characterization studies. With tert-butylhydroperoxide (TBHP), 1 gives the functionalized polyoxomolybdate (1-Hmim)4[Mo8O26(1-mim)2]·2H2O (2), which then leads to the stable salt (1-Hmim)4[Mo8O26]·2H2O (3) containing β-octamolybdate molecular anions. With H2O2, 1 gives a structurally distinct octamolybdate, (1-Hmim)4[Mo8O26] (4), with characterization data that point to the presence of [Mo8O26]n4n− chains. In the reactions of cis-cyclooctene or dl-limonene with H2O2, 4 is a reaction-induced self-separating catalyst, i.e., in the initial stages it dissolves to give a homogeneous solution, but then self-precipitates once the oxidant is consumed. In the sulfoxidation of methyl phenyl sulfide, 4 was effective in producing the sulfoxide selectively with TBHP, and the sulfone with H2O2.

O desenvolvimento de filmes e revestimentos biodegradáveis tem ganho grande relevância nos últimos anos face a dois grandes problemas atuais, o desperdício alimentar e a poluição causada pelos plásticos tradicionais. No entanto, estes podem ser produzidos a partir de subprodutos da indústria alimentar. Tendo em consideração que são substitutos plásticos e reduzem o impacto no meio ambiente, e contribuem para o aproveitamento de resíduos. O presente trabalho tem como objetivo o desenvolvimento de um revestimento biodegradável e comestível, utilizando resíduos e subprodutos agroindustriais, como as cascas de batata, de laranja, de fava e de marmelo, e a trinca de arroz, para além da utilização de biopolímeros comerciais (amido, gelatina, alginato e quitosano), e limoneno como plastificante e agente antimicrobiano. Os revestimentos foram testados através da aplicação por pulverização nos espargos e os espargos revestidos foram armazenados durante 12 dias num frigorífico a 5 ± 3 ºC. Os revestimentos não causaram alterações na cor do espargo, devido à sua camada fina. A formulação com alginato, devido à sua higroscopicidade, foi o que apresentou melhores resultados na manutenção da massa do espargo, menores perdas (10 - 15 %) comparativamente ao controlo, o que proporcionou, uma melhor conservação da textura do alimento evitando a sua desidratação no armazenamento. Contrariamente, os revestimentos com quitosano promoveram o aumento dos ângulos de contacto relativamente ao espargo de controlo (mais hidrofóbico). A incorporação de limoneno demonstrou ser efetivo como antimicrobiano.De entre os 9 revestimentos avaliados, aquele com casca de fava e com alginato e (FAL) foi o selecionado como o mais promissor dado a sua eficácia na preservação global (massa e cor) e do teor de flavonóides e compostos fenólicos totais comparativamente ao controlo. Foram ainda analisados os efeitos deste revestimento nos compostos voláteis dos espargos (aroma), o qual apresentou uma maior concentração de limoneno (devido à sua incorporação na formulação como antimicrobiano) e a redução de forma menos acentuada de determinados compostos, como o 2-pentil-furano. Em suma, o revestimento comestível mais promissor (FAL) demonstrou ter efeito na manutenção da humidade e dos compostos voláteis e não voláteis do espargo durante o período de 12 dias de armazenamento, constituindo uma estratégia de preservação dos espargos e consequentemente na redução do desperdício alimentar, para além do potencial para substituir embalagens plásticas usadas no sector alimentar.

The production of polyurethane-urea microcapsules using the interfacial polymerization technology was performed. Microcapsules were produced in a basic IKA® Miniplant laboratory reactor, in order to produce microcapsules with controlled parameters. In this formulation, limonene, a fragrant chemical characteristic of the lemon oil - was microencapsulated, because lemon oil is the most used oil in perfumery. It resulted in microcapsules with bimodal distribution and average size equal to 10µm. The characterisation of the microcapsules includes particle size distribution, optical microscopy and scanning electron microscopy. Using scanning electron microscopy it is visible the presence of well defined microcapsules on the woven.

The synthesis of poly(urethane–urea) shells (PUU) using poly(ethylene glycols) of different molecular weights and methylene-bis(4-cyclohexyliso- cyanate) was performed for the microencapsulation of limonene, using a step growth polymerization process. The obtained microcapsules were structurally characterized by dynamic light scattering, optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The results showed that the core–shell microcapsules had spherical shape, a mean diameter in between 10 and 20 μm, and characteristic urethane-urea bonds. Furthermore, the molecular weight of polyol influences the entrapment efficiency, which ranged from 38 to 55%. The release data were analyzed by applying the Korsmeyer–Peppas model.

This study proposes the use of chitosan-cellulose particles to encapsulate limonene, a fragrant component widely used in the flavor and fragrance industries. As cellulose possesses a stiff molecular structure due to the threedimensional arrangement of hydrogen bonded hydroxyls, its dissolution is difficult to achieve. To surpass this constraint, and solubilize cellulose, LiOH/urea/water systems were tested using different freezing temperatures and number of freezing/thawing/stirring cycles. Then, chitosan-cellulose composite particles were produced and characterized by Scanning Electron Microscopy (SEM) to assess morphology and size, and by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) to access chitosan-cellulose molecular interactions. The release behaviour of limonene from the chitosan-cellulose particles was studied by gas chromatography (GC). The obtained particles presented an average diameter ranging from 1 to 2mm and spherical shape, characteristics very similar to the corresponding empty cellulose-chitosan composite particles. A good affinity was found between the two biopolymers, cellulose and chitosan. The achieved encapsulation efficiency of limonene was 51.29%, and the produced particles demonstrated a burst release of limonene in the first 24 h, followed by a decrease over 162 h. Based on the achieved results this system seems favourable for applications requiring preservation of sensory qualities and prolonged release of fragrances.

A bentonite collected at Serra de Dentro (SD), Porto Santo Island, Portugal, and the source clay SAz-1 (Cheto, Arizona) were ion-exchanged with different cations (Al3+, Ni2+, Cr3+ and Na+ ). Variable temperature diffuse reflectance infrared Fourier transform spectroscopy (VT-DRIFTS) of pyridine treated samples, thermal desorption of cyclohexylamine and real time mass spectrometry of the evolved gases were used to evaluate the acidic properties of the prepared catalysts. The catalytic activity of these ion-exchanged clays was tested in the acid-catalysed conversion of limonene at 150 8C, to yield isomerization products (terpinolene, a-terpinene, g-terpinene and isoterpinolene), disproportionation products ( p cymene and p-menthenes) and high molecular-weight compounds. The possibility of increasing the selectivity toward p-cymene, over a catalyst with substantial Lewis acid character, was particularly envisaged. Catalysts derived from SD were significantly more active than their SAz-1 counterparts. This was mainly attributed to the greater inherent acidity, to the higher structural iron content (providing dehydrogenation activity) and to the higher nitrogen surface area of the starting SD clays. Within the Mn+ -SD series, the order of activity decreased as Ni2+ > Al3+ > Cr3+ > Na+ . A direct comparison between Al3+-SD (with maximized Bro¨nsted acidity) and Ni2+-SD (with predominant Lewis acid character) provided no support for enhanced p-cymene production over Lewis acid sites.

A series of acid-activated clay catalysts were prepared from a purified bentonite, rich in structural iron, collected at Serra de Dentro on the island of Porto Santo. The purified bentonite exhibited a surface area of 130 m2 g 1 which increased to values as high as 500 m2 g 1 following activation with 4M HCl at 95 8C for 30 min (SD-4M-95-30). The ability of the activated samples to convert limonene to p-cymene was evaluated using a reaction time of 15 min at 80 8C. The sample prepared using 3M HCl at 95 8C for 30 min (SD-3M-95-30) offered the optimum combination of surface area (470 m2 g 1 ) and acidity (0.26 mmol g 1 ) and 95% of the limonene was converted to product. About 15% of the product mixture was p-cymene whilst non-volatile products and polymeric species made up 54% of the product mixture. The presence of iron in the octahedral sheet of the SD bentonite appears responsible for the dehydrogenation activity. TG–MS analysis of acid activated samples, saturated with cyclohexylamine, reflected the dehydrogenation capabilities of the catalysts in that SD-3M-95-30 produced the most benzene and aniline as decomposition/ transformation products.

Important bentonitic deposits are present in Porto Santo Island, part of the Madeira Archipelago. Several locations were selected and samples were collected and characterised. The bentonite obtained at Serra de Dentro (SD) was selected for further laboratorial work. The fine fraction of SD bentonite was purified using several methods and the sodium homoionic form was prepared. This was the starting material used in the three generic types of modifications: metal exchange, acid activation and pillaring. These modifications produce materials with markedly different acidic (e.g. Brönsted and/or Lewis acidity), textural (e.g. increase of the surface area and active site accessibility) or structural (e.g. creation of permanent porous structures) properties. The wide range of materials obtained (including reference clays counterparts) was characterised in terms of chemical, structural, textural and catalytic properties. Limonene is an important raw material produced in Portugal, and its aromatisation reaction was chosen for the catalytic characterisation of the clay catalysts prepared.