Processing of berries – Effects on functionality, stability and bioactivity of anthocyanins

Berries are rich natural sources of anthocyanins, water-soluble pigments in plants that have been linked to beneficial effects against chronic diseases, such as cardiovascular diseases, type 2 diabetes and neurodegenerative diseases. However, anthocyanins as well as other polyphenolic compounds are often sensitive to degradation during processing, storage and digestion. The stability of anthocyanins is affected, for example, by exposure to high temperatures, oxygen and increasing pH. \ua0Non-thermal and mild processing approaches have been revealed as useful tools to extend the shelf-life of berries and preserve phenolic compounds during processing.\ua0 The overall aims of this thesis were first to evaluate different mild drying techniques and the fractionation of bilberry press cake from juice production toward obtaining phenolic-rich ingredients for incorporation into value-added food products. Second, to assess the recovery of anthocyanins in semi-dried berries and in coated whole berries, and for future analyses of compounds derived from breakdown or metabolism of anthocyanins, by developing a sensitive LC-MS/MS method.\ua0 The recovery of anthocyanins was measured after non-thermal treatments and simulated gastrointestinal digestion of i) strawberry samples pre-treated with pulsed electric fields (PEF) prior to osmotic dehydration (OD) and ii) blueberry samples coated with chitosan and procyanidin. The third aim was to investigate the protective effect of digested anthocyanin extracts against H2O2-induced oxidative stress in yeast cells (Saccharomyces cerevisiae).Hot air drying and microwave drying applied to bilberry press cake resulted in a small and similar reduction in the content of anthocyanins. Milling of bilberry press cake into powders with small particle size (< 500 \ub5m) provided a powder with the highest apparent content of phenolic compounds. Considering the non-thermal treatments, the application of PEF-assisted OD of strawberries and the use of edible coatings to blueberries maintained or enhanced the stability of anthocyanins during in vitro gastrointestinal digestion. Digested strawberry samples osmotically dehydrated with trehalose and digested blueberries coated with chitosan and stored for 14 days, had the highest recovery of anthocyanins. A protective effect of anthocyanins from berry extracts was observed only when the yeast cells were pre-incubated with digested extracts. The results imply a biological effect, i.e. a changed phenotype during growth induced by digested anthocyanin-rich extracts, rather than a chemical effect.In summary, berries can be tailored by mild processing to produce fortified ingredients and stabilise (poly)phenols during digestion. Also, the changes in their initial structures, occurring during digestion of berry extracts, are crucial to consider. Further studies on the bioactivities of anthocyanins and their transformed derivatives are needed to clarify the protective effects of digested anthocyanin-rich extracts

Production and electrical characterization of microsensors for marine mutagens and carcinogens monitoring

Field effect-based devices (FED) show several advantages when implemented as biosensors, such as small dimensions, fast response, low-cost mass production and easy integration with CMOS or TFT technol- ogies. However, conventional architectures have some inherent drawbacks that hinder further miniaturisation. Recently, a charge-modulated field-effect transistor (CMFET) architecture has been developed, following the operation principle of the floating-gate transistor, used in memory devices, having a control-gate functioning as reference electrode and a sensing area activated by charge induction, which modulates the channel of an integrated MOS transistor. This work focuses on the development and optimization of CMFET sensor archi- tecture produced for the first time on eco-friendly and flexible paper substrates. The performance of these paper based CMFETS was then compared with the previously developed sensors produced on substrates such as Corning glass and polyethylene naphthalate (PEN), which shared an identical fabrication process already established at CENIMAT|I3N. Measurement and analysis protocols were created and optimized to assess the sensors’ performance and establish a comprehensive comparison between sensors fabricated on different sub- strates. Furthermore, an alternative connecting topology was tested for the developed charge-modulated field- effect sensing architecture, with results of sensitivity scaling up to 300% relative to the values obtained with the standard connecting topology, identical to the ones reported in the literature. Although it was not possible to attain a batch of devices without considerable variability in capacitance, sensors on paper substrates were capable of outputting distinct current levels for each pH buffer solution tested (7, 4 and 10) exhibiting a sen- sitivity of 14 ± 2 mV/pH (Whatman paper) and 32 ± 6 mV/pH (CelSmartSense paper), relative to 33 ± 3 mV/pH obtained for sensors produced on Corning glass and 28 ± 2 mV/pH for sensors on PEN substrate, improving the sensitivity and signal to noise ratio previously reported for this architecture.Dispositivos baseados em efeito de campo (FED) apresentam inúmeras vantagens quando implemen- tados como biossensores, entre as quais, reduzidas dimensões, resposta rápida, produção em massa de baixo custo e fácil integração com tecnologias CMOS ou TFT. No entanto, as arquiteturas mais comuns apresentam algumas desvantagens que criam uma barreira ao processo de miniaturização. Recentemente foi desenvolvida uma arquitetura sensorial baseada em modulação de cargas por efeito de campo (CMFET), que segue o prin- cípio de operação do transístor de porta flutuante, utilizado em dispositivos de memória, fazendo uso de um elétrodo de controlo e uma área sensível ativada por indução de cargas, que modula o canal de condução de um transístor MOS integrado. Este trabalho foca o desenvolvimento e caracterização elétrica de sensores ba- seados na arquitetura CMFET em substratos de papel ecológicos e flexíveis. A performance destes sensores foi por sua vez comparada com sensores fabricados substratos de referência como vidro Corning e naftalato de polietileno (PEN), que partilharam um processo de fabricação idêntico, já estabelecido no CENIMAT|I3N. Protocolos de medição e análise foram criados e otimizados para comparar o desempenho dos sensores fabri- cados em diferentes substratos. Além disto, um esquema de conexão alternativo foi testado para esta arquite- tura de sensores, exibindo resultados de sensibilidade que escalaram 300% face a resultados testados com a conexão standard, idênticos aos reportados na literatura. Embora não tenha sido possível produzir lotes de dispositivos sem uma variabilidade considerável na sua capacitância, os sensores fabricados foram capazes de produzir níveis de corrente distintos para cada pH testado (4,7 e 10), exibindo uma sensibilidade de 14 ± 2 mV/pH (papel Whatman) e 32 ± 6 mV/pH (papel CelSmartSense), em relação a 33 ± 3 mV/pH, valor obtido com sensores produzidos em vidro corning e 28 ± 2 mV/pH para sensores produzidos em substrato de PEN, melhorando a sensibilidade conseguida anteriormente com esta arquitetura

Food Tailoring bilberry powder functionality by processing: effects of preprocessing.

Berry powders are popular as ingredients in a range of food products, where they naturally provide flavor, color, texture, polyphenols, fiber, and other nutrients. The choices regarding processing techniques and conditions influence the quality attrib- utes of berry powders. The aim of this study was to study the effects on bilberry powder functionalities of applying different preprocessing techniques (purée mixing and juice pressing vs. untreated whole berries) prior to hot air drying and milling. Drying of press cake reduced the drying time by 72% and increased the total appar- ent phenolic content of the final powder by 44%, as compared to the powder of dried whole berries. The press cake powder showed an easier flowing behavior than the powders from whole berries and puréed berries. Dispersibility (in water and dairy cream) was 60% higher for powders from whole berries and puréed berries, as com- pared to press cake. The total phenolic content of the dispersed powders was highest for whole berries and puréed berries. Bilberry powder functionality can be modu- lated through the selection of an appropriate preprocessing technique before drying and milling. This tailors the powder properties into food ingredients ready for differ- ent applications, without the need for additives

Bouncing solutions in Rastall's theory with a barotropic fluid

Rastall's theory is a modification of Einstein's theory of gravity where the covariant divergence of the stress-energy tensor is no more vanishing, but proportional to the gradient of the Ricci scalar. The motivation of this theory is to investigate a possible non-minimal coupling of the matter fields to geometry which, being proportional to the curvature scalar, may represent an effective description of quantum gravity effects. Non-conservation of the stress-energy tensor, via Bianchi identities, implies new field equations which have been recently used in a cosmological context, leading to some interesting results. In this paper we adopt Rastall's theory to reproduce some features of the effective Friedmann's equation emerging from loop quantum cosmology. We determine a class of bouncing cosmological solutions and comment about the possibility of employing these models as effective descriptions of the full quantum theory.Comment: Latex file, 14 pages, 1 figure in eps format. Typos corrected, one reference added. Published versio

Conspecific and allospecific larval extracts entice mosquitoes to lay eggs and may be used in attract-and-kill control strategy.

One of the strategies of integrated vector management is to lure gravid mosquitoes for surveillance purposes or to entice them to lay eggs in water containing toxins that kill the offspring (attract-and-kill or trap-and-kill). Typically, the major challenge of this approach is the development of a lure that stimulates oviposition plus a toxin with no deterrent effect. Bacillus thuringiensis var. israelensis (Bti) satisfies the latter criterion, but lures for these autocidal gravid traps are sorely needed. We observed that gravid Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus laid significantly more eggs in cups with extracts from 4th-stage larvae (4 L) of the same or different species. No activity was found when 4 L were extracted with hexane, diethyl ether, methanol, or butanol, but activity was observed with dimethyl sulfoxide extracts. Larval extracts contained both oviposition stimulant(s)/attractant(s) and deterrent(s), which partitioned in the water and hexane phases, respectively. Lyophilized larval extracts were active after a month, but activity was reduced by keeping the sample at 4 °C. In the tested range of 0.1 to 1 larvae-equivalent per milliliter, oviposition activity increased in a dose-dependent manner. In field experiments, Ae. aegpti laid significantly more eggs in traps loaded with larval extracts plus Bti than in control traps with water plus Bti