Chlorophyll Oxidative Metabolism During the Phototrophic and Heterotrophic Growth of Scenedesmus obliquus.

Different cultivation strategies have been developed with the aim of increasing the production rate of microalgal pigments. Specifically, biotechnological approaches are designed to increase antioxidant metabolites as chlorophyll and carotenoids. However, although significant advances have been built up, available information regarding both the chlorophyll metabolism and their oxidative reactions in photobioreactors is scarce. To unravel such processes, the detailed chlorophyll and carotenoid fraction of Scenedesmus obliquus has been studied by HPLC-ESI/APCI-hrTOF-MS from phototrophic and heterotrophic cultures. Scenedesmus is provided with a controlled strategy of interconversion between chlorophyll a and b to avoid the formation of reactive oxygen species (ROS) at high irradiances in addition to the photoacclimation of carotenoids. Indeed, precise kinetics of 132-hydroxy- and 151-hydroxy-lactone chlorophyll metabolites shows the existence of a chlorophyll oxidative metabolism as a tool to manage the excess of energy at high light conditions. Unexpectedly, the oxidation under phototrophy favored chlorophyll b metabolites over the chlorophyll a series, while the heterotrophic conditions exclusively induced the formation of 132-hydroxy-chlorophyll a. In parallel, during the first 48 h of growth in the dark, the chlorophyll fraction maintained a promising steady state. Although future studies are required to resolve the biochemical reactions implied in the chlorophyll oxidative metabolism, the present results agree with phytoplankton metabolism.

The effect of enzymatic crosslinking on the viability of probiotic bacteria (Lactobacillus acidophilus) encapsulated by complex coacervation.

Lactobacillus acidophilus were encapsulated by complex coacervation followed by transglutaminase crosslinking, aiming to improve the resistance of the microcapsules and improve the protection for probiotics. Subsequently, microcapsules were dried by freeze drying. The encapsulation efficiency, morphology, thermal resistance, gastrointestinal simulation and storage stability were analysed for wet and dry forms. The treatments offered high encapsulation efficiency (68.20-97.72%). Transglutaminase maintained the structure rounded, multinucleate and homogeneous distribution of probiotics in the microcapsules. In relation to the thermal resistance, in general, microencapsulation was effective in protecting and crosslinked microcapsules demonstrated greater protection for probiotics, obtaining viable cell counts of up to 10 log CFU g-1, approximately. On exposure to the simulated gastrointestinal tract, microencapsulation coupled to crosslinking demonstrated good results and the dry form was more efficient in the protection and the treatment with greater amount of transglutaminase was highlighted (9.07 log CFU g-1). As for storage, probiotic viability was maintained for up to 60 days in freezing temperature, with counts of up to 9.59 log CFU g-1. The results obtained in the present work are innovative and present a promising alternative for the protection of probiotics and their addition in food products.

Encapsulation of Lactobacillus acidophilus and different prebiotic agents by external ionic gelation followed by freeze-drying / Encapsulação de Lactobacillus acidophilus e diferentes agentes prebióticos por gelificação iônica externa seguida de liofilização

ABSTRACT: The aim of this study was to investigate the influence of the addition of prebiotics rice bran, inulin and hi-maize, on the survival of Lactobacillus acidophilus in alginate microparticles obtained by external ionic gelation followed by freeze-drying. The microparticles size ranged from 127.5μm to 234.6μm. Microparticles added from the different prebiotics demonstrated an increase in the protection of the microorganism, which presented greater viability against the gastrointestinal simulation. As for storage under different conditions, rice bran treatment at 25ºC kept probiotics viable for 30 days. Under storage conditions -18°C and 7°C, treatments containing prebiotics hi-maize and rice bran maintained viable probiotic microorganisms for a period of 60 days.

RESUMO: O objetivo desse estudo foi investigar a influência da adição dos prebióticos farelo de arroz, inulina e hi-maize, na sobrevivência de Lactobacillus acidophilus em micropartículas de alginato obtidas por gelificação externa seguida de liofilização. Analisou-se o tamanho das micropartículas, a viabilidade, em simulação gastrointestinal e estabilidade, durante armazenamento. O tamanho das micropartículas variou de 127.5µm a 234.6µm. As micropartículas adicionadas dos diferentes prebióticos demonstraram um aumento na proteção do microrganismo, que apresentou maior viabilidade frente à simulação gastrointestinal. Quanto ao armazenamento em diferentes condições, a 25ºC o tratamento farelo de arroz manteve os probióticos viáveis por 30 dias. Nas condições de armazenamento -18ºC e 7°C os tratamentos contendo os prebióticoshi-maize e farelo de arroz mantiveram os microrganismos probióticos viáveis por um período de 60 dias.

Development, characterization and viability study of probiotic microcapsules produced by complex coacervation followed by freeze-drying / Desenvolvimento, caracterização e estudo da viabilidade de microcápsulas probióticas produzidas por coacervação complexa seguida de liofilização

ABSTRACT: Technique of complex coacervation was used to produce microcapsules of Lactobacillus acidophilus La-5 encapsulated in gelatin and gum arabic which were then freeze-drying. Microcapsules were characterized using scanning electron and optical microscopy, and resistance of probiotics was evaluated during release into a simulated gastrointestinal tract and storage at different temperatures. The complex coacervation process produced microcapsules with a high encapsulation efficiency (77.60% and 87.53%), ranging from 127.14-227.05 μm with uniform distribution. Microencapsulation was an efficient approach to achieve significant protection of probiotics against simulated gastrointestinal conditions compared with free cells. Encapsulation also improved the viability of probiotics during storage at either −18 ºC for 120 days, 7 ºC for 105 days or 25 ºC for 45 days. Therefore, complex coacervation was demonstrated to be adequate and promising for encapsulation of probiotics.

RESUMO: A técnica de coacervação complexa foi utilizada para a produção de microcápsulas contendo Lactobacillus acidophilus La-5 em gelatina e goma arábica seguida de secagem por liofilização. As microcápsulas foram caracterizadas por microscopia óptica e eletrônica de varredura, assim como a resistência dos probióticos frente à liberação "in vitro" ao trato gastrointestinal simulado e ao armazenamento em diferentes condições de temperatura também foram avaliados. O processo de coacervação complexa formou microcápsulas com alta eficiência de encapsulação (77,60% e 87,53%), tamanho compreendido entre 127,14 e 227,05 µm e distribuição uniforme. As microcápsulas foram eficientes em promover a proteção substancial dos probióticos frente às condições gastrointestinais simuladas, em comparação às células livres. A encapsulação também foi eficiente em manter a viabilidade dos probióticos durante o armazenamento em temperaturas de −18 ºC por 120 dias, 7 ºC por 105 dias e 25 ºC por 45 dias. Dessa forma, a coacervação complexa se mostra adequada e promissora para a encapsulação dos probióticos.

Determinação do teor de umidade em grãos empregando radiação micro-ondas / Determination of grain moisture content using microwave radiation

A determinação de umidade em grãos é um parâmetro de qualidade importante, uma vez que o teor de água presente no alimento tem influência tanto no armazenamento quanto na comercialização do produto. Os métodos usados como referência na determinação de umidade em grãos empregam a perda por dessecação em estufa (LOD). Apesar de ser de fácil execução, esse método dispende cerca de 24h de aquecimento, normalmente, em 105°C, para obtenção do resultado. No presente estudo, é proposta a determinação da perda por dessecação assistida por radiação micro-ondas (MALOD) para amostras de grãos moídos de arroz branco, arroz integral, ervilha, feijão branco, feijão carioca, feijão preto, grão-de-bico, lentilha e milho, buscando reduzir o tempo de análise. Parâmetros como potência irradiada, massa de amostra, influência do recipiente e tempo de irradiação com micro-ondas foram avaliados e os resultados obtidos foram comparados com a LOD (sugerido pelo MAPA) e, também, por radiação infravermelha (IRLOD). Verificou-se que não houve diferença significativa do teor de umidade empregando massas de amostra entre 2 e 15g por LOD, porém, para MALOD, ocorreram hot spots (carbonização da amostra) com massas superiores a 2g. Resultados similares de umidade foram encontrados entre os diferentes recipientes (pesa-filtros e frascos de polipropileno), optando-se pela utilização dos frascos de polipropileno, devido à diminuição do tempo de pré-condicionamento. A MALOD apresentou concordância entre 94% e 102% com o método oficial, sendo que apenas 50min foram suficientes para determinar a umidade para todos os grãos, perfazendo uma redução do tempo de análise de até 29 vezes.

The determination of moisture in grains is an important quality parameter, since the water content in food has an influence on both storage and commercialization of product. The methods often used for determination of moisture in grains are based on the loss on drying in an oven (LOD). Although it is easy to perform, this method spent about 24h of heating, usually at 105°C, to obtain the result. In the present study is proposed the determination of the loss on drying assisted by microwave radiation (MALOD) for samples of grounded grains of white rice, brown rice, peas, beans, bean, black beans, chick-peas, lentils and corn, in order to reduce the analysis time. Parameters such as irradiated power, sample mass, container and influence of irradiation time with microwave were evaluated and the results were compared with those obtained by LOD (suggested by MAPA) and also by infrared radiation (IRLOD). It was found that there was no significant difference in moisture content in samples between 2 and 15g using LOD, but there were hot spots for MALOD (carbonization of the sample) with masses higher than 2g. Similar results for moisture content were found by the use of different containers (glass weighing bottle and polypropylene flasks) and the polypropylene cups were selected due to the reduction of conditioning time of flasks. The agreement of MALOD with the official method was between 94% and 102% and only 50min were enough to determine the moisture of all grains, making a reduction of analysis time by 29 times.

The kinetics of the removal of nitrogen and organic matter from parboiled rice effluent by cyanobacteria in a stirred batch reactor.

The aim of this research was to evaluate the kinetics of the removal of nitrogen and organic matter from parboiled rice effluent by the cyanobacteria Aphanothece microscopica Nägeli. From the results obtained, it was verified that maximum efficiency for the removal of organic matter expressed as COD and total nitrogen (N-TKN) occurred after 15 h of cultivation, being 83.44% and 72.74, respectively. The scale-up process indicated that the volume of the estimated reactor would be 100.2m(3), containing parboiled rice effluent and biomass.