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The effects of grinding (medium-coarse) and extraction time (14–22 h) on the physicochemical and sensorial properties of cold brew coffee produced using two types of Colombian specialty coffees (Huila and Nariño) were evaluated. Cold coffee brewed under coarse grinding and 22 h of extraction exhibited the highest values of total dissolved solids, extraction yield, pH, titratable acidity (TA), and total phenolic content. The type of coffee used mainly affected the TA and pH. All cold brew coffee samples had lower TA values than their hot counterparts. Nariño cold brew samples had higher TA values than those of Huila in all treatments evaluated. Higher scores were reported in the sensorial evaluation of cold brew coffee when prepared using the shortest time (14 h) and coarse grinding for both coffee types. These coffees were characterized by strong sweetness, fruity and floral flavours, medium bitterness and acidity, and a creamy body. Furans, pyrazines, ketones, aldehydes, pyrroles, esters, lactones, furanones, and phenols were detected as odour-active compounds. The findings of this study demonstrate that the particle size, contact time, and coffee type affect the physicochemical and sensorial characteristics of cold brew coffee, leading to cold brew coffees with different flavour profiles.

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O acido indolacético (IAA) é uma auxina natural e um dos principais reguladores do crescimento de plantas superiores. A quantidade de ácido indolacético extracelular produzida pela cultura de microalga verde Scenedesmus obliquus foi estabelecida por cromatografia líquida de alta eficiência (HPLC). Avaliou-se o efeito de três variáveis de processo na produção de IAA extracelular nestas culturas usando planejamento fatorial 2 3 para uma metodologia de screening. As variáveis de planejamento experimental foram agitação, iluminância (intensidade do fluxo luminoso) e fonte de carvão (mistura CO 2 /air v/v (%)) em três diferentes níveis. A concentração de IAA e a taxa de crescimento específico foram usadas como variáveis de resposta. As análises de HPLC mostraram que em condições experimentais, a quantidade de IAA que foi liberada no meio pela alga S. obliquus depende somente da variável iluminância. Os efeitos da luz e as concentrações de carvão no meio de cultura foram significantes (p < 0.05) para uma taxa de crescimento específico.The indoleacetic acid (IAA) is a natural auxin and one of the main growth regulators in higher plants. The extracellular indoleacetic acid (IAA) amount produced by the green microalga Scenedesmus obliquus culture was detected by high performance liquid chromatography (HPLC). It was evaluated the effect of three process variables in the extracellular IAA production in these cultures using 2 3 factorial design for screening methodology. The experimental design variables were agitation, illuminance (intensity of luminous flux) and carbon source (CO 2 /air v/v (%) mixture) at three different levels. The IAA concentration and the specific growth rate were used as response variables. The HPLC analyses showed that under experimental conditions, the IAA amount that is released to the medium by S. obliquus depends only on the illuminance variable. The light effects and the carbon concentrations in culture medium were significant (p < 0.05) for specific growth rate.

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