As embalagens biodegradáveis são provenientes de fontes renováveis, como milho, celulose e mandioca, sendo que essas matérias primas, quando associadas a outros materiais para produção de filmes biodegradáveis, podem ocasionar mudanças nas propriedades mecânicas e de barreira do produto final. A produção de embalagens ativas pode contribuir na conservação de alimentos, aumentando sua vida útil e preservando suas características físicas, químicas e sensoriais, um componente utilizado em embalagens ativas é a cafeína, que possui atividade antimicrobiana. O objetivo do presente trabalho foi produzir filmes de fécula de mandioca incorporados com cafeína irradiada e analisar possíveis alterações quanto as propriedades físico-químicas e mecânicas. Verificou-se que a espessura, a solubilidade em água, permeabilidade ao vapor de água e o ensaio de tração dos filmes não apresentaram diferença significativa entre os tratamentos (p>0,05). Porém houve alteração de cor e de resistência a perfuração dos filmes com a incorporação de cafeína irradiada, onde os filmes apresentavam-se mais frágeis e com coloração mais escura a medida que as doses de radiação aplicadas foram aumentando. A incorporação de cafeína irradiada permitiu a obtenção de um filme de boa qualidade mecânica, porém as doses estudadas não apresentou efeito nas propriedades dos mesmos.
The objective of this work was to apply the adaptive evolution technique using the Saccharomyces cerevisiae T73 strain to increase its tolerance to ethanol and to evaluate its behavior in co-culture with Saccharomyces kudriavzevii CR85 in the production of fermented Myrciaria jaboticaba. Fermentations were carried out at 25 °C for 186 hours under agitation of 150 rpm, according to a central. The consumption of sugar, ethanol, glycerol and acetic acid formed during the fermentation process was evaluated. The results showed that there is an improvement in ethanol tolerance in S. cerevisiae T73 when submitted to the evolution process. Its use for the production of fermentation of Myrciaria jaboticaba in co-culture shows that the highest yield was observed when 0.0372 g.L-1 and 0.0648 g.L-1 of S. cerevisiae T73 PE (that underwent evolution) and CR85 respectively. These results differed statistically from the experiments using the original T73 strain. Regarding the production of ethanol in co-culture there is a significant increase when using the evolved T73 strain, showing possible changes in the primary metabolism of the ethanol production process, due to the changes promoted during the adaptive evolution of the T73 strain. The results show the potential of the new strain for the production of fermented with higher concentrations of sugars in the must.
In the Brazilian industries, the inoculum used throughout the harvest of ethanol production consists of a combination of two or more yeast strains. The combination of yeasts may influence in the metabolic pathways of microorganisms and increase the yields and production rates of some compounds. In biotechnological processes with co-culture, one microorganism can prevail over the other. Therefore, the knowledge about how the population dynamics occurs during fermentation allows modifications in the process in order to obtain higher yields and to achieve greater fermentative efficiency. The aim of this study was to investigate the fermentation with synthetic sugar cane broth in co-culture of Saccharomyces cerevisiae strains CAT-1 and PE-2 followed by molecular fermentation monitoring. The concentration of biomass, ethanol, glycerol, acetic acid and residual sucrose were monitored to verify the influence of different combinations during the fermentation. The mixture of CAT-1 and PE-2 presented the highest ethanol production, with higher performance of fermentative parameters than pure cultures
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