Propionic acid bacteria are the source of many metabolites, e.g., propionic acid and trehalose. Compared to microbiological synthesis, the production of these metabolites by petrochemical means or enzymatic conversion is more profitable. The components of microbiological media account for a large part of the costs associated with propionic fermentation, due to the high nutritional requirements of Propionibacterium. This problem can be overcome by formulating a medium based on the by-products of technological processes, which can act as nutritional sources and at the same time replace expensive laboratory preparations (e.g., peptone and yeast extract). The metabolic activity of P. freudenreichii was investigated in two different breeding environments: in a medium containing peptone, yeast extract, and biotin, and in a waste-based medium consisting of only apple pomace and potato wastewater. The highest production of propionic acid amounting to 14.54 g/L was obtained in the medium containing apple pomace and pure laboratory supplements with a yield of 0.44 g/g. Importantly, the acid production parameters in the waste medium reached almost the same level (12.71 g/L, 0.42 g/g) as the medium containing pure supplements. Acetic acid synthesis was more efficient in the waste medium; it was also characterized by a higher level of accumulated trehalose (59.8 mg/g d.s.). Thus, the obtained results show that P. freudenreichii bacteria exhibited relatively high metabolic activity in an environment with apple pomace used as a carbon source and potato wastewater used as a nitrogen source. This method of propioniate production could be cheaper and more sustainable than the chemical manner.

In Poland, fruit wines or aromatized fruit wines are semi-sweet or sweet and contain approximately 15-16% (v/v) ethanol. Their production can be classified as a very high-gravity (VHG) fermentation. Magnesium has a beneficial effect on VHG fermentations as it protects the yeast cells against ethanol, osmotic and temperature stress. The effect of the magnesium concentration in an apple must, containing 32% sugars, on the fermentative parameters of batch and continuous fermentations was assessed. In the batch process, a magnesium concentration of~8.5 mg/L resulted in decreased the ethanol production in comparison to a magnesium concentration of~250, 490 and 970 mg Mg 2+ /L. The highest amount of Mg also caused a metallic taste. A continuous fermentation was carried out for 2.5 months in a four-column packed-bed fermentor. The medium contained~50, 250 and 490 mg Mg 2+ /L and the yeast was immobilized on foam glass. During the continuous fermentation, no differences at p ≤ 0.05 in terms of fermentative parameters were seen with magnesium additions. The same beginning amount of magnesium ions in the medium led to a similar use of this element, both in batch and in continuous fermentation. The more Mg 2+ that was present in the medium, the more Mg 2+ was used by the yeast. The results suggest that the minimal dose of magnesium, under the described conditions, is 50 mg/L, corresponding to the amount of Mg in the medium prepared using concentrated apple juice and tap water. This finding has industrial significance, as Polish wine companies prepare their fruit musts using tap water.

Os periódicos científicos caracterizam-se como meios de divulgação da produção científica de determinada área, sendo importantes canais para a socialização do conhecimento.

O turismo se constitui em uma atividade de grandes impactos, nos quais se incluem os ambientais. A partir da compreensão que a atividade turística depende do meio

O surgimento do vírus COVID-19 tornou-se muito rapidamente uma pandemia e a educação também sofreu incontáveis impactos como, por exemplo, a suspensão das aulas. Muitas instituições de ensino superior optaram pela substituição das aulas presenciais pelas virtuais, exigindo adaptações tanto de docentes, como de discentes. O objetivo desse estudo é caracterizar o atual perfil discente do curso superior de tecnologia em hotelaria da Faculdade Senac Porto Alegre e os impactos advindos desse cenário de pandemia e distanciamento social. A pesquisa foi realizada em junho de 2020 por meio de um formulário online enviado por e-mail para os acadêmicos do referido curso. Os principais resultados apontam que 20% dos estudantes respondentes foram desligados do trabalho devido à crise provocada pela pandemia. Para a maioria dos alunos as atividades remotas são acessadas e acompanhadas no ambiente residencial por meio de notebooks. As dificuldades para enfrentar as aulas remotas mais apontadas consistem em conexão de internet lenta, dificuldade de concentração no ambiente de estudos e o acúmulo de atividades remotas por semana. Foram salientados como pontos favoráveis a interação com o docente, o contato humano com colegas e a possibilidade de tirar dúvidas pontuais.