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Monitorização do oxigénio na etapa de filtração da cerveja e implementação de medidas de mitigação
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Abstract(s)
A cerveja é uma bebida alcoólica ancestral com grande relevância cultural. As matérias-primas para a sua produção sofreram algumas alterações ao longo do tempo, mas hoje em dia esta é composta essencialmente por cereais maltados ou não, água, lúpulo e leveduras do género Saccharomyces. O oxigénio, apesar de ter um papel benéfico em algumas etapas do processo produtivo é prejudicial durante a filtração, uma vez que, a sua incorporação é a principal causa do rápido envelhecimento/oxidação da cerveja embalada, assim é fundamental que esta apresente um teor de oxigénio dissolvido (OD) abaixo de 50 ppb.Durante este trabalho foi acompanhada a incorporação de oxigénio na etapa de filtração da cerveja através da medição do teor de OD antes e após a realização da filtração por: i) por cartuchos e ii) terra de diatomáceas. Na maioria dos lotes de cerveja filtrados por cartucho verificou-se um decréscimo da concentração de OD e, nos casos em que ocorreu incorporação de OD, o nível mais elevado descrito foi 160 ppb. Ao invés, verificou-se a presença de teores de OD muito superiores aos recomendados aquando da realização do método de filtração por terras diatomáceas em todos os lotes analisados, tendo sido obtidas medições acima de 90 ppb, sendo que três dos lotes em estudo apresentaram teores de OD mais discrepantes, respetivamente, 267, 215 e 213 ppb.Desta forma, após a identificação das principais causas foram destacadas medidas de mitigação a implementar durante o processo produtivo, nomeadamente, a medição contínua do OD no equipamento de filtração a terras diatomáceas, de modo a evitar a incorporação de oxigénio e, assim, conservar as propriedades sensoriais, conferir uma maior estabilidade e incrementar o tempo de vida da cerveja embalada.
Beer is an ancestral alcoholic beverage with great cultural relevance. The raw materials that compose it have undergone some changes over time, but today it is essentially composed of cereals, malted or unmalted, water, hops and yeasts of the Saccharomyces genus.Even though oxygen has a beneficial role in some stages of the production process, it can be harmful during filtration, since its incorporation is the main cause of the fast ageing of the packaged beer, so it must present a dissolved oxygen content (DO) below 50 ppb.During this work, the incorporation of oxygen in the beer filtration step was monitored by measuring the DO content before and after filtration by: i) cartridges and ii) diatomaceous earth. In most of the cartridge filtered batches of beer there was a decrease in the concentration of DO and, in cases where there was incorporation of DO, the highest level described was 160 ppb. On the contrary, it was verified that the presence of OD contents when performing the diatomaceous earth filtration method in all analysed batches was much higher than those recommended with measurements above 90 ppb, and three of the studied batches presented the most discrepant OD contents, respectively, 267, 215 and 213 ppb.Thus, after identifying the main causes, mitigation measures were highlighted to be implemented during the production process, namely, the continuous measurement of the DO in the diatomaceous earth filtration equipment, in order to avoid the incorporation of oxygen and, nevertheless, conserve the sensory properties, provide greater stability and increase the shelf life of packaged beer.
Beer is an ancestral alcoholic beverage with great cultural relevance. The raw materials that compose it have undergone some changes over time, but today it is essentially composed of cereals, malted or unmalted, water, hops and yeasts of the Saccharomyces genus.Even though oxygen has a beneficial role in some stages of the production process, it can be harmful during filtration, since its incorporation is the main cause of the fast ageing of the packaged beer, so it must present a dissolved oxygen content (DO) below 50 ppb.During this work, the incorporation of oxygen in the beer filtration step was monitored by measuring the DO content before and after filtration by: i) cartridges and ii) diatomaceous earth. In most of the cartridge filtered batches of beer there was a decrease in the concentration of DO and, in cases where there was incorporation of DO, the highest level described was 160 ppb. On the contrary, it was verified that the presence of OD contents when performing the diatomaceous earth filtration method in all analysed batches was much higher than those recommended with measurements above 90 ppb, and three of the studied batches presented the most discrepant OD contents, respectively, 267, 215 and 213 ppb.Thus, after identifying the main causes, mitigation measures were highlighted to be implemented during the production process, namely, the continuous measurement of the DO in the diatomaceous earth filtration equipment, in order to avoid the incorporation of oxygen and, nevertheless, conserve the sensory properties, provide greater stability and increase the shelf life of packaged beer.
Description
Keywords
cerveja filtração por terras diatomáceas filtração por cartucho oxigénio dissolvido