Investigation of Different Regimes of Beer Fermentation with Free and Immobilized Cells

Three different kinetic models – Monod’s model, Monod’s model with substrate inhibition, and Monod's model with substrate and product inhibition were developed for studying of beer fermentation with free and immobilized cells at different main fermentation and maturation temperatures. The most accurate model was Monod's model with substrate and product inhibition. It showed that maturation temperature had no effect on primary metabolism but it affected significantly the secondary metabolites production. In regard to carbonyl compounds and esters, the increase in maturation temperature led to different trends for free and immobilized cells. Regarding the higher alcohols, the increase in maturation temperature resulted in increase in their yield coefficients for both immobilized and free cells. A sensory evaluation of beers produced with free and immobilized cells were also carried out and the results showed similar results for two beer types

Investigation of Fermentation Regimes for the Production of Low-alcohol and Non-alcohol Beers

The combination of modified mashing method and arrested fermentation for the production of low-alcohol and non-alcohol beers was studied. Therefore, five regimes for fermentation of wort with reduced fermentable sugar content with top-fermenting yeast strain at low temperatures and pitching rates were investigated. According to the fermentation dynamic results the decrease in the fermentation temperature from 10 °C to 5 °C at pitching rate of 109 Colony Forming Units cm−3 ( CFU cm−3 ) led to significantly reduced concentrations of ethanol and secondary metabolites in beer. The temperature decrease from 10 °C to 7 °C at pitching rate of 107 CFU cm−3 resulted in a decrease in the alcohol concentration and increase in all the secondary metabolite concentrations except for the vicinal diketones concentration. Data show that yeast biomass does not grow at 5 °C and at inoculum concentration of 107 CFU cm−3, which makes fermentation impossible. Fermentation kinetics using Monod's model supplemented with product inhibition was also investigated. Up to 1.7 % of alcohol accumulates in the beer in some of the variants within 7 days. At low fermentation temperatures, yeast biomass utilizes part of the substrate to maintain its vital activity under stress fermentation conditions, which leads to a reduction in the amount of alcohol synthesized. The synthesis and reduction of the secondary metabolites was delayed compared to conventional beer fermentation. The sensory evaluation of the beers produced showed that the most appealing beer was the one produced at 10 °C and pitching rate of 109 CFU cm−3

Diseño mecánico y simulación de control de temperatura de un fermentador de cerveza artesanal

El presente Informe de Suficiencia Profesional tiene en cuenta la problemática presente en el Perú en referencia a la baja investigación tecnológica de fabricación de equipos y control de temperatura en el proceso de fermentación de cerveza artesanal. El objetivo de este trabajo es rediseñar, mecánicamente, el fermentador de forma cilíndrica-cónica que soporte la presión de trabajo, y un controlador PID, para mantener constante la temperatura del fermentador, teniendo en cuenta los factores físicos y químicos que afectan al proceso de fermentación alcohólica. Una de las metodologías usadas en este informe es el cálculo del espesor adecuado para la fabricación del recipiente sometido a presión utilizando el código ASME, sección VIII, división 1, otra metodología usada, se basa en los modelos matemáticos de la cinética del proceso de fermentación y del intercambiador de calor que se produce entre el recipiente y la chaqueta, para posteriormente, diseñar y simular el controlador PID mediante el uso del software MATLAB R2016a, y, por último, el cálculo de los parámetros del controlador PID mediante la sintonización de controladores por ubicación de polos y ceros. Como resultados, se calculó el espesor optimo en el recipiente para su uso en una producción de 500 litros batch, así como, el cálculo de los parámetros PID para el control de temperatura y su implementación y simulación en el software MATLAB. Se obtuvo buenos resultados en el análisis de estabilidad del sistema desarrollado, al simularse el comportamiento de la temperatura del fermentador en respuesta a dos valores de consigna de 14 y 16° C.Trabajo de suficiencia profesionalCampus Lima Centr