Abstract Traditional solid-state fermentation processes can give fluctuating product quality and ... more Abstract Traditional solid-state fermentation processes can give fluctuating product quality and quantity due to difficulties in control and scale up. This paper describes an engineering study of an industrial-scale anaerobic solid-state fermentation process for Chinese liquor (Baijiu) production, aimed at better understanding of the traditional process, as an initial step for future optimization. This mixed-culture fermentation is done in 0.44-m3 vessels embedded in the soil. At this scale, the fermentation is limited by product inhibition. We developed mathematical models based on the Han-Levenspiel equation for product inhibition, with parameters derived from measured data. The models accurately predicted the concentrations of starch and dry matter. A model with radial conduction into a small soil volume around the fermenter and consecutive vertical conduction into the underlying soil accurately predicted the pit temperature in the heating and cooling phases. This model is very sensitive to the values used for the enthalpies of combustion, meaning that direct measurement of the heat production rate would be preferable. In the industry practice, the fermenter volume can be from around 0.20 to 15.00 m3. The model predicts that overheating will occur not only in larger fermenters, but also in the 0.44-m3 fermenters when the soil temperature is high in summer. Our model predictions are consistent with observed behavior in the industry. Our findings can be used to improve this traditional process, as well as similar systems.
Food is correlated with fungi in two opposite ways. In a positive way, we think of traditional an... more Food is correlated with fungi in two opposite ways. In a positive way, we think of traditional and exotic fermented foods from different parts of the world. The variety of those foods is wide, ranging from tempe and soy sauce in Asia to different types of cheese in Europe and the Middle East (Campbell-Platt, 1994). For the case of these fermented foods, we use the ability of fungi to degrade complex polymeric substrates to smaller compounds that are easily taken up by men. Some fungi can also consecutively convert the degraded compounds into other type of desirable metabolic products that determine the typical composition, taste, odour, consistency and colour of fermented foods. In a negative way, we think of unwanted spoilage or rotting of foods. A negative view on fungi includes exactly the same principles of digestion of complex substrates and production of other products. In both views the benefit of the fungi is served namely, the optimal survival by living in, growing on, and colonising a food matrix. The process of how fungi grow on and colonise a solid food matrix is described as solid-substrate or solid-state fermentation (SSF). A growing interest in SSF has been shown by a significant increase in numbers of publications on this topic in the past 20 years. Sufficient knowledge about the process of how fungi interact with a substrate matrix is absolutely needed to manipulate SSF processes, in order to: (1) improve the desired fermented (food) products yield and quality, and (2) prevent food spoilage. However, the knowledge of basic phenomena and their influence on metabolic responses in SSF is still relatively limited including such subjects as kinetics of enzyme production, release and transport, and kinetics of substrates conversion. Those processes are determined by transport phenomena of substrates, metabolites and hydrolytic enzymes. Knowledge of these transport phenomena is crucial to a further understanding of the kinetics in SSF. In this chapter, transport phenomena during fungal colonisation on a substrate matrix are described. Firstly, the occurrence of those phenomena and the complex consequences in SSF are explained. Secondly, some examples from published modelling and experimental work using diffusive transport phenomena are shown. Due to the complex features of SSF and based on diffusion as the transport mechanism, many authors have produced mathematical models to study and understand SSF, e.g., to predict biomass growth. Finally, possible transport phenomena other than diffusion are discussed.
... include: microbiology of sulfate reduction; competition for substrates; inhibition by inorgan... more ... include: microbiology of sulfate reduction; competition for substrates; inhibition by inorganic sulfur compounds; guidelines for anaerobic treatment of sulfate-containing waste water; and results obtained with anaerobic treatment (sludge digestion and waste water treatment in the ...
Different control strategies of bed temperature and moisture were investigated using various inle... more Different control strategies of bed temperature and moisture were investigated using various inlet air temperatures and air fluxes in both the ordinary packed bed bioreactor (without cooling water in the jacket) and the bioreactor with cooling water in jacket. The experiments were carried out within a 1-L solid-state packed bed bioreactor in which Aspergillus niger was cultivated on wheat bran. On-line measurements of oxygen quantity in the outlet air and temperature of the bed and the inlet air flux were carried out in both types of the bioreactors. Effects of certain control strategies on fungal growth rate were compared in both the bioreactors. According to experimental results, using the bioreactor with the cooling water in the jacket is a better strategy for control of bed temperature and moisture during packed bed solid state fermentation. Cumulative oxygen consumption in this bioreactor was approximately 1.7 times higher than other control strategies used in this study.
The production of lipids by oleaginous yeast and fungi becomes more important because these lipid... more The production of lipids by oleaginous yeast and fungi becomes more important because these lipids can be used for biodiesel production. To understand the process of lipid production better, we developed a model for growth, lipid production and lipid turnover in submerged batch fermentation. This model describes three subsequent phases: exponential growth when both a C-source and an N-source are
Abstract Traditional solid-state fermentation processes can give fluctuating product quality and ... more Abstract Traditional solid-state fermentation processes can give fluctuating product quality and quantity due to difficulties in control and scale up. This paper describes an engineering study of an industrial-scale anaerobic solid-state fermentation process for Chinese liquor (Baijiu) production, aimed at better understanding of the traditional process, as an initial step for future optimization. This mixed-culture fermentation is done in 0.44-m3 vessels embedded in the soil. At this scale, the fermentation is limited by product inhibition. We developed mathematical models based on the Han-Levenspiel equation for product inhibition, with parameters derived from measured data. The models accurately predicted the concentrations of starch and dry matter. A model with radial conduction into a small soil volume around the fermenter and consecutive vertical conduction into the underlying soil accurately predicted the pit temperature in the heating and cooling phases. This model is very sensitive to the values used for the enthalpies of combustion, meaning that direct measurement of the heat production rate would be preferable. In the industry practice, the fermenter volume can be from around 0.20 to 15.00 m3. The model predicts that overheating will occur not only in larger fermenters, but also in the 0.44-m3 fermenters when the soil temperature is high in summer. Our model predictions are consistent with observed behavior in the industry. Our findings can be used to improve this traditional process, as well as similar systems.
Food is correlated with fungi in two opposite ways. In a positive way, we think of traditional an... more Food is correlated with fungi in two opposite ways. In a positive way, we think of traditional and exotic fermented foods from different parts of the world. The variety of those foods is wide, ranging from tempe and soy sauce in Asia to different types of cheese in Europe and the Middle East (Campbell-Platt, 1994). For the case of these fermented foods, we use the ability of fungi to degrade complex polymeric substrates to smaller compounds that are easily taken up by men. Some fungi can also consecutively convert the degraded compounds into other type of desirable metabolic products that determine the typical composition, taste, odour, consistency and colour of fermented foods. In a negative way, we think of unwanted spoilage or rotting of foods. A negative view on fungi includes exactly the same principles of digestion of complex substrates and production of other products. In both views the benefit of the fungi is served namely, the optimal survival by living in, growing on, and colonising a food matrix. The process of how fungi grow on and colonise a solid food matrix is described as solid-substrate or solid-state fermentation (SSF). A growing interest in SSF has been shown by a significant increase in numbers of publications on this topic in the past 20 years. Sufficient knowledge about the process of how fungi interact with a substrate matrix is absolutely needed to manipulate SSF processes, in order to: (1) improve the desired fermented (food) products yield and quality, and (2) prevent food spoilage. However, the knowledge of basic phenomena and their influence on metabolic responses in SSF is still relatively limited including such subjects as kinetics of enzyme production, release and transport, and kinetics of substrates conversion. Those processes are determined by transport phenomena of substrates, metabolites and hydrolytic enzymes. Knowledge of these transport phenomena is crucial to a further understanding of the kinetics in SSF. In this chapter, transport phenomena during fungal colonisation on a substrate matrix are described. Firstly, the occurrence of those phenomena and the complex consequences in SSF are explained. Secondly, some examples from published modelling and experimental work using diffusive transport phenomena are shown. Due to the complex features of SSF and based on diffusion as the transport mechanism, many authors have produced mathematical models to study and understand SSF, e.g., to predict biomass growth. Finally, possible transport phenomena other than diffusion are discussed.
... include: microbiology of sulfate reduction; competition for substrates; inhibition by inorgan... more ... include: microbiology of sulfate reduction; competition for substrates; inhibition by inorganic sulfur compounds; guidelines for anaerobic treatment of sulfate-containing waste water; and results obtained with anaerobic treatment (sludge digestion and waste water treatment in the ...
Different control strategies of bed temperature and moisture were investigated using various inle... more Different control strategies of bed temperature and moisture were investigated using various inlet air temperatures and air fluxes in both the ordinary packed bed bioreactor (without cooling water in the jacket) and the bioreactor with cooling water in jacket. The experiments were carried out within a 1-L solid-state packed bed bioreactor in which Aspergillus niger was cultivated on wheat bran. On-line measurements of oxygen quantity in the outlet air and temperature of the bed and the inlet air flux were carried out in both types of the bioreactors. Effects of certain control strategies on fungal growth rate were compared in both the bioreactors. According to experimental results, using the bioreactor with the cooling water in the jacket is a better strategy for control of bed temperature and moisture during packed bed solid state fermentation. Cumulative oxygen consumption in this bioreactor was approximately 1.7 times higher than other control strategies used in this study.
The production of lipids by oleaginous yeast and fungi becomes more important because these lipid... more The production of lipids by oleaginous yeast and fungi becomes more important because these lipids can be used for biodiesel production. To understand the process of lipid production better, we developed a model for growth, lipid production and lipid turnover in submerged batch fermentation. This model describes three subsequent phases: exponential growth when both a C-source and an N-source are
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Papers by Arjen Rinzema