Authors: Shima Saffarionpour
Source: Research Repository (Delft University of Technology) (article, 2018-01-01)
Field: Chemistry — Spectroscopy

Tuning flavor-active components Flavor-active components are key contributors to the profile of the final produced beer product. Their preservation and control during different stages of processing is crucial, since they might be lost during processing due to their volatile nature. In order to produce a final beer product with balanced flavor profile, which is acceptable by the consumer, the level of these components in the beer matrix should be adjusted and controlled. Various techniques can be applied for flavor control and recovery, such as distillation/stripping, pervaporation, supercritical extraction, and adsorption. Chapter two of this thesis discusses the recent advances in various techniques, which are applied for flavor recovery among which adsorption is a technique, which showed potential for selective removal and recovery of flavor/non-flavor-active components. This technique can be combined with heat processing, distillation/stripping, or can be used as a standalone technique. The focus of the work presented in chapter three of this thesis is on method development for selective removal and recovery of flavoractive volatile components mainly belonging to the group of esters, higher alcohols, and diketones, through adsorption technique. In order to investigate the single and competitive adsorption behavior of flavor-active components and their synergistic effects, high throughput experimentation technique is applied, improved for volatile components and isotherms are obtained using batch uptake experimentation. The competitive adsorption behavior of flavor-active components is investigated on various food-grade hydrophobic adsorbents, in order to study the influence of physical and chemical nature of the components and adsorbent properties on selectivity for each tested adsorbate over ethanol. Based on the results obtained from thermodynamic studies through various isotherm models, the appropriate adsorbent material is selected for further studies in the design stage. In the next step, deeper study is conducted on flavor-active esters, presented in chapters four, five, and six, which contribute to beer with a fruity taste and aroma. With adjusting their level in the final beer product and their fractionation, various products can be produced with fruity taste. Further investigation is performed on their competitive adsorption behavior both through batch uptake experimentation, and dynamic breakthrough analysis tests, discussed in chapters four and six respectively. Since ester components are present at low concentration level together with ethanol, which is present at higher concentration in comparison in various process streams, the influence of ethanol and temperature on their competitive adsorption is further investigated, discussed in chapter four. Physical properties such as isosteric heat, entropy, and Gibbs energy of adsorption, are calculated from performed thermodynamic studies, which contribute to our deeper understanding of the adsorption phenomena on the selected adsorbents. Considering the time-consuming steps, which are required to be followed for constructing the adsorption isotherms through batch uptake experimentation, the application of predictive models developed based on adsorbed solution theory, is evaluated in chapter five, for prediction of multicomponent adsorption isotherms for flavor-active esters from single-component adsorption isotherms, when experimental data for multicomponent behavior is not available. The predictive model developed based on IAST, was capable to predict the multicomponent adsorption behavior for the tested condition with accuracy and can be used as a tool for prediction of isotherms, when data on multicomponent adsorption is not available. Possibility for separation of flavor-active esters is further investigated in a fixed-bed column in lab-scale, discussed in chapter six, to study their breakthrough behavior and their separation under various process conditions (ethanol concentration and temperature). The results of the experimental tests obtained through breakthrough analysis and fractionation, are used for validation of simulations. Based on the results obtained in lab-scale, separation of flavor-active components is further investigated in a large-scale column, through simulation of various scenarios for separation. The performed experiments in the lab-scale and results of the simulations at large-scale give an insight on competitive adsorption behavior of these components, when present in a mixture. For a more detailed prediction of the adsorption behavior, future outlooks are discussed in chapter seven, to study the optimized condition considering the process conditions, and integration of the adsorption with other alternatives such as distillation/stripping. Flavor ; Adsorption ; Chemistry ; Distillation ; Process engineering ; Stripping (fiber) ; Chromatography ; Organic chemistry ; Materials science ; Food science ; Engineering Analytical Chemistry and Chromatography ; Process Optimization and Integration ; Food Chemistry and Fat Analysis