Technical Session 08: Sensory Session
Heinrich Rübsam, Institute of Brewing and Beverage Technology, TUM-Weihenstephan,Freising. Germany
Co-author(s): Martina Gastl, Institute of Brewing and Beverage Technology, TUM-Weihenstephan, Freising, Germany; Martin Krottenthaler, Hochschule Weihenstephan-Triesdorf, Freising, Germany; Thomas Becker, Institute of Brewing and Beverage Technology, TUM-Weihenstephan, Germany
ABSTRACT: The content of high and low molecular weight maltodextrins, as well as their structural properties in beer, may influence the palate fullness of this beverage. Therefore, the possible association between sensory impressions and structural analysis of maltodextrins was investigated. To achieve this, a series of tasting sessions using different beer and maltodextrin samples was performed in parallel with various measurements of different structural parameters using field-flow fractionation techniques. For these purposes a selection of different maltodextrins products (2–100 kDa) was required. These maltodextrins were classified, using different dextrose equivalents (DE). First, the taste threshold of each maltodextrin in beer was determined. To do this, the different maltodextrins were independently added in increasing concentrations in a pilsner beer, and all samples were tasted. Seven samples (control and 0.25, 0.5, 1, 2, 4, and 8% maltodextrin in beer) were presented to the panelist, and these were evaluated for the intensity of the palate fullness. Further, in the same tasting, the threshold concentration of each maltodextrin at which the flavor was not pleasant for the degustation panel was also determined. To validate the previously determined threshold values and to compare the characteristics of each type of maltodextrin in the beer sample, a series of taste sessions was conducted. In these sessions, 4% of maltodextrin was added to the corresponding beer sample. Furthermore, the influence of maltodextrin to palate fullness was determined by the application of defined matrices (maltodextrin-beer and maltodextrin-water). Finally, a number of different commercial pilsner beers (same wort extract and alcohol content) was selected and tested for sensory palate fullness. All sensory tests were conducted 10 times to obtain trustworthy results. Finally, the structural analysis of the tasting matrices was carried out by means of a field-flow fractionation-refractive index-light scattering measurement system. The system was calibrated with different standards (pullulans, beta-glucan, and proteins) at a molecular weight range of 6–800 kDa, and the corresponding reproducibility was examined. All pilsner beers used for the tasting sessions were analyzed. The correlation between the analytical results and the sensory impressions was determined by the comparison of the molecular weight distributions of the pilsner beers with the degree of intensity of the palate fullness of each beer. From the tested beers, it was found that the molecular weight distribution ranged from 2 to 15 kDa. By correlation of the analytical data and the results obtained from the tasting sessions, it is possible to conclude that the beers with the higher palate fullness intensity corresponded to the beers with molecular weight distributions from 6 to 15 kDa, while the beers with molecular weight distributions from 2 to 15 kDa were considered by the panelists to have lower palate fullness.
Heinrich Rübsam completed his Dipl.-Eng. degree in chemical engineering at the Metropolitan University, Caracas, Venezuela, in July 2004. He was then employed by Polar Brewery Company at the research center. He participated in different research projects: synthesis of alpha-dicarbonyl compounds by application of HPLC, GCMS, and mass spectrometry and quantification of alpha-dicarbonyl compounds and Strecker aldehyde during the aging process of beer (2004–2006). The results of this work were published in the Journal of Agricultural Food Chemistry (56(11), pp 4134-4144, 2008). In 2007, he did an internship at the Paulaner Brewery in Munich, Germany. He worked in the Production, Bottling, and Quality Assurance departments. Additionally, he participated in an independent project for the taste stability determination of beer. Later, he studied brewing and beverage technology at the Technische Universität München (TUM) in Germany and obtained his M.S. degree in 2009. His work, in cooperation with the Paulaner Brewery on optimizing brewhouse technology with reference to dimethyl sulfide, was published in Brauwelt International in 2010. Currently he is pursuing his Ph.D. at the Institute of Brewing and Beverage Technology, TUM-Weihenstephan, Germany. His research focus is on the characterization of the degradation of starch during the mashing process, as well as the contribution of the content of high and low molecular weight maltodextrins and their structural properties to palate fullness of beer.