ASBC Journal 2007 - Steps Toward the Formulation of a Model Foam Standard.

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VIEW ARTICLE DOI: 10.1094/ASBCJ-2007-0111-02

Steps Toward the Formulation of a Model Foam Standard. Waha Vundla (1) and Phill Torline, Group Brewing Research, SABMiller plc., Sandton, South Africa. (1) Corresponding author. E-mail: <waha.vundla@za.sabmiller.com>; Phone: +27 11 881 9713; Fax: +27 86 681 4759. J. Am. Soc. Brew. Chem. 65(1):21-25, 2007.

A potential model foam standard has been formulated. It comprises defined quantities, by weight, of analytically pure bovine serum albumin (BSA; 0.075%), protamine sulfate (0.006%), tetrahydroiso-alpha-acid (tetrahop; 0.026%), ethanol (2%), cobalt sulfate (0.012%), glycerol (0.2%), dextrin (0.2%), polydextrose (0.1%), ethylenediaminetetraacetic acid (EDTA; 0.001%), carbon dioxide (0.3%), and water (97.085%). The concentration of the different components relative to one another was important. In particular, the hop/protein ratio (approximately 1:3) was very important, as was the 1:2 metal ion/tetrahop ratio. Although BSA was the main foaming protein, the smaller protein, protamine sulfate, had an additional stabilizing effect on the foam. Ethanol was essential for foam formation, with an optimum concentration of 2%. The optimum interval between carbonation and packaging under these conditions was 48 hr. In addition to stabilizing the model foam standard microbiologically, Pasteurization (20 PU) had a positive effect on the foam. The model foam had a Nibem value of approximately 277 ± 2.2 sec. Further, the rate of foam collapse, as measured by a pour method, was approximately 30 mL/min (r > 0.98) compared with approximately 46 mL/min (r > 0.98) for a beer standard. At 865 mL (340-mL sample), the foam head (as measured by a pour method) was slightly less than that of lager beer. Overall, the model foam was more stable than the beer standard foam, although the latter had more foam. The dynamic viscosity of the foam standard was 1.25 mPa·sec. It had a density of 0.998 g/mL, slightly lower than that of beer (1.004 g/mL), and a pH of 4.1, very similar to the beer standard (4.2). The cling was 99.5 ± 0.5 compared with 85.5 ± 4.5 for beer. Keywords: Beer foam, Foam standard, Model foam

Se ha formulado un estándar modelo de espuma potencial. Se compone de cantidades definidas, por peso, de la albúmina analíticamente pura del suero vacuno (BSA; 0.075%), sulfato de protamina (0.006%), tetrahidroiso-alfa-ácido (tetrahop; 0.026%), etanol (2%), sulfato de cobalto (0.012%), glicerol (0.2%), dextrina (0.2%), polidextrosa (0.1%), ácido etilendiaminotetraacético (EDTA; 0.001%), dióxido de carbono (0.3%), y agua (97.085%). La concentración de los diversos componentes relativo a uno otra era importante. Particularmente, la relación del lúpulo/proteína (aproximadamente 1:3) era muy importante, al igual que la relación del iones metal/tetrahop de 1:2. Aunque BSA era la proteína principal que hacía espuma, la proteína más pequeña, sulfato de protamina, tenía un efecto adicional en estabilizando la espuma. El etanol era esencial para la formación de la espuma, con una concentración óptima de 2%. El intervalo óptimo entre la carbonatación y el empaquetado con estas condiciones era 48 hr. Además de estabilizar el estándar modelo de espuma microbiológicamente, la pasterización (PU 20) tenía un efecto positivo en la espuma. La espuma modelo tenía un valor de Nibem de aproximadamente 277 ± 2.2 sec. Además, el índice del colapso de la espuma, medido por un método de vertido, era aproximadamente 30 mL/min (r > 0.98) comparado con aproximadamente 46 mL/min (r > 0.98) para un cerveza estándar. En 865 mL (muestra de 340 mL), la espuma (medido por un método de vertido) era levemente menos que una cerveza dorada. Total, la espuma modelo era más estable que la espuma estándar de cerveza, aunque la espuma estándar de cerveza tenía más espuma. La viscosidad dinámica del estándar de espuma era el 1.25 del mPa·sec. Tenía una densidad de 0.998 g/mL, levemente menos que la cerveza (1.004 g/mL), y un pH de 4.1, muy similar al estándar de cerveza (4.2). El adhesión era 99.5 ± 0.5 comparados con 85.5 ± 4.5 para la cerveza. Palabras claves: Espuma de cerveza, Estándar de espuma, Modelo de espuma

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