Search Results (3)

Headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME/GC-MS), sensory evaluation, and multivariate analysis were applied to monitor and compare the evolution of the aromatic profile of a lager beer in different types of containers (aluminum cans and glass bottles) during the natural ageing process. Samples were aged naturally for a year in the absence of light with a controlled temperature of around 14 °C +/− 0.5 °C. The sensory evaluation applied was a blind olfactometric triangle test between canned and bottled samples at different periods of aging: fresh, 6 months, and 11 months. The sensory evaluation showed that the panelists were able to differentiate between samples, except for the fresh samples from the brewery. A total of 34 volatile compounds were identified using the HS-SPME/GC-MS technique for both packaging types in this experiment. The application of multivariate analysis to the GC-MS data showed that the samples could not be differentiated according to the type of packaging but could be differentiated by the ageing time. The results showed that the combination of sensory, HS-SPME-GC-MS, and multivariate analysis seemed to be a valuable tool for monitoring and identifying possible changes in the aroma profile of a beer during its shelf life. Furthermore, the results showed that storing beer under optimal conditions helped preserve its quality during its shelf life, regardless of the type of packaging (aluminum can and glass bottle). Full article

Foam stability and retention is an important indicator of beer quality and freshness. A full, white head of foam with nicely distributed small bubbles of CO₂ is appealing to the consumers and the crown of the production process. However, raw materials, production process, packaging, transportation, and storage have a big impact on foam stability, which marks foam stability monitoring during all these stages, from production to consumer, as very important. Beer foam stability is expressed as a change of foam height over a certain period. This research aimed to monitor the foam stability of lager beers using image analysis methods on two different types of recordings: RGB and depth videos. Sixteen different commercially available lager beers were subjected to analysis. The automated image analysis method based only on the analysis of RGB video images proved to be inapplicable in real conditions due to problems such as reflection of light through glass, autofocus, and beer lacing/clinging, which make it impossible to accurately detect the actual height of the foam. A solution to this problem, representing a unique contribution, was found by introducing the use of a 3D camera in estimating foam stability. According to the results, automated analysis of depth images obtained from a 3D camera proved to be a suitable, objective, repeatable, reliable, and sufficiently sensitive method for measuring foam stability of lager beers. The applied model proved to be suitable for predicting changes in foam retention of lager beers. Full article

The aim of this research was to assess whether the grist mixture (50% malt, 34% maize grits, and 16% unmalted wheat) used for the production of beer 1 could be appropriate for lager to retain the declared quality and colloidal stability during the commercial shelf life (6 months) in regards to beer 2 produced completely out of barley malt. Raw materials, worts, and beers were analyzed before and after production and over the period of 6-month storage. All analyses were done in accordance with the European Brewery Convention methods. Beer 1 resulted in a more desirable wort composition considering the total, high molecular weight (HMW) proteins, and viscosity. Beer 1 had less total proteins and polyphenols, lower viscosity and color, and higher starting clarity than beer 2. Haze measurements showed that even though beer 1 had lower starting haze, it resulted in significantly less colloidal stability during the storage of 6 months, in comparison to beer 2. The results indicate that the production of light lager beer using unmalted wheat in grist could be acceptable for colloidal stability only if such beer is to be stabilized by operations that ensure the removal of haze inducers (primarily haze active proteins). Full article