Despite decades of extensive research, beer flavour instability remains a challenge for both brewing and malting industries. Malt impacts the brewing process as well as the quality of the final beer. It also affects the stability of beer flavour, as it delivers to the brewing process various compounds with the potential to compromise the desired flavour characteristics of beer. These include staling aldehydes and their precursors, such as amino acids, reducing sugars, α‐dicarbonyls and bound‐state aldehydes. In general, the content of these compounds depends on barley variety and quality, the malting regime and final malt quality. Malt that represents a low potential for beer staling, i.e. that has low values of Kolbach Index, heat load, colour, LOX activity, Strecker aldehydes, transition metal ions and high antioxidative activity, leads to beer with enhanced flavour stability. However, the consistent production of malt with the desired quality remains challenging. Approaches to achieve this include adjustment of steeping and germination conditions, allowing control of grain modification and thus, the reservoir of aldehydes precursors. Also, the application of alternative kilning technologies may reduce the applied heat load, responsible for the formation of staling aldehydes and triggering development of the oxidising free radical species. This review provides an evaluation of current knowledge on the contribution of the malting process and malt quality to the formation of beer staling aldehydes. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

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Throughout history, the fermentation of fruit juices has served as a preservation method and has enhanced the retention of bioactive constituents crucial for human well-being. This study examined the possibility of orange and black currant juice fermentation with the probiotic yeast Saccharomyces cerevisiae var. boulardii. Saccharomyces bayanus was used as the reference. The ethanol concentration of the orange juices fermented without added glucose was close to 27 g/L. Adding glucose to the juice increased the alcohol produced by up to 65.58 ± 1.84 g/L (for the orange juice). For the same wort fermented by S. bayanus, the final ethanol concentration was 71.23 ± 1.62 g/L. Regardless of the type of yeast and additives used, the samples retained much of the color of the unfermented juice. The polyphenols content in the fermented samples was close to the initial polyphenols content in the juices. The sensory attributes of the juices fermented by the probiotic yeast did not differ from the samples fermented by S. bayanus. Fermenting fruit juices with probiotic yeasts offers a commercially viable and sensorially appealing method to enhance the product’s value by imparting it with probiotic properties.

In recent years, there has been a surge in the production of kombucha—a functional beverage obtained via microbial fermentation of tea. However, fres

Why was the work done: The deterioration of the flavour of fresh beer is challenging for the brewing industry. Despite extensive research on flavour instability, the focus has centred on a limited set of parameters, rather than taking a broader approach. How was the work done: in this study, the intent was to produce a flavour stable beer. Using a low kilning temperature, malt of low staling potential was used in combination with best brewing practice to produce three batches of unpasteurised top fermented pale beers at a pilot scale. Forty-three markers were analysed in the fresh and aged beers (30°C for 15, 30, 60 and 90 days). Staleness was evaluated by a trained sensory panel and multivariate data analysis was used to explore how the markers contribute to staleness. What are the main findings: Repeatability was achieved between replicate brews and, subsequently, staling. Polyphenols, haze, total reactive antioxidant potential (TRAP), iso-α-acids, colour, furfural, 2-methylpropanal and 2-methylbutanal showed a strong correlation with staleness. Staleness doubled after 60 days of storage at 30°C, despite volatile aldehydes remaining below their sensory thresholds, implying a synergistic effect of carbonyls contributing to staleness. A Partial Least Square (PLS) model was established, modelling the sensory staleness from 2-methylpropanal, furfural, TRAP and the trans-/cis-iso-α-acids ratio. Why is the work important: The staling phenomena could be reproduced in beers from parallel brewing trials with only minor variations. The four parameters in PLS modelling indicate that beer staling involves a combination of oxidative and non-oxidative pathways.