Development of Natural Antioxidant Blends for Improved Beer Oxidative Stability

Increasing numbers of small and medium-sized breweries are packaging beer but often lack the technology or infrastructure to ensure freshness and extended shelf life. Additionally, the export of craft beers has increased, further highlighting the need for prolonged shelf life and product stability. Antioxidant blends provide a practical and effective solution to enhance beer stability and maintain quality throughout distribution. In this study, we evaluated the effects of adding antioxidant blends at multiple stages of the brewing process on both fresh and aged beers.

 Two 7-hL batches were brewed at the ICBS Research Brewery, University of Nottingham: a control (C) and a beer that received a mash antioxidant blend (MA) containing pomegranate extract (PE) and tannic acid (TA). After fermentation, both beers were transferred to 50-L kegs, where blends of PE, TA, α-tocopherol (AT), and rosemary extract (RE) were added. Additionally, two kegs from each mash treatment received no further antioxidant additions, resulting in a total of eight experimental conditions. After 24 hours, the beer was filtered, bottled in-line, and pasteurized. 
Throughout the brewing process, wort samples were collected and analyzed for metal ion content, thiobarbituric acid index (TBI), and oxidative stability using ESR (T150). Fresh bottled beers were evaluated for standard specifications, metal ion content (ICP-AES), foam stability, chill haze, antioxidant activity (FRAP, ORAC), and oxidative stability (ESR (T150)). Two forced-aging studies were conducted: one at 45°C for seven days to assess color, colloidal stability, and oxidative stability, and another at 32°C for two and four weeks to examine flavor stability through the analysis of staling aldehyde formation (GC-MS).

Fresh beers that received a mash antioxidant (MA) addition of PE and TA exhibited significantly lower levels of transition metal ions (Fe, Cu, Mn) and improved oxidative stability and FRAP, compared to the control, regardless of downstream additions. T150 was reduced by up to 87%, and Fe levels dropped by up to 95%. Colloidal stability was enhanced with multistep antioxidant additions, particularly in the MA + downstream PE+AT+TA additions, supporting prior findings on α-tocopherol’s role in preventing haze formation under adverse conditions. Mash antioxidant addition also slowed furfural formation during aging, particularly when combined with downstream antioxidants. Additionally, these beers retained a stronger ester profile over time. Preliminary sensory analysis of the four-week-aged beers showed that the control beer exhibited the most pronounced staling, with all panelists agreeing that antioxidant addition, especially in the mash, enhanced flavor stability.

Overall, the use of antioxidant blends at multiple stages of the brewing process offers a feasible and flexible solution for brewers to enhance beer freshness and stability while mitigating oxidation.