Nils Rettberg

Why was the work done: The brewing industry faces growing challenges from stricter regulations and from climate change, driving the need for sustainable innovation. One approach is the use of legumes as brewing adjuncts, given their low carbon footprint and ability to fix atmospheric nitrogen in soil. Incorporating diverse crops, such as barley, wheat, oats, and faba bean, promotes regenerative agriculture but also broadens raw material use in brewing. With the aim of promoting regenerative agriculture and sustainability in brewing, this study explores a ‘crop rotation’ beer made from barley, wheat, oats, and faba bean. How was the work done: The use of malt bills including barley, wheat, oats, and faba bean would support crop rotation and diversify raw materials. Faba bean was incorporated in both a raw and malted form. Brewing was performed at both laboratory and pilot scale, and the physicochemical and sensory properties of the beers were evaluated in comparison to barley malt beers. What are the main findings: The results show that crop rotation worts made with malted faba beans (Sprau®) were superior to raw faba beans with improved maltose levels, greater free amino nitrogen, and more protein, alongside lower polyphenol concentration. Further, pilot scale crop rotation beers brewed with Sprau® and its starch fraction achieved a more balanced flavour profile and higher ratings for taste, aroma, and overall quality, compared to those brewed with raw faba beans. The quality scores of the beers containing Sprau® were considered 'good' (>6) and on par with those observed with commercial malted barley beer. Why is the work important: A ‘crop rotation’ beer, utilising malt made from four different crops, can be produced with similar physicochemical and sensory properties to beer from malted barley. Incorporating legumes in the malt bill supports sustainable farming practices, enhances biodiversity, and reduces reliance on cereal grains such as barley. Compared to raw faba beans, malted faba beans (Sprau®) exhibited superior physicochemical, functional, and sensorial properties, making them more suitable for brewing application. Therefore, incorporating malted legumes can yield beers with a balanced flavour profile and this offers brewers new alternatives for improving the sustainability of their products.

Nineteen globally diverse rice cultivars were analyzed for various chemical parameters important to malting, including germination energy, protein, apparent amylose content, and gelatinization temperatures (GT). The rice cultivars were then malted, and congress mashes were produced. Several parameters important to brewing were then assessed in the malts and worts (i.e., extract, soluble protein, free amino nitrogen (FAN), GT, etc.). The rice malts produced were saccharified to varying degrees, had high limit dextrinase activities, and contained sufficient FAN/protein concentrations. This suggests their potential to yield robust fermentations in beer styles with high adjunct inclusions without requiring additional nitrogen supplementation. Rice cultivars with purple-pigmented bran were found to yield unique wort colors and could serve as novel natural gluten-free colorants for future recipes. Overall, these findings suggest that malted rice could offer a more local and gluten-free source of starch for brewers and beverage/food producers.

The sensory, volatile, and physiochemical profiles of nineteen commercial non-alcoholic pilsner-style beers produced by different production techniques were analyzed and compared with a dry-hopped non-alcoholic IPA. NABs made only with either physical dealcoholization or restricted fermentations differed significantly in chemistry and flavor. Generally, NABs produced by restricted fermentations were the most worty, thick, and sweet, whereas NABs that were physically dealcoholized had the lowest taste/aroma intensities and were the sourest, most thin, and least sweet. Interestingly, the method of dealcoholization had a minor impact on the flavor profile. The use of maltose intolerant yeast as well as the implementation of combined treatments, such as blending dealcoholized beer with beer containing alcohol, were the techniques found to produce NABs with more harmonious and multifaceted chemical and flavor profiles. NABs with increased hop aroma volatiles were the most harmonious, particularly highlighted by the NA IPA reference. Even though dry-hopped character might be atypical for pilsner-style beer, dry-hopping appears as a simple application to produce NABs with more harmonious flavor.