AbstractThe starch of pulse (Fabaceae) grains, such as faba bean (Vicia faba L.) and pea (Pisum sativum L.), offers an environmentally sustainable raw material for the beverage alcohol industry due to their ability to satisfy their entire nitrogen fertiliser requirement through the natural process of biological nitrogen fixation (BNF). To this end, the potential of utilising legumes, when grown as a mixed crop (intercrop, IC), to support traditional cereal crops was evaluated. The suitability of utilising the harvested pulse crop as a source of fermentable material in the production of beer and distilled spirits was then assessed along with the associated protein rich by-products.
The IC studies successfully demonstrated the potential of growing malting quality barley in the presence of legumes without the application of N fertiliser. Opportunities for breeding specifically for IC conditions, for example increased cereal tillering and N availability complementarity, combined with a refresh of malting barleys desired characteristics could allow ICs to develop as a viable low input agriculture alternative.
The use of pulses as an adjunct in brewing and as the sole raw material in distilling was investigated. The gelatinisation properties of pulse starch were assessed, identifying a high temperature pre-cook and exogenous enzymes to be necessary in producing a wort with a run-off rate, primary amino nitrogen (PAN) content, and fermentability comparable to a 100% malted barley wort.
The impact of removal point on distillery fermentation kinetics and distillate quality was assessed. Removal of the insoluble material during the mashing step resulted in a faster fermentation and a spirit with lower congeners levels. However, fermentable materials were also lost during the separation process resulting in a decrease in ethanol yield. Investigation of pulse starch, a by-product of the plant protein industry, found fermentation to progress slowly and fail to reach completion within a commercial fermentation schedule. Additions of a portion of whole peas (25% by weight) provided sufficient nutrition to support the complete conversion of the fermentable sugars to ethanol thus presenting a new market for this by-product.
Commercially available pulse-based beers and spirits have been released during, and as a direct result of, this research. Consumer, nutritional and anti-nutritional analysis of beer brewed using faba beans as an adjunct to malted barley was conducted and found they could be used to produce a nutritionally enriched beer without negatively impacting flavour and with limited concerns around antinutritional properties.
Finally, an assessment of the impact of pulses on by-product value (feed and commercial) demonstrated the potential benefits and further valorisation of these products in their existing markets.
|Date of Award||26 Jan 2022|
|Sponsors||The James Hutton Institute|
|Supervisor||Graeme Walker (Supervisor) & Athina Tziboula-Clarke (Supervisor)|
- Vicia Faba L
- Pisum sativum L
- Sensory evaluation