FEATURE
WHOLE FABA BEANS (100%)
Dehulling KERNELLS 80% of whole bean
HULLS 18% of whole bean Milling & Air Classification
Protein Concentrate 20% of whole bean (11:1, protein; starch)
Starch Concentrate 60% of whole bean (1:3, protein; starch)
SALMON
PIGS & POULTRY
RUMINANTS
FIGURE 1: Whole faba bean classsification
their skins removed, may be ground to a meal, which has been used successfully in farmed salmon feeds for more than 20 years. Furthermore, the bean inclusion rate could be doubled were it possible to isolate the kernel protein from its starch component. Demand is high for farmed salmon feed in the UK with 200,000 tonnes used every year, and as they have been bred to have an excellent feed conversion ratio of 1.25, or 0.8 kg of fish produced for every kg fed. Thus, 160,000 tonnes of fish are produced annually with a fish-farm gate value of £600m and this represents Scotland’s second largest export - since most of the UKs farmed salmon production units are based there.
Air Classification
The beans4feeds approach centred on a technology called Air Classification. Here an air cyclone is use to separate the milled bean kernel flour into lighter protein bodies as an upper fraction from heavier starch granules in the lower fraction. The resultant products are bean protein and starch concentrates, respectively. The former was trialled for salmon production, and the latter as a pig and poultry feed.
Bean protein concentrate as a fish feed
The project results showed that air classified protein concentrate used salmon feed with inclusion rates of up to 20 percent presented no disease challenges, there were no obvious effects of bean anti-nutritionals, and feeding and growth was equal or faster than fish fed conventionally - and whether fish were raised as juveniles (in freshwater), or mature fish (in salt water). Fish fed bean protein concentrate also showed normal yields, with good colour and no ‘gaping’, which is separation of the muscle blocks. Fillets from bean concentrate fed fish also appeared 15-20 percent firmer, and this is expected to help extend shelf life.
UsingBean starch concentrate as a fish feed
Results were obtained for the starch concentrate fed to pigs and poultry, and soya could be completely replaced by beans in feeds
for these animals. However, this process was certainly not plain sailing, and key technical and commercial challenges still remain for successful commercialisation of the approach. Then there is the Lack of UK processing capability. Bean dehullers, millers and air classification facilities are not common, co-localised or co-owned so centralising processing would improve commercial efficiency. Also, a commercial scale air (or wet) protein-starch classification plant for beans remains to be established in the UK. The bean starch concentrate is also too expensive. Generally, animal feeds must be in inexpensive, and the air classified starch concentrate is too expensive at, and estimated as approximately £300/tonne, at current bean qualities and processing efficiency. This is a serious short-coming as the starch concentrate is the bulk of the by-product, 80 percent of the material or 60 percent of the whole bean. That is, high volume users are required for the co-product.
Possible commercial solutions
Higher protein beans. As the protein content of individual beans increases the minimum costs of the starch concentrate decreases. Therefore, breeding beans for higher protein content increases the commercial efficacy of air classification, and the James Hutton institute has identified key germplasm with protein levels of almost 40 percent protein. These are now being used to develop a high protein specifically for air classification. Develop higher value products from the bean starch concentrate, and hulls: the use of the air classified starch for making healthy breads, ales and for distilling has been trailed successfully in collaboration with Barney’s Beer (Edinburgh), Prof. Graeme Walker (Abertay University, Dundee), and Arbikie Distillery (Manger, Kirsty Black). Also, these brewing and distilling approaches are now being extended to the use of whole beans: removing the starch from milled whole beans by fermentation and production of high value beer and neutral spirits is proving successful, with high protein co-products currently being assessed for exploitation as an aquaculture feed.
International Aquafeed - September | October 2016 | 39