Variances in nutritient content and yield of alfalfa protein concentrate processed with five mthods from high yielding biomass type alfalfa

Abstract

The demand for protein is growing with increased populations and world affluence. A sustainable and affordable protein source is needed to support the growing aquaculture industry worldwide. Alfalfa produces high levels of protein and provides numerous environmental services, potentially making it an ideal feedstock in aquaculture. This project evaluates five methods of alfalfa protein concentrate (APC) coagulation for yield and nutritional content. A biomass-type alfalfa was harvested at full flower with a flail mower, fresh material homogenized in a laboratory blender, juice expressed by hand, and protein coagulated using five methods. The methods were: (1) heating in an 80°C water bath for 30 minutes, (2) freezing the juice at -15°C, (3) lowering the pH of the juice to 4.0 with hydrochloric acid, (4) lowering the pH of juice chilled in refrigeration with chilled hydrochloric acid, (5) first, raising the pH of the juice to 10.0 with sodium hydroxide, letting it set for 15 minutes, then lowering the pH down to 4.0 with hydrochloric acid. The temperature and pH based methods resulted in significant differences in protein yield and concentration. While the acid based coagulation methods resulted in the highest yield and lowest fiber content, temperature methods resulted in higher concentrations of protein. Extraction methods also impacted crude fat, sugar, and specific amino acids. Acid coagulation resulted in decreased fiber and fat content, which may be beneficial for aquaculture uses. Heat treatment resulted in increased concentration of limiting amino acids and lower sugar content compared to the other methods. These findings show that APC producers can adjust production methods for a specialized APC product meant for specific diets or uses.