Legume characterization tests and bioactivity tests
Advances made on Work Packages 3 and 5
February 15, 2023
Earth Day, 22nd of April 2023
April 22, 2023
A glimpse in the work carried out by UVIGO in WP3 and WP5
The University of Vigo team is integrated by scientists with expertise in the field of protein chemistry, enzyme technology, physiology and nutrition. Our role in ALEHOOP is, in the first place, to complete a specification sheet for the proteins obtained from the legume by-products and marine macroalgae.
In Work Package 3, a complete analysis of the physicochemical and techno-functional characteristics of the legume protein powders was done. The results will help to define their suitability to be used as ingredients for the different end-products considered in Work Package 7, intended for human consumption. All the extracts showed a very high protein content, which accounts for more than 80% of the total dry weight. Excepting the natural deficit of legumes in sulphur amino acids, the nutritional quality of these protein extracts can be considered very good since the score values calculated for most of the essential amino acids were higher than 100%.
The potential bioactivity of the protein extracts was also evaluated measuring their phenolic content and the antioxidant activity of the protein powders. The bean protein extract showed the highest antioxidant activity, followed by lentil and pea. Finally, the presence of trypsin inhibitors and phytic acid as antinutritional factors was analysed. The legume powder with the lowest trypsin inhibitor activity was lupin and lupin and lentil showed the lowest concentration of phytic acid.
Texture is an important food property. It plays a critical role in the palatability and acceptance of a particular product. Fibrous proteins are responsible for the characteristic texture of meat and fish muscle. Globular proteins can generate the gel texture of cheese or yoghourt from milk, the unique structure of the gluten network elaborated from wheat flour, or the attractive foam of bier and meringue. In these cases, the mode of elaboration of the final product results in the structural changes of the native proteins leading to these textures.
According to that, the development of a protein ingredient to be included in different food formulations must consider the evaluation of those properties directly involved in texture: gelling, emulsifying and foaming. All the protein extracts obtained from legume by-products showed good techno-functional properties, which endorse their suitability for the final applications considered in this case.
Regarding gelling, all the powders were able to form gels in conditions compatible with a wide range of food formulations, especially in the case of bean and lupin proteins. The emulsification capacity was quite similar for all the protein extracts, which form cream emulsions very white, viscous and stable. Best foaming capacity was for bean and lentil protein extracts.
After the complete evaluation of the protein extracts, the chemical composition of the solid and liquid side-streams generated in the process of protein extraction from legumes revealed the great potential of these by-products as new feedstocks for the recovery or the generation of new different products. All the liquid streams and the solid raw materials obtained from bean, lentil and pea were rich in starch and showed a remaining fraction of non-extractable protein. This composition makes them an interesting base material to be used as ingredient for the formulation of culture media for the biotechnological production of a number of compounds of great interest for the industry such as enzymes, lactic acid, PAHs or building blocks. For the lupin solid-stream, the higher fat, pectin and xylan content allows to broaden the array of possible new products.
Finally, it is worth to mention the high content of lutein of lentil side stream. Lutein is a yellow carotenoid with interesting applications in the feed industry as natural colorant, and in the food, cosmetic and pharmaceutic industries due to its recognized beneficiary effects on health.
After the physicochemical and techno-functional characterization of all the legume protein extracts, in vivo studies of bioavailability are currently running. Among the ALEHOOP legume proteins obtained, lupin and lentil were selected as the best nutrient-profile powders for in vivo studies with animal models (Male Sprague-Dawley rats) in metabolic cages. The goal of in vivo metabolic studies is to evaluate the short-effect administration of ALEHOOP proteins on body composition and on the main biochemical and metabolic parameters.
Rats were randomly assigned to control and experimental dietary treatment: one group was subjected to a standard rodent diet with 15% of animal protein, meanwhile the experimental groups were subjected to a protein-free chow with the incorporation of 15% of vegetable protein ALEHOOP lupin and lentil extracts. All rats preserved their diets for 28 days and had water and food ad libitum (in accordance with their wishes). All procedures were carried out in accordance to the European Community Directive 2010/63/UE and Spanish animal welfare laws and policies.
