Protein extracts from lentils and beans can compete with soy

But the results of the PlantPro research project show that there are many more plants which are suitable for the production of protein compounds as food supplements.

ttz Bremerhaven examined 20 plants amongst which lentils and white beans particularly stood out due to their content in terms of nutritional physiology and their excellent functional features. The magazine “European Food Research and Technology” has just published an article in its web edition by Marie Bildstein, Dr. Mark Lohmann, Caroline Hennings and Dr. Hauke Hilz, scientists at ttz Bremerhaven, which gives a first detailed synopsis of the results. Co-author Alexander Krause, Managing Director of Gewürzmühle Nesse GmbH, a firm taking part in the project, was particularly interested in putting these results into practice in an efficient and economical way.

High nutritional value and more moist baked goods

Parallel to the growing demand for animal protein, the availability of this type of protein has also improved continuously over the last 40 years. The market will however reach the limit of its growth potential in the foreseeable future. In order to continue to satisfy demand, the search for sources of well-tolerated and low-fat protein compounds is very important. To date, soy beans and peas have been the main suppliers of vegetable protein. However, their utilisation is looked at with a critical eye or even boycotted in view of an increasing use of genetic engineering. In addition, a large number of consumers suffer an allergic reaction if they frequently eat soy products or milk proteins (caseins). Other pulses, such as lentils or white beans, have proven to cause less allergies.

Gentle protein extraction with water

Various types of plants have a high protein content – mostly in a concentrated form in their seeds. In the PlantPro project, which was funded by the German Ministry of Education and Research, ttz Bremerhaven, together with Gewürzmühle Nesse and a partner from Israel, extracted proteins from 20 different plants which so far have scarcely been used as a source of protein. A gentle extraction method using water was developed and deployed at an ideal temperature and pH value. However, since the tough cell wall structures and starch content made extraction difficult, the scientists were only able to recover very small yields.

Enzymes increase yield by 19 percent

The food technologists therefore incorporated an intermediate stage into the extraction process where selected enzymes were added to the solution. “The enzymes split the starch and, in so doing, improve the extraction of the proteins. In the case of white beans and lentils, this process increases the yield by 19 percent by adding the enzyme glucoamylase”, explains Marie Bildstein, the Project Manager at ttz Bremerhaven. The optimum constellation of the factors of reaction time, concentration of the raw material and the enzyme, pH value and temperature also contributed to optimising the result. In order to obtain the extract in a powder form and to be able to process it further in a wide variety of ways, the extract passes through the following process stages after separation: Dissolution, filtration and, finally, spray drying.

Comparison of nutritional value and functionality

Not only an efficient extraction process but also the nutritional value of the protein formulations obtained must be convincing if animal proteins or vegetable proteins from soy and peas are to be substituted in the long term. The extract fulfils the requirements of industry in terms of further processing: It is a light-coloured powder which is odourless and tasteless and raises the functional content of the foodstuff without drastically increasing the fat content.

In the case of the following features, the protein extract from lentils or white beans scores better than reference products from soy or peas:

– Foam formation and foam stability which are important for achieving a firm structure in foodstuffs

– Gel-forming characteristics

– Heat resistance

In a comparison of emulsion stability, the extract achieves the same result as alternatives from soy or peas. An important indicator for the quality of a product in terms of its nutritional physiology is the PDCAAS (Protein Digestibility Corrected Amino Acid Score). This value indicates to what degree a protein corresponds to the optimum protein in terms of nutritional physiology (set at 100). The PDCAAS of lentil protein was 51 percent, that of white beans 65 percent. By comparison, soy achieves a value of 91 percent and wheat protein 42 percent. Extracts from lentils and beans therefore produce a mid-range PDCAAS value.

Improved quality of baked goods

The use of protein extract from lentils and white beans in the production of white bread results in a crumb with a coarser pore structure. The quality and appearance of the white bread improve through this structure since the bread can bind more moisture. The bread keeps longer as a result. Thanks to the softer and more moist mouth feel, the consumer rates the bread as “fresher”.

Contact:
Britta Rollert,
ttz Bremerhaven, Public Relations
Telephone 0471 / 4832-121/-124, Fax 0471 / 4832-129
Email: brollert@ttz-bremerhaven.de