Protein quality more important than source, say scientists

By Jess Halliday

- Last updated on GMT

Related tags Protein Amino acid

It does not matter so much whether protein is sourced from animals
or vegetables as whether it is of sufficiently good quality and has
the functional characteristics that enable it to be used in food
applications, scientists said at a debate hosted by Solanic.

The First International Vegetable versus Animal Protein Debate took place in Amsterdam last month, and was attended by academics and industry members invited by the subsidiary of Dutch group Avebe. The group was set up this year to develop value-added potato-based ingredients. When it comes to protein quality, there are a number of pertinent questions. These include the amino acid content, the digestibility of the amino acids, whether there are any anti-nutritional factors at play, and how the protein can help fortify amino acid patterns in weaker proteins. "On such quality issues, potato protein scores even better than soy protein, which is regarded as one of the best vegetable proteins. In fact, the origin of protein, be it vegetable or animal, is not even what matters. What counts is the quality of the protein, period,"​ said Professor Gertjan Schaafsma of Schaafsma Advisory Services. However Professor Daniel Tome of AgroParisTech/INRA said that there are still some aspects of the proteins which remain to be explored - such as the extent of their low-allergen properties. "In general, we know that cereals are limiting in the indispensable amino acid lysine and legumes are limiting in methionine and cysteine,"​ he said, "while animal proteins have no limiting amino acids."​ But he also said that there are big differences between the various vegetable protein sources. "In my view, animo acids in proteins are not the most important issues anymore, as the diet in the West covers the necessary intake. When it comes to the quality of proteins, their specific role in energy homeostasis and health related consequences is an important issue for further investigation."​ For a long time, the humble potato was not regarded as a commercially viable source of protein, since its protein content is only one to two per cent. Likewise, the juice has a low protein content. But when the waste material is separated out, the dry matter has a protein content of 27 per cent, and that is​ commercially interesting. Most starch production uses up a lot of water and energy, and generates much waste material. But Solanic says its mild separation process reduces the water and energy needs (the latter by up to 30 per cent), and also transforms the waste product into a useful protein. The potato juice passes though pre-treatment and absorption steps, then is divided according to molecular weight. The high molecular faction contains mainly patatine, resulting in a dry food ingredient. The low molecular faction is a liquid containing mainly protease inhibitors. The technology allows for the isolation of soluble proteins from potatoes, covering the whole pH range. Protein from legumes and cereals is usually insoluble. "Furthermore, purified potato protein has good foaming, emulsifying and bio-functional properties,"​ said Harry Gruppen of Wageningen University in The Netherlands. The first commercial applications of Solanic's potato-derived proteins are expected to be launched this autumn, at Food Ingredients Europe in London.

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