Optimising sunflower protein: from protein extraction to sunflower tofu

Sunflower tofu – an alternative to soya products.
As part of Svenja Herzog’s bachelor’s thesis, the study examined how the solubility and yield of sunflower proteins can be improved by specifically adjusting pH, temperature and extraction time. The aim was to lay the foundations for producing protein-rich sunflower extracts and to assess their suitability for developing an allergen-free sunflower tofu. Various sunflower proteins from AOT GmbH were analysed and examined for their extraction properties.

The results showed that up to 45% of the protein contained could be dissolved simply by varying temperature and extraction time. However, raising the pH into the alkaline range had the greatest influence on yield. Using sodium carbonate and adjusting to pH 8, protein yields of up to 90% were achieved. 80 °C and an extraction time of 15 minutes proved to be particularly efficient extraction conditions. Depending on the starting material, the sunflower extracts obtained reached protein contents of up to 74% of dry matter.

In addition, one to two washing steps reduced the colouring polyphenols by up to 98%, while at the same time increasing the protein content to up to 76%. By comparison, the soya protein used as a reference achieved protein yields of just under 50% under the selected conditions. A sunflower tofu was successfully produced from the sunflower extracts. It had a neutral taste and properties comparable to soya tofu in terms of colour and consistency. The thesis shows that sunflower proteins can be a promising raw material for allergen-free plant-based protein products and provides a basis for further studies and process optimisation.

Source: Svenja Herzog 2016