Plant proteins and plant-based protein ingredients should be technologically functional, sensory neutral and nutritionally high-quality in order to be suitable for milk and meat alternatives. Important techno-functional properties include good solubility and pronounced emulsifying, foaming and gel-forming properties. They should also be able to form fibre structures. Equally important are a neutral smell and taste, a colour that is as light as possible, good digestibility and a balanced amino acid profile. Only in this way can products be created that are technologically feasible, nutritionally sound and sensorially appealing.

We mainly deal with proteins from legumes and oilseeds. These belong to the so-called storage proteins and can be easily enriched or even isolated from the raw materials using process engineering. This is an important advantage, because if the technical effort becomes too great, production costs rise significantly – which quickly calls into question the economic viability of implementation.

The characterisation of plant proteins can be carried out at very different levels – for example, if sustainability aspects are also to be taken into account. I myself am primarily concerned with functional properties, especially techno-functional characteristics, but also with the chemical composition of the ingredients. This involves not only value-adding ingredients, but also potentially unwanted substances such as anti-nutritional ingredients as well as the digestibility of proteins. This information is crucial for comprehensively evaluating plant-based ingredients and the products made from them.

We primarily work with non-thermal processes, such as the targeted use of enzymes, to improve the solubility of proteins and thus specifically influence their emulsifying or foaming properties. Enzymatic processes can also be used to cross-link proteins and thereby create specific textures. In addition, fermentation can be used to optimise flavour and break down anti-nutritive ingredients, to name just a few examples. This results in ingredients with tailored properties that can be specifically used in various product applications.

We could now delve deep into protein chemistry, but I don't want to make it that complicated. In the food sector, for example, high temperatures, salt content and pH value play a major role. Such factors alter the structure of proteins and thus also their function.

Hemp is a great plant, and I see a lot of potential here – provided we succeed in (re)building the infrastructure for hemp processing. In our project, we are investigating how functional protein isolates can be obtained from hemp and how by-products such as husks or fibres, which are left over after protein extraction, can be reused. It was particularly exciting that we were able to scale up the process previously developed on a laboratory scale to pilot scale as part of the BMFTR-funded project – a great opportunity that would not have been possible without the project funding. This is because upscaling in the field of plant proteins remains a major challenge. For the first time, we were able to produce larger quantities – over 30 kilograms – of hemp protein, which were tested by our industrial partners in various applications such as sausage or fish alternatives.

Interview: Beatrix Boldt