The technology

Six projects are concerned with the question whether it is possible to make a tasty product and whether it can be done from a technological point of view. Different points of focus are the crop, product aspects (texture and flavour) and the production chain.

The production chain

Options for non-protein fractions in a transition from meat to plant proteins
To enable a transition from meat to plant proteins, it is important to consider what options exist for the non-protein fraction. Any crop that is used to produce protein-rich food products will, at one or more points in the production chain, also produce one or more fractions that cannot be used for the plant protein product. These residues may arise in various different forms and may have different compositions depending on the crop used, the part of the production process where they arise, and the actual production techniques used. This means that both the economic value and the environmental impact of the non-protein fraction can vary greatly. The likely uses for the non-protein fractions that arise as a result of a possible protein transition are investigated. As these investigations are part of the PROFETAS programme in which the pea was chosen as a model crop for enabling a protein transition, the pea will be used as a starting point. Other crops and their non-protein fractions are discussed and conclusions are drawn concerning contribution of the non-protein fraction to the suitability of (groups of) protein producing crops for a large-scale protein transition. Finally, changes in world agriculture inevitably accompany a large-scale transition from meat to plant protein. The role of the non-protein fraction in these changes has two different faces. The decrease in feed crop production has important consequences such as decreasing the availability of current feed crop by-products, but at the same time this opens up possibilities for large changes in land use. Through such large changes in land use the protein transition could not only make food production more sustainable, but it could also assist in making the world’s water use and energy supply more sustainable.
For more information please contact Frank Willemsen

Methodology for efficient chain design
This study looks at chain design focusing on product attributes rather than on delivery of the product, as is the case in traditional supply chain management. Food chains are made up of links and are designed to deliver a particular product with consumer-specified attributes. These attributes are used to select goals (quality, cost and environmental load) to optimize the chain. In this study, the goals were first looked at independently of each other. Multicriteria decision making is used now to integrate the goals. This is done by proposing many alternatives and ranking the goals as desired by the decision makers.
The developed methodology presents a systematic way to identify problem areas in supply chains. The entire chain from primary production up to and including consumer processing may influence the attributes of the final product. It is shown, however, that the relative contribution of the links to the product varies according to the goal for which the chain is being designed and optimised. The choice of the performance indicator is critical as it traces the changes in the goal as the product moves through the chain.
Case studies on a novel protein food made from pea protein are presented to showcase the methodology. The three goals were looked at independently. The quality of the NPF was traced by studying the water holding capacity of the pea protein through the chain. Consumer processing, product processing and ingredient preparation were the links that influenced the quality most. The cost to produce the NPF was studied by looking at alternative supply chains. The total supply costs appeared lower than current products available in the market. Exergy analysis of the NPF chain was used to show that the NPF chain has a marginally lower environmental load (in terms of exergy input and efficiency) than the reference pork meat chain.
For more information please contact Radhika Apaiah  

Product aspects

Protein-induced texture formation in NPFs
The most important globular pea proteins are legumin and vicilin, and a minor protein is convicilin. The first two have extensive molecular heterogeneity that is well documented in literature, and the latter possesses a distinctive highly charged N-terminal extension region. Characterisation of two vicilin fractions (one contaminated by convicilin) via column chromatography, gel electrophoresis, differential scanning calorimetry (DSC), circular dichroism and solubility experiments lead to the conclusion that convicilin is not a separate protein. It was denoted as the α-subunit of vicilin, and is another heterogeneous factor of this protein. Further experiments showed that when present in large amounts these α-subunits increase the minimum gelling concentration of purified pea proteins at near-neutral pH, and cause transparent heat-induced gels to be formed. This behaviour was attributed to the repulsive forces on the N-terminal extension region at near-neutral pH, and was supported by the fact that no difference in the gelation behaviour of the two vicilin fractions was observed at low pH values where the repulsive charges would have been neutralised. These α-subunits also appeared to have an impact on the gelation of the pea protein isolates when present in sufficient quantity. Heat-induced gelation of legumin was compared with its analogous protein in soybean, namely glycinin. Overall the results of DSC and small deformation rheology showed that both the proteins have the same physical and chemical driving forces acting during gelation, but soybean glycinin, unlike legumin, was consistently able to form reheatable gels. Comparison of the amino acid profiles of the two proteins gave no indication as to why these homologous proteins form gels with different gel network stabilities. When comparing protein isolates and legumin from different pea cultivars it was shown that the contribution of legumin to pea protein isolate gelation was cultivar specific and that disulphide bonds played a role in gelation, but they did not demonstrate the gel strengthening ability that they are often reported to possess.
For more information please contact Francesca O'Kane

Protein-flavour interactions in NPFs
Flavour involves aroma and taste, which are important characteristics for the acceptability of novel protein foods (NPFs). Peas contain both volatile and non-volatile flavour compounds that influence aroma and taste. The volatile organic compounds (VOCs) in peas belong to 3 main groups, the aldehydes, ketones and alcohols, whereas the non-volatile compounds consist of 2 types, the DDMP saponin and saponin B. Pea flour contains the highest amount of VOCs compared to its protein preparations, and the type and amount of VOCs released are influenced by protein purification and pH. Pea vicilin showed affinity for exogenous aldehydes and ketones, whereas legumin showed affinity only for the aldehydes. Vicilin preparations at various pH contained non-protein components, lipids and carbohydrates, which exhibit greater affinity for VOC than vicilin itself. DDMP saponin was stable at around pH 7 and at ethanol concentrations > 30% (v/v), but lost its stability and was converted to saponin B with the loss of the DDMP group at acidic and alkaline pHs, and at temperature > 30 oC. Both DDMP saponin and saponin B have a bitter taste, which is related to their saponin contents. DDMP saponin is significantly more bitter than saponin B. The contents of DDMP saponin and saponin B differed among 16 varieties. DDMP saponin predominates over saponin B in all varieties except in 2, in which DDMP saponin was the only saponin present. There are numerous types of saponins in the plant kingdom and they are structurally summarised into 22 simplified skeletons and classified into 6 main classes using oxidosqualene as the starting point. The mother of all saponin skeletons is that of the oleanane, which is widely distributed in many plants. The type of substituents and their position of attachment to oleanane skeleton do not seem to be plant order-specific. Sugar chains of up to 8 sugar residues can be attached and are commonly at C2 and/or C18 of the skeleton. Overall, the results obtained in this research have provided essential knowledge on flavour aspects, especially with respect to off-flavours, in the development of NPFs.
For more information please contact Lynn Heng

The crop

Designing sustainable plant-protein production systems
An indispensable component of PROFETAS is to gain insight into the options for sustainable production of the raw plant-protein material and to design tools and strategies for the development of such sustainable systems. The complexity of primary production systems calls for a systems approach such as process-based crop modelling. As in other crops, seed yield per hectare in protein-rich crops (e.g. the PROFETAS model crop pea) depends on both the cultivar and the environment. A new, innovative generic crop growth model GECROS (Genotype-by-Environment interaction on CROp growth Simulator) was developed. By using such a model, an optimal production system can be defined with respect to pea production and resource use efficiency. Furthermore, potential pea producing areas can be identified. The model was applied to a range of European conditions for pea crop. We run the model with three water supply scenarios. Predicted crop productivity depends strongly on water supply scenarios. Yearly variability in predicted crop productivity was greater under water-limited conditions. Areas with potentially high predicted productivity, such as Scotland, Denmark, North Germany, and part of France, are also regions in Europe where pea is widely grown. The Netherlands seems to be well suited for growing pea. From a PROFETAS point of view, it is noteworthy to mention that the model predicts little chance to increase total seed protein production per unit area (the maximum being 1.8 ton/ha) by using pea cultivars having a high protein content, because these cultivars would have lower seed biomass yields. With respect to the future development of PROFETAS, the GECROS model could be a powerful tool in identifying the difference among various (leguminous) crops in resource use efficiency in terms of biomass, protein and starch production and assessing quantitatively the consequences of an increased cultivation of (leguminous) crops on soil fertility and environmental load.
For more information please contact Xinyou Yin

Modification of pea protein composition by genetic and conventional methods
Pea (Pisum sativum L.) seeds are a rich and valuable source of proteins, which can have potential for food industrial applications. Pea storage proteins are classified into two major classes: the salt soluble globulins, and tile water-soluble albumins. The globulins are subdivided into two major groups based on their sedimentation coefficient: the 11S fraction (comprising the class of legumin with various isoforms) and the 7S fraction (comprising the classes of vicilin and convicilin, each with various isoforms). Pea cultivars with extreme variation in globulin composition (i.e. lacking a particular class of proteins) might become important for the food industry, because they could provide new raw materials for specific applications, like the production of NPFs, which receive attention as possible meat replacers. This research aimed at (i) to determine the existing natural variation in pea's globulin content and composition, in order to identify suitable cultivars for the production of NPFs, (ii) to develop a more efficient protocol for genetic modification of pea, and (iii) to modulate pea protein composition, based on dsRNA directed silencing. An inventory of protein content and composition of pea was performed to characterize the genetic variation for these traits. To include a wide range of natural genetic variation, cultivars from a wide geographic distribution, with differences in leaf and seed characteristics, were selected and characterized. Large variation was observed between the various lines. Results on protein content showed a variation from 16.3% 36.6% of dry matter (DM), with an overall average content of 26.6%. Globulins content varied between 49.2% and 81.8% of the proteins of the total pea protein extract (TPPE). On individual globulins level, legumin content varied between 5.9%o and 24.5%. Vicilin was the most abundant protein of pea, and its content varied between 26.3% and 52.0% of the TPPE. The processed vicilin was the predominant of the two, with values between 17.8% and 40.8%, whereas the non-processed ones constituted between 3.1% and 13.5% of the TPPE. Convicilin was the least abundant globulin having an average content of 6.1%. Its content ranged from 3.9% to 8.3%. Finally, the globulin-related proteins were present in amounts ranging from 2.8% to 17.3% of the TPPE. The globulins showed the largest relative variation of the four globulin classes. It is known that a low vicilin/convicilin ratio can result in poor gelation. Based on our data and the literature, it is concluded that pea isolates have a more favourable protein composition for gelling applications as compared to those from soybean. Moreover, the genetic variation for this trait appears to be larger in pea than in soybean, which might offer opportunities to reduce the convicilin content further. Our inventory did not show cultivars lacking a specific globulin. Such cultivars might be important, because they could have more favourable physical properties for the production of NPFs. To produce such lines genetic modification approaches were employed. To carry out genetic modification a reliable protocol is needed. At the time this study started, protocols for the production of genetically modified peas were available, but particularly the regeneration of plants from transgenic cells was very inefficient. Most of the plants obtained were either escapes or chimeric (not all cells of a plant are genetically modified). Therefore, our study focused on obtaining a novel regeneration protocol, which in combination with the transformation procedure would result in an improved method for obtaining transgenic pea lines.
For more information please contact Manolis Tzitzikas

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