Fragen und Antworten zur Verarbeitung pflanzlicher Proteine

Q: Has the use of enzymes been studied instead of alkali and acid for to extract protein?

A: Alfa Laval has an ongoing study on this topic. It should be emphasized that there are two options for using enzymes. The first is using enzymes for hydrolyzation, and second is using enzymes for true extraction. The main product that results from enzymatic hydrolysis are hydrolyzates, which do not have the native properties of the proteins. Therefore, enzymatic hydrolysis is not referred to as extraction. The second type of enzyme use breaks down the components within the flour/flakes to release more protein; these types of enzymes produce native proteins. One has to keep in mind that alkaline method of extraction is a more economic method, and the attractive forces of the enzymes are greater when the standard alkaline extraction has some complications such as unwanted taste or colour.


Q: Is using carbon dioxide for acid treatment a good option to control the ash content in the final isolate?

A: It is an interesting idea that, until now, has not been commonly used for protein precipitation. Carbon dioxide treatment has some limitations. First, it seems relatively difficult to lower the pH values below 6, which is usually not sufficient for protein precipitation and means that an additional acid dosage would be required. Secondly, the effect of lowering the pH of carbon dioxide appears to be slower than that of other common acids, which therefore increases the capital expenses for such a setup.


Q: Can you reach food-grade plant protein?



Q: Do you source a membrane filtration system from one of your suppliers or do you use and Alfa Laval membrane filtration system?

A: Alfa Laval has a membrane filtration department, which has extensive experience in using membrane filtration systems across the membrane industries.


Q: Why are the membrane filtration systems not used for protein extraction instead of precipitation and the decanter?   Is the functionality of the proteins not affected by the precipitation with acid?

A: Membrane systems can be used for precipitation instead of acid precipitation and, in certain cases, they have been used. One has to keep in mind that an acid precipitation and decanter separation setup is normally a more robust setup and therefore it is also preferred. Membrane precipitation requires fine process optimization to make it a viable option.


Yes, the functionality of the proteins can be affected, especially when using higher extraction pH values. On the one hand, it is a question of the pH values used in the process and of residence time. On the other hand, it has been identified that in some cases the precipitated protein has lower amount of anti-nutritional compounds compared to the membrane precipitated protein.


Q: How do you quantify the quality of protein? Can Alfa Laval quantify it?

A:There are many parameters that can describe the quality of the protein, including essential amino acid composition, amount of anti-nutritionals, protein digestibility, functional properties, and organoleptic properties. Alfa Laval generally uses some certified laboratories to evaluate these parameters.


Q: Do you partner with anyone to also understand this? We are looking to investigate a new product in this area.

A: If the question is continuation of the previous question, please see the answer above.


Q: What are the options for removing colour and flavour that are typical to the vegetable proteins?

A:Typically, the removal of colour is only a concern for plant proteins such as sunflower, where the formation of a dark green colour is occurring. We have some solutions to prevent this and you are welcome to contact us to learn more. Alfa Laval is currently investigating various options for flavour removal; currently, we address flavour issues to certain extent by performing a flash step after pasteurization. However, there are also other methods, such as the use of enzymes, that are still being studied.


Q: What is the pH level of white flakes before the protein decanter?

A: Normally around 4.5. This may differ based on the feedstock.


Q: How is the protein loss controlled during the washing step with water, for example, with respect to water soluble proteins?

A: Normally, water soluble proteins do not reach the washing stage, and most of these proteins will already be removed at the protein decanter. The losses are quite low since the pH is still quite low.


Q: For the PHE evaporation duties mentioned, do you tend to only offer AlfaVap or have conventional PHEs also been used?

A: We offer AlfaVap PHEs, which have been specifically designed for evaporation duties.


Q: Which are the most promising plant protein sources in Europe?

A: It is not easy to provide an answer without taking into account a broad range of considerations. Assuming that these should be locally grown crops, then the most promising sources seem to be yellow pea and faba beans for starch crops and rapeseed and sunflower for oilseed crops.


Q: In whey processing UF + NF, what is a typical permeate/concentrate ratio over the systems’ phases?

A: Normally in the NF system, the volumetric concentration factor is around 2 while in the UF system it is approximately 7. Again, these should be understood as best estimates and depend upon the specific feedstock.


Q: Can Alfa Laval do further separation of protein isolate into different major components?

A:This is not currently a focus area at Alfa Laval.


Q: Any ballpark figure on specific energy consumption per ton of products?

A: Please contact us with a specific case since the specific energy consumption depends on many variables such as feedstock and extent of processing.


Q: How are the solubility of the sunflower seed white flake and rapeseed oil white flake? Is there the protein isolate from the flakes?

A: The flakes themselves are insoluble but we can discuss the solubility of the proteins. The solubility normally increases with pH and then after an optimal pH has been reached, the solubility drops. The optimal solubility based on the white flakes appears to be in the range of 60-70%.


Q: What are the proven feedstocks for the Alfa Laval wet fractionation process?

A: The most proven feedstock at this point is soy because Alfa Laval has 40+ years of experience in processing soy feedstock. However, our technology has been also proven when using sunflower, yellow pea, mung bean and other plant proteins.


Q: Are you able to remove off-flavour components from the proteins (soy and pea proteins) during the wet and dry processes? If so, how does Alfa Laval do this?

A: To certain extent, the off-flavours are currently removed by heat treatment. Complete removal seems to be a challenge.


Q: What kind of milling would you recommend for "wooden" by-products such as grape stalk?

A: It is not a feedstock that has been considered until now and would require more study to understand the specifics, such as whether it is possible to extract protein from it.


Q: Do you have lab equipment for protein processing?

A: Yes.


Q: To what extent are the extraction lines compatible for similar crops within one of the two categories (oilseed and starch crops)?

A: The extraction lines are quite similar for protein precipitation and washing. There are also similarities within the extraction, but the biggest difference lies in how the solids from the extraction decanter are treated. It should be also emphasized that oilseeds with low oil content (1-2%) have higher protein content and therefore provide more protein per ton of feedstock.


Q: Is the functionality of the proteins not affected by the precipitation with acid?

A: It is not something that has been studied extensively by Alfa Laval, but the proteins may be affected to a certain extent.


Q: If I would like to process X tons of yellow peas, can Alfa Laval build a complete factory and deliver the full business case?

A:Please contact us with your specific case.


Q: Do you have processes to extract functional protein while keeping the temperature below 60-70° Celsius, so without heat steps.

A: Yes, Alfa Laval can handle that. We would still use a pasteurization step but minimize pasteurization time and therefore also denaturation.


Q: Do you have ion exchange equipment to reduce salts?

A: No, Alfa Laval does not currently supply this equipment but if a customer buys a system from Alfa Laval then it can be included in the scope of supply.


Q: Any experience with extracting proteins from oat fibres?

A: That depends where the fibres are sourced. If the oat fibres are from an oat milk process, then some studies have been conducted and it seems quite difficult to extract proteins with an enzymatic or alkaline extraction because the proteins are severely denatured by the upstream enzymatic steps.


Q: Which types of membranes does Alfa Laval produce (hollow fibre or HF, ceramic, or spiral wound)?

A: Alfa Laval produces spiral wound and plate-and-frame.


Q: Is it possible to combine the wet processing and dry processing to get the protein isolate – first, dry processing and then isolate the protein using wet processing?

A: Yes, it is possible but not something that we would recommend due to the fact that dry processing mills the flour so finely that it is not suitable for proper wet processing. Alfa Laval has identified the following two main issues with this approach:

  • The starch granules appear to be severely damaged, which reduces the effectiveness of the extraction step and also appear to be unsuitable for subsequent starch washing. This product is likely of lower value than handling the starch granules properly.
  • Dry fractionation also concentrates the fats as a side effect, which means there may be issues reaching isolate levels of protein purities within the wet process.


Q: Is it possible to process more than one product on the same line? Does this affect the product quality even after conducting Cleaning-in-Place (CIP)?

A: It is possible, but one has to keep in mind that the performance from the line then will be different. If CIP is conducted properly, then there should not be any issues with quality.


Q: Are there any feed % limitations for flash desolventizing?  How energy efficient is it compared to something like spray drying?

A: Alfa Laval does not supply equipment or process lines for flash desolventization so this question should be directed to one of the companies active within this area. It is probably not fair to compare these two technologies as flash desolventization is used for removing solvent from oil extraction, while spray drying is used to dry the final product such as the produced isolate.


Q: Between the two routes, oilseed-based or starchy grains, which is a more capital-intensive process, that is to say, which one has a higher capex component?

A: That depends on the extent of processing and should be considered on case-per-case basis.


Q: The next stage after isolating the protein is to make protein chubbs through extrusion, which is the main ingredient for vegetable meat. Does Alfa Laval provide equipment/technology for this final step?

A: It should be noted that extrusion is only one outlet of the protein isolate and there could be other applications such as usage as protein powder, usage within drinks, usage within fake-meat burgers, etc. Alfa Laval does not currently have a supply for extrusion.


Q: Has the use of enzymes together been studied instead of alkali and acid for the extraction of protein? If yes, how does one control the protein loss during the washing step with water, such as water-soluble protein?

A: The enzymes are mostly used within the extraction step. The enzymes do not provide any replacement for the precipitation, unless the proteins are hydrolized which is a completely different protein product than that in the extraction step. The use of enzymes for extraction is an ongoing study. If the enzymes are used for extraction followed by acid precipitation, then wash losses will be minor as the protein at this point is still at a low pH. If hydrolyzates are produced, then other washing technologies such as using diafiltration membranes can be used to minimize the loss.


Q: Why are membrane systems not used for the protein extraction instead of precipitation and the decanter?

A: They are used in certain cases, but it is a matter of robustness and making a good analysis about the operation of membranes against the caustic/acid extraction/precipitation with decanter.