Challenges on the hunt for new dairy substitutes
Plant-based dairy products are gaining more and more popularity due to increasing interest in alternative diets and lifestyles, as well as the increasing awareness about the sustainable production of food and especially proteins.
Despite the growing interest and awareness from consumer site, the market is still in its infancy and still needs to process. Soy-, rice- and almond-based dairy products were a good start, but they are often not produced under sustainable farming conditions or just have a low protein yield. Therefore, they are not yet fulfilling the current desires of many consumers. Alternative plants have to be found, which are healthy and nutritious, have a pleasant taste already or can easily be transformed by simple techniques into a pleasant tasting product, are non-allergenic, gluten-free, not genetically modified and of course affordable to fit consumer desires.
Legumes, like peas or beans, seem to be the most promising candidates at the moment, as they are affordable, relatively easy to grow and already come with a high in protein content, which is one of the most important factors on the hunt for new plant sources for dairy substitutes.
Why? The answer is simple. The consumer should be able to switch fully to plant-based milk without diminishing his or her total protein intake. Especially as bovine milk contributes one-sixth of the daily protein intake of most consumers. The final plant-based milk substitute should, therefore, have a protein content of around 3.1-3,5g protein per 100ml, which is for a legume-based milk a manageable goal.
A more difficult goal for legume-based milk to reach is the provision of a broad spectrum of amino-acid, which is currently a problem of legume-based kinds of milk and is limiting the bioavailability of the consumed proteins. This means that although the protein content of the legume-based milk is equally high compared to bovine milk, the uptake by the consumer's body is not. Beans and peas are often lacking in the amino-acids methionine and cysteine, which is limiting factor when it comes to the bioavailability of their proteins. Product developers of legume-based milk should, therefore, make sure that they should use plant varieties, which are higher in those limiting amino acids or that they blend them in by using an additional plant protein source containing those limiting amino acids.
In addition, product developers should not just have an eye on the spectrum and sequence of the amino acids because of the nutritional value of the final dairy alternative, but also because they are defining the tertiary structure and thereby the functionality of the proteins. The sequence and amino-acid spectrum are, for example, defining the strength of internal bonds, which determine the technological properties, such as the isoelectric point, the strength of potential gels and the rheology of the final product, which are of major importance when you think of much more complex dairy alternatives, like plant-based yogurts or even cheeses.
It is a complex system of interactions, which is still not a hundred percent understood, especially as the room or tertiary structure and therefore the functionality of the proteins is not just influenced by the pure amino acid spectrum and sequence itself, but also by other factors, like the presence of salt and minerals in the surrounding medium, or the surrounding temperature and pH-Level. Just to name a few of the many factors influencing the structure and function of proteins.
That's why there is still a lot of trial and error involved when it comes to the development of plant-based dairy substitutes and especially in yogurts and cheese substitutes. A situation with is really limiting the development of more complex dairy alternatives at the moment and challenge which will probably still take some years to be solved.
Turning away from the plant-based proteins, there are also other challenges in the development of plant-based and especially legume-based dairy alternatives. Two major ones are the calcium content and the taste.
Legumes, of course, come along with a beany taste, which is not desired by customers and is why many are switching more and more to a nut or oat-based milk substitutes. The two main reasons responsible for the beany flavours are the presence of unsaturated fatty acids and the enzyme lipoxygenases, which catalyses the formation of nonvolatile hydroperoxides from unsaturated fatty acids and turns it into medium-chained aldehydes and alcohols such as n-hexanal and n-hexanols which create the bean-like flavour. Heat treatments like UHT are probably the most common techniques to deactivate the lipoxygenases and eliminate potential beany flavours, but this also sometimes leads to an undesirable alteration of proteins. Enzymatic treatments with enzymes like aldehydrogenase, able to convert aldehydes into the corresponding acids, seem to be a better option but need significantly more time. A promising approach seems to be to carry out the milling and the rest of the production produces under an oxygen-free atmosphere or even without any contact with any atmosphere. As the lipoxygenase needs oxygen it can’t convert the unsaturated fatty acids into the beany flavour components.
The easiest option to get rid of the beany flavour would be of course to mask the flavour, with sugar or sweeteners, artificial flavours, but with increasing Clean label trend, this is maybe not a desirable option.
Last but not least, also the calcium content of plant-based dairy products is a challenge. Dairy products are for most consumers the main source of calcium and are contributing in regions like North-America and Europe more than 50% to the daily calcium intake. Soy milk on the other hand just contains one-fifth of the calcium concentration of bovine milk and can't, therefore, be seen as a full dairy replacement. That’s why many plant-based milks are fortified with extra calcium carbonate or tri-calcium phosphate salts to compensate the missing calcium.
Most of the time producers are even adding more calcium to the plant-based milk, as milk alternatives like oat and soy milk contain significant concentrations of phytic acid and oxalate, which are diminishing the bioavailability of minerals like calcium, but also iron, zinc, and magnesium. Substances which can't be filtered out easily, without losing other nutrients or functional properties of the final product. Another challenge with still has to be overcome.
As you can see there are still a lot of challenges to be solved and things to be considered while developing a plant-based milk alternative or even while you are looking for new raw material for a new plant-based dairy alternative. It still a long journey in front of us and we believe that there will probably not the one plant, which will be able to provide the same nutritional values and technological features, equal to bovine milk. It will probably be a combination of different plant ingredients and maybe also synthesised additives.