The role of additives in plant based mylks

Manufacturers offer a selection of different stabilisers, emulsifiers, regulators and nutritional additives, on top of the core ‘plant-based’ ingredient. That ingredient itself can be as little as 2% of the mylk, so what makes up the rest of the mylk? Luckily a food technology degree is not needed to improve your understanding of the roles that each of the additives play in creating a mylk that is fit for purpose and nutritious.

Many of the additions to plant based mylks provide the functions that dairy milk have. While others give it the form that gives familiarity to the mylk, without the downsides that dairy milk can have for some people. For example foamability and consistency.

In dairy products, milk proteins, mainly whey but also caseins, play a role as surfactants and foam stabilisers due to their amphiphilic nature. Therefore, to obtain a dairy milk-like foam structure, it is necessary to add surface-active agents (surfactants) to the vegetable mylk, since some of them are naturally low in protein, such as oat milk, which consists mainly of carbohydrates. For this reason, soy milk is often used as a base for other types of mylk, as it provides the amount of vegetable protein required for nutritional value and foam stability.

In short, proteins form a thin film on the surface of air bubbles and stabilise them. Surfactants act in a similar way, adsorbing to the air-water interface and preventing air bubbles from coalescing.

To understand the difference between the properties of dairy milk and vegetable mylk, let's look more closely at their composition and nutritive value. The main difference is in the amount of protein. Whole milk (3.5 - 4% fat) and semi-skimmed milk (1.5 - 2% fat) contain an average of 3.5 g of protein per 100 ml of milk, while most plant-based alternatives, with the exception of soy milk, contain less than 1 g of protein in the same amount. An important point here is that the quality and, consequently, nutritional value of milk proteins and plant proteins are different. For example, the same amount of essential amino acids found in a glass of milk is found in 1.7 glasses of soy mylk, 7.9 glasses of oat mylk, and 58.2 glasses of almond mylk (data provided by FrieslandCampina). Amino acids are the building blocks of protein. Essential amino acids are amino acids that the body cannot produce itself, we can only get them from food. Protein is broken down into these amino acids during digestion in the intestines. The body needs them to make new protein for our bones and muscles. Proteins that contain many of these essential amino acids are considered higher quality proteins.

As far as micronutrients are concerned, milk and dairy products are the main sources of calcium in our diet. On average, they contain 120 mg of this micronutrient per 100 ml of milk. In addition, the bioavailability of calcium from dairy products is higher because the calcium ions are bound by relatively weak bonds with phosphorylated fragments of serine in casein, whereas the calcium ions in plant alternatives are strongly bound with oxalates, phytates, etc., which lowers their bioavailability to the human organism.

Manufacturers of plant mylks usually enrich their products with calcium to achieve the average amount of that micronutrient in dairy milk (120 mg/100 ml). Dairy milk is also a source of phosphorous and iodine which is essential for the synthesis of thyroid hormones. The amount of iodine is quite low in soy, rice, oat, and almond mylks. (Angelino et al, 2020)

It is important to understand that plant mylks, i.e., almonds, are not identical to almonds themselves in terms of nutritional value. On average, mylks contain between 2% and 15% plant base, such as soy, almond, rice, oat, or coconut.

So how are raw plant materials processed so that they are suitable for foaming? Fermentation is the key process in the production of plant mylk. Fermentation involves the conversion of complex carbohydrates, such as starch, into simple products such as alcohols and acids, followed by the formation of CO2 under the action of enzymes. In general, the fermentation softens plant fibre, improves the product’s organoleptic properties, and develops new flavours and aroma.

To make oat mylk, for example, the oats are first mixed with water and milled, then enzymes (amylases) and/or microorganisms are added to the mixture to break down the starch molecule into smaller components, primarily the disaccharide maltose, which gives the drink its natural sweetness. In the next step, the oat base is separated from the remaining solid particles and other necessary components (depending on the manufacturer) are added. To ensure microbiological safety, the mylk must be heated (pasteurised or UHT treated). It is then homogenised to achieve a consistent, smooth texture and stability. This prevents the separation of the fats from the liquid. When manufacturers want to make a mylk for baristas that is suitable for heating and foaming, they usually add some additional components. These ensure the formation, stability and texture of the foam suitable for latte-art. Let us take a closer look at the most common components of a professional mylk for baristas.

Chemical compounds can be added to the plant base to improve its organoleptic properties and the ability to make stable foams, and it is important to note that manufacturers ensure the safety of these additives for human consumption. Furthermore, not all additives are synthetic, they can also be 100% natural in origin.

In mylks designed for coffee drinks, the stability of the proteins has been increased by acidity regulators. Carbonates, phosphates and citrates (dipotassium phosphate (Е340iii); monopotassium phosphate (E340i); calcium carbonate (E170) are an alkaline buffer to the coffee. They prevent a rapid reduction in pH when the plant-based beverage comes into contact with acidic coffee. In other words, these acidity regulators increase the pH (increase the alkalinity) of the plant mylk so that when the more acidic coffee is mixed with the mylk, the regulators are able to buffer the acidity to stop the mylk from becoming acidic and splitting.

Emulsifiers are surface-active components that provide foam formation and stability when insufficient proteins are present in the mylk. They prevent coalescence of air bubbles and retain the liquid in the foam to restrict drainage. In terms of mylks, soybeans often play a role as an emulsifier, as they are rich in proteins; also, tricalcium phosphate (E341) a multi-purpose additive acting as an acidity regulator, anticaking agent, emulsifier and stabilizer; You may also see these ingredients on label of plant mylks: gums - gellan gum (Е418), which is also a thickening agent or xanthan gum (E415); emulsifiers and stabilisers lecithins (E322); mono- and diglycerides of fatty acids (E471) that are made from vegetable fats, mainly from soy, palm, or rapeseed oil and glycerine.

Stabilisers give stability to the mixture and prevent it from separation. In addition to above-mentioned substances mylks frequently contain sodium polyphosphate (E452) and/or carrageenan (Е407);

Plant mylks often contain added fat, such as sunflower or rapeseed oil, for a pleasant taste and texture.

Vitamins and minerals are often added to mylks to increase their nutritional value. For example, mylks are often fortified with calcium, vitamins D and B2, and, less frequently, iodine.

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There is often confusion in the nomenclature of flavours. Flavours are added in very small amounts and vary or enhance the flavour of a product. There are three main groups of flavours: natural, nature-identical, and artificial. Natural flavours are derived from animal or plant materials and are not further chemically modified, e.g., vanilla extract. Nature-identical flavours are obtained by chemical processing or modification of other natural compounds and are chemically identical to them, e.g., vanillin, which is identical to the vanillin in vanilla but is not derived from vanilla beans. Finally, artificial flavourings are all flavourings that are not defined as natural, even if they have the exact same chemical composition as flavourings isolated directly from nature.

Milk packaging often has the claim "No added sugar" but the nutritional information still lists "carbohydrates". The "No added sugar" claim ensures that the manufacturer has not added any mono- or disaccharides, such as sucrose, to the product. Carbohydrates are nevertheless included, as they are naturally present in the raw materials and can also be produced during fermentation.

Professional mylks for baristas are vegetable-based multicomponent blends. Mylk can be successfully foamed thanks to the proteins naturally present in the plant base. The group of components called emulsifiers stabilise the air bubbles in the foam. The taste and quality of a mylk strongly depends on the combination of these components as well as on the quality and origin of the raw materials - plant base and additives. Plant mylks play a valuable role in catering to people with preferences and/or needs for non-dairy alternatives. The range of options today mean that avoiding dairy milk, does not mean missing out on your favourite espresso drink.

References

Angelino, D., Rosi, A., Vici, G., Dello Russo, M., Pellegrini, N., Martini, D. (2020). Nutritional Quality of Plant-Based Drinks Sold in Italy: The Food Labelling of Italian Products (FLIP) Study. Foods (Basel, Switzerland), 9(5), 682

Dainese-Plichon R, Schneider S, Piche T, Hebuterne X (2014) Lactose malabsorption and intolerance in adult subjects. Nutrition clinique et metabolisme: 46

Dhesi, A., Ashton, G., Raptaki, M., Makwana, N. (2020) Cow's milk protein allergy. Paediatrics and Child Health 30 (7): 255-260

Gänzle MG, Haase G, Jelen P (2008) Review: Lactose: Crystallization, hydrolysis and value-added derivatives. International Dairy Journal 18: 685-694

Güngörmüş, C., Kılıç, A., Akay, M. T., & Kolankaya, D. (2010). The effects of maternal exposure to food additive E341 (tricalcium phosphate) on foetal development of rats. Environmental Toxicology and Pharmacology, 29(2), 111–116

Leksmono, C. S., Manzoni, C., Tomkins, J. E., Lucchesi, W., Cottrell, G., & Lewis, P. A. (2018). Measuring Lactase Enzymatic Activity in the Teaching Lab. Journal of Visualized Experiments, (138)