Oat milk is a type of plant milk derived from whole oat (Avena spp.) grains by soaking the plant material to extract its nutrients. Oat milk naturally has a creamy texture and a characteristically oatmeal-like flavor, though it is sold commercially in various flavor-varieties such as sweetened, unsweetened, vanilla, and chocolate. Unlike other plant milks, whose origins date as early as the 13th century, oat milk is a modern creation, developed by the Swedish scientist Rickard Oste in the early 1990s.
Oats contain high amounts of functional protein, dietary fiber (β-glucan), and unsaturated fatty acids, which make oat milk a significant source of nutrients, though uncertainty surrounds its practical use as a dairy milk substitute. Regardless, oat milk is often consumed to replace dairy milk in vegan diets, or in the cases of medical conditions where dairy is incompatible, such as lactose intolerance or a cow's milk allergy (CMA).
Soy milk predates all other alternative milks, including oat milk, both as a cultural and commercial product. Within the past hundred years, soy milk made its way from Asia to European and American grocery stores, initially as a dairy substitute due to lactose intolerance. The increase in consumption of soy milk since its global distribution created a large market for plant-based, non-dairy milks like oat milk.
Oats have traditionally been grown as a minor cereal crop for animal feed, but have more recently been used in the production of functional foods, due to their high nutrient density and known beneficial health effects. The first example of an oat-based plant beverage was in the early 1990s, when Rickard Oste developed oat milk. Oste was working as a food scientist at Lund University in Lund, Sweden, researching lactose intolerance and sustainable food systems, when he invented the drink. Soon after, Oste founded Oatly, the first commercial manufacturer of oat milk.
The pioneer in commercial oat milk, Oatly, now has its products in over 2,200 coffee shops and 1,000 grocery stores across the United States, but is not the only prominent oat milk producer. Oat milk can be found under brand names Oatly (Sweden), Pureharvest (Australia), Alpro (UK), Bioavena (Italy), Simpli (Finland), Vitasoy (Hong Kong), and Pacific (USA), among others.
The large market expansion was officially recognized by the United Kingdom in March of 2017 when "non-dairy milk drinks" were added to the Office for National Statistics' inflation basket for the first time. Another indication of oat milk's rise in popularity is the 2018 decision of PepsiCo (a company ranked #102 on Forbes' 2018 Global 2000 List of the World's Largest Public Companies) to develop an oat drink of its own, "Quaker Oat Beverage," under the Quaker Oats brand.
There have been numerous occasions of oat milk shortage from unprecedented demand in Europe and North America, highlighting the high level of consumer demand for this product.
The production of oat milk is similar to that of most other plant milks. Cereal grains like oats are indigestible when unprocessed due to their hard, outer hull, so processing is necessary to create a product with nutrients which are bioavailable. The procedure starts by grinding, or milling, oats to break apart their outer hull.
Soaking and subsequently extracting nutrients from the oats have the most direct implications on the final milk product. Increasing the yield in this step may be assisted by chemical catalysts, enzymes, or an increase in temperature, all in order to remove nutrient molecules from the solid byproduct and incorporate them into the liquid. Chemical catalysts increase the pH of the mixture, enzymatic catalysts induce partial hydrolysis of proteins and polysaccharides, and higher temperatures increase reaction rates. Separating the liquid from the solid byproduct is a simple step achieved through filtration, decanting, or centrifugation.
Once the liquid product is isolated, adding other ingredients, such as fortifying vitamins and minerals, or sweeteners, flavorings, salts, oils, and similar, formulates the final product. Oat milk is naturally lower in calcium, iron, and vitamin A than dairy milk, so the addition of these nutrients is necessary in order for the product to be a viable dairy milk substitute. Homogenization and heat-treatments such as pasteurization or ultra-high temperature (UHT) treatments are used to extend the product's shelf life.
Challenges to processing
Because oat milk is produced by the disintegration of plant materials, the resulting particle sizes are not as uniform as bovine milk. This variation in particle size is due to the vastly different lipid and protein molecules. Decreasing particle size, improving particle solubility, and using hydrocolloids and emulsifiers are common ways to improve product quality via homogenization.
Another problem posed by the natural composition of oats is their high starch content. The starch content (50-60%) is challenging during UHT treatments because of starch's relatively low gelatinization temperature. To overcome this, producers use an enzymatic hydrolysis of starch by alpha- and beta-amylase, producing maltodextrins which gelatinize at higher, more suitable temperatures.
Adding ingredients as fortifying nutrients is also a difficult procedure. The nutrients must be bioavailable and stable in the final product, otherwise the quality or effectiveness of the product may be insufficient. Research is often funded to discover procedures which successfully incorporate bioavailable nutrients into oat and other plant-based milks.
Oat milk is highly applicable for diets of individuals who suffer from lactose intolerance (LI), cow's milk allergy (CMA), celiac disease (CD), irritable bowel syndrome (IBS), radioiodine cancer treatment, eczema, inflammatory bowel disease (IBD), and possibly other conditions which cause poor reactions to dairy. The worldwide prevalence of lactose intolerance is 75%, and while not all individuals affected by LI may be potential customers for oat milk, the pervasiveness of LI provides a strong future outlook. Oat milk is a recommended dairy milk substitute for individuals who suffer from IBS and IBD as part of the Anti-Inflammatory Diet (AID), thus IBS and IBD patients report a much higher intake of oat milk than other demographics.
Use of oat milk in one's diet can also be a lifestyle choice, independent of medical dietary restrictions. Consumers may opt to buy oat milk for its more environmentally sustainable footprint, compared to dairy milk, or in protest of the inhumane treatment of animals in some dairy productions.
Multiple studies have found that oat milk is also viable substitute for dairy milk in producing fermented milk products such as yogurts, kefir, prebiotics, and probiotics, retaining its characteristic nutrient content.
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