1. Introduction
For more than 8000 years, cow milk has been an essential part of human nutrition. Milk contains several essential nutrients and is in many countries an important part of dietary recommendations [
1]. In Austria for example, three portions of milk are recommended daily, due to its high content of calcium, proteins, and vitamins (A, B2, and B12) [
2]. However, dairy production has a considerable environmental impact. The main environmental issues related to milk production are soil degradation, air and water pollution, and loss of biodiversity [
3]. In the bigger context, one third of households’ total environmental impact in the EU countries is connected to food and drink consumption [
4].
The rising emergence of lactose intolerance, milk allergies, environmental concerns, and problems due to diets rich in cholesterol are leading toward a growing demand for dairy alternatives [
5]. Negative headlines in the internet, such as “Milk Life? How About Milk Destruction: The Shocking Truth About the Dairy Industry and the Environment” [
6] from an animal welfare organization, “11 Reasons to Stop Drinking Cows’ Milk” [
7] from an environmental platform, or “Milk is not good for your bones” [
8] from a popular food blogger are exemplary for a rise of critical voices. Plant milk is often presented as a healthy, sustainable, and animal-welfare-friendly alternative [
9,
10,
11]. Derived from the water extraction of legumes, nuts, or cereals, plant milk is completely free from animal-based ingredients [
12]. Plant milk is similar in appearance and taste to conventional milk and is used for the same purposes [
13]. Dietary lifestyles such as veganism and flexitarianism are drivers behind a rising demand for plant milk [
13,
14]. Plant milk has somehow become a lifestyle instrument, consumed by many not only because of dietary issues, but also because of individual beliefs [
15]. The available plant milk products on the market vary with respect to their nutrients, and it is common practice to add vitamins, minerals, and proteins to them [
13]. Vegan plant milk alternatives often contain added calcium to serve as a comparable cow milk substitute. Worldwide, the plant milk market is growing substantially. It is leaving the niche market and becoming main stream [
16] (see also the next Section).
The category of plant milk is not really new on the market; leading companies such as Oatly or Alpro started in Europe in the 1980s. New is the dynamic growth in recent years [
16]. Despite the rising economic success of plant milk beverages, there has been no study undertaken comparing the product image of cow milk with plant milk. Subsequently, there has been no study published yet comparing the motives of European consumers for consuming plant milk versus cow milk. There are three studies available that investigate the acceptance of soy-based products compared with conventional milk products [
17,
18,
19], and one study done with consumers in North Carolina, looking at the importance of specific product attributes of cow milk versus plant milk [
20]. This gap in the research leads to the two-fold research objective of this paper: first, to quantitatively measure the product image of cow milk and plant milk, and second, to qualitatively investigate the motivational structures of plant milk consumers versus cow milk consumers. Understanding the motives and the product image of both product categories delivers important insights for the plant milk sector; namely, how to further develop and explore a fast-growing food market category, and for the dairy sector, how to respond to changing consumer preferences.
The structure of the text is as follows: in
Section 2, we will present trends and sustainability challenges in the global milk and plant milk market, followed by a literature review on consumer studies about cow milk and plant milk in
Section 3. At the end of the literature review, we will present the research questions for Study 1, the quantitative part of this article including the derived hypotheses (product image analysis), and the research questions for Study 2, the qualitative part (means-end chain analysis).
Section 4 describes the materials and methods of Study 1 and Study 2,
Section 5 the results, followed by
Section 6, where the results are discussed with respect to findings from literature and conclusions are drawn.
2. Trends and Sustainability Challenges in the Global Market for Dairy and Plant Milk
Worldwide, milk is one of the most valuable agricultural raw materials. In 2013, global milk production reached a value of US
$328 billion, with a share of cow milk at 82.7%, buffalo milk (13.3%), goat milk (2.3%), sheep milk (1.3%), and camel milk (0.4%) [
21]. For 2025, global milk production is forecasted to rise by 23% compared to the global production level in 2013 [
21]. The increase of demand for dairy will mainly happen in Africa, South Asia, and East Asia [
22]. The level of liquid cow milk consumption in Asia is significantly lower than that in developed countries, yet in the last decades, dairy consumption doubled in East Asia [
22]. In the USA and in Europe, cow milk consumption is steadily declining [
23].
The global plant milk market reached an estimated size of US
$8.51 billion in 2016 and is forecasted to rise to a CAGR (compound annual growth rate) of 12.5% to triple to a market volume of US
$24.6 billion in 2025. Soy milk is globally the dominant plant milk with respect to market shares [
24]. The highest consumption of plant milk is in the Asian-Pacific area [
25].
US market data from the retail sales research company Nielsen shows that cow milk’s sales have declined in the USA by 6% in 2017 [
26]. Over the course of decades, the decline of cow milk sales in the USA was even more dramatic. The consumption of liquid cow milk in the USA has dropped by 35.6% from 1975 to 2016. From 2000 to 2004, it fell by 5.1%, but from 2010 to 2014, it decreased by 10.2% [
27]. In contrast, plant milk sales are up by 9% compared to the previous year [
26]. Even more impressive is the growth in the categories of plant-based yogurts (+55%), plant-based cheeses (+43%), and plant-based creamers (+131%) in the USA [
26]. In the beginning, US consumers used soy milk to replace cow milk, but in recent years, other plant milk alternatives have gained popularity. Soy milk sales in the USA declined by “double digit per capita consumption” in 2014, while the milk alternative category with grain, nuts, rice, and seed milk had a 28% consumption gain [
27].
In Europe, plant milk is on the way to leave its niche position. An estimated 15% of Europeans does not consume dairy anymore, resulting in a plant milk market share of 4% in Europe [
13], which is still small; however, in the last decade, sales more than doubled, especially for non-soy beverages, which went from a 17% to a 40% share in the plant milk category [
28]. In Austria, for example, the share of households using plant-milk—at least occasionally—amounts to 26% [
29]. In 2015, more than 130 plant milk alternatives were available on the European market, with a value of US
$1.5 billion [
30]. In comparison, the turnover of the European dairy processing sector reached a value of €117 billion in 2004, which represents an approximate value of US
$138 billion [
31]. In EU-15, the per capita consumption of liquid milk declined by 6 kg to 52 kg from 2008 to 2018. The decline in the EU is expected to slow to half the rate of the last decade, resulting in 49 kg per capita by 2030 [
28]. However, the production method has an influence on the growth rates of liquid milk. In France, conventional liquid milk consumption fell by 4%, while organic milk grew by 18% in 2018 [
28].
From an environmental point of view, the dairy (and meat) sector is one of the biggest greenhouse gas producers in agriculture. Additionally, the water and ecological footprint for milk and dairy products is significantly higher than for fruits and vegetables [
32]. On a global scale, the top 20 meat and dairy corporations emit more greenhouse gases than the whole country Germany [
33]. Confirming a systematic review on greenhouse gas emissions of fresh food [
34], the carbon footprint (CF) of cow milk is estimated to amount on average to a mean of
M = 1.39 CO
2-eq/kg (median 1.29; min 0.54, max 7.50); the CF of soy milk amounts to
M = 0.88 (median 0.77; min 0.66, max 1.40). The relevant data for almond milk are
M = 0.42 CO
2-eq/kg (median 0.42; min 0.39, max 0.44) [
34]. Confirming another study, the water footprint of cow milk is 3.5 times higher compared with soy milk [
35]. Altogether, these estimations show that the consumption of plant milk products seems to be much more sustainable compared with the consumption of cow milk.
Cow milk also has a significant environmental impact, because its productions is linked to extensive cultivation of soy beans. Soy bean is a major feed ingredient for dairy cows, and its production is forecasted to double until 2050 [
23]. The main drivers behind the rising dairy demand is a growing middle class in China and other emerging countries, who are switching to a Western-oriented diet. It is highly probable that the additional agricultural area necessary to produce the rising supply of soy bean will be at the expense of rapidly shrinking rainforests. This will further contribute to the loss of biodiversity, whose speed and rate are unprecedented in human history [
36]. In 2017, the EU used 12% of the global soybean production (i.e., 34.4 million tons), of which only 13% (4.5 million tons) can be considered deforestation-free [
37]. Approximately 90% of its use was for feed and less than 5% for human food consumption [
37]. Because of consumer concerns, European soy milk brands aim to source most of its supply from European farmers [
38]. The impact of unhealthy and unsustainable produced food poses a great risk not only for the health of the people, but also for the health of the planet. “Healthy diets have an appropriate caloric intake and consist of a diversity of plant-based foods, low amounts of animal source foods, unsaturated rather than saturated fats, and small amounts of refined grains, highly processed foods, and added sugars” [
39] (p. 448). If more and more consumers are switching from cow milk to plant milk, that could lessen the environmental foot print. Nevertheless, not all plant milk products may be considered sustainable per se. California produces 80% of the world’s almonds, while having experienced four severe droughts in the last decade. Intensive irrigation with aquifer water has led, in some areas, to an annual subsidence of approximately 28 cm per year, which also damages the infrastructure (bridges, roads, etc.) [
40].
3. Literature Review on Consumer Studies about Cow Milk and Plant Milk
A study from 2017 [
20] done with consumers of cow and plant milk from North Carolina applied a choice-based conjoint analysis to rank the importance of specific product features for cow milk and plant milk. For cow milk, the most important attributes identified were fat content (1–2% fat), packaging size (gallon), and label claims (locally farmed). Based on an additional Kano Analysis, “Attractive features for fluid milk (i.e., cow milk) consumers (n = 827) included milk that was all natural, organic, reduced fat, and vitamin fortified” [
20] (p. 6131). However, usually, cow milk is not a natural, untreated product. For example, in Austria, it is not allowed to sell raw milk in retail [
41].
The most important attributes for plant milk were sugar level (naturally sweetened), plant source (almond), and the size of the packaging (half a gallon). Important values for both consumer groups were to achieve a healthy lifestyle and a balanced diet. Both consumer groups reported healthy nutrients, taste (sweetness, creaminess, aftertaste), and interestingly, being lactose free as important product attributes. The interviewees, who consumed only plant milk, reported as motives: the goal to consume fewer animal-derived foods and perceived lower negative impacts on the environment. They had strong beliefs about the abuse of livestock during rearing and slaughtering. Both groups mentioned protein and calcium content as important product attributes. For cow milk consumers, cow milk is seen as a staple food that is often consumed out of habit [
20].
Besides the study from North Carolina, all other studies investigated soy milk or soy products in comparison with cow milk. Palacios et al. found that cow milk is significantly better evaluated with respect to taste and other sensory attributes than soy milk [
17]. Variables like ethnicity, age, gender, or lactose intolerance had no influence. In a follow-up study with children and adolescents, they found similar results. Soy milk without added flavor was the least preferred alternative [
18]. Villegas et al. did a similar study about soy milk with vanilla flavor, and again, cow milk was much more preferred than soy milk [
19]. In those soy milk studies, the consumers were not dedicated plant milk consumers. Taste was the main reason to prefer cow milk over soy milk [
17,
18,
19].
A study with Australian consumers reported better perceptions of cow milk versus soy milk with respect to sensory quality and convenience. Cow milk was perceived as a good source of nutrients with good taste. Negative perceptions of cow milk were related to high cholesterol, fat and energy content of whole milk [
42]. Other studies have shown that cow milk is also consumed because of its nutritional and health benefits [
42,
43,
44,
45]. Lea et al. [
46] observed for consumers of plant-based food products health and nutritional benefits as important factors.
Research indicates that in general consumers are aware of the health benefits of cow milk, especially its importance for bone health and as a source of calcium [
47,
48]. Although soy milk contains about 10 times less calcium compared to cow milk [
49], the studies of McCarthy et al. [
20] and Bus and Worsley [
42] observed that consumers see plant/soy milk as an important source for calcium. Both studies do not clarify if this is a misconception or if it is related to the fact that many plant milk products on the market are fortified with calcium. A study in Switzerland analyzed 45 plant milk products (soy, rice, coconuts, etc.) from the main supermarket chains with respect to their nutrient content. They found that replacing cow milk with plant milk leads to a reduced intake of calcium, proteins, minerals, certain vitamins, and an increased intake of salt [
49].
In 2016, a study of Finnish consumers investigated the motives to replace animal proteins with plant proteins and found the main motives to be environmental concerns, health, weight control, and social aspects [
50]. A focus group study of US consumers and non-consumers of soy food products found that consumers switched to soy because of a lifestyle change [
51]. Lactose intolerance, starting a vegetarian diet, and environmental concerns were the decisive factors to consume soy products. However, as shown by Hajek [
52], many consumers are reporting food intolerances based on their believes and not on medical diagnosis.
The good taste of these products was the reason to continue the consumption of soy products [
51]. For non-consumers, soy had a bad product image, they were not familiar with soy products, they reported that the taste of animal-based products was not replaceable, and they had a lack of knowledge concerning the preparation and use of soy products. The higher costs and reduced availability were the main barriers against the consumption of soy products [
51].
It makes sense to also look at the motives leading to a flexitarian [
13,
14], vegetarian, or vegan lifestyle [
53,
54], because these lifestyles are closely related to consuming more plant milk products. Over the last decades, the motives to become a vegetarian have changed. A study done between 1993 to 1995 reported that the main reason to be a vegetarian was to live healthy. Less prominent reasons were ethical, taste, social, environmental, and economic aspects [
53]. Today, many studies report ethical considerations with respect to animal welfare as the main reason to pursue a vegetarian lifestyle [
54,
55,
56,
57,
58]. Animal welfare is especially, for vegans, the most prominent argument for dietary choices. Less prominent than animal welfare are wellness, health, and environmental concerns [
54]. An international study from 2015 came to similar results. Ethical concerns about animal welfare represented, for 81% of the vegan consumers, the most important motive, and only 19% mentioned health as the main motive (which could also have been influenced by social desirability) [
56]. Another common finding between all of these studies is that mostly women are prone to lead a vegan or vegetarian lifestyle [
54,
55,
56,
57].
Health and environmental aspects are reoccurring motives in those mentioned studies. Other important aspects influencing consumers in their food choice are in particular the local or regional origin [
59], tradition [
60], and the support of farmers and the local economy [
43]. The preference for local, domestic produced food is a form of consumer patriotism, which is also observed in the dairy sector [
43].
Based on these studies the different views of consumers regarding cow milk and plant milk are connected to different values (health, animal welfare, environment, etc.), lifestyles (vegetarian, vegan, etc.), and consumption versus non-consumption or familiarity (factors such as taste, experience, etc. influencing product acceptance [
61]). Such values might influence the perception of a product category and the motivation to consume it. In addition, the product image of a specific product (such as plant milk) is also depending on the product image of competing products (such as cow milk) [
62]. Product images are important means in marketing because they deliver essential information to create unique “brand worlds” and insights into future communication strategies [
63]. This leads to the following research questions (RQ) for the quantitative part of this study (Study 1: Product Image Analysis):
- RQ1.
Is there a difference in the product image of cow milk and plant milk?
- RQ2.
Is the assessment of the product image influenced by the consumption versus non-consumption of plant milk?
As mentioned above, health is an important factor for the food product choice [
20,
50,
51]. “Liking, Habits, Need & Hunger, and Health were rated as triggering eating behavior fairly often” [
64] (p. 125). Therefore, we assumed that the assessment of a product image is influenced in particular by health consciousness. The variable “health consciousness” was used as a mediator variable [
65]. More health-conscious persons will probably try to reduce animal products in their diet, as mentioned above [
20], and will therefore evaluate cow milk worse and soy milk better than persons with less healthy behavior. The inclusion of mediator variables such as health consciousness to explain purchase behavior is comparable to studies from the literature [
66]. The relevant research question 2 is:
- RQ3.
Is health consciousness influencing the product image evaluation of cow milk and plant milk?
The corresponding hypotheses for research questions 1 to 3 are:
Hypotheses (H1). There are significant differences in the assessment of the product image of cow milk compared to plant milk.
Hypotheses (H2). The consumption of plant milk influences the evaluation of the product image of plant milk positively and the evaluation of cow milk negatively.
Hypotheses (H3). There is a positive correlation between health consciousness and the evaluation of the product image of plant milk and a negative correlation between health consciousness and the evaluation of the product image of cow milk.
The product image analysis delivered first insights into the different perceptions of cow milk versus plant milk. The literature about the consumption of plant milk showed that most studies are dealing with the acceptance of plant milk in comparison to cow milk. However, there is still a lack of literature dealing with motives in connection with values of consumers and specific product attributes. This information was obtained from consumer interviews through a means-end chain analysis. Therefore, in the second, qualitative part of this study (Study 2: Means-End Chain Analysis), in depth qualitative interviews with two separate groups, cow milk and plant milk consumers, were applied. The corresponding research questions are:
- RQ4.
Which motives are determining the consumption of plant milk in comparison to cow milk?
- RQ5.
Are environmental aspects and animal-welfare important motives for the consumption of cow milk and plant milk?
Because of the qualitative and explorative nature of the second method, it is not possible to test hypotheses. In accordance with theory of science, the results of the qualitative interviews represent hypotheses.