[MUSIC] Hi, my name is Wender Bredie. I am Professor of Sensory Science, Faculty of Science at the University of Copenhagen. At the Department of Food Science, we are about 180 scientists and technical staff working on the many different aspects of foods and the technology to produce them. In my research group, the Section for Sensory and Consumer Science, we focus on the sensory quality of foods and the role and meaning of sensory properties for consumers. We just work with highly experienced people, so called analytical panels, who can evaluate the different nuances in taste, textures, and appearances of different kinds of foods using the five senses under controlled experimental conditions. Besides measuring sensory quality of foods with well trained sensory panels, we also work on understanding the mechanisms of food acceptance by consumers. This is particularly interesting since sensory acceptance and the eating habits people develop over their life span are closely related which in turn influences people's personal health and well being. We believe that sensory properties of foods play an important role in the different habits people develop with foods. In a world where global trade makes food more widely available across different cultures, our exposures to food items change and our eating habits are continuously adjusted in small steps, at a time. Given the fact that over the next decade more than 3 billion people are moving from poverty to middle class status, they will get access to new food commodities. We have two major global challenges. On the one hand, there's a proportion of the world population who has developed food habits being programmed to overeat, while at the same time, in other parts of the world, the evolving segment of middle class consumers should be prevented for this to happen. We can only contribute to the understanding of how foods become accepted or rejected and how food behaviors and habits develop over the life span. In this respect, one also has to realize that foods are eaten at different times of the day for different purposes and occasions and that food items often are consumed as part of a meal, this making the topic of the study of food acceptance complex and challenging. In my presentation, I will present different ways people learn to accept foods, mainly from a sensory perspective. I will give arguments to support that the acceptance of foods varies over the lifespan and show evidence that food acceptance can evolve from early exposures and simple conditioning mechanisms. I will conclude with an example showing the difficulties in creating accept for healthy foods in a case study with Nordic muesli bars. This is a major challenge facing food manufacturers and restaurant and in, and catering businesses when trying to introduce healthy food alternatives to consumers. Let us first look what already may happen in programming of food acceptance in very early life. It is well established that the earliest occurances of sensory inputs already take place before birth. In the utero, the unborn child is exposed to tactile and sound inputs, but also to different tastes and smells via amniotic fluid. For instance, preferences for sweet tastes are already developed before birth just like the rejection for bitter and sour tastes. In an elegant study, the prenatal exposure to aniseed flavor was shown to exhibit positive head movements towards aniseed odor in infants just after birth. In infants for mothers not exposed to aniseed flavor, the response was indifference. In general, exposure to flavor substances are expected to derive from the mother's diet and related homeostasis processes. There is a clear evidence for a relation between what a mother eats during pregnancy and the initial stages of flavor programming in the unborn child. This relationship becomes even clearer after birth when the infant is fed by mother milk or formula milk. Research has shown that the extent to which flavor components in the mother's diet can be transmitted through the milk varies widely. For instance, mentol, a major component in chewing gum, can enter mother milk and remains present up to eight hours after ingestion. Carvone, a major component in caraway seeds, is even more pronouncedly present when consumed in the same quantity as mentol. On the other hand, isopentyl acetate, a common component present in banana, or banana flavored sweets, and model for other esters, is broken down and metabolized so quickly that it cannot be traced back in mother's milk. Other [UNKNOWN] components, for example present in fruits, perfumes, and food flavorings, tend to be detectable in mother's milk continuously. Just indicating a slow rate of metabolic removable from the body after uptake or possibly even storage in the adipose fat. Since the eating behavior and physiology of the mother is individual, it is obvious that the exposure of the infant during this pre and early post natal periods vary within and between individuals. Individual differences can be nicely illustrated by a rather large variation in the levels of carvone in mother milk after intake of a similar amount of this flavor component in different test process. But formula milk, being more constant in flavor composition than mother milk, differences in the easiness of acceptance of novel flavors in the weaning period have been related back to the kind of milk feeding the infant did receive. Breast fed infants showed a greater accept of novel flavors than infants fed with formula milk. These early differences in flavor experiences clearly have some impact on the development of food preferences in individuals. Some studies report that the learned preferences in the first two years of life even remain all the way into adulthood. Another aspect with infants is that, in comparison with toddlers and other children, they tend to accept new flavors more rapidly with relatively few exposures required. Early exposure to a variety of flavors during pregnancy and lactation may therefore being important in assisting desirable long term dietary outcomes. Further more, varying formula milk rather than being fixed on a particular brand, might be beneficial for this purpose as well. The exact outcomes remain still difficult to predict at the individual level and other aspects of acceptance learning also need attention. When looking at other age groups across the lifespan, it is interesting to observe that acceptance of food is not learned as easily across different ages. After the first say, two years of life, introduction of new foods can become more difficult. At age between two and six years, a greater decline in accepting novel foods is generally observed. This, again, disappears for most people in later childhood and adolescence. Not until old age, this phenomenon may return when people can become particular picky about their food likes and dislikes. I've introduced some of the phenomena occurring in sensory acceptance of foods. I would now like to turn to some mechanisms that have been recognized in relation to food acceptance learning. Food acceptance learning in real life is not an explicit task, but rather a cascade of less organized occasions in which one gets confronted with different food offerings while being influenced by several other factors. From a sensory perspective, preference learning can be seen as a conditioning towards specific sensory product attributes or combinations of these. We can distinguish between four kinds of preference learning. Namely, the medicine effect, flavor-flavor learning, flavor-nutrient learning, and mere repeated exposure. Let's first have a look at the medicine effect. The effect is known from rat studies when the animal is given a dose of toxin causing temporal malaise. When presenting a flavor A to the rat just before onset of the illness and subsequently presenting another flavor B just before recuperation, repeated exposure to these flavors will show a greater preference for flavor B. This is an example of linking a flavor to a negative experience while subsequently competing with a flavor linked to a positive experience. Taste aversions can also be induced in this way in humans. But, aversions are more commonly learned after exposure to an off flavor in a food, leading to a decreased preference for that particular food over a prolonged period of time. The second preference learning mechanism, flavor-flavor-learning, lets people associate a positively experienced flavor with a novel or less liked flavor. In popular language, this is sometimes called, ketchup effect. This learning can be used to gradually get people acquainted to the novel flavor and subsequent removal of the light flavor may result in acceptance of the novel or less liked food. This mechanism has proven successes with children with a high degree of resistance to engage in eating novel foods. In other popular versions, flavored pairing is utilized in high end cuisine. Although, here, the preference for a flavor pair is often confused by the chef with novelty or surprising effect of the flavor pair. The third principle, called flavor-nutrient learning, pairs a target flavor with a specific nutrient content. For instance, a food that typically produces a pleasant feeling of satiety. This is done to increase the liking of the target flavor. In this way, the nutrient experience reinforces the flavor of the food. An example could be the increase of liking for artichoke puree by adding vegetable oil. The prior condition would be a low or disliked artichoke puree which after conditioning with the vegetable oil will give a higher liking of the artichoke puree alone, or the after conditioning situation. Experience learns that this is a difficult conditioning task. The reverse of nutrient flavor conditioning may also be utilized, although flavor will normally only be used to reinforce the intake of nutrients. For instance, in malnurished patients in a hospital. In this case, the individual flavor preferences of the patient need careful attention. The last principle using the senses to accept foods is called mere repeated exposure principle. Here, the absence of a negative consequence or flavor leads to a gradual increase of the liking for the product upon repeated exposure. The principle works even well at subliminal level where subjects have no idea of what series of stimuli they are being presented to. The mere repeated exposure mechanism works well with adults, especially when they are not aware of being subjected to repeated exposures. In our own research on acceptance of new Nordic foods in school children, we used this principle to see if it could work with school children aged nine to 11. We wanted to learn the children to eat a healthy muesli bar which contains sea buckthorn, a berry with a high vitamin C content that grows particularly well in the Nordic countries. In the first test, we made a selection of muesli bars based on the preference expressed by school children in Denmark and Sweden. We selected a bar with sea buckthorn, which was not liked very much, as well as the muesli bar with kamut, which was liked particularly well, but had a significant higher energy content. The challenge was to see if repeated exposure over a period of several weeks could lead to a greater acceptance in terms of liking and intake of the sea buckthorn bar. In this way, we could show that the more reasonable muesli bar, for a morning break at school, sea buckthorn, could become a wanted item. The mere repeated exposure study clearly showed that the kamut bar remained popular, but at both the liking and the amount eating of the sea buckthorn bar reached similar levels after nine exposures. This effect remained present in a follow-up test. This strongly indicated that the mere exposure principle worked for the least-liked muesli bar. This study also showed an important dilemma for introducing new healthy foods, namely that several exposures are needed until sensory accept. In many real world situations, such practice would not be chosen and the kamut bar would have been selected. Rounding off my presentation, I have introduced several principles that exist in sensory acceptance of foods and indicated that over the lifespan, different periods of sensitivity for acceptance may exist. The challenge for letting people eat responsibly may already start at early life, but the situation is complex and the timing when different principles work best still needs further clarification. Combining mere repeated exposure with a selection of choices could be, for instance, a strategy to let people, especially children, learn to eat foods with desired health benefits. The field of food acceptance is still developing and research on different principles and strategies, including timing of interventions, will help widen the area of possibilities to learn people to adapt to more healthy eating practices. Especially in public institutions, such as schools and canteens, such techniques may be utilized in the future. Although sensory acceptance may have a high priority, it should not be neglected that many of our food preferences and food habits develop in coexistence with our environment, social, and cultural, and economic context. Therefore, other factors beyond sensory accept also need further attention. Thank you. [MUSIC]
