Elizabeth H. Zandstra

Effects of variety and repeated in-home consumption on product acceptance.

The present study was designed to investigate the effect of variety on long-term product acceptance and consumption in a home-use situation. Subjects (N= 105) consumed a meat sauce once a week at dinner at home for a period of 10 weeks. Three variety groups were designed. The monotony group (N= 45) consistently received the same flavour of meat sauce across all 10 weeks; the imposed variation group (N= 30) received one from three different flavours of the meat sauce in random order, and the free choice (N= 30) in variation group was allowed to choose among three flavours of the meat sauce. Results showed a substantial increase in boredom and decline in acceptance ratings after repeated consumption. As hypothesized, this effect was the largest for the monotony group and was least pronounced in the free-choice group, with the imposed variation group in between. Consumption data were in line with these acceptance ratings; the monotony group consumed less of the food than the free-choice group over that time. In conclusion, repeated consumption of a food product only once a week at home resulted in a remarkable increase of boredom over time. The boredom effect was the largest for subjects who consistently received the same food, and was least pronounced for subjects who were allowed to choose among three different flavours of the food.

Influence of health and taste attitudes on consumption of low- and high-fat foods

Abstract The present study investigated the relationship between health and taste attitudes and the total dietary behaviour as measured by a validated 104-item food frequency questionnaire. The study population consisted of 132 adults (mean 53 years of age, range 18–76 years; 82 women and 50 men). Health and taste attitudes were assessed by a validated questionnaire which consisted of three health sub-scales ( general health interest , light product interest and natural product interest ) and three taste sub-scales ( craving for sweet foods , using food as a reward and pleasure ). Dietary behaviour was expressed as nutrient intake and in terms of the intake of various types of foods (low-fat vs. high-fat foods). The health sub-scales general health interest and light product interest were good and useful predictors of dietary behaviour. General health interest was associated with a lower intake of fat, a lower consumption of high-fat savoury snacks and high-fat oils and fats, and an increased consumption of vegetables and fruit. Light product interest was associated with a higher consumption of low-fat dairy products and vegetables and fruit. The taste attitudes were not related to any type of dietary behaviour; only the taste sub-scale craving for sweet foods predicted food consumption of high-fat sweet snacks. In conclusion, general health interest was related to a more healthy food consumption pattern. Healthier food choices were made in line with nutrition education messages, but only with respect to those foods where the fat content was clearly visible.

Short- and long-term effects of changes in pleasantness on food intake.

This study concerns the effects of pleasantness on ad libitum food intake, liking and appetite over 5 successive days. Pleasantness was manipulated by varying the salt level in bread. Thirty-five students consumed ad libitum sandwiches for lunch, made with bread individually perceived as low, medium or high in pleasantness, in a balanced cross-over design. Pleasantness and desire-to-eat the sandwich were rated at first bite, after the consumption of each sandwich and at the end of the lunch. Fullness was rated just before and at several intervals after lunch. On the first day, the students ate less of the least pleasant bread than of the medium and most pleasant bread. On the fifth day, however, consumption of all breads was similar. For the least pleasant bread, energy intake at lunch, desire-to-eat and fullness, all increased over days, whereas these variables remained constant for the medium and most pleasant bread. Mean pleasantness ratings for all breads remained unaltered across the days. We conclude that, with repeated exposure, the desire-to-eat, fullness and intake of a less preferred food can increase over time. Thus, the relationship between pleasantness and food intake changes over this period.

Effects of learned flavour cues on short-term regulation of food intake in a realistic setting

The present study examined the effects of repeated midmorning consumption of novel-flavoured low- and high-energy yoghurt drinks on subsequent energy intake at lunch in 69 adults under actual use conditions. Subjects consumed 200 ml of low- and high-energy yoghurt drinks (67 and 273 kcal/200 ml, respectively), with 20 exposures to each drink on alternate days. Analyses focused on the development of compensation for the differences in energy content of the beverages, due to learned satiety. Results revealed incomplete energy compensation for the beverages, both at first exposure and also after 20 exposures. Relative to the no-yoghurt condition, energy intake compensation (+/-S.E.M.) averaged 39+/-36% for the low-energy yoghurt and 17+/-9% for the high-energy version, with no evidence of any change in compensation with repeated exposures. When the flavours of the yoghurt drinks were covertly switched after 20 exposures, subjects increased their energy intake after the high-energy yoghurt drink containing the flavour that was previously coupled with the low-energy yoghurt drink. Vice versa, however, when subjects switched to the low-energy yoghurt drink containing the high-energy flavour, subjects ignored the flavour cue and ate the same lunch size regardless of the energy in the yoghurt drink. We conclude that adults do not readily acquire accurate conditioned adjustments for the energy content in food after repeated experience with the food in free-living natural-eating conditions.

Expecting yoghurt drinks to taste sweet or pleasant increases liking.

This experiment studied the effect of cues on liking of yoghurt drinks. We examined how hedonic (degrees of like/dislike) and sensory (level of sweetness/saltiness) cues affected liking ratings. In the learning phase, thirty-nine participants learned to associate cues with yoghurt drinks. Cues were learned for mildly and highly salty and sweet yoghurts. Sweet yoghurts were used as liked, salty yoghurts as disliked stimuli. Half the participants associated the cues with yoghurt liking (i.e. hedonic cues), the other half with the sweetness or saltiness of the yoghurt drink (i.e. sensory cues). In the test phase a cue was presented to participants subliminally (20 ms) or supraliminally (500 ms) before they tasted and rated liking of one of three yoghurt drinks in each category. The three yoghurt drinks consisted of the trained samples and a new third drink situated approximately half-way in between. The cue-drink combination was either congruent (the cued drink was given) or incongruent (two degrees of incongruence). For sweet yoghurt drinks cue-following assimilation effects were found for the supraliminal but not the subliminal cue presentations. For salty yoghurts, no effects of cue were found. This indicates that the nature of the drinks itself plays a critical role in modulating assimilation.

Effects of energy conditioning on food preferences and choice.

This study investigated the development of conditioned preferences for foods varying in energy content in human adults in a laboratory setting. In a within-subjects design, 44 participants consumed high and low energy yoghurt drinks (255 kcal and 57 kcal per 200 ml serving, respectively) first thing in the morning following 8 h of fasting, every day for two weeks, with 5 exposures to each yoghurt drink on alternate days. The high and low energy yoghurt drinks were paired with two coloured labels (blue or pink), with the pairings fully counter-balanced. Every day of the third (test) week, participants were given a free choice of either consuming the pink or the blue labelled yoghurt drink. Participants chose the high energy drink significantly more often over the low energy drink, suggesting a conditioned preference for a delayed (energy) reward. These findings provide further evidence for energy based learning in human adults. This study also provides a new approach to the conditioning paradigm (cueing energy via a coloured label instead of flavour) and includes a new and important measure in this research area (preference instead of liking).

Social and physiological factors affecting food intake in elderly subjects : an experimental comparative study

Abstract The decline in average food intake in elderly people is attributed to both physiological and social factors. These factors are usually studied in isolation. The present study concerns an experiment in which the effect of social setting on food intake is compared with the effect of physiological challenges on food intake in 24 elderly subjects (6 men and 18 women, age: 75± 4.9 years, BMI=26.6±3.5 kg/m2). Physiological effects were assessed using a preload-test-meal design with a no load, 0 kJ; and 4 preload conditions: low carbohydrate/low fat, low energy, 0.4 MJ; high fat, low carbohydrate, medium energy, 1.1 MJ; high carbohydrate, low fat, medium energy 1.1 MJ; high fat, high carbohydrate, high energy, 1.8 MJ. The preloads consisted of 300 g of strawberry yogurt drink, and were served at 10:00 a.m. The test-meal, served 90 min after the preload consumption, was a lunch of which subjects could eat ad libitum. Social effects on food intake were assessed by using two social settings at lunchtime: cozy and non-cozy. Dependent variables were food intake at lunch and ratings of appetite assessed before the preload, and between preload and test-meal. Results showed that energy intake at lunch was significantly decreased after the high carbohydrate preload and the high fat–high carbohydrate preload (intake compensation of 23 and 15%, respectively), compared to the no preload condition. The other preloads did not have a significant effect on food intake. Energy intake was of 2.5±0.5 MJ in the cozy social setting and of 2.5±0.6 MJ in the non-cozy one. Appetite feelings were generally lower after the preload conditions compared to the no load condition (P

Evidence for the role of cognitive resources in flavour-flavour evaluative conditioning

One way that dis/likes are formed is through evaluative conditioning (EC). In two experiments we investigated the role of cognitive resources in flavour–flavour conditioning. Both experiments employed an EC procedure in which three novel flavoured conditioned stimuli (CSs) were consumed. One was consumed with a pleasant unconditioned stimulus (US; CS+ sugar), one with an aversive US (CS+ saline), and a third with plain water (CS–). Half of participants in each experiment performed a cognitive load task during conditioning. We measured EC using self-reported measures of liking (Experiments 1 and 2) and an indirect measure of liking: drink pick-up latency (Experiment 2). In both experiments, differential EC was observed in the no cognitive load condition but not in the cognitive load condition. This pattern of results was observed in self-reported measures of liking as well as in the drink pick-up latency data. Results from both experiments show that EC occurs only when there are sufficient cognitive resources available. The fact that this was observed using both self-reported and indirect measures suggests that insufficient cognitive resources affect learning itself rather than merely obstructing reporting.