Effects of starting weaning exclusively with vegetables on vegetable intake at the age of 12 and 23 months.

BACKGROUND: The low vegetable intake in children may be attributed to their low preference for vegetables. During the first year of life, first taste preferences are formed, which may track over time. In a previous study to increase infants' vegetable intake and liking, we found that at the start of weaning, infants had a higher vegetable intake in the lab after repeated exposure to vegetable purées than to fruit purées. The current study is a follow-up of these infants at the age of 12 and 23 months, and examined whether the group that started weaning with vegetables continued eating more vegetables than the group that started weaning with fruits. METHODS: At 12 (n = 86) and 23 (n = 81) months of age the children's daily vegetable consumption was reported by their parents using a 3-day food diary. The intake of green beans and apple purée was measured in the laboratory. RESULTS: Reported daily intake of vegetables at 12 months of age was 38 % higher (P = 0.02) in the vegetable group (75 ± 43 g) than in the fruit group (54 ± 29 g), but was similar for both groups at 23 months of age (49 ± 43, 57 ± 35 g, respectively; NS). Both at 12 and 23 months of age, apple and green beans intake in the lab did not differ significantly between the groups. CONCLUSION: These findings suggest that weaning exclusively with vegetables results in a higher daily vegetable consumption until at least 12 months of age. More research is needed to investigate how to maintain this effect.

Selecting food. The contribution of memory, liking, and action.

The goal of the present experiment was twofold: identifying similarities and differences between flavour memory and visual memory mechanisms and investigating whether kinematics could serve as an implicit measure for food selection. To test flavour and visual memory an 'implicit' paradigm to represent real-life situations in a controlled lab setting was implemented. A target, i.e., a piece of cake shaped like either an orange or a tangerine, covered with either orange- or a tangerine-flavoured icing, was provided to participants on Day 1. On Day 2, without prior notice, participants were requested to recognize the target amongst a set of distractors, characterized by various flavours (orange vs. tangerine) and/or sizes (orange-like vs. tangerine-like). Similarly, targets and distractors consisting of 2D figures varying in shape and size were used to assess visual memory. Reach-to-grasp kinematics towards the targets were recorded and analysed by means of digitalization techniques. Correlations between kinematic parameters, memory and liking for each food item were also calculated. Results concerned with memory recollection indices provided evidence of different key mechanisms which could be based either on novelty of flavour memory or visual memory, respectively. To a moderate extent, kinematics may serve as an implicit index of food selection processes.

The role of novelty detection in food memory.

Memory plays a central role in food choice. Recent studies focusing on food memory in everyday eating and drinking behaviour used a paradigm based on incidental learning of target foods and unexpected memory testing, demanding recognition of the target among distractors, which deviate slightly from the target. Results question the traditional view of memory as reactivation of previous experiences. Comparison of data from several experiments shows that in incidentally learned memory, distractors are rejected, while original targets are not recognised better than by chance guessing. Food memory is tuned at detecting novelty and change, rather than at recognising a previously encountered food.

Incidental and intentional flavor memory in young and older subjects.

Incidental and intentional learning and memory for 2 novel flavors were compared in young and elderly subjects. Incidental and intentional learning groups rated 2 new soups on acceptability for different occasions and were tested for memory the next day. On the first day, only the intentional group was asked to memorize the stimuli. With incidental learning, elderly and young were equally good, but the young performed better with intentional than with incidental learning, whereas the elderly did not. There were no age-related differences in perceptual discrimination. When comparing perceived flavor with the memory of it, the elderly tend to overrate intensities of remembered flavor attributes, whereas the young tend to underrate them. Memory was not related to flavor pleasantness or neophobia. Like memory for taste and texture, flavor memory seems to be mainly tuned at detecting changes and based on "feelings of not knowing" rather than on precise identification and recognition of previously encountered stimuli.

Food perception with age and its relationship to pleasantness.

Differences between elderly subjects (n = 46, 61-86 years) and young subjects (n = 36, 18-25 years) in food perception and food liking were investigated. Intensity and liking ratings were assessed for custard dessert, in which flavor enrichment, textural change, and irritant addition were incorporated as strategies to compensate for sensory losses with increasing age. The sensory acuity (taste, olfaction, irritation, chewing efficiency) of both young and elderly subjects was measured with the help of different sensitivity tests. The elderly perceived the custards differently from the young, mainly as less intense in flavor (cherry/vanilla) and less intense in creaminess/swallowing effort. Several of the observed interaction effects were different for the elderly and the young. The majority of these differences manifested as lower intensity slopes for the elderly. Losses in sensitivity to taste and to olfactory and trigeminal stimuli as well as a reduced chewing efficiency were observed on average for the elderly compared with the young. Furthermore, subgroups of the elderly were observed in which the compensatory strategies flavor enrichment, textural change, and irritant addition led to an increase in food liking. However, these subgroups did not differ in their sensory acuity. The present study does not support the assumption that age-associated changes in food perception-caused by losses in sensory acuity-inevitably reduce the food liking of the elderly.

Compensation for age-associated chemosensory losses and its effect on the pleasantness of a custard dessert and a tomato drink.

Differences between elderly subjects (n=52, 60-85 years) and young subjects (n=55, 18-35) in their food liking and their olfactory capability were investigated. Two food systems were used: custard desserts and tomato drinks. Flavor enhancement/enrichment, textural change, and/or irritant addition were incorporated as compensatory strategies into these foods. The addition of low concentrations of both cherry flavor and cream flavor to the custard desserts influenced their pleasantness for the majority of the elderly. The addition of cream topping increased the pleasantness of the custard desserts for both the elderly and the young. The elderly equally liked the tomato drinks with no or with low irritant addition, whereas the young generally disliked an irritant addition. However, the food liking of the elderly was not generally increased by these different compensatory strategies. Instead, subgroups were observed for each compensatory strategy, in which applied compensatory strategies led to an increase in product pleasantness. Age-associated losses in olfactory capabilities did not sufficiently explain differences in food liking, as only elderly with similar olfactory capabilities to the young demonstrated a liking of enhanced flavor. The present study does not support the assumption that age-associated impairment in olfactory capability will inevitably lead to changes in food liking.

Electro-olfactograms are present when odorous stimuli have not been perceived.

After chemical stimulation of the human olfactory epithelium it is possible to record a negative response (electro-olfactogram, EOG) which is interpreted as the summated generator potential of olfactory neurons. The aim of the present investigation was to test whether the EOG is present when olfactory stimuli have not been perceived. Stimulation was performed with vanillin and eugenol at supraliminal and subliminal levels. Twelve healthy volunteers participated in the experiments. Stimuli were applied at an interstimulus interval of approximately 60s. Although recordings were successful in 4 of the 12 subjects, for both stimulants EOG could be obtained even when the stimuli had not been perceived by the subjects. EOG recordings in response to supra- and subliminal stimuli exhibited no major differences, except for the onset of the EOG in response to subliminal eugenol-stimuli which were prolonged compared to supraliminal stimulation. All in all, the present data provide a physiological basis for the subliminal influence of odorous stimuli on human behavior.

Effect of concentration on taste-taste interactions in foods for elderly and young subjects.

An increase in concentration of one of the tastants in a 'real food' might affect not only the perception of the taste quality of that manipulated tastant but also the other perceivable taste qualities. The influence of concentration increase of sodium or potassium chloride in tomato soup, sucrose or aspartame in iced tea, acetic or citric acid in mayonnaise, caffeine or quinine HCl in chocolate drink, monosodium glutamate (MSG) or inosine 5'-monophosphate (IMP) in broth on the other perceivable taste qualities in these foods was studied in 21 young subjects (19-33 years) and 21 older subjects (60-75 years). The results showed that for each of these tastants, except for the two acids, increasing the concentration provoked significant positive or negative interaction effects on the perception of one or more other taste qualities of the product. Especially in the young, olfaction plays a larger role in the assessment of taste intensity than has been hitherto assumed. The elderly are less able to discriminate between the taste qualities in a product, whereas the young are more able to do so.

Taste perception with age: generic or specific losses in supra-threshold intensities of five taste qualities?

The influence of ageing on supra-threshold intensity perception of NaCl, KCl, sucrose, aspartame, acetic acid, citric acid, caffeine, quinine HCl, monosodium glutamate (MSG) and inosine 5'-monophosphate (IMP) dissolved in water and in 'regular' product was studied in 21 young (19-33 years) and 21 elderly (60-75 years) persons. While the relative perception (intensity discrimination) seems to be remarkably resistant to the effect of ageing, the absolute perception (intensity rating) decreased with age for all tastants in water, but only for the salty and sweet tastants in product. When assessed while wearing a nose clip, only the perception of salty tastants was diminished with age. The slopes of the psychophysical functions were flatter in the elderly than in the young for the sweet, bitter and umami tastants in water, and for the sour tastants in product only. The age effects found were almost exclusively generic and never compound-specific within a taste. This study indicates that the relevance of determining intensities of tastants dissolved in water for the 'real life' perception of taste in complex food is rather limited.