Pairing vegetables with flavours that are liked by children is a strategy UK mothers already employ in an effort to promote consumption (Chapters 3 and 4). Mothers report the addition of seasonings such as salt as well as offering vegetables with dips and sauces, but it is yet to be established whether such strategies assist children in developing preferences for vegetables. For example, the use of salt has been found to increase vegetable
consumption amongst infants when compared with intake of unsalted vegetables (Bouhlal et al., 2010). However, it has been suggested that repeated exposure to salty foods
reinforces children’s preference for salt (Harris & Booth, 1987) indicating that children may learn to prefer vegetables that are seasoned in this way. Similarly, offering liked dips with vegetables appears to promote initial tasting in young children but has not been shown to offer any advantage in improving liking and consumption over and above simple RE (Anzman-Frasca et al., 2012).
Nonetheless, pairing unfamiliar or disliked flavours with those that are already well liked has been found to induce conditioned preferences in both adult and child participants via flavour flavour learning (FFL) (Appleton, Gentry, & Shepherd, 2006; Brunstrom & Fletcher, 2008; Hausner et al., 2012; Havermans & Jansen, 2007; Johnston, Palcic, Tyler et al., 2011; Mobini et al., 2007; Remy et al., 2013). As previously described, learnt associations
between the two flavours result in an increase in liking and intake of the target flavour even when it is presented on its own. This method has proven effective in producing increases in both liking and intake of vegetables amongst young children. In Havermans and Jansen’s (2007) study primary school children (average age of 5 years) received six pairs of conditioning trials to sweetened and unsweetened vegetable juices. Results demonstrated a significant increase in children’s preference for those juices which had been paired with the sweet taste when subsequently presented unsweetened.
Interestingly, Havermans and Jansen did not observe any change in preference for the unsweetened juices to which children were also repeatedly exposed. It is worth noting, however, that no measure of intake of the vegetable juices was taken during this
intervention so it is difficult to draw conclusions about how this increase in preference might impact on consumption. Several recent studies have shown FFL to be an effective method of increasing vegetable intake in preschool aged children (Caton, Ahern, Remy et al., 2013; Hausner et al., 2012; Remy et al., 2013). Using similar designs and the same artichoke puree target, these three studies compared the relative effectiveness of FFL, RE, and FNL (see Chapter 5 for procedure). Following ten exposures to a sweetened version of the puree, children in the FFL condition of all three studies demonstrated a significant increase in intake of an unsweetened version given post-intervention. However, none of the studies were able to demonstrate any advantage of sweetening the artichoke puree when FFL was compared with repeated exposure to the plain artichoke.
Collectively these interventions offer promising results however, their success seems dependent on the use of a sweet taste as the unconditioned stimulus. Sweet tastes are associated with positive affect (Booth, Higgs, Schneider, & Klinkenberg, 2010) and are particularly enjoyed by children who exhibit an innate preference for sweet tastes
(Steiner, 1979; Ventura & Mennella, 2011). Thus offering children vegetables paired with a sweet taste is likely to boost intake by establishing liking. However, in much the same way that mothers are being advised to reduce children’s salt intake, they are also being encouraged to cut down on added sugars (Department of Health, 2013). For this reason using naturally sweet ingredients such as fruit or pureed fruits might be effective and attractive to parents.
While evidence for the use of RE to promote children’s vegetable consumption appears strong (Anzman-Frasca et al., 2012; Caton, Ahern, et al., 2013; Hausner et al., 2012;
Lakkakula et al., 2010; Maier, Chabanet, Schaal, Issanchou, et al., 2007; Remy et al., 2013), research in support of FFL is limited suggesting further investigation is needed. The
addition of a familiar, already liked flavour may facilitate preference development by encouraging initial acceptance of a vegetable (Anzman-Frasca et al., 2012). That is to say that diluting the intense or bitter vegetable flavour with the addition of a well-liked sweet taste may encourage initial consumption, increasing the opportunity for taste exposure and this may be particularly effective for food fussy children.
The current study set out to establish whether pairing a novel target vegetable with the added sweetness of a fruit puree would successfully induce a conditioned preference for that target compared to RE. It was predicted that both RE and FFL would produce an increase in vegetable intake relative to the control. It was also expected that the addition of the sweet fruit puree would produce greater initial intake of the FFL puree than RE puree (at exposure 1) and that fewer exposures would be needed to the sweet FFL puree than RE puree to produce a significant shift in intake.
In order to effectively test these hypotheses it was first necessary to establish that the addition of a fruit puree would effectively increase the sweetness of the target vegetables. For this reason this chapter will begin by describing the sensory analysis employed to select the target vegetables and to determine the concentration of fruit puree to be used during the intervention before describing the intervention itself.