Study protocol of the sweet tooth study, randomized controlled trial with partial food provision on the effect of low, regular and high dietary sweetness exposure on sweetness preferences in Dutch adults

Table 5 Test foods used in the preference and intensity testing with sweetness and saltiness concentration levels and percentages of added sweetener (sugar + non- and/or low-calorie sweeteners) and salt in % by weight, for each level. The stimuli are used to assess the primary (preference) and one of the secondary outcome measures in the Sweet Tooth trial

	Test food	Food form	Serving size	Sweetener concentration^a (% by weight)
	Test food	Food form	Serving size	L-2	L-1	L-0	L + 1	L + 2
Familiar	Strawberry flavoured lemonade^b	Liquid	20 ml	0.00	1.26^c	3.08^c	8.56^c	15.06^c
	Chocolate flavoured custard^b	Semi-Solid	15 g	3.41^c	6.59^c	12.37^c	17.57^d	26.33^d
	Plain Cake^b	Solid	20 g	9.13^c	16.74^c	19.15^d	21.88^d	25.10^d
Unfamiliar	Watermelon flavoured lemonade	Liquid	20 ml	0.00	1.26^c	3.08^c	8.56^c	15.06^c
	Elderflower flavoured custard	Semi-Solid	15 g	3.61^c	6.98^c	13.05^c	18.90^d	27.59^d
	Tamarind flavoured cake	Solid	20 g	9.13^c	16.74^c	19.15^c	21.88^d	25.10^d
				Salt concentration^a (% by weight)
				L-2	L-1	L-0	L + 1	L + 2
Familiar	Gazpacho	Liquid	20 ml	0.05	0.15	0.30	0.72	1.46
Familiar	Butter cracker	Solid	3.5 g	0.00	0.71	1.37	3.50	7.05

^aFive sweetness/saltiness levels, with the middle level (L-0) representing the optimal sweetness/saltiness sensation, initially based on the quantity present in the commercial products or recipes as described by Urbano et al. [65], and to some degree adjusted after pilot testing with Dutch consumers
^bRecipes for food preparation adapted from Urbano et al. [65]
^cAdded sucrose
^dAdded sucrose and liquid sweetener based on cyclamate and saccharin (Rio Zoetstof, Sweet Life AG, Switzerland)

ISSN: 1471-2458