Using reporting guidelines to improve the reproducibility of cooking Christmas tree meringues: the "People tasting...

To test whether improving a Christmas tree meringue recipe using reporting guidelines yields more appealing and sweeter meringues.

A prospective, superiority, single-blind, cluster-randomised (1:1) controlled trial.

A public participatory event in a large cultural facility in France.

Budding chefs with basic culinary skills, possessing the utensils necessary for baking Christmas tree meringues, and not having burned pasta in the past month (for safety reasons). Bunding chefs represent the cluster and meringue the unit.

Each budding chef was randomised to a standard recipe for making Christmas tree meringues or to the same recipe written in consultation with a professional baker using the TIDieR checklist-a reporting guideline for description of complex interventions-plus a short video tutorial.

The primary outcome was reproducibility in terms of visual aspect. Secondary outcomes included colour, size, taste and survival time in the course of a sale organised as part of the public event. The visual aspect, colour and size was rated by an independent jury which compared the cooked Christmas tree meringues with the recipe picture on a scale from 1 to 10. Analyses were performed in intention-to-eat (randomization unit: budding chefs / analysis unit: Christmas trees).

60 budding chefs (30 in each group) baked a total of 845 Christmas tree meringues. There was no significant difference between the groups (mean difference = -0.1; [95%CI -0.99; 0.80]; p-value = 0.84; intra-cluster correlation, ICC = 0.77) on visual aspect. No difference was found for reproducibility in terms of colour (mean difference = -0.31; [95%CI -0.97; 0.35]; p-value = 0.35; ICC = 0.67) or size (mean difference = -0.17; [95%CI -1.07; 0.73]; p-value = 0.71; ICC = 0.74). There was no significant difference in terms of taste between the groups (mean difference = -0.55; [95%CI -1.62; 0.52]; p-value = 0.31). 400 meringues were sold during the public event with no difference in survival time between groups (hazard ratio = 1.26 [95% CI 0.75-2.09], p-value = 0.38, with values > 1 in favour of the control group). e.g. 75% survived for 134 min in intervention group and for 124 min in the control group.

Our study failed to demonstrate that an improved recipe using the TIDieR reporting guideline with a video tutorial improved the reproducibility in terms of visual aspect, colour, size, taste and sales for Christmas tree meringues. The best way to succeed in reproducing Christmas tree meringues alike those showcased by the recipe-and thereby to improve reproducibility of experiments-remains a mystery still to be solved by further explorations.

https://osf.io/dnhbx .