Crystallization of Caramels

I would appreciate any suggestions on how to prevent delayed crystallization of my caramels. I have been using Recchiuti's Fleur de Sel recipe from his 'Chocolate Obsession' book which uses the dry technique for making caramels. I've noticed that my caramels start graining up about a week out, despite enrobing them in chocolate and storing them in a sealed container to hopefully limit moisture attraction. I'm wondering if there isn't enough 'doctoring agent' in this recipe? Here is my current recipe:

5 drops Lemon Juice
298 g Sugar
1/2 Vanilla Bean
232 g (1 cup) whipping cream
38 g light corn syrup
14 g 82% Butter
1/2 tsp fleur de sel

Are there any general guidelines for the ratio of corn syrup to sugar? If I do increase the corn syrup and decrease the sugar by equal amounts, will this affect the texture of the caramels.

Thanks in advance for your suggestions.

Alan

updated by @alan-b: 04/13/15 05:49:32PM

If you reduce fat, you will increase the stickiness of the final product. If you decrease corn syrup or glucose the flow properties will change. Less glucose/corn syrup, less flow in the final product. The reverse is also true, more fat, less stickiness, easier to bit. More glucose, more flow. Play with these only in small percentages (like 2-4% adjustments at most). Make sure all your sugar is fully melted. Add glucose/corn syrup only after you have dissolved all sugars.

Hi Jeff,

Thank you for these guidelines. That's exactly what I've been looking for. I'll start by increasing the corn syrup slightly, with a corresponding decrease in caster sugar and see how this affects crystallization and flow.

Cheers,

Alan