While creating multiple products, you could set a distinct branding for tickets created through emails. You could have this done by setting up a dedicated support email addresses for each Product.
When you create a new product(under Admin > Support Operations > Multiple Products > New Product), you would be asked to provide a separate support email address for that portal. This would be the primary support email address for that product portal and emails sent to this email would get created as tickets and would be updated with the corresponding Product. By default, replies to customers would also be sent through this dedicated email address.