Мой вариант:
Moreover appearance of healthy and ready-to-eat product capable to quench thirst on a hot day in any company assortment line helps not only to keep customer loyalty but also largely is able to change the character of strongly marked seasonality in product selling.

Заранее большое спасибо

The introduction of ... into any company's product line ...

если речь о напитке, замените ready-to-eat на ready-to-consume и далее: thirst-quenching beverage

...не только помогает сохранять лояльность потребителя, но и в значительной степени изменить характер ярко выраженной сезонности в продажах продукта. --> not only helps maintain consumer loyalty (to the product), but also breaks/[considerably changes] the largely seasonal pattern of product sales.