Substring function in Feeds xpath parser module

Hi,
I am using Feeds module. Feeds xpath parser in the feeds module.
after mapping field. i trying to enter the xpath expression to display all content in the content after the "keyword".
i used substring.
it's working. i am doing something wrong.
can anybody help me out?

how to use substring with the keyword search in the tag.
The keyword i have to search is "Ingredients:".
In the tag i have some paragraph of texts . i want to display only the texts after the keyword "ingredient".
please help me to achieve this.