Multiple keyword loop?

If I have this text file:
—keywords.txt
banana
grapes
apple
mango
orange
pear
coconut
strawberry
—
..and I want to see if any of those words are in a string:
ie:
If (banana or apple or orange or pear are contained in my text file) {
$keyword = "the word that was found";
}
for example: if apple was a line in the text file, then:
$keyword = "apple"; //apple was found in the list and has become the $keyword
also, if there are multiple keywords – just the first one found would do….
Multiple keyword loop?

See original post by MrLeN