Please check if Following helps:
#!/bin/bash
while [ 1 ]
do
ls -ltr /dir_to/Monitor > out.txt # you can try ls -1l as well, depending upon the requirement
sleep 600
ls -ltr /dir_to/Monitor > out1.txt
if diff out.txt out1.txt > diff.txt; then
echo "Not Changed"
else
echo "Changed" # diff is changed
cp diff.txt diff_$(date +%s).txt #Copy the diff to a different file.
fi
done