Sarah picked 200 apples and discarded \( \frac{1}{10} \) of them as defective. To find out how many apples were discarded, we can calculate:
\[ \text{Defective apples} = \frac{1}{10} \times 200 = 20 \]
Now, to find out how many apples were sold as fresh fruit, we subtract the number of defective apples from the total number of apples picked:
\[ \text{Fresh apples} = 200 - 20 = 180 \]
So, the number of apples sold as fresh fruit is \( \mathbf{180} \).