The number of loaves from each company is 60, 76, and 84. To ensure that each store has the same number of loaves from just one company, the total number of stores should be the least common multiple (LCM) of 60, 76, and 84.
First, find the LCM of 60, 76, and 84. The prime factorization of these numbers is:
\[
60 = 2^2 \times 3 \times 5, \quad 76 = 2^2 \times 19, \quad 84 = 2^2 \times 3 \times 7.
\]
The LCM is found by taking the highest powers of all prime factors:
\[
\text{LCM}(60, 76, 84) = 2^2 \times 3 \times 5 \times 7 \times 19 = 4 \times 3 \times 5 \times 7 \times 19 = 7980.
\]
Thus, the minimum number of stores is \( \frac{7980}{60} = 133 \), \( \frac{7980}{76} = 105 \), and \( \frac{7980}{84} = 95 \). The least value is 55, so the minimum number of stores is \( \boxed{55} \).