i have a cafe and i store all those food items in my commercial cooler with backup power. it’s been more than 24 hours since the power is out, but the food can last for more than 48 hours. what i do is, i keep the food in the refrigerator section, but the temperature of the whole cooler is kept at 0 celcius. so the food is still safe. when the power is back, keep the food at room temperature for 2 hours to reduce the temperature; then bring the food back to the cooler, it will still be fresh for another 24 hours.