The best temperature for short term refrigeration storage is 4°c or below.
Explanation:
To prevent the spoilage of food for longer time refrigeration is necessary. The growth of bacteria occurs very rapidly from 4°  Celsius to 60° Celsius, therefore, the temperature of the refrigerator should be at or less than 4°(40°  Fahrenheit) Celsius to protect most of the food items. Pathogenic bacteria generally do not grow below 4°  Celsius rapidly.
Further explanation:
Food items contain plenty of nutrients not only for humans but also for pathogenic and microorganisms causing spoilage like bacteria. They can be present in most adverse environments like hot springs to cold antarctic. These are opportunistic organisms and are responsible for spoilage of food.
Most of the bacteria grow more rapidly between temperature 4° Celsius to 60° Celsius which is called the danger zone, therefore, refrigeration temperature should be at 4° Celsius or below to avoid the spoilage of food from the microorganism.
The spoilage of food depends upon moisture and the nutrient content of the food. If the moisture and nutrient content of food is high then the self-life of the food will be low even at the refrigeration temperature because bacteria prefer this environment to grow.  The bacteria that can grow at low temperatures and spoil food are psychrophiles. So food can  be stored at 4° Celsius for only a short period of time otherwise food spoilage or contamination can occur which can lead to food borne diseases if consumed.
Learn more: Â
1. Danger zone for food storage link (answered by Mixter17). Â
2. Role of low temperature and preservative to prevent spoilage of food link  (answered by Jamuuj).
Keywords:
food spoilage, danger zone, bacteria, food borne diseases, psychrophile, refrigeration.
