Name a food preservative which is most commonly used by food producers.

Explanation

**Step-by-Step Solution:**

1. **Understanding Food Preservatives**: Food preservatives are substances added to food to prevent spoilage, maintain natural colors, and flavors. They help in extending the shelf life of food products.

2. **Criteria for Selecting Preservatives**: When choosing a food preservative, it is important that it is non-toxic, flavorless, and economical. These criteria ensure that the preservative does not alter the taste of the food and is safe for consumption.

3. **Reasons for Using Preservatives**: The primary reasons for using food preservatives include preventing spoilage due to oxidation and microbial contamination. Oxidation can lead to the degradation of food quality, while microbial contamination can cause foodborne illnesses.

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