In fast food restaurants, solid fats such as shortening or lard are often used instead of liquid oils for frying due to several advantages in terms of performance, cost, and texture of the fried food.
- Stability at High Temperatures:
- Solid Fats: Solid fats, such as partially hydrogenated oils or animal fats, have a higher smoke point compared to many liquid oils. This makes them more stable and less likely to break down or oxidize when exposed to the high temperatures commonly used in fast food frying (350°F to 375°F).
- Liquid Oils: Some liquid oils, like vegetable oil or canola oil, can have lower smoke points, which can lead to faster degradation and the production of undesirable flavors and harmful compounds.
- Longer Shelf Life:
- Solid Fats: Because solid fats are more resistant to oxidation, they have a longer shelf life both in storage and during use in the fryer. They can be used for longer periods without needing to be changed as frequently, making them cost-effective.
- Liquid Oils: Liquid oils tend to oxidize faster and may need to be replaced more often, especially in commercial settings, leading to higher maintenance and cost.
- Crispiness and Texture:
- Solid Fats: Solid fats, especially when used in deep frying, contribute to a desirable crispy texture in fried foods. Fast food chains often aim for this crispy exterior, which solid fats can enhance. Solid fats can also give fried foods a richer mouthfeel.
- Liquid Oils: Liquid oils may not produce the same level of crispiness. They tend to soak into the food more, resulting in a slightly greasier texture. They may not create the same crunchy exterior as solid fats do.
- Note: the temperature recovery and thus the power of fryer also plays an important role to determine the crispiness of fried foods
- Flavor:
- Solid Fats: Many fast food chains prefer the flavor imparted by solid fats. Fats like beef tallow or lard can add a distinct taste to fried foods, such as French fries, which is often associated with traditional fast food flavors.
- Liquid Oils: Liquid oils like soybean or sunflower oil have a more neutral flavor, which may be preferred in some applications but may lack the characteristic taste provided by solid fats.
- Health Considerations:
- Solid Fats: Many solid fats used in fast food, such as partially hydrogenated oils, contain trans fats, which are harmful to cardiovascular health. However, some chains have moved away from these and switched to healthier alternatives.
- Liquid Oils: Liquid oils such as olive oil, sunflower oil, or canola oil contain healthier fats (unsaturated fats) and are generally considered a better choice from a health perspective. However, they may not perform as well under high-heat commercial frying conditions.
- Cost:
- Solid Fats: In the past, solid fats like partially hydrogenated oils were often cheaper than healthier liquid oils, making them more attractive to fast food chains looking to reduce costs.
- Liquid Oils: Some liquid oils, especially those with healthier profiles (e.g., olive oil or avocado oil), can be more expensive, which makes them less commonly used in large-scale commercial frying.
Safety Precaution
When using solid fat, make sure you wrap the solid fat around the fire tubes of gas fryer or heating elements of electric fryer. Always start from the lowest temperature setting. Click here to read more.
Conclusion:
Fast food restaurants often prefer solid fats for frying because they are more stable, last longer, provide a crispier texture, and impart distinct flavors. However, health trends have led to a shift toward liquid oils in some places, especially those with better health profiles. The choice ultimately depends on balancing performance, cost, flavor, and health considerations.