A health expert from Mahidol University dispels common misconceptions about processed foods, confirming that modern refrigerated and frozen products don't require preservatives and maintain nutritional value when microwaved. The expert advises consumers to carefully read nutritional labels rather than avoid all ultra-processed foods, noting that many ready-to-eat options are nutritionally sound when properly selected.
Many consumers still believe that refrigerated and frozen food products contain harmful preservatives, that microwaving boxed meals destroys nutritional value, and that eating processed foods causes disease. We're here to clear up these misconceptions and explain how to properly and safely select processed foods with Dr. Wanaporn Thongchom, a health educator and professional dietitian from the Health Promotion Division at Ramathibodi Hospital's Faculty of Medicine at Mahidol University.
Do Refrigerated and Frozen Foods Contain Preservatives?
"Preservatives are another concern many people worry about. Even though there are healthy refrigerated, frozen, and ready-to-eat food options, consumers may still wonder if they contain preservatives.
Modern production processes no longer require preservatives. Instead, foods stay fresh through temperature control, specifically freezing at temperatures below -18 degrees Celsius, which prevents disease-causing microorganisms from growing. High-pressure processing kills pathogens, and specialized packaging like Retort Pouches—multi-layered laminated food containers that are durable and withstand high heat and pressure—are also used. Ready-to-eat foods frequently use Retort Pouches, which preserve food through sterilization and oxygen removal, preventing pathogenic microorganisms from developing.
Therefore, refrigerated, frozen, and ready-to-eat food products don't need preservatives. Consumers can read the nutrition labels and ingredient lists on packaging before purchasing," Dr. Wanaporn Thongchom said.
Does Microwaving Boxed Meals Destroy Nutritional Value?
"This may be a misconception. During freezing, major nutrients like protein, carbohydrates, fats, and fiber don't break down. Research shows that when temperature is properly controlled for long-term storage, certain nutrients are preserved, such as vitamin A, folate, and vitamin C. Microwaving is very safe, and the main nutrients remain at satisfactory levels," Dr. Wanaporn Thongchom said.
How Safe Are Containers Used in Microwaves?
"Some people wonder if microwave-safe containers can withstand heat. The answer is yes, they must be. Plastics come in different grades, and containers labeled as microwave-safe are Food Grade Plastic that can withstand heat and are safe. However, be careful—products may not be designed for repeated microwaving. After using them once or twice in the microwave, you shouldn't reuse them. If you need to microwave more than twice, it's recommended to transfer the food to a different container," Dr. Wanaporn Thongchom said.
Do Frozen Foods Actually Cause Disease?
"Pre-prepared foods that are frozen to extend shelf life fall into the fourth category of the NOVA Classification—Ultra-Processed Foods. However, this isn't necessarily concerning. Industrial production processes inevitably result in foods being classified as Ultra-Processed.
I don't want people to think all Ultra-Processed Foods are health risks. You need to examine each product individually. Today, many ready-to-eat rice bowls are quite healthy because they have clear nutritional labels, confirming we get the energy and nutrients we need," Dr. Wanaporn Thongchom said.