Abstract

Freeze-drying is a dehydration process that uses low temperature and pressure to remove moisture from food. With an annual market value of over $35 billion in 2023, freeze-dried foods are widely used in various situations requiring long-term storage such as military rations, emergency food supplies, and space exploration. Freeze-dried foods are becoming more popular for their quality, light weight, easy storage at room temperature, and quick rehydration. Moreover, many freeze-dried food manufacturers claim that their freeze-dried food products can last for 25 years or more. However, there are currently no published studies supporting such claims. Chemical, physical, and sensory properties of freeze-dried foods stored for over 50 years were compared to 1-2 year-old products to better understand their shelf-life potential and the changes that occur during extended storage. Products included in the study were beef, beef stew, scrambled eggs, green beans, carrots, sweet corn, apples, and ice cream. We evaluated key factors such as water activity (Aw), moisture content, rehydration ratio, fat percentage, volatiles, vitamins, and consumer preferences for appearance, aroma, texture, and flavor. Results showed that water activity (Aw) for all freeze-dried foods ranged from 0.02 to 0.3, indicating all the FD foods were safe to consume. The moisture content varied widely across food types, with aged beef having the lowest at 0.96% and new green beans having the highest at 5.26%. Nutrient degradation was notable in water-soluble vitamins, particularly thiamine. Aged beef and green beans lost 78% and 49% of their thiamine, respectively. Moreover, aged eggs had higher levels of vitamin B12 than new eggs. Moreover, fat-soluble vitamins also showed significant changes, with vitamin D reduced by 45% in aged eggs, while aged beef had higher vitamin E than the new FD beef. The findings suggest that while freeze-dried foods may remain safe over long periods, their nutritional content, especially vitamins, can degrade over time. The sensory results also showed some variations among the stored and new FD foods in different sensory parameters. However, almost 98% of the panelists from the sensory study responded that they would be willing to consume the aged FD foods during an emergency. Key

Degree

College and Department

Life Sciences; Nutrition, Dietetics, and Food Science

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