|Don't fall for the "trick! In fruit A loss of water weight can cause "increases" in relative vitamin content.|
To be more specific, the scientists evaluated the ascorbic acid, riboflavin, α-tocopherol, and β- carotene in corn, carrots, broccoli, spinach, peas, green beans, strawberries, and blueberries.
As you can see in Figure 1, the the loss of vitamin C is minimal compared to non-frozen foods, where much of the vitamin C content is lost after a few days of storage. commodities.
|Figure 1: Changes in vitamin content of selected vegetables after freezing and storage for 90 days (Bouzari. 2014)|
The distribution cold chain has to remain intact! Theoretically frozen vegetables are an excellent source of vitamins. Unfortunately this is true only if the foods are handled properly. When the cold chain is broken, the advantage of freezing fruit and veggies is lost and the vitamins are lost, because the drip loss increases by ~760% (Gonçalves. 2011)!That sounds great, but just like similar changes in strawberries, these effects are brought about by a loss of water weight during freezing and storage and are thus not actually good news. Furthermore, the scientists were able to show that...
- none of the commodities showed significant differences with respect to riboflavin content
- three commodities had higher levels of α -tocopherol in the frozen samples,
- β carotene was not found in significant amounts in blueberries, strawberries, and corn,
- peas, carrots, and spinach were lower in β -carotene in the frozen samples
- Bouzari, Ali, Dirk M. Holstege, and Diane Marie Barrett. "Vitamin Retention in Eight Fruits and Vegetables: A Comparison of Refrigerated and Frozen Storage." Journal of Agricultural and Food Chemistry (2014).
- Gonçalves, Elsa M., et al. "Degradation kinetics of colour, vitamin C and drip loss in frozen broccoli (Brassica oleracea L. ssp. Italica) during storage at isothermal and non-isothermal conditions." International Journal of Refrigeration 34.8 (2011): 2136-2144.
- Gil, María I., Federico Ferreres, and Francisco A. Tomas-Barberan. "Effect of postharvest storage and processing on the antioxidant constituents (flavonoids and vitamin C) of fresh-cut spinach." Journal of agricultural and food chemistry 47.6 (1999): 2213-2217.
- Mullen, William, et al. "Effect of freezing and storage on the phenolics, ellagitannins, flavonoids, and antioxidant capacity of red raspberries." Journal of Agricultural and Food Chemistry 50.18 (2002): 5197-5201.