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Frozen waffles or pasta are go-to favorites that let you skip the hassle of cooking when you're on a time crunch. But there's a price for that convenience: the nutritional content in some frozen foods can be lacking, or contain too much sodium or fat.
While there are good choices in the frozen food aisle, there are plenty of bad ones, too. These are the frozen foods nutritionists avoid, and the alternatives they recommend instead.
By : Marissa Laliberte
Source: Frozen Foods You Should Avoid at All Costs | The Healthy @Reader's Digest
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Critics:
The process of flash freezing itself generally effectively retain the nutrient content of foodstuff with minor losses of vitamin, making them a cost-effective and nutritious substitute for fresh equivalents. However, pre-seasoned frozen food, such as packaged meals, may have a significant amounts of salt and fats added. It is therefore recommended to read the nutrition label.
Vitamin C: Usually lost in a higher concentration than any other vitamin. A study was performed on peas to determine the cause of vitamin C loss. A vitamin loss of 10% occurred during the blanching phase with the rest of the loss occurring during the cooling and washing stages. The vitamin loss was not actually accredited to the freezing process. Another experiment was performed involving peas and lima beans.
Frozen and canned vegetables were both used in the experiment. The frozen vegetables were stored at −23 °C (−10 °F) and the canned vegetables were stored at room temperature 24 °C (75 °F). After 0, 3, 6, and 12 months of storage, the vegetables were analyzed with and without cooking. O'Hara, the scientist performing the experiment said,
"From the view point of the vitamin content of the two vegetables when they were ready for the plate of the consumer, there did not appear to be any marked advantages attributable to method of preservation, frozen storage, processed in a tin, or processed in glass."Vitamin B1 (Thiamin):
A vitamin loss of 25% is normal. Thiamin is easily soluble in water and is destroyed by heat. Vitamin B2 (Riboflavin): Not much research has been done to determine how freezing affects Riboflavin levels. Studies that have been performed are inconclusive. One study found an 18% vitamin loss in green vegetables, while another found a 4% loss.
It is commonly accepted that the loss of Riboflavin has to do with the preparation for freezing rather than the freezing process itself. Vitamin A (Carotene): There is little loss of carotene during preparation for freezing and freezing of most vegetables. Much of the vitamin loss is incurred during the extended storage period. Freezing is an effective form of food preservation because the pathogens that cause food spoilage are killed or do not grow very rapidly at reduced temperatures.
The process is less effective in food preservation than are thermal techniques, such as boiling, because pathogens are more likely to be able to survive cold temperatures rather than hot temperatures. One of the problems surrounding the use of freezing as a method of food preservation is the danger that pathogens deactivated (but not killed) by the process will once again become active when the frozen food thaws. Foods may be preserved for several months by freezing.
Long-term frozen storage requires a constant temperature of −18 °C (0 °F) or less. To be used, many cooked foods that have been previously frozen require defrosting prior to consumption. Preferably, some frozen meats should be defrosted prior to cooking to achieve the best outcome: cooked through evenly and of good texture.T he defrost system in freezers helps the equipment to perform properly, without thick layers of ice developing, thus preventing the evaporator coil from absorbing heat and cooling the cabinet.
Ideally, most frozen foods should be defrosted in a refrigerator to avoid significant growth of pathogens. However, this can require considerable time. People sometimes defrost frozen foods at room temperature because of time constraints or ignorance. Such foods should be promptly consumed after cooking or discarded and never be refrozen or refrigerated since pathogens are not killed by the refreezing process.
The speed of freezing has a direct impact on the size and the number of ice crystals formed within a food product's cells and extracellular space. Slow freezing leads to fewer but larger ice crystals while fast freezing leads to smaller but more numerous ice crystals.
This difference in ice crystal size can affect the degree of residual enzymatic activity during frozen storage via the process of freeze concentration, which occurs when enzymes and solutes present in a fluid medium are concentrated between ice crystal formations. Increased levels of freeze concentration, mediated by the formation of large ice crystals, can promote enzymatic browning.
Large ice crystals can also puncture the walls of the cells of the food product which will cause a degradation of the texture of the product as well as the loss of its natural juices during thawing. That is why there will be a qualitative difference observed between food products frozen by ventilated mechanical freezing, non-ventilated mechanical freezing or cryogenic freezing with liquid nitrogen.
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