What indicates that frozen food should be rejected?

The presence of water stains on packaging or ice crystals is a strong indicator that frozen food should be rejected. This signifies that the food has likely been subjected to temperature fluctuations, which can lead to thawing and refreezing. Such fluctuations can compromise the safety and quality of the food, as they may encourage the growth of harmful bacteria and affect the texture and flavor of the product. Ice crystals indicate that moisture has escaped, which can also result in freezer burn, making the food unappetizing and potentially unsafe.

While frost on the packaging might suggest some fluctuation in temperature, it does not necessarily mean the food is unsafe. Unsealed packaging can also be a concern, as it can lead to contamination, but it doesn't directly indicate the product's handling history. Color changes in food can indicate spoilage or degradation, but they are not definitive proof that the food was improperly handled as the other indicator is. Thus, the presence of water stains or ice crystals is the clearest sign of potential problems that warrant rejection.