If ice cream has not been opened for a couple of days, it could be spoiled. In such cases, the ice cream might have a sour or slimy feel, or it might have discoloration, but it is still safe to eat. If you see ice crystals, wash your hands thoroughly and then look for the signs of spoilage. You may be able to spot an ice cream that has become spoiled by shards of icy ice on the lid.
When you are buying ice cream, always check the container before putting it into the freezer. It may have been melted in the store and may not be good to eat. It may also have developed freezer burn or ice shards. You may be able to scrape off these pieces but this should be your first clue to toss it out. Fortunately, the ice cream may still be edible if you do not eat it.
Although freezing food slows the growth of bacteria, they still expire after some time. A clear sign that ice cream is going bad is a layer of tiny ice crystals on top. If these ice crystals cover the top layer, it’s time to throw it away. Many people try scraping off the ice crystals to save the ice cream, but this is not recommended. If the crystals haven’t overtaken the entire carton, it might be safe to eat it.