What does bad butter look like

Butter is greatly affected by temperature and will go bad even if left at room temperature of 20 degrees for 2 to 3 days, so we choose to store it in the refrigerator. The smell of spoiled butter is very strange, and different people have different senses. In summary, it is a kind of clam smell, sour smell, rotten smell, sour smell or wine smell. It is very easy to distinguish. You can obviously feel the difference when you smell it. Don't eat spoiled butter.

What does bad butter smell like?

Rancid taste

Common foods: various oils and foods high in fat, including vegetable oil, lard, butter, cream, nuts, fried foods, pastries, bacon, dried fish, etc.

Source of the odor: Due to being left for too long or being stored improperly, high-fat foods will produce an unpleasant, bitter taste, which we usually call "rancid smell". Rancid smell mainly comes from the products of fat oxidation and rancidity, namely small molecule aldehydes, ketones, alcohols, acids, etc. produced by the decomposition of hydroperoxides. The lipid peroxides produced during the oxidation of fats and oils will not only cause the appearance, texture and nutrition of food to deteriorate, but may even produce mutagenic substances. For example, hydroperoxides can react with almost all molecules or cells in the human body and damage DNA and cell structures. The generation of rancid smell is often accompanied by browning of color, such as the fat part of bacon turning from white to yellow, and changes in food texture, such as pastries becoming dry and hard and unpalatable.

Countermeasures: The oxidation and rancidity of fats and oils are affected by many factors such as oxygen in the air, light, microorganisms, moisture and enzymes. Therefore, when storing the above foods, you must pay attention to sealing, keeping them away from light, moisture and high temperature.

Rancid smell

Common foods: fish and shellfish, livestock and poultry meat, eggs, tofu, dried tofu and other foods rich in protein.

Source of odor: High-protein foods are easily contaminated by microorganisms, causing them to spoil and produce a rancid odor. The rancid smell mainly comes from the decomposition products of protein and fat, such as indole, sulfide, thiol, skatole, cadaverine, aldehydes, ketones and bacterial toxins, which can cause human poisoning. In addition to the foul smell, this type of food also shows signs of spoilage, such as a sticky surface and green color.

Countermeasures: In order to avoid spoilage as much as possible, such foods should be eaten promptly after purchase, or refrigerated or frozen. If you find that these foods have a rotten smell, you should not continue to eat them.

Sour or alcoholic taste

Common foods: foods rich in carbohydrates, such as grains, vegetables, fruits, sugars and their products.

Source of odor: High-carbohydrate foods will decompose into monosaccharides, disaccharides, organic acids, alcohols, and aldehydes under the action of microorganisms, which will emit a sour or winey smell. This is also the basic principle of wine and vinegar making. However, when the above-mentioned foods develop a sour or alcoholic smell during home storage, it usually means that the food has been contaminated by microorganisms and has deteriorated, such as rice becoming spoiled, pastries becoming sour, or fruits becoming rotten, and should not be eaten.

Countermeasures: Do not buy too much food, fruit, etc. at one time. It is best to store them in a dry and ventilated place.

Musty

Common foods: staple foods such as bread, steamed buns, cake, rice, and nuts such as peanuts and melon seeds.

Source of the odor: The above-mentioned foods are likely to become moldy after being left for a few days, and will then emit a musty smell. If they continue to be left there, the mold colonies will grow more and more, and the musty smell will become stronger and stronger. The main reason for mildew is that the food is contaminated by mold and the storage environment is relatively humid. Molds may produce toxins, such as the familiar aflatoxins. Therefore, food must be discarded resolutely after it becomes moldy.

Countermeasures: This type of food should be stored in a dry, ventilated and cool place. If you can’t finish it, you can store it in the freezer.

Ammonia smell

Common foods: pickled fish, dried shrimps, dried shrimps, shredded squid, scallops, dried fish and other dried seafood.

Source of the odor: If dried seafood such as dried shrimps are stored for too long, a distinct ammonia smell will appear and the color will turn pink. This is mainly because the protein contained in them is broken down into peptides and amino acids by microorganisms, and then further broken down into low-level amines and ammonia. Low-level amines are not only toxic in themselves, but also easily combine with nitrites in aquatic products to form strong carcinogens - nitrosamines. If you find that the above foods have ammonia smell or other strange smells, you must throw them away, because even after washing with water, you cannot eat them safely.

Countermeasures: Dried seafood must be kept in a dry storage environment. If possible, you can dry it in an oven before storing it.

How to tell if your butter is fresh?

Cut a piece and if the outside is the same color as the inside, it means it is fresh. If the outside is darker than the inside, the butter has oxidized. At this point you can freeze the butter for about 6 months and then thaw it before using.