DEAR DR. BLONZ: A local store was selling butter in the dairy section, but it was not refrigerated. Then, while at a friend’s house, I saw that she kept her butter at room temperature year-round. Her thought was that butter is saturated fat, so there was nothing that could go wrong, plus it makes the butter easy to spread. She does not feel there is any danger in this practice. I know it is wrong and unhealthy, but I cannot articulate to her the reason why. I would also like to pass something on to my local store. -- K.E., Hayward, California
DEAR K.E.: Storing butter at room temperature, exposed to air, will invite spoilage. The issue is that fats can react with oxygen in the air. As this happens, the fats become rancid; they develop “off” flavors and are no longer healthy to eat. It is a gradual process, and the reaction is slowed considerably at refrigerator temperatures.
It is true that saturated fatty acids tend to be more resistant to this type of breakdown, but they are not immune. Even saturated fats can oxidize and turn rancid. It is also important to consider that while most people think of butter as entirely “saturated,” this is not the case. According to the USDA, butter fats are 68 percent saturated, 28 percent monounsaturated and 4 percent polyunsaturated.
As a fat becomes rancid, it develops a foul, unappealing taste. However, there are degrees of rancidity, and one cannot always identify low levels, especially when present in dishes with strong flavors. Another insidious fact is that eating food with oxidized fats will not bring on food poisoning-like symptoms. Rather, the effects are cumulative, and thought to play a role in the risks of cardiovascular disease, cancer and aging.
You help prevent spoilage by keeping fats in well-sealed containers that prevent exposure to air, and by storing them in an appropriate low-temperature environment.
There is also a chance that butter might be affected by yeast and mold organisms in the air. Ongoing storage at room temperature would make butter vulnerable to this type of attack, as well.
My final spread: You won’t have to toss the butter if you accidentally leave it out overnight, and it is reasonable to take it out before mealtime if you want a softer spread. But the habitual storing of butter at room temperature is not recommended. If kept in an airtight container, such as a crock or butter keeper, the butter can be kept out for a few days, but even this method is not recommended with indoor temperatures that rise about 70 degrees F.
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