To freeze or not to freeze, that is the question. Food scientists have weighed in to see if butter is better refrigerated or not. Anyone who has baked before knows that taking butter out of the fridge is of the utmost importance. However the answer to the question might be found by looking at the ingredient at a molecular level first.
Unlike other dairy products, butter has high fat content and relatively low water content, making it hard for bacteria to grow. Even more if butter is salted that makes the water content even lower making it an inhospitable place for bacteria to grow.
But just because your butter doesn’t have the potential for bacteria growth, that doesn’t mean it can’t go bad and become rancid.
According to Healthline, oxidation causes rancid fats where the fat’s molecular structure is altered and produces potentially harmful compounds. It also results in off flavors in any foods made with the rancid fats.
However, keeping your butter in the fridge is encouraged if you have unsalted, whipped or raw, unpasteurized butter. Butter has been associated with bacteria such as S. aureus, L. monocytogenes, and Y. enterocolitica. Bacteria can be introduced to the butter during handling at home or by a food handler at a restaurant.
But if you use margarine no worries, here’s what Food Network has to say about the butter substitute.
Like butter, margarine must have at least 80% fat by law; if it has less than 80% fat, it’s considered a “spread.” The lower the fat content of the spread, the more water it contains. If not refrigerated, especially soft tub margarine can separate into water and oil or solids.
To maintain its quality, both margarine and buttery spreads should be refrigerated immediately after use and not left out.
Sources
https://www.healthline.com/nutrition/does-butter-go-bad#TOC_TITLE_HDR_4
https://www.usdairy.com/news-articles/does-butter-need-to-be-refrigerated
