Final answer:
Partially hydrogenated oils are less likely to go rancid due to the hydrogenation process that converts some unsaturated cis-fats into more stable trans fats. These trans fats increase shelf life but are associated with health risks, such as higher 'bad' cholesterol levels and cardiovascular disease.
Step-by-step explanation:
Partially hydrogenated oils are less likely to go rancid compared to foods made with unprocessed plant oils because they undergo a process of hydrogenation. This process involves the addition of hydrogen gas, which solidifies the oils and makes them more chemically stable. During hydrogenation, some of the cis-conformation in the unsaturated fats are converted into trans-conformation, leading to the formation of trans fats. These trans fats are more stable than their cis counterparts, extending the shelf life of products such as margarine, baked goods, and fried foods.
Trans fats, however, are not considered a healthy choice because of their association with increased levels of low-density lipoprotein (LDL), often referred to as 'bad' cholesterol. While initially thought to be a healthier alternative to saturated fats, research has shown that trans fats can lead to health issues such as cardiovascular disease. Thus, despite the benefits of longer shelf life and stability, partially hydrogenated oils come with significant health risks, which is why their use has been regulated or banned in many countries around the world.