This margarine taste a bit soapy. Well. I am not surprised.
Margarine. Base on wikipedia and youtube, it is emulsion of water in oil. Eighty percent of which is fat, 16 % water and the rest are others that perhaps added to prolong shelf life and make it taste better. Basic formula as it suggest, taste bland. The tasty and popular brand you know might be less or healthier than your favorite cooking oil. Maybe more dangerous.
Margarine and soap share the same key ingredient. It is not surprising for an oil refinery to produce margarine and soap. In other cases, a margarine manufacturer making soap as alternative income source and vice versa. The two products, clearly, need separate processing plants. However, they may choose do it with minimal walling. Separate buildings but in proximity. Then same truck for logistics. Strict protocols are needed to prevent margarine getting soapy taste and odor. Soap on the other hand, getting some margarine attributes may not be a big deal.
I actually saw a company making both at the same time. So the scenario above is not based on science and speculations.
Even if that is not the case, a not well protected and handled product may get undesirable flavor whenever given opportunity. Speaking of margarine, they are usually plain wrapped with wax paper and seen in chilled section of groceries. In any case the logistic, grocery owner or the consumer do the forbidden thing, it gonna have the unpleasant soap taste.
From the website canitgobad.net, one of margarine signs of spoilage is the soapy taste. Soap is made from oil through saponification process. Random presence of alkali and heat is likely to trigger this process.
Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.