From a scientific perspective, the sourest foods in the world are typically measured by their pH levels. Here are some of the sourest foods:
Lime - With a pH value of around 2.0-2.4, limes are among the most acidic fruits commonly found in daily life.
Lemon - Lemons have a pH value between 2.0-2.6, making them another extremely sour fruit.
Vinegar - Particularly white vinegar, which typically has a pH value between 2.4-3.4. Some specialty fermented vinegars can be even more acidic.
Umeboshi (pickled plums) - These traditional Asian preserved plums are incredibly sour, with a pH value of approximately 2.5-3.0.
Hawthorn - Raw hawthorn berries have a very low pH value of about 2.5-3.5.
It's important to note that while these foods are all very acidic, the perception of sourness can vary from person to person, as our taste experience depends not only on the actual pH value but also on individual taste bud sensitivity. Additionally, some foods might have a higher pH but can taste extremely sour due to specific chemical compounds.
From a health perspective, it's not recommended to consume highly acidic foods in excess, as they can damage tooth enamel and potentially irritate the stomach.