Meaning: Green apples are the most tart of all the other colored apples.
Choice of Words: Tartest is a superlative adjective that means most tart. Apples are a type of fruit, and green is a color.
Alternative Expressions
Green apples are the most sour.
Meaning: This means that green apples have a more sharp or unpleasant taste compared to other apples.
Choice of Words: Green is the color of the apples. Apples are a type of fruit. Sour means sharp or unpleasant in taste. So, "Green apples are the most sour" means that green apples are the most sharp or unpleasant-tasting of all apples.
Green apples are the most acidic.
Meaning: This means that green apples have the highest level of sourness or sharpness compared to other apples.
Choice of Words: Green is the color of the apples. Apples are a type of fruit. Acidic means having a sour or sharp taste. So, "Green apples are the most acidic" means that green apples are the most sour or sharp-tasting of all apples.