A research study aiming to prevent the settling of banana ketchup solids may not be a researchable topic. You may still want to do some experimentation to stop it. All I am saying is, it is not worth the effort. Why? Solids settling to bottom does not affect the product chemically. The upper portion becomes softer and the upper portion becomes harder. The overall flavor stays the same. Shaking the product well before use will make the solids evenly suspended again. The very reason why the slogan “shake well before using” is not legibly written somewhere on the label. The things that will surely cause deterioration are improper sealing, unfavorable storage condition and poor processing operations.
Well, the same holds true for peanut butter. Oil and solid separation is a natural thing. Oil will go on top and solid to bottom. Stir it well and it will go back to the texture you always expected. However, it may not be as easy as shaking ketchup bottle well.
Peanut oil going on top with the presence of oxygen hastens rancidity. True if oxygen is present. True if the jar is not well sealed, else, you never put back the cap tightly after use. So the culprit here is not the oil separation but the rancidity which occurs in presence of oxygen. Seeing clear liquid on top is fine as long as oxygen is kept away. A manufacturer may safely claim “oil separation is natural and never affects flavor in any way”. A slogan “stir well before using” may also be written.
The idea is a gamble. When a clear liquid on top is visible, people assume the product is already spoiled!