When you are pouring spices from a jar, why do some stick together more (e.g. paprika, curry powder) while some pour more readily (e.g. chili powder, turmeric)?

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When you are pouring spices from a jar, why do some stick together more (e.g. paprika, curry powder) while some pour more readily (e.g. chili powder, turmeric)?

In: Chemistry

I’ll provide a basic answer to not get to confusing.
If the chemical structure of the walls of the jar and the and the spice, if they are similar or contain components that attract watcher like magnetic forces than they will be more likely to stick. There a lots of different reasons but if two surfaces like such as two polar surfaces come into contact, they will display certain attractive forces and thus stick to the jar. The stronger the forces the better the attraction. Some compounds them selfs are extreme polar or non polar and thus attract to themselves more so than they attract to each-other and may clump, similar to how oils and water separate themselves in solution.

Some spices are more moist and oily than others, so they tend to clump, whereas dry spices will pour like sand. This is because most spices have essential oils in them that bring the flavour, so you have oils mixed in with the solid matter. Some spiaces don’t though – chili powder is a mix of things like onion powder and ground dry chilis – neither of which have much in the way of essential oils (at least, not in the same volumes). This is why dried herbs will also pour more easily (e.g. thyme, oregano, rosemary). While they still contain oils and flavour compounds, they’ll mostly be within the herb itself and not have been released through a grinding process.

Some also absorb moisture from the air, so can crystallize or become more moist over time (which is a bad thing! Always cover your ground spices).