They sound like mites of some sort. Have you had damp problems? Are you sure they are only in your kitchen? If they are hiding in dark places, check elsewhere in your flat carefully.
Check any opened food very carefully, especially flour cereals etc and destroy any that is contaminated (as if you would eat it!!)
Mites are difficult to get rid of with domestic insect sprays.. It may pay to get the council or a local pest control company in to advise you.