Does coffee residue have caffeine? The surprising truth
                                
                                
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                                    5 min read                                
                            
                                A 2021 study revealed that spent coffee grounds can still contain a significant concentration of caffeine, ranging between 3.59 and 8.09 milligrams per gram of dry residue. This confirms that answering the question, "does coffee residue have caffeine?", is a resounding yes, although the amount is lower than in fresh grounds.