An electrifying test to find a good coffee

RESEARCH HIGHLIGHT 30 April 2026 Technique determines roast level and strength by applying voltage to the brew. A coffee’s strength can be assessed from the electrical current generated when a voltage is applied to the liquid. Credit: Getty A quick electrical test is as good as a person’s taste buds at determining the strength and roast of a cup of coffee1. Access options Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any time Subscribe to this journal Receive 51 print issues and online access $199.00 per year only $3.90 per issue Rent or buy this article Prices vary by article type from$1.95 to$39.95 Prices may be subject to local taxes which are calculated during checkout Additional access options: Log in Learn about institutional subscriptions Read our FAQs Contact customer support doi: https://doi.org/10.1038/d41586-026-01289-y Subjects Latest on: Chemistry The news is not all bad: five inspiring science stories to lift your mood News 01 MAY 26 Continuously graded-doped SnO2 for efficient n–i–p perovskite solar cells Article 30 APR 26 ‘Beyond COP’ climate summit puts scientists at the centre of the action News 30 APR 26