The Mercaptan Sensing Pad is a smart freshness indicator designed for durian and other sulphur‑rich foods. It uses a mercaptan‑responsive chemosensing ink to detect mercaptan gas, a key aromatic compound released as durian ripens and deteriorates. As mercaptan levels rise, the pad or label changes from brown to black, providing a clear visual signal that the product is moving from optimal ripeness to over‑ripe or spoiled. This helps gift box producers, retailers and central kitchens adjust selling strategies, remove risky stock in time, reduce returns, and protect brand reputation without complex testing equipment.