A Review of Methods for Detecting Calcium Carbide Induced Ripening in Fruits

Abstract

The use of calcium carbide (CaC₂) as a ripening agent for fruits is banned in most countries across the world, including India (under the prevention of Food Adulteration Act (PFA: 44 AA), 1955 and Food Safety and Standards Regulation Act, 2011). Yet, in our country; it is a common practice to use industrial-grade Calcium Carbide for ripening of climacteric fruits like mango, banana, papaya etc. which leaves behind traces of arsenic and phosphorus, along with heavy metals like Fe, Co, Hg, Pb etc. CaC₂ reacts with moisture to produce acetylene gas, which accelerates the ripening process, but the byproducts of this process pose a severe threat to human health. Hence, there is a need of accessible and economically feasible methods for detecting CaC₂ induced ripening in fruits, for all stakeholders in the fruit supply chain, especially the end consumer. This review investigates the utility, limitations, and underlying principles of key methods. While laboratory-based techniques like gas chromatography-mass spectrometry are highly accurate, they are time-consuming and destructive. Sensor-based and colorimetric methods target residues of CaC₂, arsenic, and the VOC (volatile organic compound) profile of fruit. Spectroscopy based methods have been explored, including the more accurate hyperspectral imaging and the low-cost, portable sensors in the visible-near infrared wavelength band, which show potential for hand-held applications.