Photodynamic regulation of potato greening: sodium copper chlorophyllin-functionalized alginate/sanxan nanocomposite films with spectral-selective barrier properties

Abstract

An innovative sodium alginate/sanxan (SA/SAN) composite film incorporating sodium copper chlorophyllin (SCC) was used to control postharvest potato tuber greening. Comprehensive investigations were conducted on the stability of SCC and the composite film's physicochemical properties and anti-greening efficacy. Results demonstrated that SCC exhibited strong absorption at 402 nm and excellent light, thermal, and pH stability and enhanced the mechanical strength of the SA/SAN films (18% increase in tensile strength at 0.4% SCC) while reducing moisture content and improving barrier properties (11% lower water vapor transmission rate at 2% SCC). The SA/SAN/SCC composite films showed substantial UV and blue-light blocking (transmittance of <20% at 200–315 nm and <40% at 400–450 nm), which are crucial for suppressing total chlorophyll (TC) synthesis. Notably, potato tubers coated with SA/SAN/SCC (2%) showed considerably reduced greening, 25.82% decrease in TC content after 72 h and sustained inhibition after over 60 days of storage. X-ray diffraction and thermogravimetric analyses confirmed enhanced intermolecular interactions and thermal stability in the SCC-incorporated films. These findings establish an effective and eco-friendly strategy for preventing potato tuber greening, offering foundational insights for the development of advanced food preservation materials.