Curcumin-loaded electrospun nonwoven as a colorimetric indicator for volatile amines

Colorimetric indicators are useful in intelligent food packaging applications. As a natural food colorant, curcumin is a promising colorimetric indicator for the detection of alkaline compounds produced during food spoilage. In this study, curcumin-loaded electrospun nonwovens were developed for the detection of amines, which are principal spoilage volatiles of fish and aquatic products. The spin dope solution for electrospinning was prepared by dispersing curcumin (0.32% w/w) in 14% (w/w) polyvinylpyrrolidone (PVP) or 9% (w/w) ethylcellulose (EC)/0.2% (w/w) poly(ethylene oxide) (PEO) solution in anhydrous ethanol. Curcumin-loaded nonwovens were obtained by free surface electrospinning and subsequently characterized for amine detection. When exposed to amine volatiles, the nonwoven indicators exhibited striking yellow-to-orange/red color transition, along with a reduction in curcumin's fluorescence intensity. Both EC/PEO- and PVP-based nonwovens were capable of discriminating six different volatile amines (trimethylamine, ammonia, dimethylamine, triethylamine, piperidine and hydrazine) at 0.2 mmol level. Comparing the two nonwoven carriers, EC/PEO resulted in smaller fiber diameter (1.06 μm) and higher curcumin loading efficiency (91%) than those derived from PVP (83% loading efficiency and 1.52 μm diameter). The limit of detection (LOD) and limit of quantitation (LOQ) of using EC/PEO-based fiber for amine detection were lower than PVP-based fiber, except for TMA.