Application of nisin-embedded pectin microcapsules for ‘Guiqi’ mango fruit postharvest preservation

In this study, nisin-embedded pectin microcapsules (NPM) were prepared and applied to preserve the freshness of mangoes. Nisin was embedded into the an "egg-box" structure crosslinked by pectin molecules and calcium ions (Ca2+). Optical microscope revealed that NPM were round or elliptical in shape. The analysis of Fourier transform-infrared spectrometry (FTIR) and X-ray diffraction (XRD) confirmed the combination of the nisin with pectin and Ca2+. The determination of release effect showed that NPM had a release efficacy of 74.00% ± 4.30%. Moreover, the determination of biological toxicity exhibited that NPM had exceptional biocompatibility with no toxicity. Antifungal activity assays revealed that NPM had confirmed antimicrobial activity against Colletotrichum gloeosporioides. Application in 'Guiqi' mangoes 8-day preservation (25 ± 2 °C) suggested that NPM significantly mitigate decay by 28% compared with control group (P < 0.05). Moreover, NPM treatment was found to successfully sustain mangoes' soluble solid content (SSC) of 6.45% ± 0.7%, titratable acidity (TA) of 2.20% ± 0.40%, and firmness of 20.50 ± 3.30 N, while limiting weight loss (3.40% ± 0.03%) and respiration rate increase after 8-day storage. Furthermore, NPM boosted the activities of certain enzymes linked with antioxidant capacity and inhibited enzymes responsible for softening. These findings highlight the potential of NPM as a safe, eco-friendly strategy to control postharvest rot and maintain mango quality.