Prolonged preservation of tangerine fruits using chitosan/montmorillonite composite coating

Chitosan (CS) and chitosan/montmorillonite (CS/MMT) coatings have been applied on fresh tangerine fruits to compare their preservation effects. After coating, fruits were stored with the untreated (CK) and prochloraz treated group (PC) at 10 degrees C for 11 d to evaluate their quality, as well as the changes of coating structures. The free-standing films of CS and CS/MMT were also prepared and characterized. Results showed that CS coating inhibited the decay rate of fruits only at the first 5 d of storage, followed by a rapid increase. Notably, fruits coated by CS/MMT coating containing 1% (w/w) MMT (CS/MMT-1) presented lower decay rate and weight loss, higher contents of total soluble solids (TSS) and titratable acidity (TA) compared to other groups during the whole storage. At day 11, the decay rate of CS/MMT-1 was only 28.3%, which was 5.8% lower than that of CK. Moreover, micro-pores in coatings were observed during storage, which appeared much later in CS/MMT-1 coatings than in CS. For the free-standing films, addition of 1% (w/w) MMT was able to enhance the oxygen barrier properties of CS films, which further supported the good structural stability of CS/MMT films. These results demonstrated that CS/MMT coating with enhanced stability provided longer shelf life for tangerine fruits.