Preparation of Hydroxypropyl Methyl Cellulose Based Coating and the Effect of Banana Preservation

Some fruits show a short shelf life after being picked, resulting in rotting and wasting during the transportation. In order to prolong the shelf life of fruits, a new type of coating was prepared by using hydroxypropyl methyl cellulose (HPMC) and glycerol as film-forming substrate and plasticizer, simultaneous adding barberry root extractive (BRE) with different contents of 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1.0%. The mechanical property, optical property, barrier property and antibacterial property of the films were tested. Moreover, the film-forming solutions were divided into coating groups of control, HPMC, HPMC/BRE-0.6 and HPMC/BRE-1.0 to coat the bananas, respectively, and then stored at room temperature. Sensory evaluation of the bananas was performed regularly, and weight loss rate, V_C content and titratable acidity were determined. The results showed that increased BRE content led to a general increase of tensile strength, elongation at break and haze. As it was up to 0.6%, the film had excellent ultraviolet-light shielding, favorable water vapor barrier performance and antibacterial property, which could shield almost light in the wavelength range of 200~400 nm, present the minimum water vapor permeability of 3.5 g m⁻¹ s⁻¹ Pa⁻¹×10⁻¹⁰ and good inhibition on Staphylococcus aureus. In the preservation of bananas, different coatings had significant effects on the weight loss rate, V_C content and titratable acidity of bananas (P<0.05). After 5 days, the weight loss rate, V_C content and titrable acidity of bananas in control group were 18.08%, 2.88 mg/mL and 0.31%, respectively, while those in HPMC/BRE-0.6 group were 11.79%, 4.40 mg/mL and 0.21%, indicating that the coating effectively reduced the weight loss rate of bananas, the loss of V_C and the increase of titrable acidity, making them more similar to fresh bananas. This study developed a new type of fruit coating which could extend the shelf life of fruit and was promising to promote the green development of fruit coating field potentially.