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, VC 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, VC content and titratable acidity of bananas (P<0.05). After 5 days, the weight loss rate, VC 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 VC 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.