Effect of carboxymethylcellulose/candelilla wax coating containing potassium sorbate on microbiological and physicochemical attributes of pears

- KS-free and KS-added coatings control the growth of phytopathogenic fungi on pears.
- The coating was very effective against B. cinerea and M. fructigena.
- The coating inhibited both loss of firmness and skin color changes in pears.
- Use of CMC-based emulsion coatings resulted in anaerobic respiration of pears.

The main objective of this study was to assess the efficacy of a coating composed of carboxymethylcellulose (CMC), candelilla wax and potassium sorbate (KS) as a post-cold-storage treatment to prevent fungal infections in pears stored under simulated retail display conditions. Moreover, the effect of coating on the physiology and biochemistry of pears was investigated. The coating was very effective against Botrytis cinerea and Monilinia fructigena, while Rhizopus nigricans was the most resistant to KS. The KS-free coating also delayed the fungal growth rate, probably due to modification of the gaseous atmosphere within the fruit tissues. Coated pears showed slower ripening than the uncoated samples, as indicated by unaffected green skin color and inhibited loss of firmness. Unfortunately, coating induced anaerobic respiration and the symptoms of superficial scald in pears. Overall, the results showed that KS can be added into a coating formulation to control fungal growth; however, CMC-based emulsion is not a suitable carrier for KS, when coating is intended to be applied to pears exposed to postharvest cold storage.

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