Treatment of feijoa fruit with carnauba wax to reduce water loss and preserve postharvest quality

Fruit treatment with carnauba wax surface coating aims to create a protection barrier, preserve physical-chemical attributes and improve the skin finish. This study was carried out to assess the effects of feijoa fruit (LSQUOAlcântaraRSQUO) treatment with different concentrations of carnauba based wax coating (18% of active ingredients, made of carnauba wax emulsion, colophony resin and water) on water loss and postharvest quality. Fruit were treated with the commercial coating diluted with distilled water at the concentrations of 0 (control), 25, 50 and 100%. After treatment, fruit were cold stored during 15 days at 4±1°C (90±5% RH), followed by 48 h of shelf life at 23±1°C (75±5% RH). Fruit were assessed for skin finish (gloss), skin permeance to water loss, weight loss (% of initial weight), titratable acidity (TA), soluble solids content (SSC), SSC/TA ratio, pH and internal browning. The increase of coating concentration improved the skin gloss. Fruit treated with coating at the concentrations of 25, 50 and 100% had reductions of skin permeance to water loss compared to the control of 32, 40 and 49%, respectively. The fruit weight loss was of 3.05, 2.04, 1.77 and 1.40% for fruit treated with coating concentrations of 0, 25, 50 and 100%, respectively. The increase of coating concentration reduced SSC and TA and increased pH, without affecting the SSC/TA ratio. Fruit treated with coating at the concentration of 100% had slightly lower internal browning. There is a beneficial effect of feijoa fruit treatment with carnauba wax, since the coating improves the skin finish and reduces water loss without detrimental effects on fruit internal quality.