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Effects of controlled atmosphere and novel antifungal pre-treatments on quality and storability of 'Golden Delicious' apple

Cecchini, M., Monarca, D., Carletti, L., Stella, E., Moscetti, R., Massantini, R., Contini, M.
Acta horticulturae 2015 no.1071 pp. 173-179
Alternaria alternata, Botrytis cinerea, Metschnikowia pulcherrima, Penicillium expansum, apples, carbon dioxide, chemical treatment, chemometrics, color, consumer acceptance, discriminant analysis, electronic nose, ethylene production, fungal antagonists, fungicides, hot water treatment, multivariate analysis, near-infrared spectroscopy, oxygen, pathogens, pretreatment, principal component analysis, quercetin, respiratory rate, sensory evaluation, sensory properties, storage quality, thermotherapy, wavelengths, yeasts
The effects of chemical, physical and biological microfungi control on the sensorial quality and storability of ‘Golden Delicious’ apple when stored under controlled atmosphere (1% O2, 3% CO2) at 2±0.5°C for 2 months were investigated through sensorial evaluation in combination with non-destructive assessments. Antagonist yeast Metschnikowia pulcherrima strain MACH1 (10(8) cells ml-1), flavonoid quercetin (5 g L-1), and hot water treatment at 45°C, were used as alternatives means for chemical fungicides against different pathogens of apple (Alternaria alternata, Botrytis cinerea and Penicillium expansum). Quality changes in fruit were studied performing sensorial quality evaluation test in combination with the following non-destructive technologies: peel color measurement, near infrared (NIR) spectroscopy, electronic-nose (e-Nose) detection, respiration rate and ethylene production. Sensorial descriptive data and non-destructive data were subjected to principal component analysis (PCA), resulting in a multidimensional product space that was related to the consumer acceptance. The selected PCs were used to compute a multivariate analysis of variance (MANOVA) and the Mahalanobis distance between samples. NIR spectra were also subjected to feature selection using an iterative Linear Discriminant Analysis (LDA) routine. Several spectral pretreatments were also tested to improve spectra quality. Each group of wavelengths selected was subjected to hierarchical clustering with Ward’s method to identify agglomerates by type of treatment used as well as by days of storage. The use of quercetin and thermotherapy worsened several sensorial quality parameters. The results were confirmed by the chemometric analyses of the non-destructive data. The results indicated that the effects on sensorial quality and storability were dependent on the method of treatment used. Thus, antagonistic yeast was the best alternative to chemical treatment among those tested during the experimentation.