'Abbé Fétel' pears, the most important pear cultivar in Italy in terms of production, can be stored in normal air (NA) no longer than four months, when fruit become sensitive to superficial scald and lose their ripening ability, remaining firm, grainy and without flavor. Controlled atmosphere (CA) storage could preserve pears from superficial scald and allows the extension of postharvest life up to six months, even if the low levels of O2 used in CA can induce soft scald. Treatment at harvest with 1-methylcyclopropene (1-MCP) or the storage in controlled atmospheres with low levels of O2, such as with dynamic controlled atmosphere (DCA), are effective in preventing superficial scald.
Italian scientists studied how postharvest conditions (storage atmosphere, temperature and time) can affect ripening, ethylene production and texture of 1-MCP treated 'Abbé Fétel' pears. Particularly, in this study, the spectral indices IAD and Icarot related to chlorophyll and carotenoids content in the skin, respectively, have been used to better elucidate the impact of storage atmosphere, storage temperature and storage time on the maturation of 'Abbé Fétel' pears already for storage removal.
For the study, control and 1-MCP treated (SmartFreshTM, 300 nL/L) pears stored in air (NA), controlled atmosphere (CA) and DCA at either -0.5°C or 1°C for 20 and 28 weeks were evaluated for ripening in storage by relating the spectral maturity indices IAD (index of absorbance difference), bound to chlorophyll, and Icarot (carotenoids index), bound to carotenoids, to ethylene production, background skin color, mechanical properties of the pulp (firmness, stiffness and energy-to-rupture) and sugar (soluble solid content) and organic acid (titratable acidity) contents.
Results showed that 1-MCP treatment at harvest, as well as the storage temperature, influenced the physiological and quality changes of 'Abbé Fétel' pears during storage in CA, DCA and NA. The 1-MCP treatment drastically reduced the ethylene production, impaired skin yellowing and fruit softening already in storage in fruit stored at -0.5°C, independently of storage atmosphere and length of storage. The 1-MCP treatment combined with storage in NA at 1°C succeeded in maintaining firmness and green color in storage but without blocking them, as indicated by the significant decrease in texture parameters and background skin hue achieved already in storage.
At harvest IAD index better correlated to quality parameters than Icarot index. After storage, in control fruit, IAD index better correlated to titratable acidity and ethylene production, while Icarot index better correlated to pulp mechanical properties and allowed the differentiation of control samples according to the ripeness degree reached already in storage, with the NA samples stored at 1°C for 28 weeks being the ripest and the DCA samples stored at
-0.5°C for 20 weeks, the least ripe.
Scientists conclude that for 'Abbé Fétel' pears IAD index is more suitable to determine the fruit maturity degree at harvest, whereas Icarot index is more suitable to determine the fruit ripeness degree after storage.
Study is available online since June 18th 2015 at:
www.sciencedirect.com/science/article/pii/S0925521415300351
Source: Anna Rizzolo, Maurizio Grassi, Maristella Vanoli, 'Influence of storage (time, temperature, atmosphere) on ripening, ethylene production and texture of 1-MCP treated 'Abbé Fétel' pears', November 2015, Postharvest Biology and Technology, Vol. 109, pages 20–29.
Contacts:
Anna Rizzolo
Consiglio per la Ricerca in Agricoltura e l'analisi dell'economia agraria, Unità di Ricerca per i Processi dell'Industria Agroalimentare (CRA-IAA)
Via Venezian 26
I-20133 Milan, Italy
Email: [email protected]
