Use of Vis/NIR Spectroscopy to Assess Fruit Ripening Stage and Improve Management in Post-Harvest Chain

摘要

Fruit "quality" is a concept encompassing sensory and mechanical properties, nutritive values, safety and defects. Fruit quality has declined, determining consumer dissatisfaction, largely due to the wrong harvest date; in addition, quality is badly defined since the parameters mainly considered are fruit size and skin color. Other attributes such as flesh firmness, sugar content, acidity and aroma, are perceived by the consumer as fruit global quality, are seldom considered by the farmer and by other individuals along the chain. Up to now, several studies have been carried out on fruit quality assessment by using traditional methods, which are affordable and fast, but do not consider other quality traits, as antioxidant power, aroma volatile emission, soluble sugars and organic acids content. The assessment of these parameters is time consuming and requires sophisticated equipments (i.e. HPLC, GC-MS). Moreover, destructive analyses can be performed only on a limited number of fruit. In recent years, extensive research has been focused on the development of non-destructive techniques for assessing internal fruit quality attributes allowing extending the assessment to a high number of fruit, to repeat the analysis on the same samples monitoring their physiological evolution, and to achieve real-time information on several fruit quality parameters at the same time. Among the non-destructive techniques, visible/Near Infra Red spectroscopy (vis/NIR) can be efficiently used for determining traditionalfruit quality traits and concentration of the main organic acids and simple sugars. In addition, this technique allows defining a new maturity index strictly related to fruit ethylene emission and ripening stage. This index, called "Absorbance Difference" index (IAD), which can be used for precisely determining harvest date, and for grouping harvested fruit in homogeneous classes which show a different evolution of the ripening syndrome during shelf-life.