Guglielmo Costa
University of Bologna

Normally fruit quality is defined for several fruit specie mainly on the basis of size and skin color. Considering the importance that fruit quality and ripening stage reached at harvest do represent for the post-harvest management, fruit quality will have to be defined more precisely considering other attributes. In fact, depending to the considered fruit, fruit quality, ripening stage and harvest time are decided on the basis of other attributes such as flesh firmness, sugar content, acidity and starch by using traditional methods (penetrometer, refractometer, Lugol test, etc), which are cheap and fast. Unfortunately these determinations do not precisely define the ripening stage while instead other quality traits. In fact antioxidant power, aroma, soluble sugars and organic acids content are more and more requested by the consumers and better characterize fruit ripening. However, the assessment of these parameters is time consuming and requires sophisticated equipments, trained personnel, etc and requires the destruction of the batch of considered fruits.
As far as disease determination, the diagnosis is normally based on visual symptoms while other more precise determination are carried out in equipped and dedicated laboratories.
In recent years, extensive research has been focused on the development of non-destructive techniques (visible/Near Infrared Red spectroscopy, impact systems, fluorescence, Nuclear Magnetic Resonance and NM Imaging, electronic-nose, etc) for assessing both internal fruit quality attributes allowing extending the assessment to a high number of fruit, to repeat the analysis on the same samples and to achieve information on several fruit quality parameters. Several of these techniques have been also used to perform fungal and bacterial disease diagnosis. Beside the innovative aspect of these techniques, it has to be underlined that such non-destructive methods are giving information on asymptomatic plant material (fruit, scion, etc) and allow saving time.
Among these non-destructive techniques, vis/NIRs technique found commercial use in the practice, mainly for determining traditional fruit quality traits (SSC, internal and external defects).
A simplified version of the vis/NIRs technique is represented by the DA-Meter, an innovative non-destructive device patented by the University of Bologna, Italy, which allows defining a new maturity index strictly, related to fruit ethylene emission and ripening stage. The IAD called “Absorbance Difference”, is the difference in absorbance between two wavelengths near the chl-a peak. The IAD-index can be used for precisely determining harvest date, and for grouping harvested fruit in homogeneous classes.of ripening. The IAD-index might also be used as a DSS (decision support system ) tools allowing “in field conditions” to use the best targeted cultural management technique (pruning , nutrition) to reduce the fruit ripening variability in planta, in “packing house” to group fruits in homogeneous classes of ripening and establish the best storage strategy and market, “at point of sale” to determine the shelf-life duration, and, as a consequence, reducing fruit losses to offer to the consumers a better and more uniform fruit quality.
The DA-Meter has been also preliminary used for bacterial disease determination. Among the non-destructive techniques quite interesting results in bacterial diagnosis have been also achieved with the use of the electronic nose able to detect the olfactory fingerprinting emitted by different bacteria.