Non-destructive detection of internal defects in apple fruit by time-resolved reflectancespectrscopy

• Main Authors: Vanoli, Maristella, Rizzolo, Anna, Zerbini, Paola Eccher, Spinelli, Lorenzo, Torricelli, Alessandro
• Other Authors: Nunes, Carla
• Format: Book Part
• Language: English
• Published: Universidade do Algarve 2010
• Subjects: Absorption coefficient; Internal browning; Mealiness; Scattering coefficient; Watercore; Browning; Smith Sound; Smith sound
• Online Access: http://hdl.handle.net/10400.1/3058

Proceedings of the International Conference “Environmentally friendly and safe technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro, Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924. In the present research Time-resolved Reflectance Spectroscopy (TRS) technique was tested to detect some internal defects in different apple cultivars. The absorption (μa) and the reduced scattering (μs’) coefficients were measured at different wavelengths in ‘Braeburn’ (mealiness), ‘Granny Smith’ (internal browning) and ‘Fuji’ (watercore) apples. Afterwards, each fruit of ‘Granny Smith’ and ‘Fuji’ were cut and evaluated for internal defects. ‘Braeburn’ apples were submitted to sensory analysis (firm, crispy, mealy and juicy), percent juice and relative intercellular space volume (RISV) determinations. In addition, for ‘Granny Smith’, the colour of the pulp was measured. ‘Granny Smith’ sound fruits on average showed μa750=0.029 cm-1 and μs’750=12.2 cm-1; with the development of internal browning, μa750 increased to values >0.04 cm-1 and μs’750 decreased to values <10 cm-1 in severely affected fruit. Non-mealy ‘Braeburn’ apples were characterized by significantly lower μs’790, μs’912 and higher μa912 than mealy ones. Sensory mealiness was positively related to μs’790 and μs’912 and negatively to μa912. The regions of ‘Fuji’ apples affected by watercore showed significantly higher μa790 and lower μs’790 values than the healthy regions. Results confirm the suitability of the TRS technique to inspect apples for internal defects, highlighting the need of determining the TRS threshold values as well as the number of measurement points specific to the cultivar and disorder.