Assessment of quality-assured Tarocco orange fruit sorting rules by combined physicochemical and sensory testing.

BACKGROUND The aim of this study was to extract a sorting rule for Tarocco orange fruit from several physicochemical and sensory tests performed on a marketable lot of 399 Tarocco orange fruits. RESULTS The elastic tension at 5% strain (T₅ ) was found to be linearly correlated (r = 0.65) with the Magness-Taylor (MT) index. Thus T₅ was regarded as a non-destructive parameter quantifying fruit firmness and used to categorise the aforementioned lot in three different firmness classes, high (HF), medium (MF) and low (LF). Only the MT index, fruit rind thickness near the fruit peduncle, lightness coefficient and yellow/blue hue component of the orange flesh, as well as total soluble solid content, confirmed the validity of this discrimination at the significance level of 5%. Sensory professionals recognised the greater compactness (7 ± 2) but lower ease of peeling (4 ± 2) and segment separation (4 ± 2) of the HF oranges with respect to the corresponding sensory attributes of orange fruits grouped in the MF and LF classes. CONCLUSION To limit the costly rejection of Tarocco orange fruit considered too soft, especially after long-term shipping, it would be reasonable to select only fruits characterised by a compressive force or tension at 5% strain in the range 23-41 N or 300-540 N m⁻¹ respectively.

[1]  Milind S. Ladaniya,et al.  Citrus Fruit: Biology, Technology and Evaluation , 2008 .

[2]  M. S. Howarth,et al.  Nondestructive dynamic testing of apples for firmness evaluation , 2003 .

[3]  Instrumentation and procedures for commercial non-destructive determination of firmness of various fruits , 2005 .

[4]  E. Pagliarini,et al.  Valutazione sensoriale : aspetti teorici, pratici e metodologici , 2002 .

[5]  Orange fruit rheometrical characterization using stress-relaxation tests , 2010 .

[6]  James Freeman Steffe,et al.  Rheological Methods in Food Process Engineering , 1992 .

[7]  C. Costa,et al.  Viscoelastic Properties of Tarocco Orange Fruit , 2012, Food and Bioprocess Technology.

[9]  De-Xing Hou,et al.  Potential mechanisms of cancer chemoprevention by anthocyanins. , 2003, Current molecular medicine.

[10]  S. P. Lloyd,et al.  Least squares quantization in PCM , 1982, IEEE Trans. Inf. Theory.

[11]  P. Rapisarda,et al.  Reliability of analytical methods for determining anthocyanins in blood orange juices. , 2000, Journal of agricultural and food chemistry.

[12]  Dominique Barthès-Biesel,et al.  Effect of constitutive laws for two-dimensional membranes on flow-induced capsule deformation , 2002, Journal of Fluid Mechanics.

[13]  G. Lanza,et al.  Prediction of blood orange MT firmness by multivariate modelling of low alterative penetrometric data set: a preliminary study. , 2009 .

[14]  David C. Slaughter,et al.  Introducing Nondestructive Flesh Color and Firmness Sensors to the Tree Fruit Industry , 2003 .

[15]  H. Macfie,et al.  DESIGNS TO BALANCE THE EFFECT OF ORDER OF PRESENTATION AND FIRST-ORDER CARRY-OVER EFFECTS IN HALL TESTS , 1989 .

[16]  M. Ruiz-Altisent,et al.  Non-destructive fruit firmness sensors: a review , 2005 .

[17]  Dominique Barthès-Biesel,et al.  Compression of biocompatible liquid-filled HSA-alginate capsules: determination of the membrane mechanical properties. , 2003, Biotechnology and bioengineering.

[18]  Federico Pallottino,et al.  Assessment of the mechanical properties of Tarocco orange fruit under parallel plate compression , 2011 .