# Advances in apple texture researches : first results of a french regional project

Francois Laurens, D. Bertrand, M. Chevalier, Pascale Guillermin, Frédérique Jourjon, Emira Mehinagic, C. Renard, G. Royer, Ronan Symoneaux, Yves Lespinasse

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## ► To cite this version:

Francois Laurens, D. Bertrand, M. Chevalier, Pascale Guillermin, Frédérique Jourjon, et al.. Advances in apple texture researches : first results of a french regional project. Eufrin Workshop on Fruit Quality, Università di Bologna [Bologna] (UNIBO). Bologne, ITA., Jun 2003, Bologna, Italy. hal-01601286

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Submitted on 4 Jun 2020

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DIPARTIMENTO DI COLTURE ARBOREE
COLLEGE OF AGRICULTURE
University of Bologna - Italy

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# Eufrin Workshop
On Fruit Quality

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BOLOGNA, 11-14 JUNE, 2003

COLLEGE OF AGRICULTURE
UNIVERSITY OF BOLOGNA
VIALE FANIN 46, BOLOGNA - ITALY
# Advances in Apple Texture Researches: First Results of a French Regional Project

F. LAURENS¹, D. BERTRAND², M. CHEVALIER¹, P. GUILLERMIN³, F. JOURJON⁴, E. MEHINAGIC⁴, C. RENARD⁵, G. ROYER⁴, R. SYMONEAUX⁴, Y. LESPINASSE¹

¹ INRA Centre d'Angers. Unité d'Amélioration des Espèces Fruitières et Ornementales. BP57. 49071 Beaucouzé Cédex 01, France

²UMR INRA-ENITIAA Sensométrie et chimiométrie. BP 82225. 44322 Nantes Cédex 03, France

³ INH Angers. Laboratoire d'Arboriculture fruitière. 2, rue Le Nôtre. 49045 Angers Cédex 01, France

⁴ ESA Angers. Laboratoire Grappe. BP 748. 49007 Angers Cédex 01, France

⁵ INRA Centre de Rennes. Station de Recherches cidricoles et biotransformation des fruits et légumes. BP35327. 35653 Le Rheu Cédex, France

The INRA Angers Fruit and Ornemental Shrub Breeding Station is coordinating a regional project which deals with two main objectives:

1. the development of new tools to assess apple texture and find out new selection criteria

2. the study of the main variability factors of fruit quality within a tree

We will just present the first point in this paper.

The project started four years ago with five main partners sharing various and complementary knowledge: INRA Angers (instrumental measurements, cyto-histology, genetic diversity genetics, genomics), Enitiaa-INRA Nantes (Visible/Near-Infra-Red Spectroscopy, chemometrics), ESA Angers (sensory evaluation, instrumental measurements), INH Angers (histology, Near Infra Red Spectroscopy, factors of variability); INRA Rennes (cell wall biochemical analyses).

The studies on texture have been undertaken following four main approaches: instrumental measurements with destructive (penetrometry, compression) and non-destructive methods (Visible/Near-Infrared Spectroscopy, sonometry), sensory evaluation, histology and cell wall biochemical analysis. Most of the instrumental methods and sensory methodology are described in Mehinagic et al (2003). Histological studies aim to measure different cell and inter-cellular space parameters. Biochemical analyses included determination of the cell wall content and pectin extractability and measurement of the fruit polyphenol pool during apple growth and maturation.

Experimentations have been performed in a cooperative way by the different partners. They have been based on commercial cultivars but also on a large range of French local cultivars.

The most advanced results have been obtained with penetrometry, visible/NIR and sensory evaluation. It is possible to extract from the penetrometry curves much more data than the usual "Fmax" widely used by the growers to assess firmness. Penetrometry tests are performed on unpeeled apples using a 4-mm diameter cylindrical probe. Force/deformation curves were analysed and seven parameters were estimated (Fig 1; Duprat et al, 2000).

Visible/NIR Spectroscopy allows a good discrimination either of the cultivars (Fig 2) or the fruit maturity stages.

Sensory evaluation started in 1999 at ESA Angers. The first two years have been spent to train the panel and set up a methodology. The panel is working today with 17 sensorial descriptors, eight of them are related to texture attributes. For 2 years, it shows very high repeatability, reliability and efficiency. The sensory analysis is a central point of this project as it allows us to correlate all instrumental measurement with sensorial perception.

Correlations between the different measured parameters have been investigated on a set of 19 local French cultivars (Mehinagic et al, 2003). Some sensory textural attributes, "crispness", "chewiness", "fondant" are highly correlated with some parameters measured by penetrometry ($r > 0.8$). Further experimentations developed in this project confirm the good level of correlation between sensory evaluation and penetrometry. Some visible/NIR wavelengths are also significantly correlated with some sensory attributes but the relationship is not
high enough to use this non destructive tool for texture quality prediction. This could be due to the fact that NIR data were averaged to fit with the sensory evaluation which was not carried out on individual fruits. In the future, some attempts will be made to overcome the sampling issues linked to sensory methodology.

In the next future, the aim is to carry on the already developed approaches but also to develop or test new tools: i.e. assessment of the juiciness, testing of acoustic methods to estimate texture quality parameters. Another wish would also be to include a team from Enitiaa Nantes working on aroma to study how aromas are released taking into account various texture parameters of the fruit. This project will also be widened towards genetics aspects in connection with the European project HiDRAS.

## REFERENCES

- DUPRAT F., GROTTE M., LOONIS D., PIETRI E. 2000. Etude de la possibilité de mesurer simultanément la fermeté et la chair de l'épiderme des pommes. Sciences des Aliments, 20, 253-265.

- MEHINAGIC E, ROYER G, BERTRAND D, SYMONEAUX R, LAURENS F, JOURJON F. 2003. Relationship between sensory analysis, penetrometry and visible-NIR spectroscopy of apples belonging to different cultivars. Food quality and Preference, 14, 473-484

<figure><img src="image_6.png" /><figcaption>Figure 2. Discriminant analysis on 3 cultivars: Gala (G), Elstar (E), Smoothee (S). Results of year 2002.</figcaption></figure>

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