Article pp.142-145 du Vol.23 n°1 (2003)

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142-145 Sci. Aliments 23(1), 2003 J.P. Frencia et al.

FOCUS : JSMTV

Measure of meat tenderness using front-face fluorescence spectroscopy

J.P. Frencia¹, E. Thomas¹ & E. Dufour²

AIM

Although food safety becomes a major concern for consumers, the organo- leptic characteristics of meat and , particularly, meat tenderness remains a major purchasing and loyalty factors of consumers. However, meat industries do not set out rapid and reliable methods allowing the assessment of the tenderness of marketed meat.

In 1999, in the scope of a project funded by INTERBEV and OFIVAL, ADIV in collaboration with ENITA Clermont-Ferrand has carried out a program aiming at the evaluation of fluorescence spectroscopy as a method for the determination of meat tenderness.

The obtained results showed that it was possible to discriminate muscles as a function of the 2 components of tenderness:

– basic hardness related to the different contents in collagen varying with the type of muscle

– myofibril component related to the proteolysis during meat ageing

Considering these promising results, a program aiming at the validation of the method on industrial samples has been set up (INTERBEV and OFIVAL fun- ding).

1. ADIV Association, 2, rue Chappe, 63039 Clermont Ferrand cedex 2.

2. ENITA, UR Typicité des produits alimentaires, site de Marmilhat, 63370 Lempdes.

4-FOCUS (142-145) Page 142 Jeudi, 15. mai 2003 8:32 20

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Measure of meat tenderness using front-face fluorescence spectroscopy 143

MATERIAL AND METHODS

During the feasibility study, ENITA Fluoromax spectrofluorimeter (Spex Jobin Yvon) was used. It is a very sensitive machine, but it is bulky. A laptop spectrofluorimeter has been developed by ADIV. It is built from a Xenon-Mercury lamp, an interference filter (wavelength: 290 nm, band pass: +/– 5 nm), a spectrometer (Intaspec II oriel) and a coaxial optic fiber allowing direct measurement on the muscle (Figure 1).

Figure 1

Spectroscopic device developed by ADIV

Principle: the excitation light beam at 290 nm wavelength go through the optic fiber. In contact with the crude meat sample, fluorophores (mainly protein tryptophans, ..) are excited and emitted photons. This signal is collected by the optic fiber and is analysed by the spectrometer connected to a data recording software. Using chemometric tools, the recorded spectra are compared with data obtained from different methods.

RESULTS

In order to evaluate the spectroscopic method, the spectral data were analysed by multidimensional statistical methods.

Light

source Optic

fiber Sample

Data recording software

Spectrometer Interference

filter

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144 Sci. Aliments 23(1), 2003 J.P. Frencia et al.

1 – Discriminant ability of the method for samples exhibiting different collagen amounts and ageing times.

According to the two first principal components, the samples are split up into 4 groups (Figure 2). Fluorescence spectroscopy allows discrimination of the samples as a function of muscle type and ageing time.

Figure 2

Principal component analysis similarity map 1-2 or tryptophan emission fluorescence spectra

2 – Correlation of spectral data with other methods of tenderness measurement.

Table 1

Correlation coefficients between the different methods of meat tenderness measurement Method of meat tenderness measurement Correlation coefficients

Sensory analysis/ Spectroscopy ADIV 0.769

Sensory analysis / Spectroscopy ENITA with optic fiber 0.933 Sensory analysis / Spectroscopy ENITA without optic fiber 0.956

Sensory analysis / Texturometer 0.945

Texturometer / Spectroscopy ADIV 0.523

Texturometer / Spectroscopy ENITA without optic fiber 0.951 Texturometer / Spectroscopy ENITA with optic fiber 0.914 Spectroscopy. ENITA without optic fiber / Spectroscopy ADIV 0.814 Spectroscopy. ENITA without optic fiber / with optic fiber 0.965 Spectroscopy. ENITA with optic fiber / Spectroscopy ADIV 0.834

- -

CP 1 (67,9 %) CP 2 (15,5 %)

Dufour et al

Group 3: chuck Beginning of ageing

Group 1: sirloin Beginning of ageing

Group 2: sirloin End of ageing

Group 4: chuck End of ageing

2,50E-03 2,00E-03

1,00E-03 5,00E-04 0,00E+03 -5,00E-04 1,00E-03

-1,50E-03

-2,00E-03 -2,50E-03 1,50E-03

-5,00E-03 -4,00E-03 -3,00E-03 -2,00E-03 -1,00E-03 0,00E+00 1,00E-03 2,00E-03 3,00E-03 4,00E-03 5,00E-03 6,00E-03

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Measure of meat tenderness using front-face fluorescence spectroscopy 145

The spectroscopic data have been compared with sensorial and instru- mental texture measurements (Table 1). The obtained results allowed to validate fluorescence spectroscopy as a method for tenderness determination.

Figure 3

Canonical correlation analysis between sensory analysis and ENITA optic fiber data

Spectral data are highly correlated with the sensory data (Figure 3). It appears that fluorescence spectroscopy is a relevant method for the determination of meat tenderness.

Canonical correlation analysis considers the 2 whole data sets containing the fluorescence spectra and the sensory attributes recorded for all the investigated samples. CCA is a multivariate treatment, which describes the correlation between two sets of variables. Linear combinations of the variables of each data set are assessed by CCA so that these linear combinations are as correlated as possible.

CONCLUSION

Fluorescence spectroscopy is a reliable method for the determination of meat tenderness allowing to discriminate samples as a function of muscle type and ageing time. In addition, the method is rapid, non-destructive, easy to use and may be used on-line or at-line in slaughterhouses.

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