(231au) Rapid Freshness Assesment of Bakery Products Using Discriminant Analysis and FTIR Spectroscopy

Bakery products are one of the most widely consumed staple food all over the world. Since fresh consumption of bakery products is typically preferred, freshness is one of the key determinates of consumer acceptance and a major contributor to the product quality (Heenan et al. 2009). Although freshness is a complex collective quality measure of a product involving sensory properties, such as appearance, odor, taste and texture, instrumental techniques can also be put in practice to devise analytical methods for qualitative assessment of food freshness (MacFie and Hedderley, 1993; Kalua et al. 2006;Sinelli 2007).

A pragmatic approach to classify scones as a model bakery product according to state of freshness was developed using a chemical profile specific analytical tool, Fourier Transform Infrared (FTIR) spectroscopy, and chemometrics. Spectral responses of the ester (C=O), aliphatic chain (C-H) stretch and water (O-H) bend vibrational modes were found to be affected due to molecular transport of fat and moisture over four-day storage period. Multivariate discrimination models were constructed to classify fresh and aged products with respect to the extent of storage on the basis of surface chemical profile information, employing a composite partial least-squares- canonical variate analysis (PLSâ??CVA) algorithm. The fingerprint, the ester & moisture and the C-H stretch regions of spectra were evaluated separately to find out the best freshness correlated spectral features from discrimination patterns which are statistically determined in PLS-CVA plots. It was shown that the degree of freshness was better correlated with the combined fatty acid ester & moisture and the C-H stretch regions of mid-IR spectrum.

The talk will be primarily on discussion of spectroscopic determination of physicochemical changes in scones due to molecular transport of moisture and fat. Then, use of spectral features to create discriminant models will be introduced. Discrimination of fresh bakery products and storage day based classification of samples on 2D plots will be illustrated to show effectiveness and potential of the proposed analytical approach.

References:

Heenan, S.P., Hamid, N., Dufour, J-P., Harvey, W., Delahunty, C.M. (2009). Consumer freshness perceptions of breads, biscuits and cakes. Food Quality and Preference, 20(5), 380-390

Kalua C.M., Bedgood D.R., Bishop A.G., Prenzler P.D. (2006). Discrimination of storage conditions and freshness in virgin olive oil. Journal of Agricultural and Food Chemistry, 54(19), 7144-7151.

MacFie, H.J.H., Hedderley, D. (1993). Current practice in relating sensory perception to instrumental measurements. Food Quality and Preference. 4(1), 41-49

Sinelli, N., Cosio, M.S., Gigliotti, C., Casiraghi, E. (2007). Preliminary study on application of mid infrared spectroscopy for the evaluation of the virgin oil freshness. Anaytica Chimica Acta. 598(1),128-134.