Fresh, freeze-dried or cell wall samples: Which is the most appropriate to determine chemical, structural and rheological variations during apple processing using ATR-FTIR spectroscopy?

• Published in: Food chemistry 2020-11, Vol.330, p.127357-127357, Article 127357
• Main Authors: Lan, Weijie, Renard, Catherine M.G.C., Jaillais, Benoit, Leca, Alexandre, Bureau, Sylvie
• Format: Article
• Language: English
• Subjects: Apple processing; Biotechnology; Chemical and Process Engineering; Discrimination; Engineering Sciences; Food and Nutrition; Life Sciences; Malus domestica Borkh; Mid infrared spectroscopy; Partial least-squares regression (PLSR)
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2020.127357

•Proposition of puree sample preparation according to the expected quality traits.•Similar spectral fingerprints due to processing in fresh and freeze-dried samples.•ATR-FTIR on fresh purees could predict particle size and volume affecting texture.•ATR-FTIR on freeze-dried purees could assess viscosity and viscoelasticity.•ATR-FTIR on cell walls could highlight their changes during processing. Attenuated total reflectance Fourier transform spectroscopy (ATR-FTIR) was applied on fresh (NF), freeze-dried (FD) and cell wall materials (AIS) of raw and processed apples. These samples prepared from 36 apple sets and the corresponding 72 purees, issued from different varieties, agricultural practices, storage periods and processing conditions, were used to build models including exploratory analysis, supervised classification and multivariate calibration. Fresh and freeze-dried samples presented similar fingerprint spectral variations due to processing. ATR-FTIR directly on fresh purees satisfactorily predicted textural properties such as particle average size and volume (RPD > 3.0), while freeze-drying improved assessment of chemical (RPD > 3.2) and rheological (RPD > 3.1) parameters using partial least-squares regression. The assessment of texture and macrocomponents of purees can be obtained with a limited sample preparation. For research applications because of a need of sample preparation, changes of cell wall composition during fruit processing could be assessed in relationship with pectin degradation.