title: Effect of sample preparation on the measurement of sugars, organic acids, and polyphenols in apple fruit by mid-infrared spectroscopy.
abstract: The objectives of this study were (i) to test different conditions of freezing, thawing, and grinding during sample preparation and (ii) to evaluate the possibility of using mid-infrared spectroscopy for analyzing the composition of sugars, organic acids, and polyphenols in apples. Seven commercial apple cultivars were chosen for their large variability in composition (total polyphenols from 406 to 1033 mg kg(-1) fresh weight). The different conditions of sample preparation affected only the phenolic compounds and not sugars or organic acids. The regression models of the mid-infrared spectra showed a good ability to estimate sugar and organic acid contents (R(2) ≥ 0.96), except for citric acid. Good predictions were obtained for total phenolic, flavan-3-ols, and procyanidins (R(2) ≥ 0.94) provided oxidation was avoided during sample preparation. A rapid and simple procedure was then proposed for phenolic compounds using sodium fluoride during sample homogenization at ambient temperature and freeze-drying before spectra acquisition.
authors.affiliation: UMR408 Sécurité et Qualité des Produits d'Origine Végétale, INRA, F-84000 Avignon, France. sylvie.bureau@avignon.inra.fr
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bureau
authors.forename: Iwona
authors.initials: I
authors.lastname: Scibisz
authors.forename: Carine
authors.initials: C
authors.lastname: Le Bourvellec
authors.forename: Catherine M G C
authors.initials: CM
authors.lastname: Renard
mesh_terms: D002241:Carbohydrates / Q000032:analysis*; D002264:Carboxylic Acids / Q000032:analysis*; D005511:Food Handling / Q000379:methods; D005519:Food Preservation / Q000379:methods; D005638:Fruit / Q000737:chemistry*; D027845:Malus / Q000737:chemistry*; D010084:Oxidation-Reduction; D059808:Polyphenols / Q000032:analysis*; D013045:Species Specificity; D013055:Spectrophotometry, Infrared
chemical_list: D002241:Carbohydrates; D002264:Carboxylic Acids; D059808:Polyphenols