Prediction of tannin profile in grape (Vitis vinifera L.) skins during berry maturation using a rapid mechanical puncture approach. (15th August 2022)

• Record Type: Journal Article
• Authors: Duan, Bingbing; Chen, Guoqiao; Jin, Xiaoduo; Chang, Wei; Lan, Tian; Zhao, Yimei; Sun, Xiangyu; Liu, Xu
• Is Part Of: Food chemistry. Volume 385(2022)
• Publication Date: 2022-08-15
• Subjects: CTs_mg/berry CTs content expressed on a per berry basis -- CTs_mg/g berry CTs content expressed on a per gram of berry basis -- CTs_mg/g skin FW CTs content expressed on per gram of skin fresh weight basis -- CTs_mg/g skin DW CTs content expressed on per gram of skin dry weight basis -- mDP mean degree of polymerization -- MM_subunit molecular weight determined by phloroglucinolysis (g/mol) -- MM_GPC molecular weight determined by GPC (g/mol) -- EGC_ext (–)-epigallocatechin extension subunit -- C_ext (+)-catechin extension subunit -- EC_ext (–)-epicatechin extension subunit -- ECG_ext (–)-epicatechin-3-O-gallate extension subunit -- C_term (+)-catechin terminal subunit -- EC_term (–)-epicatechin terminal subunit -- ECG_term (–)-epicatechin-3-O-gallate terminal subunit -- % galloylation sum of molar percentage of (–)-epicatechin-3-O-gallate extension and terminal subunits -- Spsk skin thickness of berry (μm) -- Fsk skin break force of berry (N) -- Wsk skin break energy of berry (mJ) -- Esk skin resistance to the axial deformation of berry (N/mm); Grape -- Condensed tannin -- Molecular size -- Maturity -- Mechanical property -- Random forest; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2022.132666
• Languages: English
• ISSNs: 0308-8146

Abstract

Graphical abstract: Highlights: Dynamic variations of condensed tannin were investigated as maturation progressed. Mechanical properties showed a good correlation with the specific condensed tannin characteristics. Random forest served as an excellent model for evaluating skin condensed tannin profile. PCA and OPLS-DA obtained excellent classification results for the ripe and unripe samples. Abstract: Tannin structure and composition are variable during grape maturation, and crucially determine perceived astringency, body structure and aging capacity of red wines. This study investigated the evolution of condensed tannins (CTs) in grape skins as maturation progressed and the feasibility of using a rapid mechanical puncture approach for assessing the CTs profile. The results showed that the mean degree of polymerization (mDP), molecular mass (MM), and proportions of (–)-epigallocatechin in extension subunits (EGC_ext) and (–)-epicatechin-3- O -gallate in terminal subunits (ECG_term) of skins increased during grape maturation, while CTs content and the proportion of (–)-epicatechin-3- O -gallate in extension subunits decreased. The predictive models built by random forest for CTs content based on skin weight, mDP, MM_subunit, EGC_ext, and ECG_term obtained good results with high squared correlation coefficients of prediction and calibration (R 2 _P > 0.85 and R 2 _C ≈ 0.95). In addition, the classifications of CTs characteristics obtained from ripe and unripe samples were observed in different principal component spaces. This study indicated that the mechanical properties were useful for predicting skin CTs profile, estimating tannin maturity stages, and providing information for optimal harvesting and winemaking protocols.