Abstract
The polyphenolic composition and antioxidant activity of grape seeds, as byproducts of red winemaking, depend on various factors, such as grape cultivar, vintage effect, grape maturity and winemaking methods. In the present work, the influence of the maceration length on the polyphenolic and antioxidant characteristics of the seeds of four Italian red grape cultivars (‘Barbera’, ‘Grignolino’, ‘Nebbiolo’, and ‘Uvalino’), sampled from the fermentation tanks after short (two days) and medium-long (7–21 days) macerations, was studied with spectrophotometric methods, high-performance liquid chromatography (HPLC), and three different antioxidant assays (2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP) and 2,2 diphenyl-1-picrylhydrazyl (DPPH)). The total polyphenolic content (gallic acid equivalent (GAE)) of the seeds sampled after short macerations ranged between 24.5 and 60.1 mg/g dry weight (DW), and it dropped to 20.0–37.5 mg/g DW after medium-long macerations. The polyphenolic profile of the shortly macerated seeds was related to the varietal characteristics, while, after longer macerations, the influence of the maceration length prevailed on the cultivar effect. The multiple in vitro antioxidant activity tests (ABTS, FRAP and DPPH), although based on different mechanisms capable of highlighting behavioral differences between the different polyphenolic compounds, were highly correlated with each other and with the polyphenolic parameters; the qualitative differences between the matrices in the polyphenolic profile were probably less important than the quantitative differences in the polyphenolic content. The relations with the polyphenolic content were linear, except for the Efficient Concentration (EC20) parameter, whose relation was better described by a hyperbolic equation.
Highlights
Polyphenols can prevent the formation of free radicals in cellular tissues, providing a preventive action against various human pathologies, including cancer, cardiovascular and neurological diseases [1,2,3,4]
The total polyphenolic content (gallic acid equivalent (GAE)) of the seeds sampled after short macerations ranged between 24.5 and 60.1 mg/g dry weight (DW), and it dropped to 20.0–37.5 mg/g DW after medium-long macerations
The ABTS and DPPH values determined at racking off (Table 4b) and expressed as Trolox equivalent (TE) were compared with the results reported by [15] for seeds from French red grapes pomace with similar total polyphenols contents (GAE)
Summary
Polyphenols can prevent the formation of free radicals in cellular tissues, providing a preventive action against various human pathologies, including cancer, cardiovascular and neurological diseases [1,2,3,4]. Seeds removal can be performed as soon as the cap of skins is completely raised by directly collecting the seeds deposited at the bottom of the tank (with conical bottom), or better during a pumpover or a délestage [21]: the seeds are separated from the must when it is pumped from the lower to the upper part of the same fermenting tank to soak the floating cap (pumpover), or when it is pumped to a support tank where it is oxygenated (délestage) These seeds, collected after short macerations, should generally have a high polyphenolic content and interesting antioxidant properties
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
