Optimization of bioactives extraction from grape marc via a medium scale ambient temperature system and stability...

Area of Science:

• Food Chemistry
• Green Extraction Technologies
• Phytochemistry

Background:

• Grape marc, a byproduct of winemaking, is rich in valuable polyphenols.
• Efficient and sustainable extraction methods are needed to valorize grape marc.
• Polyphenols possess significant antioxidant properties with potential health benefits.

Purpose of the Study:

• To optimize a scalable, low-energy extraction procedure (MSAT) for polyphenols from white grape marc.
• To evaluate different GRAS (Generally Recognized As Safe) solvents and their mixtures.
• To assess the stability of the obtained polyphenol extracts under various storage conditions.

Main Methods:

• Optimization of extraction parameters (solvent volume, marc mass, marc/dispersant ratio) using response surface methodology.
• Evaluation of propylene glycol, ethanol, ethyl lactate, and their hydro-organic mixtures as extraction solvents.
• Analysis of total polyphenol content (TPC) and antioxidant activity (AA) of extracts.
• Stability testing of extracts over 62 days, assessing effects of temperature, light, and oxidative reactivity.

Main Results:

• The optimized MSAT procedure achieved high TPC (5,918 mgGAE·L⁻¹) and AA (44 mmolTE·L⁻¹).
• Ethyl lactate demonstrated superior performance compared to ethanol, propylene glycol, and water.
• Extracts showed good stability for the first month, retaining 75% of antioxidant activity and polyphenolic profile after 62 days.
• Absence of reactive oxygen species and storage at 4°C significantly enhanced extract stability.

Conclusions:

• The MSAT method offers an efficient and sustainable approach for extracting polyphenols from grape marc.
• Ethyl lactate is a promising solvent for maximizing polyphenol yield and activity.
• Controlled storage conditions are crucial for preserving the bioactivity and stability of grape marc polyphenol extracts.