Effect of the drying process on the intensification of phenolic compounds recovery from grape pomace using accelerated solvent extraction.

Hiba Rajha,Zeina Hobaika,Nicolas Louka,Richard Maroun,Eugene Vorobiev,Herbert Boechzelt,Walter Ziegler

doi:10.3390/ijms151018640

Abstract

In light of their environmental and economic interests, food byproducts have been increasingly exploited and valorized for their richness in dietary fibers and antioxidants. Phenolic compounds are antioxidant bioactive molecules highly present in grape byproducts. Herein, the accelerated solvent extraction (ASE) of phenolic compounds from wet and dried grape pomace, at 45 °C, was conducted and the highest phenolic compounds yield (PCY) for wet (16.2 g GAE/100 g DM) and dry (7.28 g GAE/100 g DM) grape pomace extracts were obtained with 70% ethanol/water solvent at 140 °C. The PCY obtained from wet pomace was up to two times better compared to the dry byproduct and up to 15 times better compared to the same food matrices treated with conventional methods. With regard to Resveratrol, the corresponding dry pomace extract had a better free radical scavenging activity (49.12%) than the wet extract (39.8%). The drying pretreatment process seems to ameliorate the antiradical activity, especially when the extraction by ASE is performed at temperatures above 100 °C. HPLC-DAD analysis showed that the diversity of the flavonoid and the non-flavonoid compounds found in the extracts was seriously affected by the extraction temperature and the pretreatment of the raw material. This diversity seems to play a key role in the scavenging activity demonstrated by the extracts. Our results emphasize on ASE usage as a promising method for the preparation of highly concentrated and bioactive phenolic extracts that could be used in several industrial applications.

Highlights

The exploitation of food byproducts has been continuously increasing due to environmental and economic interests [1]
The effect of the temperature and the solvent mixture on the extraction of total phenolic compounds from wet grape pomace was studied in order to select the optimal conditions for the process
Our results clearly show that accelerated solvent extraction (ASE) extraction with a 70% ethanol/water mixture at 140 °C, provides the highest phenolic compounds yield for wet (16.2 g Gallic Acid Equivalent (GAE)/100 g dry matter (DM))

Summary

Introduction

The exploitation of food byproducts has been continuously increasing due to environmental and economic interests [1]. Several grape (Vitis vinifera) byproducts such as pomace are rich in antioxidant substances namely phenolic compounds [4]. These have several pharmaceutical and nutritional applications. The valorization of those byproducts reduces waste and permits the purification of added-value products. It follows that apart from their individual and public health benefits, phenolic compounds are highly valuable on an industrial level; the main focus is on the environment friendly extraction methods of those molecules, using green technology by replacing the conventional methods with innovative technologies [6,7]. Accelerated Solvent Extraction (ASE), firstly described by Richter et al

Objectives

Results

Conclusion