Effect of the Drying Process on the Intensification of Phenolic Compounds Recovery from Grape Pomace Using Accelerated Solvent Extraction

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.

The Impact of Long‐Term Intake of Phenolic Compounds‐Rich Grape Pomace on Rat Gut Microbiota

“…Once defrosted at room temperature, the grape byproducts were milled in order to obtain a homogenous mixture. A heat solid/liquid extraction process of the PC with 70% ethanol/water was performed at a ratio of 1:2 (w/v) with agitation, following the experimental procedure developed in our laboratory by Rajha and others . Then the solutions were spray dried in order to obtain a powder consisting of a pure mixture of PC.…”

Pressurized hot water extraction of bioactives

“…Some studies show that crude samples with high moisture content give better extraction yields of polyphenols than dried samples [30,50,51]. …”

Electrical, mechanical, and chemical effects of high-voltage electrical discharges on the polyphenol extraction from vine shoots

“…Vine shoots are an important source of polyphenols with a yield up to 34.5 mg GAE/g DM (Rajha, Boussetta, Louka, Maroun & Vorobiev, 2014a). Compared to vine shoots, grape pomace and grape seeds contain 162 mg GAE/g DM (Rajha et al, 2014b) and 90 mg GAE/100 g DM (Boussetta, Lesaint & Vorobiev, 2013) of polyphenols respectively. The extractability of intracellular components is enhanced by the phenomenon of electrical breakdown in water that provokes cell structure damage and particle fragmentation.…”

“…The higher the polyphenols concentration were, the better the bioactivity of the extracts was (Nada El et al, 2012;Rajha et al, 2014b). Therefore the inhibition of H 2 O 2 formation is likely to be more pronounced with …”