Abstract
The current work concerns the optimization process of phenolic compounds solid liquid extraction from grape byproducts at high temperatures and short incubation times. The effect of five experimental parameters (solidliquid ratio, particle size, time, temperature and solvent mixture) mostly believed to affect the extraction process was undertaken. A first response surface methodology experimental design was used to optimize the solid-liquid ratio and milling time parameters. A second design was used for the optimization of the quantitative and qualitative parameters. The quantitative parameters studied are: total phenolic compounds, flavonoid content, total monomeric anthocyanin composition and tannin concentration. The qualitative parameters analyzed are: antiradical activity and antioxidant capacity. The second design was based on the use of time, temperature and solvent mixture as optimization parameters. The assays were first conducted separately revealing the best experimental conditions for the maximization of each response variable alone. A simultaneous response surface methodology of all the responses taken together was then conducted, showing the optimal extraction conditions to be: 93 minutes at 94?C and in 66% ethanol/water solvent. The maximal response values obtained for each parameter are: Total Phenolic Compounds yield (5.5 g GAE/100g DM), Flavonoid Content (5.4 g GAE/100g DM), Total Monomeric Anthocyanin yield (70.3 mg/100g DM), Tannin Concentration (12.3 g/L), Antiradical Activity (67.3%) and Total Antioxidant Capacity (393 mgAAE/L). All of the optimal values were acquired at 3 mL/g solid-liquid ratio and 6.8 min milling time. The obtained extracts could be used as natural bioactive compounds in several industrial applications.
Highlights
The annual production of large waste quantities by the food processing industry creates serious environmental problems as a consequence of the absence of efficient policies regarding their disposal
A simultaneous optimization of the total phenolic compounds, the flavonoids content, the anthocyanins composition, the tannin concentration, the free radical scavenging activity and the total antioxidant capacity was realized in order to produce highly bioactive compounds which could be used in several industrial application
The Folin’s phenol reagent (SCOTT SCIENCE UK) and sodium carbonate (Fluka, Buchs, Switzerland) were utilized to measure the total phenolic compounds concentrations using the FolinCiocalteu method; the calibration curve was built with gallic acid
Summary
The annual production of large waste quantities by the food processing industry creates serious environmental problems as a consequence of the absence of efficient policies regarding their disposal. Divided into two major groups (nonflavonoids and flavonoids), phenolic compounds show antioxidant and radical scavenging activities possibly responsible for many health benefit effects [6]. They appeared to have promising applications in food industries, pharmaceuticals and cosmetics. The major parameters believed to affect the effectiveness of the procedure and the quality of the extracts are: temperature, contact time, extraction solvent, solid-liquid ratio, and particle size [14]. The optimal particle size and solid-liquid ratio were firstly determined and applied in the second experimental design, which was conducted to analyze the effect of time, temperature and solvent mixture on the quality and quantity of the extracts. A simultaneous optimization of the total phenolic compounds, the flavonoids content, the anthocyanins composition, the tannin concentration, the free radical scavenging activity and the total antioxidant capacity was realized in order to produce highly bioactive compounds which could be used in several industrial application
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