Extraction and formulation intensification processes for natural actives of wine

1. Introduction

Winemaking processes generate huge amounts of waste streams, including grape pomace. The growing interest on natural-based health-promoting products, together with the 3R policies, strengthen the prospect of developing innovative, effective and sustainable valorization procedures for wine industry wastes (Barcia et al., 2014; Galanakis, 2012; Pfaltzgraff et al., 2013). WineSense, an ongoing Marie curie Project which combines the efforts of industry and academia, intends to optimize the polyphenol extraction and formulation techniques. Intensification is a common objective of the extraction and formulation processes aiming the reducing of operating time and cost while improving the quantity and quality of the extracts.

2. Microwave extraction

The advantages of adding microwaves to polyphenol extraction have been widely proved. Microwave extraction allows to reduce the extraction time and the amount of solvent required, leading to less bulky equipment. However, microwave implementation into an industrial scale is difficult due to the penetration depth limitations. In order to overcome this drawback, a microwave and pressure pretreatment has been added to the conventional solid-liquid extraction. In this new process, microwaves are combined with pressure to rapidly raise extraction media temperature, in a short but intensive pretreatment. Three energy levels have been studied: first a control sample without any pretreatment, that corresponds to conventional solid-liquid extraction; a microwave pretreatment in which temperature is raised close to the solvent boiling point (80ºC); and a combination of pressure and microwave up to 4 bar. Regarding total yield, the inclusion of the pretreatment to the extraction process increases the initial extraction rate and also enhances the final yield. This provides a concentrate polyphenol extract in much less time. Extraction kinetics corroborate this improvement: initial extraction rate is almost ten and thirty times quicker than the conventional process (see Fig. 1). Thus, a 50% more concentrated polyphenol extract can be obtained in a process ten times quicker.

Future work will be focused on the simulation, design and construction of a continuous microwave oven, which will be able to treat 20 kg/h of grape pomace and solvent. What is more, a conscious microwave cavity design has been designed taking into account the dielectric properties of the extraction media. The design will lead to a homogeneous heat dispersion, which will avoid the formation of hot spots. The result of the design will be an effective and efficient equipment to recover active compounds from grape pomace.

3. Formulation: model compounds

Two model compounds present in grape marc extracts, quercetin as non-water soluble polyphenol and epigallocatechin gallate (EGCG), as water soluble one, were selected for encapsulation studies using natural origin polymers (lecithin, b-glucan and OSA (n-octenyl succinic anhydride)- starch) as well as synthetic surfactants commonly used in pharmaceutical industry (Pluronic L-64). Both components are prominent antioxidants with valuable biological activities of interest for the food, cosmetic and pharmaceutical industries although an adequate formulation is required for protecting them from ambient factors (light, oxygen and temperature) and alkaline pH and for improving their bioavailability. Quercetin was formulated in aqueous suspensions using two different approaches based on the flow turbulent mixing between an aqueous and an organic stream, either water immiscible or miscible. Firstly, high pressure and temperature emulsion techniques followed by solvent evaporation using ethylacetate as organic solvent for the quercetin was used. Secondly, antisolvent nanoprecipitation at high pressure and temperature conditions or ambient conditions was tested using either acetone or ethanol as organic solvents. In all cases lecithin provided better encapsulation. The highest apparent solubility of quercetin achieved was 920 ppm using nanoprecipitation process with an initial quercetin concentration of 8 g/L in acetone, a lecithin concentration in the aqueous stream of 50 g/L and an organic-water ratio of 0.18 working at ambient conditions. Quercetin aqueous suspensions were further processed to obtain a powder product easier to handle and with better storage stability. Drying was performed by “Particles from gas saturated solutions process” (PGSS-Drying) in an inert atmosphere and at lower temperatures (< 70 ºC) respect to conventional spray drying by means of a hot and pressurized CO₂ stream as drying agent. A solution flow rate of 5.5 mL/min was used and it was mixed with a CO₂ flow of 10 kg/h at 130 ºC. Equally it was employed to encapsulate EGCG from aqueous solutions of EGCG (5 g/L) and lecithin (15 g/L) and also in the formulation of aqueous grape marc extract, supplied by Grupo Matarromera and obtained by traditional solid-liquid extraction. Encapsulation efficiencies up to 75 % were achieved.

4. Formulation: microencapsulation of polyphenols from grape marc extract by spray drying

This work was focused on the study of novel protein carriers such as whey and pea protein, as well as on the behavior of lower than usual wall:core ratios for all wall materials. Generally, a lower ratio can be technologically more advantageous for the food or cosmetic industry, since it provides a higher concentration of bioactive compounds per gram of powder, and less amount of the powdered product would be needed in relation to the active material, but it is important to retain a proper encapsulation efficiency and protection of the phenolic compounds. For this purpose, a grape marc extract obtained by traditional solid-liquid extraction was spray dried (GEA Mobile Minor™ spray dryer) using three different natural carriers (maltodextrin, whey and pea protein isolate). The best results in terms of total phenolic content (TPC) expressed per gram of product were obtained with MD, although WPI and PPI microparticles showed a slightly lower but generally very similar. In all cases, the highest concentration of phenolic compounds was obtained with a wall:core ratio of 0.1:1, i.e. 0.1 g of carrier per gram of solids contained in the original aqueous extract. This is an expected ‘concentration’ effect produced by the decreasing amount of carrier. When the extract was dried in the absence of carrier, strong degradation of phenolics was observed (22 %), whereas addition of as little as 0.1:1 carrier was enough to drop this value to 12.8 % for PPI, 3.4 % for WPI and 3.1 % for MD. Fig. 2 shows that the oxygen radical absorbance capacity (ORAC) of the MD samples for all ratios is very similar to that obtained in the absence of carrier (4500-5800 μmol_TEAC/g_DB). However, WPI encapsulated extract offered significantly higher antioxidant activity (7200 μmol_TEAC/g_DB) at the lowest wall:core ratio than the one using MD, even though the phenolic content for both samples was almost identical. Whey protein has been previously reported to have inherent antioxidant activity, and further studies are underway in order to validate these results. Overall, we found that proteins, and especially whey protein, are suitable encapsulating agents for grape marc polyphenols and provide excellent results in terms of phenolic recovery and antioxidant activity even at very low carrier concentrations.

Acknowledgements

WineSense Project has received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007-2013/under REA Grant Agreement nº 612208. iBET researchers acknowledges the support from COST ACTION TD1203 – EUBis.

References

Barcia, M.T., Pertuzatti, P.B., Rodrigues, D., Gómez-Alonso, S., Hermosín-Gutiérrez, I., Godoy, H.T., 2014. Occurrence of low molecular weight phenolics in Vitis vinifera red grape cultivars and their winemaking by-products from São Paulo (Brazil). Food Research International 62, 500-513

Galanakis, C.M., 2012. Recovery of high added-value components from food wastes: conventional, emerging technologies and commercialized applications. Trends in Food Science & Technology 26, 68-87

Pfaltzgraff, L.A., De bruyn, M., Cooper, E.C., Budarina, V., Clark, J.H., 2013. Food waste biomass: a resource for high-value chemicals. Green Chemistry 15, 307–314

Moreno¹; A. Matias², A. Álvarez¹, E. De Paz^1,2,4, V.S.S. Gonçalves^1,2, D. Deodato², Y. Gil³, R. Romero^1,2, O. Benito^1,4, S. Rodríguez-Rojo¹, Á. Martín¹, R. Mato¹, C.M.M. Duarte², A. Guadarrama³, H. Every⁴, M.J. Cocero^*1

¹HPP Group, Department of Chemical Engineering, University of Valladolid

²Food & Health Unit, Nutraceuticals & Delivery Lab, Instituto de Biologia Experimental e Tecnológica, Oeiras

³Bodega Matarromera S.L., Valbuena de Duero, Valladolid

⁴FeyeCon Development and Implementation B.V., Rijnkade 17a, 1382 GS Weesp

* mjcocero@iq.uva.es