超临界流体从葡萄渣中连续提取高附加值分子

Abstract

Inspired by the  concept of organic waste valorisation and heading towards a sustainable  economy, a green chemistry extraction technique involving supercritical  carbon dioxide (SC-CO₂) along with water as a  co-solvent was employed for the main winery by-product (grape pomaces).  The objective was to selectively extract high-value added molecules, in  particular phenolic compounds and polysaccharides. The experimental  design involved applying three distinct temperature conditions (40, 60,  and 80 °C), and a constant pressure of 400 bar. Phenolic compounds and   high-molecular weight isolates (449–478 kDa) containing low methoxyl (% DE = 23) pectic substances were detected in the SC-CO₂  extracts accompanied by water as a co-solvent. The phenolic acids,   namely, gallic (GA), protocatechuic (PCA), coumaric (CouA), and caftaric  (CTA), and flavonoids, namely, procyanidin B1 (PRC B1), procyanidin B₂ (+) (PRC B₂),  (+) catechin (CT), and (−) epicatechin (ECT) were found in all the   extracts under the tested experimental conditions. The following study   underscores the potential of the pressurized CO₂/H₂O  medium as an effective solvent with minimal environmental impacts for the comprehensive valorisation of the main winery by-product,   specifically targeting polysaccharides and phenolic compounds.

受有机废物价值化概念的启发，并朝着可持续经济的方向发展，一种涉及超临界二氧化碳（SC-CO2）和水作为共溶剂的绿色化学提取技术被用于酿酒厂的主要副产品（葡萄渣）。目的是选择性地提取高附加值的分子，特别是酚类化合物和多糖。实验设计涉及应用三种不同的温度条件（40、60和80°C）和400bar的恒压。在SC-CO₂提取物中检测到含有低甲氧基（%DE=23）果胶物质的酚类化合物和高分子量分离物（449-478 kDa），并伴有水作为共溶剂。在测试的实验条件下，所有提取物中都发现了酚酸，即没食子酸（GA）、原儿茶酸（PCA）、香豆酸（CouA）和咖啡酸（CTA），以及黄酮类化合物，即原花青素B1（PRC B1）、原花青素B2（+）（PRC B2）、儿茶素（CT）和表儿茶素（ECT）。以下研究强调了加压CO2/H2O介质作为一种有效溶剂的潜力，该溶剂对环境的影响最小，可全面稳定主要酒厂副产品，特别是针对多糖和酚类化合物。

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2. Materials and methods

2.1. Materials

The standards of white wine-related  phenolic compounds such as gallic, protocatechuic, hydroxybenzoic,  caftaric, gentisic, caffeic, coumaric, and chlorogenic acids and  hydroxytyrosol, tyrosol, procyanidin B1, B2, (+) catechin and (−)  epicatechin were purchased from Sigma-Aldrich (Steinheim, Germany). The  monosaccharide standards (mannitol, L-fucose, L-rhamnose, L-arabinose, D-galactose, D-glucose, D-mannose, D-xylose, D-galacturonic  and glucuronic acids) were purchased from Acros Organics and   Sigma-Aldrich. Sodium hydroxide (NaOH) solution 46/48% (Fisher   Bioblock), sodium acetate (NaOAc) (Sigma-Aldrish), trifluoroacetic acid (TFA) (Merck) and all the above-mentioned chemicals were of analytical grade.

2.2. Sample pre-treatment

2.3. Supercritical CO₂ extraction on grape pomaces

本研究中使用了超临界SC-CO₂机器（SFE process, Nancy, France），该机器配有两个泵，主CO₂泵和共溶剂泵，最大压力容量为1000bar。该仪器配备了一个容量为100毫升的提取器（不锈钢）和一个高压釜，将提取物引导到背压调节器（BPR）（图1）。冷却系统充满甘油，CO2流在系统中循环。得益于透明的蓝宝石隔膜，可以观察到提取物。系统中放置了各种温度传感器，用于监测系统内的重要温度变化。