ABSTRACT

Colombia is a tropical country with a significant biodiversity of fruits. In addition to their outstanding organoleptic properties, some of these fruits contain important biologically active compounds that can be found in their pulp, seeds and peel. The Andes Berry (Rubus glaucus benth) contains phenolic compounds, specially anthocyanins, with biological activity that may allow reducing carcinogenesis and occurrence of cancer of epithelial origin and cancer of digestive system, among other diseases (Ceron et al, 2012). In 2011, Colombia produced
94,303 tones of Andes Berry fruits (MinAgricultura, 2013), that have been processed into concentrates, jams, juices, etc. The fruit processing operations generate waste and residue streams from which anthocyanins can be extracted an utilized in chemical, cosmetic, food and pharmaceutical applications.
This work presents a study of an enhanced fluidity supercritical extraction of anthocyanins from Andes Berry wastes using CO2 and ethanol, as depicted in Figure 1. In all cases, supercritical extraction was carried out at 45 ºC. First, the effect of Andes Berry wasteâ??s mean particle size (MPS), ranging from 180 mm to 200 mm, on extraction yield was investigated in order to identify the optimal MPS. Then, the effects of pressure (150, 225 and 300 bar), and feed-to-co-solvent (Solid/ethanol) ratio were evaluated at 45 ºC using ethanol concentration of

60%, 70% and 80%. Using the identified MPS, pressure and solid-to-ethanol ratio, the effect of extraction time on yield was investigated. The anthocyanins were determined using a colorimetric method based on the effect of pH on absorbance spectra. Two buffer solutions (potassium chloride and sodium acetate) were used at pH 1 and 4.5, respectively and the absorbance obtained with each buffer was determined at recorded, at 400 â?? 700 nm, using a JENWAY 6460 UV-Vis spectrophotometer. The anthocyanins content in the extracts was expressed as the amount of cyanidin-3-glucoside.

Andes Berry

CO2

Extractor

CO2

CO2 Liquid CO2

Heat Exchanger

Pump

CO2

Ethanol

Extract

Valve

Extract

Colector

Anthocyanins-rich extract

Solids

Figure 1. Scheme of supercritical extraction of anthocyanins from Andes Berry.

Results allowed identifying the optimal MPS, pressure and solid-to-/ethanol ratio to ensure the highest yield of anthocyanins in supercritical extraction. The simplified Sovovaâ??s mass transfer model was used to estimate both, the solubility and mass transfer coefficients according to equations (1) and (2) which represent the curve extractions (Sovova, 2005).

(1) (2)
Where e is the extraction yield, q is the amount of solvent (kg(solvent)/kg(insoluble solid)), ys
is the solubility and xu is the initial concentration in the solid (kg(solute)/kg(insoluble solid)). Equations (1) and (2) are plotted to find the solubility from equation (1) and the constants C1 and C2 from equation (2). According to that, the constants C1 and C2 are used to calculate the fraction of broken cells (r as grading efficiency between 0 and 1) and solid-phase mass transfer coefficient (Ksas) (1/ms) using equations (3) and (4).

(3) (4)
Where C1 and C2 are the parameter calculated from the fitting curves while Q, Nm and qc are
the solvent flow rate, charge of insoluble solid and relative amount of the passed solvent when
the second period of extraction began, respectively. The information and data that have been established at the bench and through modelling provide the basis for future design and scale up of supercritical extractors at different production levels.
References
MinAgricultura. Ministerio de Agricultura. Anuario estadistico de frutas y hortalizas 2007 â??
2011 y sus calendarios de siembras y cosechas. 2012. Available in:
http://www.agronet.gov.co/www/htm3b/public/Anuario/ANUARIO%20ESTADISTICO%20
DE%20FRUTAS%20Y%20HORTALIZAS%202011.pdf
Ceron I. X. Higuita J. C. Cardona C. A. Design and analysis of antioxidant compounds from Andes Berry fruits (Rubus glaucus Benth) using and enhanced-fluidity liquid extraction process with CO2 and ethanol. Journal of supercritical fluids. 62 (2012) 96 â?? 101.
Sovova H. Mathematical model for supercritical fluid extraction of natural products and extraction curve evaluation. Journal of supercritical fluids. 33 (2005) 35 â?? 52.