Clinical and biological studies have proved that compounds of pomegranate juice reduce blood pressure and low density lipoprotein (LDL) oxidation and exhibit anticarcinogenic, antimicrobial, antiviral and antiatherosclerotic activity. These activities have been attributed to its phenolic fraction containing a significantly high level of hydrolyzable tannins, as well as anthocyanins (delphinidin, cyanidin, pelargonidin 3-glucoside and pelargonidin 3,5-diglucoside), which exhibit a high antioxidant activity. Consequently, industries producing pomegranate juice have increased significantly in recent years, as well as pharmaceutical companies, which extract health-beneficial compounds from the fruit. Besides, recent interest in anthocyanins has arisen not only due to their potential health benefits but also to their use as natural colorants. Fractionation and purification of anthocyanins using membrane technologies is of interest because the low temperatures involved imply that thermal degradation of these compounds can be avoided. This study aimed at determining the feasibility of using ultrafiltration (UF) to separate and purify anthocyanin compounds from the clarified pomegranate juice. Various UF membranes (Desal GK, from GE Water & Process Technologies, PES 004 from Microdyn Nadir, Etna 01 PP from Alfa Laval and MPF 36 from Koch) with different molecular weight cut-off (1, 2 and 4 kDa) and membrane material (fluoropolymer, polyamide and polyethersulphone) were evaluated in terms of productivity, fouling index and retention coefficients towards anthocyanins (delphinidin, cyanidin, pelargonidin-3-glucosides and 3,5-diglucosides), glucose, fructose, total phenolics and total antioxidant activity (TAA). All selected membranes exhibited a high retention of anthocyanins (in the range 72-98%); however, the Desal GK membrane (polyamide, 2 kDa) exhibited the lowest retention towards glucose and fructose (in the range 1-4%) when compared with the other investigated membranes. Operating at a transmembrane pressure (TMP) of 15 bar and a temperature of 27 °C according to a batch concentration mode, steady-state permeate fluxes of about 17 kg/m2h were obtained. In these conditions retentions towards different anthocyanins were in the range 82-90%. For phenolic compounds and total antioxidant activity (TAA) rejections were of 87 and 79%, respectively. This membrane was characterized by a steady increase of permeate flux and a higher retention of total soluble solids and phenolic compounds when TMP increased (Figure 1). An improved separation of anthocyanins from glucose and fructose was achieved through a diafiltration of the UF retentate.
Separation and purification of anthocyanins from pomegranate juice by ultrafitration membranes
Cassano A;Conidi C;Drioli E
2015
Abstract
Clinical and biological studies have proved that compounds of pomegranate juice reduce blood pressure and low density lipoprotein (LDL) oxidation and exhibit anticarcinogenic, antimicrobial, antiviral and antiatherosclerotic activity. These activities have been attributed to its phenolic fraction containing a significantly high level of hydrolyzable tannins, as well as anthocyanins (delphinidin, cyanidin, pelargonidin 3-glucoside and pelargonidin 3,5-diglucoside), which exhibit a high antioxidant activity. Consequently, industries producing pomegranate juice have increased significantly in recent years, as well as pharmaceutical companies, which extract health-beneficial compounds from the fruit. Besides, recent interest in anthocyanins has arisen not only due to their potential health benefits but also to their use as natural colorants. Fractionation and purification of anthocyanins using membrane technologies is of interest because the low temperatures involved imply that thermal degradation of these compounds can be avoided. This study aimed at determining the feasibility of using ultrafiltration (UF) to separate and purify anthocyanin compounds from the clarified pomegranate juice. Various UF membranes (Desal GK, from GE Water & Process Technologies, PES 004 from Microdyn Nadir, Etna 01 PP from Alfa Laval and MPF 36 from Koch) with different molecular weight cut-off (1, 2 and 4 kDa) and membrane material (fluoropolymer, polyamide and polyethersulphone) were evaluated in terms of productivity, fouling index and retention coefficients towards anthocyanins (delphinidin, cyanidin, pelargonidin-3-glucosides and 3,5-diglucosides), glucose, fructose, total phenolics and total antioxidant activity (TAA). All selected membranes exhibited a high retention of anthocyanins (in the range 72-98%); however, the Desal GK membrane (polyamide, 2 kDa) exhibited the lowest retention towards glucose and fructose (in the range 1-4%) when compared with the other investigated membranes. Operating at a transmembrane pressure (TMP) of 15 bar and a temperature of 27 °C according to a batch concentration mode, steady-state permeate fluxes of about 17 kg/m2h were obtained. In these conditions retentions towards different anthocyanins were in the range 82-90%. For phenolic compounds and total antioxidant activity (TAA) rejections were of 87 and 79%, respectively. This membrane was characterized by a steady increase of permeate flux and a higher retention of total soluble solids and phenolic compounds when TMP increased (Figure 1). An improved separation of anthocyanins from glucose and fructose was achieved through a diafiltration of the UF retentate.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
