Abstract
In this work, a membrane-based process for the purification and concentration of antioxidant compounds from aqueous Goji (Lycium barbarum L.) berry extracts was investigated. The aqueous extract was previously clarified with hollow fiber ultrafiltration (UF) membranes in order to remove suspended solids and β-carotene and to produce a clarified extract enriched in phenolic compounds. Then, three UF flat sheet polyamide membranes with a molecular weight cut-off (MWCO) in the range 1000–3500 Da were tested to purify and concentrate phenolic compounds from the clarified extract. The effect of MWCO and transmembrane pressure (TMP) on the performance of selected membranes in terms of productivity and selectivity towards total dissolved solids (TDS), total phenolic compounds (TPC), total carbohydrates (TC) and total antioxidant activity (TAA) was evaluated. Experimental results indicated that the 2500 Da membrane exhibited a lower fouling index, higher cleaning efficiency, lower rejection towards carbohydrates (lower than 30%) and higher rejection towards phenolic compounds (higher than 50%) in comparison to the other investigated membranes. The inclusion of a diafiltration process in the treatment of the clarified extract with this membrane in a spiral-wound configuration improved the concentration of sugar compounds in the permeate stream and increased the purification of phenolic compounds in the retentate fraction.
Highlights
IntroductionGoji (Lycium barbarum L.) is a traditional Chinese medicinal plant, a Solanaceous shrub, whose fruits, well known as Goji berries, are widely consumed in fresh, dried or juice form as well as in combination with tea, wine, meat and vegetarian meals [1,2].Goji berries were introduced in Europe and North America at the beginning of the 21th century and their consumption has increased rapidly due to their claimed nutritional and beneficial properties [3].In particular, Goji berries, advertised as “superfood” in Western Countries, are widely consumed as dried fruits or as concentrated extracts, as well as transformed into functional products or dietary supplements with different formulations (juices, yogurt products, cake, medicinal foods and cosmetics) [1,4].Molecules 2020, 25, 3761; doi:10.3390/molecules25163761 www.mdpi.com/journal/moleculesEpidemiological studies have suggested that Goji berries have a wide range of biological properties including antioxidant, anticarcinogenic, immune enhancing and cardiovascular protective properties as well as neuroprotection, and hypoglycaemic and anti-aging effects [5]
Permeate of flux is an Extract important inMembranes membrane systems because it is related to the productivity of the process
The aqueous extract was filtered through a nylon cloth to remove solid particles and seeds
Summary
Goji (Lycium barbarum L.) is a traditional Chinese medicinal plant, a Solanaceous shrub, whose fruits, well known as Goji berries, are widely consumed in fresh, dried or juice form as well as in combination with tea, wine, meat and vegetarian meals [1,2].Goji berries were introduced in Europe and North America at the beginning of the 21th century and their consumption has increased rapidly due to their claimed nutritional and beneficial properties [3].In particular, Goji berries, advertised as “superfood” in Western Countries, are widely consumed as dried fruits or as concentrated extracts, as well as transformed into functional products or dietary supplements with different formulations (juices, yogurt products, cake, medicinal foods and cosmetics) [1,4].Molecules 2020, 25, 3761; doi:10.3390/molecules25163761 www.mdpi.com/journal/moleculesEpidemiological studies have suggested that Goji berries have a wide range of biological properties including antioxidant, anticarcinogenic, immune enhancing and cardiovascular protective properties as well as neuroprotection, and hypoglycaemic and anti-aging effects [5]. Goji (Lycium barbarum L.) is a traditional Chinese medicinal plant, a Solanaceous shrub, whose fruits, well known as Goji berries, are widely consumed in fresh, dried or juice form as well as in combination with tea, wine, meat and vegetarian meals [1,2]. Goji berries, advertised as “superfood” in Western Countries, are widely consumed as dried fruits or as concentrated extracts, as well as transformed into functional products or dietary supplements with different formulations (juices, yogurt products, cake, medicinal foods and cosmetics) [1,4]. The health benefits of Goji berries have been attributed to their chemical composition, which includes different classes and types of antioxidants such as polyphenols and carotenoids, as well as polysaccharides, salts, vitamins, and other micronutrients [4,8,9,10]. A perusal of the literature revealed that the main polyphenols identified in
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