15E-29 |
Ultrafiltration as a tool to obtain different polymeric and monomeric anthocyanin extract compositions from grape juice with potential unique functional properties |
A. KALBASI and L. A. Cisneros-Zevallos. Dept. of Horticultural Sciences, Texas A&M Univ., Fruit & Vegetables Post-harvest & Processing Lab., 202 Horticulture & Forest Science Bldg., College Station, TX 77843 Grape juice and grape skin are a major commercial source of anthocyanins (Acy) with a composition given by high proportion of monomeric form (~60%) and smaller amount of polymeric form (~20%). This composition may affect functional properties such as color potential, antimicrobial and antioxidant activity and health benefit properties. Membrane filtration may be used as a tool to enrich extracts with monomeric or polymeric anthocyanins and thus affect their functional properties. The objective of this study was to study the effects of initial Acy extract concentration and pore size membranes on monomeric and polymeric composition of permeate and retentive fractions using a ultrafiltration system. Red grape juice (50mg Acy/100g) was diluted 5 and 10 times and ultrafiltrated with 6 PVDF membranes of MW of 1000K, 550K and 250K at a trans-membrane (TMP) pressure of 2bar and 100K, 30K and 10K at TMP of 4 bars until the initial feed volume was separated to 90% permeate and 10% retentive. Extract Acy and composition was determined with spectrophotometric methods. Initial non-diluted grape juice had 20% polymeric, 60% monomeric Acy and 20% of other forms. Results indicate that anthocyanin recovery in permeate for both dilutions was in the range of 47 to 96% for different pore membrane size. Recovery was higher with larger pore size. Permeates and retentive obtained with the first 3 membranes (1000K to 250K) had similar monomeric and polymeric composition as feed. However, the following 3 membranes (100k to 10K) caused an increase in polymeric (50 to 70%) and a decrease in monomeric Acy (10 to 20%) of the retentate. In the permeate fraction polymeric decreased (15 to 25%) and monomeric Acy increased (10%). Ultrafiltration can be used as a tool to enrich extracts with polymeric or monomeric Acy giving the possibility to tailor extracts with potential unique functional properties.
Session 15E, Nutraceuticals & Functional Foods I
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