| Membrane concentration of anthocyanins (ACYs) in fruit juices can be achieved by selective permeation of low molecular weight (MW) solutes, resulting in valuable fractionated ACY-enriched concentrates. The extracts obtained are often quite unstable and prone to oxidation, but stability can be improved by co-pigmenting ACYs with other flavonoids.; This project aimed to determine how co-pigmentation of juice ACYs with known phenolic co-factors can improve the thermal stability of pomegranate juice. Furthermore, it aimed to evaluate the technical and economical feasibility of concentrating ACYs with a low-pressure membrane system in a juice processing plant.; The co-pigmentation effect in single-strength pomegranate juice was studied for co-factors rutin (RU) and ferulic acid (FA) at molar-ratios from 0 to 20 (cofactor/pigment). The thermal stability of treated and untreated juices was assessed over 75-days at 20 and 30°C. All juice types were concentrated with an Osmonics(TM) filtration system (316SS SEPA Membrane Cell - 155 cm2 effective membrane area) at ∼25°C under N 2 headspace. Three commercia membranes were used, a 200 Dalton nanofiltration (NF) and two 1,000 and 3,000 Dalton ultrafiltration (UF) membranes, at two trans-membrane pressure (TMP) levels [UF: 690 and 1,035 kPa; and NF: 1,035 and 1,380 kPa]. A hypothetical industrial-scale OF feed-and-bleed concentration system was designed. An economic feasibility analysis was performed and cost sensitivity was determined for the proposed design.; Juice treatment with FA originated a "blueing" effect at high molar ratios not evident in RU-treated juices. FA-treated juices presented the most red color retention over the 75-day long study, possibly due to formation of pyroanthocyanins. The most favorable fractionation was achieved with the 1000 Dalton OF membrane at 1,379 kPa, with low rejection of small solutes (54.8 +/- 0.0 - 29.0 +/- 0.0% and 51.1 +/- 0.3 - 28.8 +/- 0.5% for electrical conductivity and °Brix respectively), and large rejection of ACYs (96.9 +/- 0.3 - 79.1 +/- 0.5% monomeric ACYs). During testing, permeate fluxes ranged between 4.41 +/- 0 .07 and 1.90 +/- 0.03 LMH. The economic analysis demonstrated that the designed system would be financially solvent in the first year of operation. The most influential design parameters were the membrane area used in the system and the permeate flux during filtration. |
