RECOVERY OF PHOSPHOLIPIDS FROM BUTTERMILK USING MEMBRANE PROCESSING

Buttermilk contains comparably high amounts of fragmented or vesiculat ed material from the original fat globule membrane having particle siz es of upto a few tenth of a micrometer. This study was aimed at the is olation of this phospholipid-rich fraction by the precipitation of cas ein and subjecting the resulting whey to ultrafiltration and microfilt ration. Coagulation of reconstituted buttermilk was carried out using rennet, citric acid and lactic cultures as coagulants. About 80 % of t he phospholipids originally present in buttermilk were transferred to the resulting wheys on rennet coagulation after addition of 0.1 % CaCl 2 to the buttermilk and also when reconstituted buttermilk containing 0.1 % CaCl,was heated to 70 degrees C and acidified with citric acid t o pH 5.2. On coagulation with lactic cultures only about 53 % of the t otal phospholipids could be recovered in whey. For isolation of the ph ospholipid-rich particulate fraction from buttermilk wheys a small lab oratory microfiltration unit (0.2 mu m polysulfone membrane and a pilo t scale plant equipped with 0.1 mu m ceramic membranes) having a zirco nium oxide membrane layer were used. Microfiltration including a diafi ltration step with the 0.2 mu m polysulfone membranes finally resulted in a recovery of 67 % of the phospholipids present in whey. Significa ntly higher recovery was achieved using the 0.1 mu m zirconium oxide m embranes employing an ultrafiltration of buttermilk whey to a volume c oncentration ratio of 4 as a preconcentration. However, it was decisiv e to use optimal operating conditions during microfiltration, e.g., hi gh flow velocity of the retentate, low transmembrane pressure in order to maintain rather constant filtration characteristics of the membran e. Upto 97 % of the phospholipids could be recovered from buttermilk w heys. These isolates consisted mainly of the phospholipid-rich membran e material, i. e. about 66 % total lipids and 25 % (membrane) protein in dry matter, the lipid phase containing about 22 % phospholipids.