Calcium Chelation and Other Pretreatments for Flux Improvement in Ultrafiltration of Cottage Cheese Whey

Abstract

Cottage cheese whey was treated to minimize effects of calcium on membrane fouling during ultrafiltration in a stirred Amicon cell. The treatments used were stepwise pH adjustment from 4.5 to 1.5; chelation of calcium with EDTA or citric acid; calcium chelation followed by pH adjustment to 2.5; and calcium replacement with sodium by ion exchange. All treatments resulting in elimination of free calcium improved the flux. Highest flux increase (53%) in the 8-hr processing runs was for citric acid (I .25 meqione meq Ca) after pH adjustment to 2.5. Addition of CaC12 decreased the flux. Confirmatory experiments with DDS-Lab 20 equipment showed 25% flux increase after treatment with either EDTA (one meqione meq Ca) or citric acid (I .25 meq/one meq Ca) with pH adjusted to 2.5.

Ultrafiltration flux of acid whey obtained by lactic acid fermentation

“…Addition of NaCl increases the ionic strength and, probably, it stabilized the whey proteins by enhancing hydration of the protein (Youravong et al, 2002). Significantly better results were obtained after pretreatment of the acid whey with the Ca sequestering agent EDTA (p < 0.01), in agreement with the results of Lee and Merson (1976a) and Patocka and Jelen (1987).…”

“…Delaveau and Jelen (1979) reported on negligible changes in the viscosity of cottage cheese whey from pH 2 to 6; this is a prerequisite for a high performance UF. Furthermore, it is known that acidification of whey increased permeation rates (Lee & Merson, 1976a;Patocka & Jelen, 1987). The results of flux decline of centrifuged acid whey in the quasi-steady state period of UF at VRR 2 at different pH-values are shown in Fig.…”

“…Most of the whey proteins have their isoelectric point near pH 5.0 where they are the least soluble and precipitate out at higher concentrations. Pretreatments of lactic acid whey as proposed by Lee and Merson (1976a) or Patocka and Jelen (1987) for cottage cheese whey aimed at improving solubility of whey proteins or preventing insolubilization of calcium phosphate and removal of phospholipids. The pretreatment of acid whey is generally simplified because the calcium phosphate is soluble in acid conditions (Pouliot, 1996, pp.…”

“…Several pretreatments have been proposed to improve UF performance such as a defattingeclarifying process (Fauquant, Oierre, & Brulé, 1985), removal of Ca by chelation with EDTA (Heng & Glatz, 1991;Lee & Merson, 1976a), by addition of citrate (Patocka & Jelen, 1987) or by replacement of Ca 2þ with Na þ (Ennis, Johns, & O'Connell, 1981). Whey clarification reduces both the Ca content and the protein content mainly due to removal of the highmolecular immunoglobulins (Ig) and bovine serum albumin (SA) (Musale & Kulkarni, 1998).…”

“…The most important differences are the absence of caseinomacropeptide, the high Ca content and the higher acidity. Ultrafiltration (UF) of acid whey obtained by lactic acid fermentation is difficult to practise because of membrane fouling during processing (Lee & Merson, 1976a;Musale & Kulkarni, 1998;Patocka & Jelen, 1987). Acid whey is mostly wasted or used as animal feed (Shon & Haque, 2007).…”