ALLERGY Net

Tagatose and milk allergy

S. L. Taylor*, D. M. Lambrecht, S. L. Hefle

Key words: allergy; cows' milk; tagatose.

Tagatose is a new food ingredient being used as a reduced-calorie sweetener in foods and bever- ages. Tagatose is a six-carbon ke- Tagatose does not tose sugar found contain milk residues. naturally in some dairy products and in tropical date trees. As tagatose is incompletely absorbed, it provides only 1.5 cal/g as contrary to 4 cal/g for sucrose. Tagatose has approximately the same sweetness as sucrose. Recently, a manufacturing process for tagatose has been developed allowing the production of increased quantities of tagatose. Tagatose has been affirmed as Generally Recognized as Safe (GRAS) in the US and is approved for use in foods and beverages in the US, Korea, Australia and New Zealand. Tagatose is a unique ketose sugar manufactured by the isomerization of galactose. The galactose involved in the manufacturing of tagatose is derived from lactose, the disaccharide found in the whey fraction of milk. Lactose is known to contain residual milk proteins including several of the major cowsÕ milk allergens, principally b-lactoglobulin and a-lactalbumin from whey, on occasion (1). Consequently, some questions were raised about the potential allergenicity of tagatose. Although lactose often contains resid- ual milk allergens, tagatose is much less likely to contain any milk allergens based upon knowledge of the process used to

412 ALLERGY Net produce tagatose. The steps involved in at sensitivity levels of 2.5 p.p.m. (mg/ the manufacturing of tagatose from kg) for casein and 1.0 p.p.m. (mg/kg) lactose are: for whey proteins. The minimal eliciting or threshold dose for milk in cowsÕ (a) lactose is obtained from whey by milk-allergic individuals are estimated ultrafiltration; to be in the low milligram range (4, 5). (b) lactose is hydrolyzed to galactose Thus, the ingestion of a kilogram of and glucose by immobilized tagatose, which would be virtually lactase; impossible, would be required to exceed (c) glucose is separated from the the observed minimal eliciting or galactose by chromatographic threshold doses for cowsÕ milk. separation; Therefore, tagatose should be safe for (d) the galactose stream is isomerized milk-allergic individuals and its to tagatose by adding calcium avoidance by such individuals is not hydroxide in a process that increases necessary. the pH to pH 12 for a prolonged period; *Food Allergy Research & Resource Program (e) the tagatose stream is demineralized University of Nebraska using ion exchangers; Lincoln (f) the tagatose stream is purified by NE 68583-0919 chromatographic separation; USA (g) the tagatose solution is Tel: +1 402 472 2833 decolorized using an active carbon e-mail: [email protected] filter; (h) tagatose is crystallized; Accepted for publication 29 June 2004 (i) the tagatose is dried by fluid-bed Allergy 2005: 60:412–413 drying. Copyright Blackwell Munksgaard 2005 Several steps in this process help DOI: 10.1111/j.1398-9995.2005.00701.x denature or remove residual proteins in the lactose starting material. The References chromatographic separation steps 1. Host A, Koletzko B, Dreborg S, Muraro A, separate the starting material, galactose, Wahn U, Aggett P et al. Dietary products and the finished product, tagatose, from used in infants for treatment and prevention larger protein molecules. The isomeri- of food allergy. Arch Dis Child 1999;81:80– zation process at pH 12 affects any 84. residual protein but any effect on the 2. Hefle SL, Taylor SL. A sandwich allergenicity of that protein resulting enzyme-linked immunosorbent assay from that treatment would be uncertain. (ELISA) for the detection of casein in However, tagatose is also crystallized foods. Chicago: Institute of Food Tech- in a process in which only the pure nologists. Book of Abstracts 1997:143 sugar molecules are likely to form (abstract). crystals. 3. Hefle SL, Shimakura K, Taylor SL. An Despite the high likelihood that indirect enzyme-linked immunosorbent protein was removed from tagatose assay (ELISA) for the quantitation of whey during this commercial process, in foods. J Allergy Clin Immunol commercial tagatose was analyzed for 1996;97:332 (abstract). residual casein and whey proteins. 4. Taylor SL, Hefle SL, Bindslev-Jensen C, A commercial enzyme-linked immuno- Bock SA, Burks AW, Christie L et al. Factors affecting determination of thresh- sorbent assay (ELISA) kit (Veratox old doses for allergenic foods: how much is milk assay; Neogen Corp., Lansing, too much? J Allergy Clin Immunol MI, USA) was used for detection of 2002;109:24–30. casein (2). An ELISA for whey proteins 5. Bindslev-Jensen C, Briggs D, developed at the Food Allergy Osterballe M. Can we determine a Research & Resource Program at the threshold dose for allergenic foods by University of Nebraska was also statistical analysis of published data in used (3). the literature? Allergy 2002;57:741– Casein and whey protein residues 746. were not found in commercial tagatose

413