Hong Zhang a Charlotte Jacobsen b Lars Saaby Pedersen c Morten Würtz Christensen c Jens Adler-Nissen a a BioCentrum-DTU, Technical University of Denmark, Lyngby, Denmark b Danish Institute for Fisheries Research, Lyngby, Denmark c Novozymes A/S, Bagsvaerd, Denmark Storage stability of margarines produced from enzymatically interesterified fats compared to those prepared by conventional methods – Chemical properties In thisstudy, four margarine hardstocks were produced, two from enzymatically inter- esterified fats at 80 and 100% conversion, one from chemically randomized fat and one from physically mixed fat. These four hardstocks, blended with 50% sunflower oil, were mainly used for the production of table margarines in a pilot plant. Storage sta- bility studies were carried out at storage temperatures of 5 and 25 7C for 12 wk. Mar- garines from the enzymatically interesterified fats were compared to the margarines produced by the conventional methods (chemical interesterification and physical blending) and to selected commercial margarines. The changes in the chemical prop- erties of the products, including peroxide values (PV), tocopherols, free fatty acids, volatile oxidation products, and sensory evaluation, were examined during storage. It was observed that the margarine produced from the chemically interesterified fat had higher PV in weeks 4, 8 and 10 than the margarines produced from the enzymatically interesterified fats and the physically blended fat. These differences were not caused by different contents of tocopherols in the hardstocks. The differences between the processes for chemical and enzymatic interesterification, including further treatment stages, might be responsible for the development of a high PV in the margarine pro- duced from the chemically interesterified fat. However, the contents of volatiles did not show the same tendency as observed for PV for the margarines stored at 25 7C during 12 wk. Storage at 25 7C accelerated oxidation compared to storage at 5 7C. The con- tent of d- and g-tocopherols decreased faster than the content of a- and b-tocopherols during storage. This phenomenon was only affected by storage time, not by storage temperature. Sensory analysis did not show consistent differences between the pro- duced margarines and commercial margarines, and no hydrolysis occurred for these four margarines during storage. The margarines produced from the enzymatically interesterified fats had low PV and a similar taste and smell compared to the margarine produced from the chemically interesterified fat. Keywords: Lipozyme TL IM, storage stability, interesterification, sensory analysis, sensory evaluation, chemical properties, margarine. 1 Introduction For a margarine product, storage stability is critical in practical usage. Besides microbial stability of the prod- uct, both physical and chemical storage stabilities have to be considered. During storage, the former is related to changes of the crystals and the crystal network of the margarine, and the latter reflects oxidative deterioration of the product. Both parameters directly affect sensory changes and consumption quality of the margarine. It is therefore always very important to study the storage sta- bility when a new margarine feedstock or production process is developed. In recent years, an inexpensive, cost-effective enzyme- catalyzed production process has been developed for margarine fat production [1–4]. Thus, storage stability studies on margarines produced from enzymatically interesterified fats have become an interesting topic. The changes in the physical properties of margarines produced from enzymatically interesterified fat during storage have previously been reported [5]. However, the changes in their chemical properties, considering both Correspondence: Hong Zhang, BioCentrum-DTU, Building 221, Technical University of Denmark, DK-2800 Lyngby, Denmark. Phone: 145 4525 2637, Fax: 145 4588 4922, e-mail: hz@biocen- trum.dtu.dk Eur. J. Lipid Sci. Technol. 108 (2006) 227–238 DOI 10.1002/ejlt.200500305 227 Research Paper  2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.ejlst.com