Impact of liposome-encapsulated enzyme cocktails on cheddar cheese ripening Ehab E. Kheadr a,b , J.C. Vuillemard a, *, S.A. El-Deeb b a Centre de recherche STELA, Pavillon Comtois, Universite ´ Laval, Que ´bec, Canada G1K 7P4 b Department of Dairy Science and Technology, Faculty of Agriculture, University of Alexandria, Alexandria, Egypt Received 26 February 2002; accepted 26 August 2002 Abstract Cheddar cheese proteolysis and lipolysis were accelerated using liposome-encapsulated enzymatic cocktails. Flavourzyme, neutral bacterial protease, acid fungal protease and lipase (Palatase M) were individually entrapped in liposomes and added to cheese milk prior to renneting. Flavourzyme was tested alone at three concentrations (Z1, Z2 and Z3 cheeses). Enzyme cocktails consisted of lipase and bacterial protease (BP cheeses), lipase and fungal protease (FP cheeses) or lipase and Flavourzyme (ZP cheeses). The resulting cheeses were chemically, rheologically and organoleptically evaluated during 3 months of ripening at 8  C. Levels of free fatty acids and appearance of bitter and astringent peptides were measured. Certain enzyme treatments (BP and ZP) resulted in cheeses with more mature texture and higher flavor intensity in a shorter time compared with control cheeses. No bitter defect was detected except in 90-day-old FP cheese. A full aged Cheddar flavor was developed in Z3 and ZP cheeses, while treatment BP led to strong typical Cheddar flavor by the second month and did not exhibit any off-flavor when ripening was extended for a further month. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Liposome; Encapsulation; Enzymes; Cheddar; Ripening 1. Introduction Cheese ripening is a very complex biochemical process by which the rubbery or elastic curd is converted into a smooth-bodied and fully flavored cheese. Flavor and texture are considered as the two main criteria in deter- mining the acceptability of aged cheese (Green, Turvey, & Hobbs, 1981). The time required to develop char- acteristic flavor and texture varies from a few weeks for soft cheeses up to 3 years for very hard varieties. During this period, cheeses attain their own characteristics through a multitude of chemical, microbiological and biochemical changes whereby protein, fat and residual lactose are broken-down to primary products which are further degraded to secondary products. A fine equili- brium between primary and secondary products has been shown to be responsible for typical cheese flavor and texture (El Soda & Pandian, 1991). Since the characteristic aroma, flavor and texture of a cheese is the result of the action of numerous enzymes, the use of a single enzyme to accelerate ripening is likely to disturb the flavor component equilibrium and cause flavor defects (El Soda, 1993). The use of enzyme cock- tails has therefore been proposed to keep accelerated ripening balanced. Crude cell-free extracts prepared from bacteria, yeasts or molds have been extensively studied (El Soda & Pandian, 1991). Blends of protease/ peptidase, protease/lipase or protease/peptidase/lipase have also been evaluated to accelerate maturation of several types of cheeses (El Soda, Ezzat, Hassanein, El Abbasy, & Wahba, 1990; Lin, Jeon, Roberts, & Milli- ken, 1987; Wilkinson, Guinee, O’Callaghan, & Fox, 1992). All of these studies were carried out using free proteolytic and lipolytic enzymes added to cheese milk, which may adversely affect flavor and textural criteria of the resulting cheeses by prematurely attacking sub- strates in addition to contaminating cheese whey. The use of microencapsulated enzymes has been proposed to 0963-9969/03/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0963-9969(02)00166-7 Food Research International 36 (2003) 241–252 www.elsevier.com/locate/foodres * Corresponding author. Tel.: +1-418-656-5968 ; fax : +1-418- 656-3353. E-mail address: jean-christophe.vuillemard@aln.ulaval.ca (J.C. Vuillemard).