Original article Development and evaluation of a laboratory scale conch for chocolate production Andrea Bordin Schumacher,* Adriano Brandelli, Erwino Wulf Schumacher, Fernanda Carrion Macedo, Luiza Pieta, Ta ˆmmila Venzke Klug & Erna Vogt de Jong Instituto de Cieˆncia e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonc¸alves 9500, 91501-970 Porto Alegre, Brasil (Received 24 June 2008; Accepted in revised form 8 October 2008) Summary In this study a laboratory scale conch was developed with the purpose of testing new formulations using small amounts of chocolate mass. The equipment was built with working parts of others machines and the chocolate manufactured with the conch was evaluated in relation to the viscosity, moisture, acidity and polyphenol concentration. The resulting chocolate was tempered and then evaluated by a sensory panel. The results were always compared with an industrial conching process. The material used in the assays was dark chocolate (40% cocoa). Data were submitted to variance analysis (anova) and when there was significant difference among the averages, the Tukey’s test was applied. It was verified that the reduction of moisture and viscosity of the mass in the laboratory scale was similar to industrial scale. The parameters acidity and polyphenols showed no significant alterations when comparing both process scales. However, in the sensory analysis a flavour difference between the processing scales was perceptible. Keywords Acidity, chocolate, cocoa, polyphenols. Introduction The chocolate production basically consists of five stages: mixture of ingredients, refining, conching, tem- pering and final crystallisation. For production of high quality chocolate, not only the quality of the ingredients defines the final product. Besides, there is a great influence of the productive process, the formulation, and the regional expectations in relation to this product (Cidell & Alberts, 2006). The solid ingredients are initially mixed with part of the cocoa butter to obtain a mass with the adequate consistency to be refined. The refining process must result the correct particle size (Bolenz et al., 2003). Thus, the main goal of this stage is to reduce sugar crystals and solids of the cocoa to the size that it cannot be detected in the mouth (Lucisano et al., 2006). Reaching the standardised particle size, the mass that became a fine powder is placed inside of a conch. The function of the conch was initially attributed to reduce the particle size and to guarantee the fluidity of the mass. However, after the development of refine machines this function started to be secondary, and then flavour modification is credited to the conching (Beckett, 1994). In the conch the undesirable flavours are suppressed and the pleasant ones are produced, generating the typical flavour of the chocolate (Lucisano et al., 2006). Conching influences the development of flavour and the flow properties, being a process that occurs in three steps. In the dry phase, the refined product is warmed, blended and aerated, to evaporate the water and some acids originated from the cacao liquor (residues of the fermentation). In the pasty phase, where some melted cacao butter is added, some flavour precursors are produced to generate the typical flavour of chocolate. In the final liquid phase, all the particles are covered with a thin layer of fat that will result in a decrease of viscosity, which is very important for sensory characteristics of the chocolate. The lecithin is added in the liquid phase finishing the conching process (Beckett, 1994; Bolenz et al., 2003). Mainly for dark chocolates the time of conching influences in the flavour development and still today the majority of milk and dark chocolates are processed during 5–12 h (Bolenz et al., 2003). Imperfections in the conching process may result inadequate distribu- tion of the fat on solid particles generating a hetero- geneous chocolate, migration of fat and sugar, acid flavour, and absence of desirable flavours. Thus, an adequate conching time will result in proper sensory characteristics, and it has been established in Swiss that the chocolate must be conched during 72 h (Cidell & Alberts, 2006). *Correspondent: Fax: +5551 3308 7048; e-mail: andrea.b.schumacher@hotmail.com International Journal of Food Science and Technology 2009, 44, 616–622 616 doi:10.1111/j.1365-2621.2008.01877.x Ó 2009 The Authors. Journal compilation Ó 2009 Institute of Food Science and Technology