Heat-induced chemical, physical and functional changes during grape must cooking Andrea Piva, Carla Di Mattia, Lilia Neri, Gloria Dimitri, Marco Chiarini, Giampiero Sacchetti * Dipartimento di Scienze degli Alimenti, Via C.R. Lerici 1, Mosciano Stazione, 64023 Teramo, Italy Received 10 January 2007; received in revised form 30 April 2007; accepted 12 July 2007 Abstract Cooked must is a product that could be used in food formulations, directly or after fermentation, to obtain many traditional foods. Must cooking was conducted in boilers of different materials (copper and stainless steel) for different times in order to obtain differently concentrated products. The concentration of many constituents (sugars, organic acids, nitrogen compounds, metal ions and polyphenols) was observed upon cooking, together with the increase of neo-formation compounds, such as hydroxymethylfurfural and melanoidins, which give, to the musts, the typical brown colour and caramel-like odour. The concentration of metal ions, in particular, determined high levels of lead and copper (in the case of use of copper boilers) in the final products. Polyphenol heat concentration determined the degradation of simple phenolics, such as catechins, and the formation of condensed tannins, which determined a loss of the antioxidant activity of the phenolic fraction, whereas the formation of melanoidins improved the total antioxidant activity of the product. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Grape must; Heat concentration; Browning; Hydroxymethylfurfural; Melanoidins; Polyphenols; Antioxidant activity 1. Introduction Grape must cooking is an ancestral practice in Mediter- ranean countries and it is required for the production of many traditional Italian foods and beverages, such as tra- ditional balsamic vinegars of Modena and Reggio Emilia, ‘‘vino cotto” (namely cooked wine), a liquor wine from the Marche and Abruzzo regions, Marsala wines from Sic- ily and mosto cotto (cooked must), from the Apulia region, which is used as a filling in bakery formulations (Repubb- lica Italiana, 2006). Apart from Italy, cooked must is also used for Spanish sweet wines (Rivero-Pe ´rez, Pere ´z Maga- rin ˜o, & Gonza `les-San Jose ´, 2002). Cooked must is mainly produced from white grapes (e.g. Trebbiano cultivar) and is obtained by direct heating of must over an open fire in uncovered boilers or pans which are traditionally made of copper. The must is cooked until its volume is reduced by 10–60% according to the produc- tion technology and, once cooled down, it could either be fermented in barrels or used as is, depending on the prod- uct to be obtained. Must cooking is traditionally carried out below boiling temperatures (80–95 °C) and could require quite long pro- cessing times (up to 48 h), depending on the capacity of the cooking pan. During cooking the must becomes dark and dense and many chemical changes occur due to the pro- longed thermal treatment. Product cooking determines the concentration of natu- rally occurring chemicals in must, among which are sugars and acids. Under acidic conditions, as occurring in fresh 0308-8146/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2007.07.026 * Corresponding author. Tel.: +39 0861 266913; fax: +39 0861 266915. E-mail address: gsacchetti@unite.it (G. Sacchetti). www.elsevier.com/locate/foodchem Food Chemistry 106 (2008) 1057–1065 Food Chemistry