Original article Effect of glutamate and inosinate on sensory and instrumental texture of extruded products Renata Cassar, 1 Fa ´ tima A. Sardinha 2 & Jose ´ A. G. Are ˆas 1 * 1 Departamento de Nutric¸a˜o, Faculdade de Sau´ de Pu´ blica da Universidade de Sa˜o Paulo, Av. Dr. Arnaldo, 715, 01246-904, Sa˜o Paulo, SP, Brazil 2 Departamento de Nutric¸a˜o, Universidade Paulista, Rod. Presidente Dutra, KM 157.5, CEP 12240-420, Sa˜o Jose´ dos Campos, SP, Brazil (Received 4 April 2005; Accepted in revised form 15 January 2007) Summary Expanded products have been developed by extrusion of non-conventional highly nutritious raw materials such as amaranth and chickpea blended with bovine lung. As sensory acceptance of these snacks is restricted, this study aimed at improving their texture, through the addition of monosodium glutamate (MSG) and disodium inosinate (IMP) flavor enhancers to the feeding material, or to the flavor added after the extrusion. Sensory and mechanical analyses showed that both enhancers affected texture, assessed by sensory and instrumental methods. Addition of IMP together with MSG to the chickpea-based snacks presented the best results. This beneficial effect was not observed in the amaranth-based snack, suggesting that IMP and MSG can favorably impact texture of extruded products depending on the amount and type of protein present. Keywords Amaranthus, chickpea, extrusion, ribonucleotides, sodium glutamate, snack-foods. Introduction In food production, several unconventional raw mate- rials and by-products of high nutritive value are poorly used for human feeding because of the lack of tradition in their consumption, the unfamiliarity of their use or the lack of basic requirements for their acceptability. Animal by-products, such as bovine lung that is rich in proteins of high biological value, bioavailable iron and vitamins (Areˆas, 1993; Areˆas & Lawrie, 1984; Bastos & Areˆas, 1990; Bastos et al., 1991; Campos and Areˆas, 1993; Pinto et al., 1997), some grains as chickpea (Cicer arietinum L.), that presents the best nutritional quality among the legume seeds (Chavan & Salunkhe, 1986; Chavan et al., 1986; Newman et al., 1987; Sotelo et al., 1987; Ferna´ndez & Berry, 1988; Batistuti et al., 1991; Pardez-Lo´pez et al., 1991; Avancini et al., 1992), and amaranth (Amaranthus caudatus, L), a commodity that presents great nutritional potential and the capacity for reducing blood cholesterol (Saunders & Becker, 1984; Teutoˆnico & Knorr, 1985; Bressani, 1988; Breene, 1991; Kauffman, 1992; Lehmann, 1992, 1996; Bressani et al., 1993; Plate & Areˆas, 2002), are good examples. Extrusion cooking has been one of the most suitable technological processing for these raw materials, yielding a variety of ready-to-eat products and food ingredients. Two new ready-to-eat extruded products made of chickpea and bovine lung blend (Cardoso- Santiago & Areˆas, 2001) and of amaranth (Cha´vez- Ja´ uregui et al., 2000) were developed, which proved useful for nutritional intervention (Castro-Ferreira, 1999; Moreira-Arau´jo et al., 2002; Cardoso-Santiago & Areˆas, 2001; Cardoso-Santiago et al., 2001). Accept- ance of these products needs to be improved, mainly regarding flavour and texture that still constituted a restriction to their wider acceptance. There are many citations in the literature regarding the impact of monosodium glutamate (MSG) and disodium inosinate (IMP) on the flavour, acceptance or preference of snacks (Bellisle et al., 1989, 1991; Filer & Stegink, 1994; Schiffman et al., 1994). However, there is no record of their effects on the texture of extruded products. The mechanism by which the supramolecular structure is formed and therefore the texture is obtained in the extrusion process is still unclear (Areˆas, 1992; Mitchell and Areˆas, 1992), and there is no way to forecast the impact of the MSG and IMP on the network that responds for extrudate texture. This study evaluated, by means of sensory and instrumental analyses, the texture characteristics of extruded products of amaranth and chickpea blended with bovine lung, to which MSG and MSG + IMP had been added. *Correspondent: Fax: +55-11-30667705; e-mail: jagareas@usp.br International Journal of Food Science and Technology 2008, 43, 1528–1533 1528 doi:10.1111/j.1365-2621.2007.01548.x Ó 2007 Institute of Food Science and Technology