0139–3006/$ 20.00 © 2014 Akadémiai Kiadó, Budapest Acta Alimentaria, Vol. 43 (1), pp. 19–27 (2014) DOI: 10.1556/AAlim.43.2014.1.3 EFFECT OF HEAT TREATMENT ON RHEOLOGICAL PROPERTIES OF MIXED NECTARS BASED ON CASHEW APPLE, MANGO AND ACEROLA PULPS L. SILVA a *, G. MAIA a , P. SOUSA b , R. FIGUEIREDO a , M. AFONSO a , M. GONZAGA a , C. GOMES c and E. FIGUEIREDO a a Department of Food Science and Technology and b Department of Gastronomy Federal University of Ceara Av. Mister Hull, 2977, Campus Universitário do Pici, bl. 858, Fortaleza, Ceara, 60356-000. Brazil c Biological and Agricultural Engeneering Department, Texas A&M University 201 Scoates Hall, 2117 TAMU, College Station, TX 77843. USA (Received: 10 October 2011; accepted: 25 February 2013) The purpose of this experiment was to evaluate the effect of heat treatment on the rheological properties of mixed nectars, based on cashew apple, mango, and acerola pulps. Ten different formulations with different mass fractions of cashew apple, mango, and acerola pulps were prepared using a simplex centroid design [with a total of 35% (w/w) pulp] and submitted to heat treatment at 90 °C for 1 min. Samples were collected before and after heat treatment and characterization of their rheological properties was carried out. The rheological behaviour was obtained at 25 °C, with shear rate ranging from 108 to 500 s –1 (upward curve) and from 500 to 108 s –1 (downward curve) for 1 min with 25 readings for each curve. The Ostwald de Waele model showed to be a good fit for all formulations studied, which showed a non-Newtonian behaviour and a pseudoplastic character. Results of apparent viscosity for the non-heated formulations were well fitted by the linear model and the heat treated formulations by the cubic model. The heat treated formulations had higher (P<0.05) values of consistency index and apparent viscosity, as well as lower (P<0.05) values of flow behaviour index compared to non-heated formulations. The rheological characterization of these formulations is a very useful tool during product development and processing control of mixed nectars of fruit juice. Keywords: tropical fruits, beverage, heat treatment, rheology Consumption of fruit juices is important for human health, since they are considered a major source of nutrients, and contain various phytochemicals, which reduce the risk of various diseases (CASWELL, 2009). Consumers have also become increasingly aware of the health benefits of these products, as good sources of antioxidants, such as polyphenols, vitamin C, vitamin E, Maillard reaction products, β-carotene, and lycopene (RAMADAN-HASSANIEN, 2008). Mixed fruit nectars are excellent options for tropical fruit juices consumption, not only do they introduce practical and distinct sensory characteristics, such as flavour and consistency, to fulfil consumers’ needs; but also more competition and an exclusive niche of products to fulfil the industry’s needs. The mixture of different juices can be made to combine ingredients, flavours, and aromas of different fruits, thus, increasing the acceptability and the nutritional value of these juices (LIMA et al., 2008). Mixed nectars of cashew apple, mango, and acerola present a large variety of functional compounds. Acerola (Malpighia emarginata D.C.) is a well-known tropical fruit mainly for its high vitamin C content (FREITAS et al., 2006) and also an excellent source of polyphenols, which * To whom correspondence should be addressed Phone: +55 (85) 33669738; e-mail: larissamrs@yahoo.com.br