Modelling the rheological behaviour of enzyme clarified lime (Citrus aurantifolia L.) juice concentrate

Abstract

Manjunatha S.S., Raju P.S., Bawa A.S. (2012): Modelling the rheological behaviour of enzyme clarified lime (Citrus aurantifolia L.) juice concentrate. Czech J. Food Sci., 30: 456-466.The rheological behaviour of enzyme clarified Lime (Citrus aurontifolia L.) juice was studied as a function of the total soluble solid (TSS) content (7.3-55.7°Brix), corresponding water activity (a w ) (0.985-0.831) at different temperatures o C) using co-axial controlled stress rheometer. The rheological parameter shear stress was measured up to the shear rate of 600 s -1 . The investigation showed that the enzyme clarified lime juice and its concentrate behaved like a Newtonian fluid with the viscosity (η) being in the range 3.964 to 50.290 mPa s depending upon the concentration and temperature used. The temperature dependency on the viscosity of lime juice was described by Arrhenius equation (r > 0.99) and the activation energy (E a ) of viscous flow was in the range 4.151 to 26.050 kJ/mol depending upon the total soluble solids content. The effect of total soluble solid content on the flow activation energy was described by exponential type equation (r > 0.98) and that of water activity was described by both the power law and exponential equations (r > 0.99). The effect of total soluble solid content on the viscosity of lime juice followed the second order exponential equation (r > 0.99) at the temperature used. The effect of water activity on the viscosity was described by both the power law and exponential type relationship (r > 0.97). The equations relating to the combined effect of temperature and total soluble solids content/water activity on the viscosity of enzyme clarified lime juice were established.

Rheological behaviour of enzyme clarified sapota (Achras sapota L) juice at different concentration and temperatures

“…Similar type of exponential relation was reported relating to flow activation energy to total soluble solid content. The magnitude of the coefficient concentration was found to be 0.049 and it was within the range as reported for different fruit juices such as pomegranate, pineapple, cherry, peach, chokeberry, lime, gooseberry and tender coconut water (Altan and Maskan 2005;Kaya and Sozer 2005;Shamsudin et al 2007;Giner et al 1996;Ibarz et al 1992a;Juszczak et al 2009: Manjunatha et al 2012a2012b;Manjunatha and Raju 2013). It was reported that flow activation energy increased significantly with square of total soluble solid content for blue berry and raspberry juices, where as it increased quadratically with soluble solid content in case of liquorice (Glycyrrhiza glabra ) extract (Nindo et al 2005;Maskan 1999).…”

“…The magnitude of coefficient (b) of water activity was found to be −12.985 in case enzyme clarified sapota juice. The magnitude of power law coefficient (b) of variation with flow activation energy with water activity is comparable with values of lime juice and tender coconut water (Manjunatha et al 2012a;Manjunatha and Raju 2013).…”

“…Several authors have used Newtonian equation for describing rheological behaviour of liquid food products like pomegranate juice (Altan and Maskan 2005;Kaya and Sozer 2005), Pekmez (Kaya and Belibagli 2002), lime juice (Manjunatha et al 2012a), gooseberry juice (Manjunatha et al 2012b), Tender coconut water (Manjunatha and Raju 2013), liquorice extract (Maskan 1999).…”

“…In case of enzyme clarified sapota juice soluble solids (sugars and acids) content plays a vital role in magnitude of viscosity. The increase in temperature significantly decreases the magnitude of viscosity, because of increase in thermal energy of the molecules which enhances mobility of molecules and increases inter-molecular spacing (Krokida et al 2001;Steffe 1992;Rao 2007 (Juszczak et al 2010), lime juice (Manjunatha et al 2012a), gooseberry juice (Manjunatha et al 2012b), tender coconut water (Manjunatha and Raju 2013), kiwi fruit juice (Goula and Adamopoulos 2011), clarified fruit juices such as orange, black currant, peach, pear, cherry, banana (Ibarz et al 1994;Ibarz et al 1992a;1992b;Ibarz et al 1989;khalil et al 1989), carrot juice (Vandresen et al 2009), sole juice , blueberry and raspberry juices (Nindo et al 2005), apple and pear juices (Ibarz et al 1987), black chokeberry juice (Juszczak et al 2009) Liquorice extract (Maskan 1999), aqueous carbohydrate solutions ).. The consistency coefficient k is increased with total soluble solid content as well as particle size and is decreased with increase temperature of watermelon juice (Sogi et al 2010).…”

“…The different models namely power law and exponential model of different orders were used to investigate the variation in viscosity with soluble solid content at particular temperature used. Several investigators had used these models to investigate the effect of soluble solid content on viscosity of different fluids (Ibarz et al 2009;Ibarz et al 1989;Manjunatha et al 2012a;2012b;Manjunatha and Raju 2013;Altan and Maskan 2005;Kaya and Sozer 2005;Shamsudin et al 2007;Giner et al 1996;Juszczak et al 2009;Ibarz et al 1992a;Juszczak et al 2010;Juszczak and Fortuna 2004;Nindo et al 2005). …”