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

Abstract

Rheological behaviour of enzyme clarified sapota (Achras sapota L.) juice at different temperatures (10 to 85°C) and total soluble solid content (10.2 to 55.6°brix) corresponding to a water activity (a w ) (0.986 to 0.865) was studied using controlled stress rheometer by coaxial cylinders attachment. The rheological parameter shear stress (Pa) was measured upto a shear rate of 1,000 s . The investigation showed that the enzyme clarified sapota juice and its concentrates behaved like a Newtonian liquid and the viscosity (η) values were in the range 4.340 to 56.418 mPa s depending upon temperature and concentration studied. The temperature dependency of viscosity of enzyme clarified sapota juice was described by Arrhenius equation (r >0.94) and activation energy (E a ) for viscous flow was in the range 5.218 to 25.439 KJ/mol depending upon concentration. The effect of total soluble solid content on flow activation energy was described by exponential relationship (r > 0.95, rmse% <13.5, p <0.01) and that of water activity was described by power law relation (r >0.99, rmse% <5.80, p <0.01). The effect of total soluble solid content on viscosity of enzyme clarified sapota juice followed second order exponential type relationship (r >0.99, rmse%<3.53) at the temperature used. The effect of water activity on viscosity of enzyme clarified sapota juice followed power law equation (r >0.98, rmse%< 4.38). A single equation representing combined effect of temperature and total soluble solid content/water activity on viscosity of enzyme clarified sapota was established.

Rheological characteristics of inulin solution at low concentrations: Effect of temperature and solid content

“…The magnitude of flow activation energy of inulin solution is low compared to that of other fluid foods at the same levels of solid content such as pineapple juice (Shamsudin et al. 2007), orange juice (Ibraz et al 2009), lime juice (Manjunatha et al 2013a), gooseberry juice (Manjunatha et al 2012b), Tender coconut water , sapota juice (Pranjal et al 2013), blueberry puree (Nindo et al 2007), ultravioletirradiated and thermally pasteurized pineapple juice (Shamsudin et al 2013), liquorice (Glycyrrhiza glabra) extract (Maskan 1999), carbohydrate solutions, namely fructose, sucrose and glucose (Telis et al 2007). The flow activation energy of these fluids was high because its viscosity is very sensitive to temperature due to increase in mobility of the molecules as well as an increase in inter-molecular spacing and also may be due to low molecular weight.…”

“…The parameters of the three models, correlation coefficient (r) and root mean square error percent (rmse%) values were reported in Table 3. The investigation showed that the exponential model was better describe the variation of flow activation energy with solid content of inulin solution since the correlation is high and low root mean square error values compare to that of other models such as linear and power law models and described as (Manjunatha et al 2012a), gooseberry juice (Manjunatha et al 2012b), tender coconut water , sapota juice (Pranjal et al 2013). It was reported that flow activation energy of liquorice (Glycyrrhiza glabra) extract is increased quadratically with soluble solid content, whereas it was increased significantly with square of total soluble solid content for blue berry and raspberry juices (Nindo et al 2005).…”

“…Several investigators reported that clarified and depectinated juices and their concentrates exhibit Newtonian flow behavior. Pranjal et al 2013).…”

Comportamento reológico das polpas de noni integral e concentradas

“…Deshmukh et al (2015) relataram que o aumento da temperatura dos fluidos leva ao aumento da mobilidade das moléculas e aumenta os espaços intermoleculares, o que promove o decréscimo da resistência ao fluxo, com consequente redução da viscosidade. Comportamento reológico das polpas de noni integral e concentradas Sousa, S. F. et al Com relação à concentração, as polpas de noni apresentaram um aumento expressivo nos valores de viscosidade aparente, tendo, estes mesmos valores, sido influenciados pelos demais parâmetros (temperatura e velocidade de rotação).…”

“…Para uma velocidade de rotação fixa, observa-se que a E a aumenta com o aumento do teor de sólidos solúveis totais, indicando um maior efeito da temperatura nas polpas mais concentradas, de acordo com Deshmukh et al (2015), os quais verificaram que, quanto maior o teor de sólidos solúveis totais do suco de sapoti clarificado, maior a E a (5,218 a 25,439 kJ mol -1 para 10,2 a 55,6°Brix).…”