Effect of temperature and concentration on density and rheological properties of melon (Cucumis melo L. var. Inodorus) juice

Abstract

Purpose

The aim of this study was to measure the apparent viscosity, flow behavior and density of melon juice as a function of temperature and juice concentration and to obtain simple equations to correlate experimental data.

Design/methodology/approach

Melon juice was concentrated in a rotary evaporator to 40±1, 52.5±1 and 65±1°Brix at 50°C, 80 rpm and stored at 4°C until analysis. Density of melon juice was determined with 25 ml pycnometer at 15, 25 and 35°C and was expressed as kg/m3. All experiments were conducted in triplicate. Experimental data were fitted to different models (linear, quadratic, exponential, quadratic exponential and polynomial) using Minitab 16. Significant differences in the mean values were reported at p<0.05. The flow behavior of melon juice was determined using a concentric cylinder rotational viscometer at shear rate range of 13.2-330 s−1 and temperatures of 15, 25 and 35°C. The experimental data were analyzed Slide Write V7.01 Trial Size (p<0.05) and the rheograms was plotted by Microsoft Excel 2007.

Findings

Results showed that the four-term polynomial model is the best model for computing density values from temperature and concentration (R2=0.999). The measured shear stress was within 1.69-780 Pa, corresponding to viscosity range of 0.016-0.237 Pa · s. Within the tested conditions, the concentrate exhibited a pseudo plastic behavior. Temperature had an inverse effect on shear stress and apparent viscosity.

Originality/value

No research had been done on production of melon juice concentrate.

Citation

Mohamadi Sani, A., Hedayati, G. and Arianfar, A. (2014), "Effect of temperature and concentration on density and rheological properties of melon (Cucumis melo L. var. Inodorus) juice", Nutrition & Food Science, Vol. 44 No. 2, pp. 168-178. https://doi.org/10.1108/NFS-06-2013-0065