Journal of Food Processing & Technology

Effect of vacuum ohmic evaporation on rheological characteristics of pomegranate juice concentrates

19^th International Conference on Food Processing & Technology

October 23-25, 2017 | Paris, France

Serdal Sabanci, Filiz Icier, Mutlu Cevik and Omer Faruk Cokgezme

Ege University, Turkey
Munzur University, Turkey

Posters & Accepted Abstracts: J Food Process Technol

Abstract:

Pomegranate is a seasonal fruit that is processed to juice after its harvest. Fruit juices are concentrated to prolong their shelf life and to reduce transport and handling costs. Vacuum evaporation method is commonly used in food industry while its energy utilization is high. In present study, ohmic heating method was integrated to vacuum system to reduce total energy usage and shorten the processing time. Pomegranate juice samples (17.5% total soluble solid content; TSS) were concentrated to 40% TSS by conventional vacuum evaporation (VE) (1.1 kW) and ohmic vacuum evaporation (OVE) (7.5, 10, 12.5 V/cm) under constant absolute pressure 180 ± 2 mm Hg. Rheological measurements of samples having TTS contents of 17.5%, 20%, 30% and 40% were performed by adjusting shear rate in the range of 0-264 (1/s). Experimental shear stress-shear rate data were fitted to selected rheological models (Newtonian, power-law, Bingham and Herschel-Bulkley) to determine viscous properties. The compatibility of models was determined by evaluation of root mean square error (RMSE) and chi-square (�?2) values, statistically. The most fitted model for concentrates having TSS contents of 17.5%, 20%, and 30% was determined as Power Law model. For 40% TSS content, Newton and Power Law models were determined as best fitted model. The apparent viscosity values and the flow behavior indexes of pomegranate juice concentrated by OVE and VE processes increased as TSS contents increased (p<0.05). The significant difference between the influences of evaporation methods on flow behavior index was also determined (p<0.05). Characterization of the changes of rheological properties of fruit juice concentrates due to OVE process will make an important contribution to usage of it as an alternative evaporation method. This study was financially supported by TUBITAK project no: 114O117.

Biography :

Serdal Sabanci has completed Master (2012) studies at Gaziosmanpasa University, Turkey. He is Research Assistant in Food Engineering Department, Munzur University, Turkey. He is continuing PhD education in Ege University, Graduate School of Natural and Applied Sciences, Food Engineering Section, Izmir, Turkey. He is currently working on food technology, especially ohmic heating processes