RHEOLOGICAL CHARACTERISTICS OF QUINCE NECTAR DURING OHMIC HEATING
Küçük Resim Yok
Tarih
2009
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Taylor & Francis Inc
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Electrical heating of food products provides rapid and uniform heating, resulting in less thermal damage to the product. In this study, ohmic heating as an electrical heating method was applied to the quince nectar by matching the same heating curve of conventional method by changing voltage gradient (10-40 V/cm) at 50 Hz. The change of rheological constants of quince nectar was determined for different holding times (0, 10, 15, 20, and 30 minutes) in the temperature range of 65-75 degrees C by using concentric type viscosimeter. Shear stress-shear rate data were fitted to the Newtonian, Bingham, Herschel Bulkley, Power law and Casson Models. It was found that Herschel-Bulkley model was the best model to fit the experimental rheogram adequately since higher regression coefficients (R-2; 0.9997) and low standard errors (SE; 0.054) were obtained by Herschel-Bulkley equation compared to other model equations. It was concluded that quince nectar showed time independent non-Newtonian pseudoplastic character during heating in the range of 20-75 degrees C, independent on heating method. The activation energy values were 9.88 +/-.24 kJ/mol and 10.08 +/-.53 kJ/mol for ohmic heating and conventional heating respectively. Results showed that there was no electrical effect rather than thermal effects of ohmic heating since similar rheological constants were obtained with both methods statistically (p < 0.05). Ohmic heating could be recommended as an alternative fast heating method for fruit nectars.
Açıklama
Anahtar Kelimeler
Ohmic, Rheology, Modelling, Quince nectar
Kaynak
International Journal of Food Properties
WoS Q Değeri
Q3
Scopus Q Değeri
Cilt
12
Sayı
4
