Ohmic Blanching in Vegetable Processing
August 31/Izmir, Turkey/Food Weekly News According to a study from Izmir, Turkey, "Ohmic blanching could be used as an alternative fast blanching method in vegetable processing. Artichoke is a vegetable that is a good source of natural antioxidants."
"In this study, artichoke byproduct was pretreated with ohmic blanching (25 and 40 V/cm at 85C) and water blanching (at 85 and 100C). The ohmic blanching (40 V/cm) at 85C was able to show similar peroxidase inactivation times (310 +/- 2 seconds) with the water blanching at 100C (300 +/- 2 seconds). The retention of vitamin C and the total phenolic content was found to be highest in the byproduct blanched ohmically by 40 V/cm voltage gradient at 85C. Blanched artichoke byproducts were then dried in the fluid-bed drier. The drying process was optimized by using response surface methodology. Optimum drying parameters were obtained as 80C, 0.8m/s and the pretreatment of ohmic blanching at 40 V/cm voltage gradient," wrote F. Icier and colleagues, Ege University.
The researchers concluded, "Residues can form up to 60-65% of the harvested vegetable material in the industries. These residues are very perishable products that are difficult to manage because of environmental problems. Vegetable byproducts have valuable components and should be used in the preparation of functional foods. One of these is artichoke byproducts having high amounts of phenolic substances. The use of artichoke byproduct extracts have been reported in the application of functionalization of soups and bakery products. Main processes in the treatment of artichoke and its byproduct are blanching and drying. There is no study ever done that explains theoptimization of drying of artichoke products in open literature, according to the author's knowledge. Ohmic heating is a fast and homogeneous electrical heating method inactivating enzymes faster than conventional methods in addition to preserving valuable compounds. It could also enhance the drying performance of vegetable products. The results of this study give information about the drying conditions of artichoke byproducts and the use of ohmic blanching in industrial vegetable processing."
Icier and colleagues published the results of their research in the Journal of Food Process Engineering ("Ohmic Blanching Effects On Drying Of Vegetable Byproduct." Journal of Food Process Engineering, 2010;33(4):661-683).
For additional information, contact F. Icier, Ege University, Dept. of Food Engineering, Faculty Engineering, TR-35100 Izmir, Turkey.
From the September 7, 2010, Prepared Foods E-dition