The Effects of Microwave Blanching Conditions on Carrot Slices: Optimization and Comparison

Abstract

The objectives of this study are (1) to determine conventional blanching (CB) conditions providing 100% peroxidase (POD) inactivation and adapt these inactivation conditions to microwave blanching (MB) for inactivating pectin methylesterase (PME); (2) to optimize the MB conditions by response surface methodology to ensure almost 100% PME; and (3) to compare the properties of samples at the optimum points with those of conventional blanched and unblanched carrot samples. CB conditions were found to be 300 s with 150 mL of blanching water at 94C. MB conditions of samples have been optimized by using independent variables: microwave power (360-900 W), blanching time (10-300 s) and blanching water volume (0-150 mL). Three optimum points were determined: (1) 900 W − 170 s − 75 mL water; (2) 630 W − 190 s − 75 mL water; and (3) 360 W − 300 s − 75 mL water for MB. PME inactivation ratio was determined as almost 100% optimum points. Therefore, pectin was highly retained, carotenoid contents and color values were better protected as well. In summary, 360 W/ 300 s/75 mL water conditions were found to be optimum for blanching of carrots. PRACTICAL APPLICATIONSNowadays, the food industry focuses on novel treatments for inactivating enzymes with minimum deleterious effects on texture, flavor and nutrients. Blanching is one of the preprocessing steps before canning, drying and freezing of vegetables. Blanching treatment also stabilizes color, texture, flavor and nutritional quality of the products, as well as inactivates peroxidase and pectin methylesterase which catalyzes deleterious changes. Microwave heating is a very popular food processing technique and can be utilized as an alternative to water blanching. This study explored whether microwave blanching can be used for enzyme inactivation, which, in turn, requires less processing time and water with minimal loss of quality.

Physicochemical characteristics of sweet corn kernels during microwave blanching

“…The samples in beakers were kept at the center of the rotating platform of the microwave at a rate of 5 rotations per minute. The power level was set at 180, 360, 420, 640, and 900 W (Başkaya Sezer & Demirdoven, 2015), which was controlled by adjusting the duty cycle “on” for 12, 24, 36, 48, and 60 s in 1 min and “off” for remaining time and kept for 40, 50, 60, 70, and 80 s duration. The variation in physicochemical characteristics of samples after the blanching process was measured.…”

Synergetic effect of microwave blanching and modified atmosphere packaging using laser micro-perforated bags on the storage quality of carrot

“…The carrots were first washed, peeled and finally sliced into 8-mm pieces before being blanched in water at 360 W for 300 secs using a microwave oven (Panasonic Co., Ltd, China) with a maximum rated power of 800 W at 2450 MHz. The internal dimensions of the microwave oven were approximately 302×509×348 mm (Başkaya et al, 2015). The actual microwave power level was 669 W using the IMPI-2L method (Saifullah et al, 2019).…”

“…The carotene content was determined as described (Başkaya Sezer and Demirdöven, 2015). The samples were extracted using a mixture of (acetone: hexane: ethanol, 25: 50: 25, v/v/v).…”

Effect of Blanching Pretreatments on the Physicochemical and Drying Characteristics of Chui Jhal ( Piper chaba H.) Stem

“…Total samples were divided into four batches, where the first one was untreated. The hot water blanching (HWB) was done at 90 o C for 5 min [12], water steam blanching (SB) for 1 min [13], and microwave blanching (MWB) at 600 watts for 120 sec [14]. All samples were cooled at room temperature, removing surface water using absorbent paper.…”