Thermal pretreatments of carrot pieces using different heating techniques: Effect on quality related aspects

Effects of conventional and ultrasound blanching on enzyme inactivation and carbohydrate content of carrots

“…Similarly, Lemmens et al [11] found 80 % of PME residual activity at 60°C and total enzyme inactivation at 90°C during the blanching of carrots by microwave, ohmic and conventional heating. Comparing PME results with those of POD shown above, the lower stability of PME at high temperatures was confirmed [26][27][28].…”

“…The highest residual activity (40.9 %) was observed for sliced carrots blanched at 60°C for 40 min. Lemmens et al [11] reported residual POD activities of 70 % after blanching treatments carried out under the same conditions, but with samples of 10 mm thickness.…”

“…The PME activity was determined in blanched carrots as described by Lemmens et al [11]. Tris(hydroxymethylaminomethane) hydrochloride buffer (0.2 M; pH 8) containing 1 M NaCl was added to carrots (buffer-carrots ratio, 1.3:1).…”

“…In relation to PME, this enzyme has an important role in textural changes in unblanched vegetables since it catalyses the de-esterification of pectin to pectic acid, which facilitates the link of calcium and magnesium, increasing the firmness of the cellular wall [9]. In some cases, a certain residual PME is preferred since, after drying, the texture of rehydrated product can be improved [10,11]; this is possible by blanching at low temperature and for long time (LTLT). Although the beneficial effects of blanching depend on the degree of thermal treatment applied, the quality and bioactivity of the final product can be negatively affected due to the destruction of nutrients relatively unstable to heat, the loss of water-soluble components by leaching and the changes in texture with this sample pretreatment [12,13].…”

Effect of microwave assisted blanching on the ascorbic acid oxidase inactivation and vitamin C degradation in frozen mangoes

“…Recently, several novel alternative technologies have been proposed such as high-pressure, ultrasound, microwave, ohmic, infrared, and radiofrequency heating for blanching of fruits and vegetables. Although these technologies are gaining momentum, there are still bottlenecks related to method simplicity, packaging materials and large-scale equipment that need to be solved and tangible advantages to be demonstrated before industrial implementation (Bernas & Jaworska, 2003;Jiang, Liu, Li, & Zhou, 2015;Lemmens et al, 2009;Xanthakis & Valdramidis, 2017;Xin, Zhang, Xu, Adhikari, & Sun, 2015).…”