Guiamba Isabel R F, Svanberg Ulf, Ahrné Lilia
Dept. de Engenharia Química, Faculdade de Engenharia, Univ. Eduardo Mondlane, Maputo, Moçambique.
Dept. of Biology and Biological Engineering/Food and Nutrition Science, Chalmers Univ. of Technology, Gothenburg, Sweden.
J Food Sci. 2015 Jun;80(6):E1235-42. doi: 10.1111/1750-3841.12866. Epub 2015 Apr 28.
The objectives of this work were to evaluate infrared (IR) dry blanching in comparison with conventional water blanching prior to hot air drying of mango to inactivate polyphenol oxidase (PPO) and ascorbic acid oxidase (AAO) enzymes, and to study its effect on color change and retention of vitamin C and β-carotene. Mango cylinders were blanched under similar temperature-time conditions either by IR heating or by immersion in a water bath during 2 min at 90 °C (high-temperature-short-time-HTST) or for 10 min at 65 °C (low-temperature-long-time-LTLT). After blanching mango was hot air dried at 70 °C. PPO was completely inactivated during the blanching treatments, but AAO had a moderate remaining activity after LTLT treatment (∼30%) and a low remaining activity after HTST treatment (9% to 15%). A higher retention of vitamin C was observed in mango subjected to IR dry blanching, 88.3 ± 1.0% (HTST) and 69.2 ± 2.9% (LTLT), compared with water blanching, 61.4 ± 5.3% (HTST) and 50.7 ± 9.6% (LTLT). All-trans-β-carotene retention was significantly higher in water blanched dried mango, 93.2 ± 5.2% (LTLT) and 91.4 ± 5.1% (HTST), compared with IR dry blanched, 73.6 ± 3.6% (LTLT) and 76.9 ± 2.9% (HTST). Increased levels of 13-cis-β-carotene isomer were detected only in IR dry blanched mango, and the corresponding dried mango also had a slightly darker color. IR blanching of mango prior to drying can improve the retention of vitamin C, but not the retention of carotenoids, which showed to be more dependent on the temperature than the blanching process. A reduction of drying time was observed in LTLT IR-blanching mango.
本研究的目的是比较在芒果热风干燥前，红外（IR）干热烫漂与传统水热烫漂对多酚氧化酶（PPO）和抗坏血酸氧化酶（AAO）的失活效果，并研究其对颜色变化以及维生素C和β-胡萝卜素保留率的影响。将芒果圆柱体在相似的温度-时间条件下进行热烫漂，采用红外加热或在90℃水浴中浸泡2分钟（高温短时- HTST）或在65℃水浴中浸泡10分钟（低温长时- LTLT）。热烫漂后，芒果在70℃进行热风干燥。在热烫漂处理过程中PPO完全失活，但LTLT处理后AAO仍有适度的残余活性（约30%），HTST处理后AAO的残余活性较低（9%至15%）。与水热烫漂相比，红外干热烫漂的芒果中维生素C保留率更高，红外干热烫漂HTST处理为88.3±1.0%，LTLT处理为69.2±2.9%；水热烫漂HTST处理为61.4±5.3%，LTLT处理为50.7±9.6%。全反式-β-胡萝卜素保留率在水热烫漂干燥的芒果中显著更高，LTLT处理为93.2±5.2%，HTST处理为91.4±5.1%；而红外干热烫漂的芒果中，LTLT处理为73.6±3.6%，HTST处理为76.9±2.9%。仅在红外干热烫漂的芒果中检测到13-顺式-β-胡萝卜素异构体水平升高，且相应的干燥芒果颜色也略深。干燥前对芒果进行红外热烫漂可提高维生素C的保留率，但不能提高类胡萝卜素的保留率，类胡萝卜素的保留似乎更依赖于温度而非热烫漂过程。观察到LTLT红外热烫漂的芒果干燥时间缩短。
