| 成熟度对冬枣真空脉动干燥动力学及产品品质的影响 |
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| 引用本文： | 王吉强, 邓利珍, 裴昱鹏, 王冬冬, 高振江, 肖红伟. 成熟度对冬枣真空脉动干燥动力学及产品品质的影响[J]. 农业工程学报, 2021, 37(23): 273-279. DOI: 10.11975/j.issn.1002-6819.2021.23.032 |
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| 作者姓名： | 王吉强 邓利珍 裴昱鹏 王冬冬 高振江 肖红伟 |
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| 作者单位： | 1.中国农业大学工学院，北京 100083;2.南昌大学食品学院，南昌 330031 |
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| 基金项目： | 兵团重点领域科技攻关项目（2019AB024）；国家重点研发计划课题（2017YFD0400905） |
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| 摘 要： | 为了揭示成熟度对果蔬干燥特性和品质的影响，以冬枣为试验材料，根据色泽和质构将原料分为白熟期I，半红期II和全红期III 3个成熟度，研究了成熟度对冬枣的理化性质、细胞超微结构、干燥动力学和干燥品质的影响。研究发现：随着成熟度的增加，红绿值a*、可溶性固形物、可滴定酸、总糖及还原糖含量不断增加，而亮度值L*、黄蓝值b*、维生素C含量和硬度不断下降。随着成熟度的增加，冬枣表皮细胞的中胶层逐渐溶解，细胞内容物降解，产生质壁分离现象。与成熟度I和II相比，成熟度III的果实干燥时间分别减少了20%和10%。与新鲜冬枣相比，经真空脉动干燥后的冬枣脆片脆度和褐变指数增加，而维生素C含量、复水能力和总糖、还原糖含量下降。对干燥后冬枣脆片的微观结构观察显示冬枣脆片呈现疏松多孔的结构，且随着成熟度的增加，表面孔隙直径不断增大、排列从有序向无序转变。结果表明，成熟度对冬枣理化性质、干燥动力学和干燥品质有显著（P<0.05）影响；干燥前对冬枣进行不同成熟度分级，综合干燥效率和品质，全红期果实更适于干燥加工。研究结果可为冬枣加工提供参考。
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| 关 键 词： | 干燥 品质控制 成熟度 冬枣 理化特性 干燥特性 产品品质 |
| 收稿时间： | 2021-07-30 |
| 修稿时间： | 2121-10-03 |
Effects of maturity on pulsed vacuum drying kinetics and product quality of winter jujube |
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| Wang Jiqiang, Deng Lizhen, Pei Yupeng, Wang Dongdong, Gao Zhenjiang, Xiao Hongwei. Effects of maturity on pulsed vacuum drying kinetics and product quality of winter jujube[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(23): 273-279. DOI: 10.11975/j.issn.1002-6819.2021.23.032 |
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| Authors: | Wang Jiqiang Deng Lizhen Pei Yupeng Wang Dongdong Gao Zhenjiang Xiao Hongwei |
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| Affiliation: | 1.College of Engineering, China Agricultural University, Beijing 100083, China;2.College of Food Science & Technology, Nanchang University, Nanchang 330031, China |
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| Abstract: | A winter jujube has been one of the most favorite fruits, due to the crisp texture, sweet taste, appealing flavor, and abundant nutrition. A drying process has been widely used for the storage of winter jujube. Among them, maturity can significantly determine the physicochemical properties of fresh fruits, the processing and product quality during drying. It is possible that the winter jujubes fail to reach a uniform maturity when harvesting. However, little information is available for the effect of maturity on drying and product quality. In this present study, a systematic investigation was conducted to explore the effects of different maturities on the physicochemical properties, the cell ultrastructure and microstructure, as well as the product quality of winter jujubes. The winter jujubes were classified into three maturities (stage I, II, and III), according to color and texture. Then, a pulsed-vacuum drying (drying temperature of 65℃, vacuum duration time: constant pressure duration time = 12 min: 3 min) was applied to process the winter jujubes, in order to clarify the influence of the maturity on the drying kinetics and drying quality of jujube slices. The results showed that there was an outstanding change of surface color in the jujube slices during drying, with the maturity increased from I to III. In detail, the brightness (L*) and yellowness/blueness (b*) decreased from 71.70 to 36.80 and 43.56 to 19.55, respectively, whereas, the value of red/green (a*) increased from -7.19 to 20.19. Meanwhile, there was a continuous increase in the soluble solids, titratable acid, total sugar, and reducing sugar contents, whereas, there was a significant decrease in the vitamin C content and hardness. The transmission electron microscopy (TEM) images illustrated that there was a separate wall of the adjacent cell and the disintegrated plasma membrane with the increase of maturity, indicating that the middle lamella layer of epidermal cells gradually dissolved in the winter jujube. Furthermore, the drying time of fruits at the maturity stage of I, II, and III were 360, 330, and 300 min, respectively. The lowest drying time was achieved in the fruits at maturity III, reducing by 20% and 10%, compared with maturity I and II. Meanwhile, the crispness and browning index of dried slices increased, whereas, the vitamin C content, rehydration capacity, total sugar, and reducing sugar contents decreased, compared with the fresh fruits. The Scanning Electron Microscope (SEM) images illustrated that the dried crisps presented a loose and porous structure of the dried winter jujube slices, with the increase of the maturity, where the diameter of the surface pore increased continuously, and the morphology changed from the fine order to disorder arrangement. Consequently, the maturity posed a significant impact on the physicochemical properties, drying kinetics, and drying quality of winter jujubes. A recommendation can be made to implement the maturity grading of winter jujube before drying for a better drying performance and product quality of winter jujube slices. In terms of drying time and product quality, the fruits at the maturity stage of III were more suited to the drying processing. |
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| Keywords: | drying quality maturity winter jujube physical and chemical characteristics drying characteristics product quality |
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