钱婧雅, 张茜, 王军, 方小明, 张卫鹏, 高振江, 刘嫣红, 肖红伟. 三种干燥技术对红枣脆片干燥特性和品质的影响[J]. 农业工程学报, 2016, 32(17): 259-265. DOI: 10.11975/j.issn.1002-6819.2016.17.034
    引用本文: 钱婧雅, 张茜, 王军, 方小明, 张卫鹏, 高振江, 刘嫣红, 肖红伟. 三种干燥技术对红枣脆片干燥特性和品质的影响[J]. 农业工程学报, 2016, 32(17): 259-265. DOI: 10.11975/j.issn.1002-6819.2016.17.034
    Qian Jingya, Zhang Qian, Wang Jun, Fang Xiaoming, Zhang Weipeng, Gao Zhenjiang, Liu Yanhong, Xiao Hongwei. Effects of three drying technologies on drying characteristics and quality attributes of jujube crisps[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2016, 32(17): 259-265. DOI: 10.11975/j.issn.1002-6819.2016.17.034
    Citation: Qian Jingya, Zhang Qian, Wang Jun, Fang Xiaoming, Zhang Weipeng, Gao Zhenjiang, Liu Yanhong, Xiao Hongwei. Effects of three drying technologies on drying characteristics and quality attributes of jujube crisps[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2016, 32(17): 259-265. DOI: 10.11975/j.issn.1002-6819.2016.17.034

    三种干燥技术对红枣脆片干燥特性和品质的影响

    Effects of three drying technologies on drying characteristics and quality attributes of jujube crisps

    • 摘要: 为了解决传统油炸红枣脆片含油率高、维生素C损失严重及褐变等问题,探索红枣脆片新的加工方法,该文以新鲜脆熟期红枣为原料,利用气体射流冲击、中短波红外、真空脉动3种干燥技术进行非油炸红枣脆片的生产加工,对比了3种干燥方式对红枣脆片的干燥特性、色泽、维生素C保留率、复水性能、质地以及微观结构的影响。结果表明:1)红枣脆片在3种干燥方式下均表现为降速干燥,其中气体射流冲击干燥时间最短,为105 min,气体射流冲击、中短波红外、真空脉动干燥方式的水分有效扩散系数分别为1.55×10-9、1.03×10-9、0.89×10-9 m2/s;2)干燥方式对枣片色泽具有显著性影响(P<0.05),真空脉动干燥所得枣片与新鲜枣片色泽最为接近;3)气体射流冲击、中短波红外、真空脉动干燥方式干燥后红枣脆片的维生素C保留率分别为51.5%、49.0%、66.6%,真空脉动干燥所得枣片维生素C含量保存率明显高于其他两种干燥方式(P<0.05);4)气体射流冲击、中短波红外、真空脉动干燥方式加工的红枣脆片脆度分别为8.64、8.77、11.38 N,真空脉动干燥方式所得枣片最为酥脆;5)扫描电镜观测表明3种干燥方式均能得到疏松多孔的组织结构,真空脉动干燥所得枣片比气体射流和中短波红外干燥所得枣片组织结构更为疏松。从干燥时间来看气体射流冲击干燥耗时最短,但3种干燥方式所得红枣脆片色泽、维生素C保留率、复水性能和质地均以真空脉动干燥最优。该研究为低含油率和高品质红枣脆片的加工工艺选择提供了一定的理论依据。

       

      Abstract: Abstract: With rich contents of vitamin C, various amino-acids, polysaccharide and phytochemicals, jujube is widely planted and consumed in China. Seasonality and perishability of fresh jujube demand to apply preservation technologies, such as vacuum-fried, but the favored product after this processing has the potential risk on our health because of its higher oil content and low nutrient retention. To realize product diversification and satisfy requirements of novel-health products for human beings, it is essential to exploit new processing method of jujube. In order to reduce the oil content of jujube crisps, improve the retention rate of vitamin C and explore new drying techniques for jujube crisps production, fresh jujube slices (thickness of 4 mm) in crisp ripe stage were dried with 3 new types of drying technologies, namely air impingement drying (temperature of 70 ℃, air velocity of 8 m/s), medium and short infrared wave drying (temperature of 70 ℃, air velocity of 8 m/s) and pulsed vacuum drying (temperature of 80 ℃, vacuum and normal pressure retention time of 10 and 2 min, respectively). Effects of the 3 drying technologies on the drying characteristics, color parameters, retention of vitamin C content, crispness, rehydration ratio and microstructures were investigated. Results showed that: 1) All drying process of the three drying methods showed the falling rate period without constant speed stage, and the shortest drying time was obtained under air impingement drying technology, which the drying time was only 105 min. 2) Effective moisture diffusivities were 1.55×10-9, 1.03×10-9, and 0.89×10-9 m2/s for air impingement drying, medium and short infrared wave drying, and pulsed vacuum drying, respectively. 3) Drying methods had a significant impact on the color of dried samples, and the color of jujube crisps under pulsed vacuum drying was very similar to that of the fresh ones. 4) Pulsed vacuum drying could keep more vitamin C content compared to the other two drying technologies. The retention rates of vitamin C were 51.5%, 49.0%, 66.6% for the samples dried by air impingement drying, medium and short infrared wave drying, and pulsed vacuum drying, respectively.5) Compared with air impingement drying and medium and short infrared wave drying, jujube crisps dried by pulsed vacuum drying had the highest crispness. 6) Microstructure detection indicated that all the 3 drying technologies could make a porous structure and thus change the properties of jujube slices. The pulsed vacuum drying led to a more uniform porous structure, which probably contributed to the higher crispness and rehydration ratio of the samples dried by pulsed vacuum drying. In conclusion, although pulsed vacuum drying technology took a relatively long drying time to get the same moisture ratio, the qualities of jujube crisps by pulsed vacuum drying were much better than those by air impingement drying and medium and short infrared wave drying. The findings of current work can provide theoretical basis and technical support for the practical application of pulsed vacuum drying to produce jujube crisps.

       

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