机构地区:[1]石河子大学机械电气工程学院,石河子832000 [2]农业农村部西北农业装备重点实验室,石河子832000 [3]中国农业大学工学院,北京100083
出 处:《农业工程学报》2022年第2期296-306,共11页Transactions of the Chinese Society of Agricultural Engineering
基 金:国家自然科学基金(31960488);石河子大学成果转化与技术推广计划项目(CGZH201808)。
摘 要:为解决热风干燥后枣片表面硬化结壳、酥脆性差的问题,该研究在热风干燥过程中加入射频热处理,研究不同温度(55、65和75℃)枣片质构特性和微观结构的变化规律,并从微观角度探索射频热处理对热风干燥枣片质构变化的影响机理。研究结果表明:干燥过程中,枣片硬度与咀嚼性呈现先下降后上升的变化趋势,弹性、内聚性和回复性的变化趋势则为先上升后下降,而黏附性随着水分比的下降逐渐降低;施加射频热处理后,热风干燥枣片硬度、脆性分别降低12.6%~18.7%,13.8%~20.4%,弹性和内聚性分别增加12.2%~25.3%,5.9%~13.2%;微观图像分析表明,干燥过程中枣片的微观变化主要为两个阶段,前期随着细胞内的水分去除,膨压降低,细胞壁收缩;在第二个阶段当膨压达到最小值时,枣片细胞壁发生更高程度的翘曲和起皱来适应更小的细胞液体积;施加射频热处理后,枣片内部组织排列规则,部分区域出现细微通道以及孔洞的变形、扩张。疏松多孔的组织结构有利于内部水分的迁移扩散,进而改善热风干燥后枣片的酥脆性,微观结构变化能够解释施加射频热处理后枣片硬度、脆性、弹性和内聚性等质构特性变化的产生机理。研究结果可为射频与热风联合干燥枣片技术与工艺的研究以及干燥品质的过程调控提供参考。The purpose of this research is to deal with the surface hardening and crust formation,as well as the low crispness of jujube slices during hot-air drying(HAD).A radiofrequency(RF)heat treatment was also applied to the HAD jujube slices.An influence mechanism was proposed for the texture and microstructure of hot-dried jujube slices at different temperatures(55℃,65℃,and 75℃)under the RF heat treatment.The results showed that the hardness and chewiness of jujube slices decreased first and then increased,whereas,the springiness,cohesiveness,and resilience increased first and then decreased,while the adhesiveness increased with the decrease of moisture ratio during the drying process.The hardness,crispness,chewiness,springiness,and cohesiveness of hot air-dried jujube slices decreased gradually,with the increase of temperature,but,the drying temperature had no significant effect on the resilience.The hardness and crispness of hot air-dried jujube slices after applied RF heat treatment decreased by 12.6%-18.7%,13.8%-20.4%,respectively,while the springiness and cohesiveness increased by 12.2%-25.3%and 5.9%-13.2%,respectively.A correlation analysis showed that there was a significant positive correlation between the springiness and cohesiveness of jujube slices(P<0.01).The hardness of jujube slices presented a positive correlation with the chewiness and crispness(P<0.05)during different drying.A principal component analysis(PCA)was used to establish a new model for the texture quality assessment.As such,the highest score and the best texture quality were achieved in the dried product at 75℃during RF-assisted HAD(RF+HAD).Microstructural characterization showed that the tissues of fresh jujube slices were composed of tightly connected cells with quite similar in size,indicating a clear cell edge.Furthermore,the cell structure of jujube slices deformed over time during the hot-air drying,which was mainly driven by the moisture removal from the cell fluid followed by the turgor loss.The cell deformation during dryi
关 键 词:干燥 微观结构 质构特性 射频热处理 热风干燥 枣片
分 类 号:TS255.4[轻工技术与工程—农产品加工及贮藏工程]
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