Food Science Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt.
University of La Rochelle, Laboratory of Engineering Science for Environment LaSIEUMR7356 CNRS, La Rochelle, France.
J Texture Stud. 2020 Apr;51(2):276-289. doi: 10.1111/jtxs.12468. Epub 2019 Aug 18.
In this work, development of ready-to-eat snacks from Zaghloul date using swell-drying process was studied. Pre-dried Zaghloul date samples having 12% water content on dry basis were textured by instant controlled pressure drop technique (DIC) at different operative parameters, saturated steam pressure (p) and processing time (t), ranged from 0.2 to 0.6 MPa and from 9 to 35 s, respectively. The effect of these operative parameters on texture, color, and sensory characteristics of swell-dried (SD) Zaghloul date snacks were determined and optimized through the response surface methodology. Textural (expansion ratio, hardness, springiness, cohesiveness, and chewiness) and color (L*, a*, b*, C*, and ΔE*) characteristics were significantly affected by the operative parameters of DIC. The optimized textural characteristics was identified for SD Zaghloul date at p = 0.6 MPa and t = 22 s with slight yellowness, while the best color properties were observed for texturing conditions of p = 0.2 MPa and t = 22 s. The expansion ratio ε was then 46% higher and the hardness was 262% lower for SD than airflow-dried date. Instrumental analysis such as texture profile analysis and Hunter's Lab color analyzer could be used to describe the texture and color changes occurred during food drying. Beside these analyses, the expansion ratio could be used to describe the texture as well. Swell-drying process, an alternative drying process, is defined as DIC-assisted hot air drying. The thermo-mechanical effects of DIC are mainly induced by the abrupt pressure drop toward a vacuum after short-time treatment (9-35 s) by saturated steam pressure (0.2 up to 0.6 MPa). The abrupt pressure drop rate induces an autovaporization of product's water immediately decreasing the product's temperature allowing it to cross the glass transition Tg border. The impact of DIC operative parameters on Zaghloul date could be observed through the expansion ratio, and the textural characteristics (hardness HA, springiness SP, cohesiveness CO, and chewiness CH).
本工作研究了利用膨化干燥工艺从扎格卢勒枣制备即食小吃。将预干燥的扎格卢勒枣样品在不同操作参数（饱和蒸汽压力 p 和处理时间 t）下进行瞬时控压释放技术（DIC）处理，水分含量为 12%（干基），范围分别为 0.2 至 0.6 MPa 和 9 至 35 s。通过响应面法确定和优化这些操作参数对膨化干燥（SD）扎格卢勒枣小吃的质地、颜色和感官特性的影响。DIC 的操作参数显著影响膨化干燥扎格卢勒枣的质地（膨胀比、硬度、弹性、内聚性和咀嚼性）和颜色（L*、a*、b*、C和ΔE）特性。在 p = 0.6 MPa 和 t = 22 s 的条件下，SD 扎格卢勒枣的质地特性最佳，略带黄色，而在 p = 0.2 MPa 和 t = 22 s 的条件下，颜色特性最佳。与气流干燥的枣相比，SD 的膨胀比高 46%，硬度低 262%。如质构剖面分析和亨特实验室颜色分析仪等仪器分析可用于描述食品干燥过程中发生的质地和颜色变化。除了这些分析，膨胀比也可用于描述质地。膨化干燥工艺是一种替代干燥工艺，定义为 DIC 辅助热风干燥。DIC 的热机械效应主要是由在短时间（9-35 s）内用饱和蒸汽压力（0.2 至 0.6 MPa）处理后突然降压至真空引起的。突然的降压速率会使产品中的水立即自动蒸发，从而降低产品的温度，使其越过玻璃化转变 Tg 边界。DIC 操作参数对扎格卢勒枣的影响可以通过膨胀比和质地特性（硬度 HA、弹性 SP、内聚性 CO 和咀嚼性 CH）观察到。
