Texture and Color Characteristics of Swell Dried Ready-To-Eat Zaghloul Date Snacks: Effect of Operative Parameters of Instant Controlled Pressure Drop Process.

Abstract

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\u2009MPa and from 9 to 35\u2009s, 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 instant controlled pressure drop technique (DIC). The optimized textural characteristics was identified for SD Zaghloul date at p\xa0=\u20090.6\u2009MPa and t\xa0=\xa022\u2009s with slight yellowness, while the best color properties was observed for texturing conditions of p\xa0=\u20090.2\u2009MPa and t\xa0=\xa022\u2009s. The expansion ratio εr was then 46% higher and the hardness was 262% lower for swell-dried than airflow dried date. Instrumental analysis such as texture profile analysis (TPA) 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 instant controlled pressure drop (DIC) assisted hot air drying. The thermo-mechanical effects of DIC are mainly induced by the abrupt pressure drop towards a vacuum after short time treatment (9-35\u2009s) by saturated steam pressure (0.2 up to 0.6\u2009MPa). 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). This article is protected by copyright. All rights reserved.