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 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 εr 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).

An Overview on Food Applications of the Instant Controlled Pressure-Drop Technology, an Innovative High Pressure-Short Time Process

“…Swell-drying has also been applied to develop ready-to-eat snacks and expanded granule powders from Zaghloul dates (Phoenix dactylifera L.) [40]. Dates were pre-dried under CAD until a water content of 0.12 g H 2 O/g db was reached to be DIC textured at different operative parameters (200 to 600 kPa and from 9 to 35 s).…”

Can hydro-thermo-mechanical treatment by instant controlled pressure-drop (DIC) be used as short time roasting process? Effect of processing parameters on sensory, physical, functional, and color attributes of Egyptian carob powder

“…The mixture was homogenized in a blender and presented hot to the panelists including 70 members (25 males and 45 females aged 23-65 years) in coded samples. The panelists were provided with an instructed sheet and a glass of water as described by Mounir et al (2019a). The different samples were evaluated for the overall acceptability based on their 1/appearance, 2/color, 3/taste, and 4/odor using a nine-point hedonic scale (1 = extremely dislike to 9 = extremely like) according to Leite et al (2013).…”

“…The color parameters; L*, a*, and b*, of different carob powders were evaluated according to Mounir et al (2019a) using a Hunter's Lab color analyzer (Color Flex EZ Spectrophometer, USA) which was standardized with a black and white tile before the measurement. Chroma (C*) and the total color change (DE) were respectively determined using Eqs.…”

“…Fittingly, in the complex specific treatment of carob, it was worth studying the instant controlled pressure-drop process (DIC) with two parameters; the pressure of saturated steam and processing time. Its specificity, using an abrupt drop in pressure towards a vacuum (* 50 kPa) with a rate of 0.5 MPa s -1 , has been used to study singular operations of well-controlled auto-vaporization (Mounir et al 2019a(Mounir et al , 2019b and texturing/roasting techniques. The high level of thermo-mechanical stress induced by the abrupt pressure-drop and the vapor evolution inside the treated product involve an expansion of solid matrix into a more porous microstructure (Mounir et al 2012).…”

Instant Controlled Pressure Drop as Blanching and Texturing Pre-Treatment to Preserve the Antioxidant Compounds of Red Dried Beetroot (Beta vulgaris L.)

“…After the pressure drops, several thermo-mechanical effects occur into the food material, such as expansion, instantaneous cooling of the products, and the rapid vaporization of volatile compounds [ 10 ]. Many fruit and vegetable materials have been subjected to this technology, such as strawberry [ 11 , 12 ], banana [ 13 ], pepper [ 14 , 15 ], garambullo [ 16 ], date [ 17 ] and chokecherry [ 18 ]; and research findings have shown that thanks to a porous structure newly generated by DIC, swell-drying reduced the drying time and preserved bioactive and nutritional food compounds.…”