Effects of operating parameters of the instant controlled pressure drop (DIC) texturing process followed by intermittent microwave (MW) and airflow drying were studied for the manufacture of novel swell-dried shrimp snacks. The DIC processing parameters were the absolute pressure of saturated steam (P = 0.4, 0.55, and 0.7 MPa) and the treatment time (t = 70, 100, and 130 s). Intermittent MW drying with active time t_ON of 30 s and tempering time t_OFF of 60 s followed DIC-texturing of blanched shrimp samples (30 g cubes of 1 cm³). The MW density power $\dot{\wp }$ levels tested were 6, 12, and 24 W/g wb (wet basis). The airflow condition was fixed at 3.2 m/s, 20 °C, and 276 Pa water vapor pressure. Drying performance along with the organoleptic, structural, and functional quality parameters was measured for the dried product. The results showed that the highest DIC processing parameters of P = 0.7 MPa for 170 s were the best texturing conditions, while the MW power level of 24 W/g wb yielded the most effective drying performance when 90% of moisture was removed in 10 min, with organoleptic quality attributes and structural properties better than those of conventionally dried shrimp. Furthermore, the aroma was better preserved, and the exceptionally high absolute expansion ratio (Ɛ_abs = 13.84) and porosity (φ = 92.83%) allowed enhancement of the desired crispness of the snacks as well. The highly porous microstructure also results in improved rehydration performance.

This study is aimed at comparing swell drying versus conventional shade drying and optimizing the texturing by instant controlled pressure drop (DIC) of green okra pods. Differences in quality attributes such as content of flavonoids, carotenoids, and chlorophyll pigments, functional characteristics such as the antioxidant activity (AOA), microstructure and relative expansion ratio of dried okra pods were considered. The DIC processing parameters were the saturated steam pressure (0.2-0.6 MPa) and duration (40-60 s). A 2-parameter, 5-level central composite rotatable design was selected for establishing the experimental trials. They represent 8 factorial and star trials, and five repetitions of central/middle point of the square edges. Significant variations in total phenolic and flavonoid contents, carotenoids, antioxidant activity, and chlorophyll pigments were observed between swell-dried and conventional shadow dried okra pods. An increase of 25% and 99% was respectively observed for the relative expansion ratio and flavonoid content in swell dried okra pods compared with conventional shadow dried ones. The microstructure observations showed a significantly more porous open solid matrix of swell-dried okra pods compared to the compact/dense solid matrix of the conventional shadow dried okra pods. The optimum conditions of DIC-texturing were found to be 0.4 MPa for 50 s exhibiting the highest values of total phenolic content, flavonoids, antioxidant activity, and chlorophyll pigments with good preservation of the carotenoid content.

In the present study, instant controlled pressure drop (DIC) was used as a novel texturing pretreatment of fresh chicken breast meat, before hot airflow drying, in order to modify the texture of the meat and obtain a controlled expansion. Three different drying techniques were compared: conventional hot airflow drying, freeze drying, and swell drying (a combination of DIC and hot airflow drying). DIC was carried out under various conditions in order to achieve multi-criteria optimization. A two-parameter, five-level response surface methodology was used to optimize the operating parameters of saturated steam pressure and thermal holding time, starting with the meat's initial water content. Saturated steam pressure had a significant impact on the expansion ratio. The higher the expansion ratio, the better the different functional qualities. Microstructural changes reduced drying time, and increased rehydration kinetics and water holding capacity (WHC). The starting accessibility δW_s and the internal effective water diffusivity D_eff were studied for both drying and rehydration processes in accordance with the coupled washing/diffusion (CWD) phenomenological model.

The objective of this work was to study the effect of foaming parameters on the physical and phytochemical properties of tomato powder. A central composite rotatable design of experiments was defined with two parameters (concentration of soy protein isolate [SPI]: 1–5% and whipping time: 2–14 min) with 5 levels for each parameter. The foam was prepared by whipping tomato puree after adding SPI and dried in a thin layer (4 mm ± 1) at 50 °C. The obtained results showed the predominant effect of the concentration of SPI on the physical and phytochemical properties compared to whipping time. The powder prepared under foaming conditions of 5% SPI and whipping time of 8 min showed an increase of 97, 39, 62, and 46% in the total phenolics, total flavonoids, antioxidant activity, and porosity, respectively, while the bulk density decreased by about 25%.