Food processing systematically aims at meeting the needs of consumers who are looking for total high quality and perfect food safety. As the various thermal and non-thermal food preservation technologies often affect the natural properties in terms of sensation, flavor, texture, etc., instant controlled pressure drop (DIC) has been conceived as a relevant, innovative process in this field. DIC uses high saturated steam pressure and short duration to provide a new way to expand biological matrices, improve drying, decontaminate, and extract biologically active compounds, among other attributes. Therefore, this review focuses on describing the applications of DIC technology on a wide range of products such as foods and by-products that have been processed both in the laboratory and on an industrial scale. The application of DIC has shown the possibility of a significant leap in quality improvement and cost reduction in the food industry. DIC reduces the drying time of fruits and vegetables, and improves the extraction of essential oils, vegetable oils, and antioxidant components. It also provides strong decontamination, eliminates vegetative microorganisms and spores, and reduces non-nutritional and allergenic components. Over the past 33 years, this technology has continued to expand its food applications and improve its characteristics on an industrial scale. But there are still many food unit operations that can be taken to the next level with DIC.

The impacts of total hot air drying (THD) and the swell-drying process (SD), which is hot air drying coupled with an instant controlled pressure drop DIC process, on the drying kinetics and adsorption isotherm behavior, were determined in the case of Moroccan peppers. Drying kinetics were studied through a model that takes into account the starting accessibility and the internal diffusion model with Fick's law. Adsorption experimental data were obtained by using the gravimetric method at 25, 40, and 50°C. Data were fitted to the GAB, Halsey, and Oswin models. Studied responses were: effective diffusivity (D_eff), starting accessibility (δW_s), monolayer moisture content (X_m), specific surface area (σ), internal porosity (ϵ), and microstructure. Mean relative percentage deviation (E) and root mean square (RMS) were used to evaluate the fitting of models. Results showed that: pepper adsorption isotherms followed the type II isotherm curve;the equilibrium moisture content (X_eq) depended on the temperature and the drying method; the GAB and Halsey models fitted well the experimental data; at selected conditions of the DIC treatment (0.35 MPa and 5 s), the monolayer moisture content (X_m), the specific surface area (σ), and the internal porosity values were higher than those of THD samples; the DIC process intensified the drying operation, by increasing the effective diffusivity and the starting accessibility. Although the DIC process improves the drying kinetics, this behavior could be ignored related to a higher a_w. This study shows that, thanks to the new expanded structure obtained by the DIC process (higher porosity), the adsorption capacities of products are improved (a_w is reduced). Thus, the SD process improves both the drying operation and the stability of dried pepper products.

A comparative study of various drying techniques were carried out on Green Moroccan Peppers GMPs, Traditional Hot Air Drying, Swell Drying SD, and freeze drying, in order to compare the dried product's behavior during drying and rehydration. Moreover, starting accessibility, and water effective diffusivity during drying and rehydration were studied. The water holding capacity of dried GMPs were investigated as well. The impacts of Instant Controlled Pressure Drop process (DIC) on dehydration and rehydration kinetics and functional properties (water holding capacity) were compared to Freeze Drying (FD) and Traditional Hot Air Drying processes (THD). DIC treatment was carried out on pre-dried peppers (classical hot air drying at 50°C, 265Pa initial partial pressure of vapor in the air flux, 1.2 m s-1) to reach a moisture content of 20% dry basis varying the saturated steam pressure (ranged from 0.1 to 0.6MPa) and heating time (ranged from 9 to 35 s) and keeping the initial water content constant at 20% db. Drying and rehydration kinetics of DIC-textured and untreated peppers were well interpreted by a specific model coupling a starting superficial interaction with Fickian diffusion. Response parameters (dependent variables) were the dehydration and rehydration starting accessibility Ws (g H2O/g dry matter), effective diffusivity Deff (m2 s-1) and drying time td0,05% (min). Response Surface Methodology RSM was employed. Compared to THD, DIC treatment dramatically increased the starting accessibility and the effective water diffusivity during hot air drying; it allowed the drying time needed to get a final water content of 0.05% db, to decrease by 1.7 times. Regarding the rehydration ability, the time needed to reach 300% db, were reduced 3.7 times under optimum DIC conditions. Fickian diffusion model could not explain FD rehydration, which appeared as a pure water/surface interaction. Water Holding Capacity of DIC dried products was higher than FD and THD

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.

Cardamom Essential oils are highly demanded because of their antimicrobial, anti-inflammatory, and antioxidant activities. Nonetheless, retrieving quality extracts quickly with efficient energy savings has been challenging. Therefore, green technologies are emerging as possible alternatives. Thus, this study evaluates the yield and quality of the instant controlled pressure drop (DIC) process coupled with ultrasound-assisted extraction (UAE) of cardamom essential oil (CEO). Likewise, the antioxidant activity, chemical profile of CEO, and microstructure of seeds were analyzed. This study analyzed 13 different treatments with varying saturated steam processing temperatures (SSPT), thermal processing times (TPT), and 1 control. The results showed that CEO yield increased significantly by DIC (140 °C and 30 s) and UAE compared to the control (22.53% vs. 15.6%). DIC 2 (165 °C, 30 s) showed the highest DPPH inhibition (79.48%) and the best Trolox equivalent antioxidant capacity (TEAC) by the control with 0.60 uMTE/g. The GC/MS analysis showed 28 volatile constituents, withα-Terpinyl acetate, geranyl oleate, and oleic acid being the most abundant. DIC (140 °C and 30 s) and UAE showed the best yield and chemical profile. The SEM microscopy of untreated seeds revealed collapsed structures before the oil cell layer, which reduced the extraction yield, contrary to DIC-treated seeds, with more porous structures. Therefore, combining innovative extraction methods could solve the drawbacks of traditional extraction methods.