Moreover, coupling of the DIC process with spray drying was also investigated. Mounir and Allaf defined a new industrial operation composed of three stages spry drying, DIC texturing, and hot air drying with the aim of increasing the specific surface area of some dairy powders skim milk, sodium caseinates, and whey proteins. For example, specific surface area of whey protein powder was tripled compared to conventional spray dried powders.
A positive relation was reported between the steam pressure used in DIC operation and the specific surface area. Scanning electron microscopy analyses showed that DIC textured powders have very porous textures with numerous differently sized cavities and pores, which may explain the rapid drying and improved drying kinetics [ 20 ].
Carrot swell drying was also studied compared to traditional simple hot air drying [ 44 ]. A linear correlation was defined between the product porosity and DIC operating pressure and thermal holding time. Due to important increase of effective diffusivity of moisture content, a significant reduction in drying time and energy consumption was reported in this study.
Microbiological, organoleptic, and nutritional qualities of powders and granular products are a very important issue for the researchers and industrials. Additionally, high microbial load generally characterizes the dried foods such as spices and herbs [ 45 ] due to their traditional methods of harvesting, drying, preparation, and storage [ 46 ].
The use of these ingredients in ready-to-eat plates without further heat treatment can be a serious source of hazards [ 47 ]. Moreover, it has been reported that the heat resistance of microorganisms is greater in water-poor environments such as the spices and dried herbs [ 48 ]. Thermal decontamination of microorganisms in solid foods faces several difficulties. Conventional heat exchangers are not appropriate for granular and powder products. A strong temperature gradient is often produced, during heating or cooling stages, which typically involves damage to the end product and reduces its overall quality.
The development of a specific and effective heat treatment in the case of solid or powder foods is still required. Steam treatment is a simple way to decontaminate foods [ 49 , 50 ]. However, the effectiveness of this method depends on the type of product and target microorganisms. Also, the exposure time needs to be reduced in order to limit the heat quality degradation. Moreover, due to thermal sensitivity of food powders, athermic decontamination processes seem to be more appropriate such as high pressure decontamination processes.
Beside its application as a drying method, the instant controlled pressure drop DIC technology can be used as a decontamination process for powders, species, pharmaceutical products, animal feed, and fresh-cut fruits and vegetables. The efficiency of DIC technology as a microbial inactivation process was studied and approved against spores and vegetative forms, such as Bacillus stearothermophilus , Enterococcus faecalis , Saccharomyces cerevisiae , and Escherichia coli [ 52 , 53 ] Figure 6.
DIC technology combines the advantages of steam heating and high pressure treatments. Three patents describe in detail this application [ 52 ]. The effective microbial inactivation with DIC is due to the thermomechanical impacts resulting in irreversible changes in the microorganism cells, such as protein denaturation and break of the cellular membrane.
Two main mechanisms are involved in DIC bactericidal effect: a controlled high thermal treatment and instant excessive pressure release. In addition to the well-known thermal effects on the bacterial mortality, the auto evaporation of water contained in the microorganisms, during the pressure release, causes the explosion of the bacterial cells and spores [ 8 , 52 , 54 ]. Inactivation of Bacillus stearothermophilus spores by DIC technology. The process temperature is defined by the operating pressure, data adopted from . This process is very flexible to apply. The operating parameters can be adjusted depending on the product nature and target microorganisms.
The published results show that both steam pressure, which determines the temperature, and holding time under these conditions had a significant effect on the microbial inactivation. Higher saturated steam pressure and longer treatment time result in more effective decontamination. In addition, the number of pressure-drop cycles is another important factor to take into account [ 54 ].
In addition to its application as a decontamination and intensifying drying process, DIC technology can be used in other various operations in food processing [ 15 ], such as, blanching-steaming of vegetables. DIC Treatment of fresh cut onions allows a perfect decontamination of raw materials and a preservation of the natural structure of the end product. Onion samples were treated firstly by DIC under high natural initial moisture content before a dehydration step by gentle hot air flow. In addition, natural contamination of raw onions has been eliminated.
A decontamination of 1. Similarly, as a post harvesting treatment, DIC assisted steaming and parboiling of paddy rice followed by conventional airflow drying was also studied. DIC treated rice was characterized by better cooking behavior [ 55 ]. Furthermore, the DIC process has been used to enhance or assist the conventional edible oil extraction from various vegetal materials [ 17 ].
Multi-DIC cycles allow the extraction of essential oils of aromatic plants with low energy and low water consumption. The structure expansion by DIC increases the porosity and the specific surface area of the treated plants and improves, as a result, the solvent extraction. DIC texturing is considered, thus, as a solvent extraction pretreatment, which decreases the extraction time. Other studies have showed that DIC texturing permits enhancing essential oils and lipid extraction from Jatropha and rapeseed seeds [ 57 ], rosemary leaves [ 17 ], orange peel [ 58 ], and microalgae [ 59 ]. The nutritive quality of processed food is effectively influenced by the operating conditions.
High temperature and long heating times result in important degradation of vitamins and bioactive molecules [ 60 ]. The nutritive values of DIC-treated products were evaluated [ 43 , 61 ]. Thanks to its effective heating and rapid cooling, DIC-dried products are characterized by higher content and availability of bioactive compounds. The open porous structure, because of DIC texturing, allows increasing the availability of these compounds.
Increase in the relative availability of quercetin in apple dry basis after DIC treatment compared to fresh untreated apple, data modeled from . Sensory characteristics are crucial quality attributes and normally influence the consumer preferences [ 62 ]. DIC dried, or treated products in general, are distinguished by preserved and even improved sensory properties such as flavor, color, and texture. Conventional hot air dried food products suffer from color and flavor changes as a result of severe drying conditions. Several studies have been carried out to enhance color, aroma content, and texture quality of several food products using DIC technology [ 63 ].
The results proved the high quality of swell dried carrots, potatoes, green beans, and tomatoes for example. Wang and others reported similar industrial results for green tea, wherein the DIC process intensifies the color as well as availability of antioxidant nutritional molecules [ 64 ].
Crispness is an important sensorial and textural characteristic often associated with the firmness of fresh or dried food products.
Emulsions - Schaaf - - Major Reference Works - Wiley Online Library
The dense structure of hot air dried products, due to the shrinkage phenomenon, solidifies excessively the structure. The expansion phenomenon results in increasing the specific surface area, which was two times higher for swell dried apples compared to hot air dried samples [ 40 ]. Relative expansion ratio is defined as a volumetric ratio between DIC and conventional hot air dried products, which allows evaluating the macrostructural changes caused by DIC texturing. Similar results were also reported for cheese, chicken breast meat, and sodium caseinate [ 8 ].
In the specific cases of dairy products, such expanded-granule powders have had instantaneous rehydration behavior without inserting any agglomerating steps. The rehydration of DIC dried products was compared to freeze-dried and hot-dried references. The rehydration ability of DIC swell dried chicken breast meat was higher than that of the hot dried samples but slightly lower than that of freeze-dried meat [ 66 ].
These results are in agreement with those of others studies [ 43 , 61 ]. It was found that freeze-dried Moroccan green pepper and strawberry had a better rehydration ability i. Water holding capacity is defined as the total quantity of water retained or absorbed by a food matrix under defined conditions [ 67 ]. This property is very important to be considered for incorporation of the dried ingredients into food formulation.
The high rehydration ability of DIC swell dried products is due to the open texture formed of large intercellular spaces porosity , which leads to higher water diffusivity during the rehydration process [ 8 ]. Several researchers have found that saturated steam pressure, during the DIC operation, has positively a significant impact on increasing the rehydration ability and water holding capacity of treated products.
This factor is very important in food formulation. Setyopratomo and others observed that oil holding capacity of DIC textured cassava flour increased compared to conventional hot air dried flour. It was about 2.
Find a copy online
These results may be related to starch gelatinization combined with microstructural changes as a result of DIC textured treatment [ 68 ]. This treatment and selection of the subjects is stimulating and unique. Consisting of nine chapters, each subdivided into several sections, the book addresses the high pressure aspects, providing well selected correlated information connected with a comprehensive overview together with a large number of references.
The main body of the first eight chapters refers to subjects like high pressure in general, the thermodynamics and kinetics of the fluids involved, the design of high pressure equipment, the modeling and design of reactors, separation and fractionation units, the safety aspects, the control and economics.
In the extended last chapter, examples of promising high pressure applications are explained, such as chemical and enzymatic reactions in supercritical solvents, hydrogenation under supercritical conditions, supercritical water oxidation, polymerization with metallocene catalysts, supercritical extraction, fractionation and precipitation, supercritical pharma processing, ultra-high pressure sterilization and supercritical dry-cleaning. Product details Format Hardback pages Dimensions x x 34mm 1, Other books in this series. Add to basket. Table of contents Preface. List of contributors. Thermodynamic properties at high pressure.
Kinetic properties at high pressure. Design and construction of high pressure equipment for research and production. Industrial reaction units. Product Details Table of Contents. Table of Contents Preface.
List of contributors. Thermodynamic properties at high pressure. Kinetic properties at high pressure. Design and construction of high pressure equipment for research and production. Industrial reaction units. Separation operations and equipment.
- Forgotten (Book 3 - Forsaken Series).
- High Pressure Process Technology Fundamentals and Applications.
- Top Authors.
- High pressure process technology : fundamentals and applications.
- Les cousines Muller (Littérature Française) (French Edition).
Safety and control in high pressure plant design and operation. Economics of high pressure processes. Chemical reactions in supercritical solvents SCFs. Enzymatic reactions.
Hydrogenation under supercritical single-stage conditions. Supercritical water oxidation SCWO. High pressure polymerisation with metallocene catalysts. Supercritical fluid extraction and fractionation from solid materials. High pressure polymer processing. Precipitation of solids with dense gases.
Pharmaceutical processing with supercritical fluids.
Pressure Switch Basics and Selection Tips
Treating microorganisms with high pressure. Dry cleaning with liquid carbon dioxide. Average Review. Write a Review.