Atmospheric Freeze Drying—A Review

This review article focuses on the development of atmospheric freeze drying (AFD): technological aspects, product possibilities, physical properties of products, drying kinetics, modeling, and simulation. The main motivation for developing atmospheric freeze drying as a new drying technology is the desire to reduce the energy consumption compared to vacuum freeze drying while maintaining a high product quality. One technical solution of atmospheric freeze drying is a combined atmospheric freeze drying and heat pump system with new environmentally friendly refrigerants. Temperature programs make it possible to customize products with desired qualities and properties, like retained color, instant properties, aroma, and nutritional value.     

Retention of Vitamin C in Drying Processes of Fruits and Vegetables—A Review

This article presents a review of drying processes of fruits and vegetables in which vitamin C degradation was considered. Vitamin C is an important and essential nutrient for humans and it can be taken as an index of nutrient quality of processes. Many researchers have reported the effect of different drying methods and the influence of drying conditions on the vitamin C content. In addition, the effect of other parameters related to the sample structure or to pretreatments on the final quality of the dried product is discussed. Vitamin C degradation mechanisms proposed in the literature, models applied to describe its kinetics, and recent advances in drying processes aiming high retention of this nutrient are also provided.     

Drying of Low-Rank Coal (LRC)—A Review of Recent Patents and Innovations

Despite being geographically dispersed, abundant, and accounting for almost half of the world's coal reserves, low-rank coals (LRCs) find limited use due to their high moisture content and high propensity for spontaneous combustion. Reducing the moisture content of low-rank coal enhances its heating value and reduces transportation costs, thus increasing its economic value. In addition, dried low-rank coals have been proven to improve plant efficiency, enhance safety, and reduce greenhouse gas emissions. Although numerous technologies for coal drying already exist, it is often challenging, if not impossible, to find one that is cost-effective in all aspects. When selecting a dryer for coal upgrading applications, factors such as particle size/size distribution, throughput, energy consumption, material handling capabilities, safety, carbon footprint, capital and operating costs, return on investment, etc., are important considerations. This article provides an overview of the patent literature along with the archival literature that deals with drying of coal as well as biomass, which is relevant to coal drying.     

Low-Rank Coal Drying Technologies—Current Status and New Developments

Despite their vast reserves, low-rank coals are considered undesirable because their high moisture content entails high transportation costs, potential safety hazards in transportation and storage, and the low thermal efficiency obtained in combustion of such coals. Their high moisture content, greater tendency to combust spontaneously, high degree of weathering, and the dusting characteristics restrict widespread use of such coals. The price of coal sold to utilities depends upon the heating value of the coal. Thus, removal of moisture from low-rank coals (LRC) is an important operation. Furthermore, LRC can be used cost effectively for pyrolysis, gasification, and liquefaction processes. This article provides an overview the diverse processes—both those that utilize conventional drying technologies and those that is not yet commercialized and hence in need of R&D. Relative merits and limitations of the various technologies and the current state of their development are presented. Drying characteristics of low-rank coal as well as factors affecting drying characteristics of coal samples are also discussed.     

Drying of Liquid Dispersions—A Unified Approach to Kinetics and Modeling

Abstract

The article presents a unified approach to interpretation of drying kinetics and modeling of the drying process for suspensions, solutions, emulsions and pastes. The approach is based on phenomenological analysis of temperature-moisture relationships T(X) with account for temperature plateaux that actually show-up, or could exist under certain drying conditions. In addition, a unified mathematical model is proposed that includes the differential equations for mass and heat diffusion along with their analytical solutions for a multi-layer plate, cylinder and sphere. Interconnections in the simultaneous heat-mass transfer, cross-effects and any other details of a real process are taken into account separately, by semi-empirical temperature-moisture function T(X). The principles of piece-wise multizone approximation of these temperature-moisture curves are presented. The hyperbolic and two-arc approximations for each separate zone are described. The set of 12 organic and inorganic materials either synthetic or of animal and plant origin such as meat processing sludge, heavy corn steep water, gelatin, starch, sugar, salt, combined latex emulsion, P-salt, gamma acid, dispersing and bleaching agents was taken as example for the development and validation of this approach.     

Drying of biofuels from the forest—A review

The literature during 2000–2016 about drying of biofuels from the forest has been reviewed. Biofuels constitute a low-cost energy resource that is likely to continue to increase and the dryers for such products should be simple, robust, and easy to operate. In 1970s and 1980s, rotary dryers and flash dryers were the most common types, and in 1990s, superheated steam (SHS) dryers became common. Maintenance costs and use of medium pressure steam for the SHS dryers are important topics to consider and one drawback for the rotary dryers is that high-temperature heat sources are used. The development during the last 15 years has moved toward moving bed dryers because of the possibility to use cheap low-temperature energy sources, robust design, and direct capacity control that is achieved by controlling the air temperature in the dryer. A price for the dry biofuel of 15–20 Euro/MWh has been indicated to make a dryer installation profitable based on no cost for the thermal energy and 40 Euro/MWh as the cost for the electrical energy. Shrinkage and the internal transport of moisture and heat in large particles of biofuels will need more considerations in the future. Fractionation of the biofuels, codrying with other products, the total cost for the drying process, environmental issues, and development of drying processes operating at high dew points are the other things to consider.     

Separation and extraction of Φ-methyl ester sulfoxylates: New features

This paper deals with the separation and purification of Φ-methyl ester sulfoxylates obtained through the sulfoxidation process. Two new steps are implemented during separation of the final product from the nonreacted reagent: (i) hot water is used instead of water/ethanol mixture, and (ii) n-butanol is used as the extractive phase after neutralization instead of ethanol, leading to a product with more than 75% active ingredient. A significant improvement in the separation and purification steps has been obtained. The new procedure allows a complete material balance of the main products formed during sulfoxidation of fatty acid methyl esters and thus can lead to study of the reaction conditions, which can improve both conversion and selectivity.     

Physicochemical Treatment of Distillery Wastewater—A Review

A distillery industry which represents an important segment of the world economy is amongst the highly polluting industries after the paper industries. Spent wash (SW) generated from distilleries have a very high chemical oxygen demand (COD) (i.e., 20,000–50,000 mg/dm³) and biological oxygen demand (BOD) (i.e., 7000–50,000 mg/dm³), while the COD and BOD values depend on the raw material used. If it is discharged to water-receiving bodies without treatment, it may damage the aquatic system. Apart from causing water pollution, unpleasant odor of effluent spreads several kilometers around the distillery. The untreated/partially treated effluent if discharged in the land makes it infertile. Environmental issues have become one of the important factors controlling the growth of distillery industries. Therefore, it is very necessary to investigate the efficient and cost-effective processes to treat SW. The physicochemical processes are still not being applied in many distilleries, which are possible to have feasible remediation technologies to combat environmental pollution. In the present review article, different physicochemical technologies like coagulation, flocculation, electrocoagulation, thermolysis, wet oxidation, and adsorption as well as biological treatment for the wastewater of distillery industries have been presented. The distillery wastewater management is also discussed.     

Atmospheric Freeze Drying—Modeling and Simulation of a Tunnel Dryer

Drying is an important unit operation in processing of foods and other biotechnological products. Vacuum freeze drying is said to be the best drying technology regarding product quality of the end product, but the disadvantages are, among others, expensive operational costs and batch drying. Atmospheric freeze drying was introduced to lower the production costs of high-quality dried foods, and the need of simulation tools became important in estimations of the industrial drying processes.

A simplified mathematical model (AFDsim) is developed based on uniformly retreating ice front (URIF) considerations. The model is used to calculate theoretical drying curves of atmospheric freeze dried foods in a tunnel dryer. Studies of thermal and mass transfer properties during drying are essential for understanding the changes in product quality and for designing and dimensioning the drying process. The model can be used to simulate industrial atmospheric freeze drying of different foodstuff in a tunnel. The results from AFDsim modeling are in good accordance with the experimental results.     

Separation Science—A Vital Tool of the Chemical Engineer

Abstract

Separation attempts reach back into the earliest history of mankind. Motivated by necessity, man developed methods of separation which, although crude by our standards, represented ingenious progress. Thus, food and condiment preparation had much to do with the development of processes such as leaching, solvent extraction, crystallization, evaporation, and the like.     

Simultaneous Gas Storage and Catalytic Gas Production Using Zeolites—A New Concept for Extending Lifetime Gas Delivery

Copper containing MCM-41 materials can be used to both store gaseous nitric oxide and to catalytically produce nitric oxide from nitrite. The active species for the reaction is copper (I). Addition of cysteine to the solution in contact with the material has different effects depending on how much Cu(I) is present. This is a new method of extending the lifetime of gas delivery from a gas storage material.     

Effects of Atmospheric Pressure Plasmas on Isolated and Cellular DNA—A Review

Atmospheric Pressure Plasma (APP) is being used widely in a variety of biomedical applications. Extensive research in the field of plasma medicine has shown the induction of DNA damage by APP in a dose-dependent manner in both prokaryotic and eukaryotic systems. Recent evidence suggests that APP-induced DNA damage shows potential benefits in many applications, such as sterilization and cancer therapy. However, in several other applications, such as wound healing and dentistry, DNA damage can be detrimental. This review reports on the extensive investigations devoted to APP interactions with DNA, with an emphasis on the critical role of reactive species in plasma-induced damage to DNA. The review consists of three main sections dedicated to fundamental knowledge of the interactions of reactive oxygen species (ROS)/reactive nitrogen species (RNS) with DNA and its components, as well as the effects of APP on isolated and cellular DNA in prokaryotes and eukaryotes.     

Textural,Rheological and Sensory Properties and Oxidative Stability of Nut Spreads—A Review

Tree nuts are rich in macro and micronutrients, phytochemicals, tocopherols and phenolic compounds. The development of nut spreads would potentially increase the food uses of nuts and introduce consumers with a healthier, non-animal breakfast snack food. Nut spreads are spreadable products made from nuts that are ground into paste. Roasting and milling (particle size reduction) are two important stages for the production of nut spreads that affected the textural, rheological characteristic and overall quality of the nut spread. Textural, color, and flavor properties of nut spreads play a major role in consumer appeal, buying decisions and eventual consumption. Stability of nut spreads is influenced by its particle size. Proper combination of ingredients (nut paste, sweetener, vegetable oil and protein sources) is also required to ensure a stable nut spread product is produced. Most of the nut spreads behaved like a non-Newtonian pseudo-plastic fluid under yield stress which help the producers how to start pumping and stirring of the nut spreads. Similar to other high oil content products, nut spreads are susceptible to autoxidation. Their oxidation can be controlled by application of antioxidants, using processing techniques that minimize tocopherol and other natural antioxidant losses.