The acceptance of processed or minimally processed food products by consumers is highly dependent on several quality and nutritional attributes as well as their organoleptic characteristics. Shelf-life is an additional factor that influences consumer behavior. Moreover, consumers now demand high-value food products that are healthier and have high nutritional value. The quality, nutrition level, and perception of processed foods is governed, among other attributes, by the structure of the dried product. Hence, examination of the structure of dried foods is of significant importance. Dehydration methods have a great impact on the structural properties of most food products. The effect of various dehydration methods on shrinkage and porosity of dried foods is discussed in this article following a comprehensive review of the available literature. Novel drying processes and combination of various conventional drying methods are discussed with regard to their expected impact on food structure. Finally, aspects of food formulation during diverse drying processes and recommendations for future research are presented.

The structural and thermophysical properties of freeze-dried agricultural products (potatoes, mushrooms, and strawberries) were investigated to determine whether these properties were affected by freeze drying conditions. The true density of freeze-dried products was measured with a helium stereopycnometer, and apparent density was obtained by measuring their geometric characteristics. Porosity and pore size distribution were also measured with a mercury porosimeter. The mechanical properties of freeze-dried agricultural products were obtained using a universal testing machine. Dried products were equilibrated in saturated salt solutions of constant water activity and scanned with a differential scanning calorimeter (DSC) for the evaluation of glass transition temperature. Simple mathematical models were developed in order to correlate the structural and mechanical properties with process conditions. The apparent density and mechanical properties of freeze-dried products increased with the applied freeze-drying pressure, whereas the porosity decreased. The glass transition temperature decreased with the increment of moisture content and it was not highly influenced by process conditions.

Worldwide, fruit processing industries reject high volumes of fruit waste, which represent rich sources of phenolic compounds and can be valorised through extraction, and then be reused for food, nutraceutical or cosmetic applications. In the present work, the optimisation of the recovery of phenolic compounds from apricot kernels and pulp, as well as peach pulp, through the green method of ultrasound and microwave assisted extraction (UMAE) is performed. Prior to extraction, a drying step of the pulps is conducted using freeze, vacuum and hot air drying. Except for the conventional extraction solvents of water and ethanol:water, a deep eutectic solvent (DES) formed by choline chloride/urea, and a natural deep eutectic solvent (NaDES) from choline chloride with lactic acid, are used, something that presentsecological benefits. With the aim of discovering the optimum extraction conditions, different values of the parameters of extraction time, utrasonic power and solvent/dry solid ratio are examined, and a mathematical model is developed to correlate them to the extraction yield (EY). The phenolic compounds and the antioxidant activity are determined through UV-Vis spectroscopy and High-Performance Liquid Chromatography (HPLC). The results of the study demonstrated that the most effective solvent in the extraction of apricot kernels is ethanol: water; DES is more efficient in the extraction of apricot pulp and NaDES in the extraction of peach pulps, reaching EYs of 25.65, 26.83 and 17.13%, respectively. In conclusion, both types of fruit waste are proved to have a significant content of valuable compounds, and the use of DES in fruit by-product extraction is effective and seems to be a promising alternative. Thus, the unexploited amounts of waste can be valorised through simple techniques and innovative solvents.

The meat processing industry is a very energy-intensive and water-demanding industry that produces large amounts of solid and aqueous wastes. Therefore, methods for the effective treatment of the produced wastes have been studied in order to treat and reuse water within the industry and valorize the solid wastes for the production of energy and value-added products. The primary aim of this work is to evaluate the overall sustainability of energy produced from solid waste valorization and wastewater treatment in the meat processing industry via Life Cycle Assessment (LCA). For this purpose, the total environmental impact of a typical meat industry that utilizes conventional waste management methods (Scenario A) was evaluated and compared with two different industries with appropriate waste treatment/valorization processes. In the first studied valorization scenario (Scenario B), waste management is conducted using anaerobic digestion, composting, membrane bioreactors, and ultraviolet (UV) treatment, whereas in the second studied valorization scenario (Scenario C), aeration treatment, chlorination, and hydrothermal carbonization (HTC) are the selected treatment techniques. As expected, it is evident from this LCA study, that both Scenarios B and C exhibited a significantly improved environmental footprint in all studied indicators compared with Scenario A, with the reduction in certain environmental impact categories reaching up to 80%. Between the two studied alternative scenarios, the biggest improvement in the environmental footprint of the meat industry was observed in Scenario C, mainly due to the substantial quantity of the produced thermal energy. According to the results of the present case study, it is evident that the incorporation of appropriate methods in the meat industry can result in the efficient generation of energy and a significant improvement in the environmental footprint contributing to environmental safety and sustainability.

Pore structure of foods influences the quality and texture of dehydrated food products. The development of food products with different pore structures and its effect on the sensory characteristics of the products were investigated. Potatoes and bananas were osmotically pre-treated using salt and sucrose solutions, respectively, and dehydrated with various drying methods, such as air drying, freeze drying, and vacuum drying, in order to obtain different pore structures. Simple mathematical models were developed in order to correlate the structural properties with process conditions. Depending on the drying method, porosity varied from 5% to 75% for potatoes and from 15% to 60% for bananas. Porosity was higher for the samples that were freeze-dried at lower pressures, followed by samples freeze-dried at higher pressures and, finally, vacuum- and air-dried samples. The surface areas of the dried samples varied between 0.961 and 3.040 m²/g, which are typical values for dehydrated foods. Freeze-dried potatoes and bananas were found to be saltier and sweeter (Score 6.5–7.8), respectively, than air- and vacuum-dried products (Score 4.8–5.8). Bananas and potatoes with the highest porosity and the highest specific surface areas presented more intense taste, providing the opportunity of reducing the levels of salt and sugar of the produced products without affecting the salty or sweet taste.