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For decades, frying has been a popular technique for the preparation of foods, both on domestic and industrial scales. The effects of edible oil type and frying operation conditions on the shelf‐life of fried products, the deterioration progress and the health hazards of fried foods have been studied by various researchers. To achieve a clear conception of the present situation, a collection of the results obtained from previous studies about product deterioration and safety issues due to the frying process, along with related tables, are of prime importance. According to the studies, it can be concluded that a vacuum, oil replenishment, frying temperature, and time of process are the most important parameters affecting the quality of oils and fried products; hence, by controlling them, it is possible to prevent the formation of toxic compounds and loss of nutritional components to a considerable extent during frying operation. Furthermore, according to recent studies indicating significant formation of toxic compounds before the chemical indices of the oil reach the disposal point, more studies are needed to determine whether they are formed at levels that compromise safety and affect consumers’ sensory perception before the established discard points.

Adhesion is the most important factor in product loss in the spray drying of syrups and juices. The main solution to reduce adhesion is using drying aids. The aim of this study was to evaluate effect of maltodextrin (MD) and gum Arabic as drying aids, and pectin and whey protein concentrate (WPC) as complementary drying aid on the powder yield, physical, functional and microstructural properties of spray dried apple juice concentrate. The studied variables and composition of the carriers were used. The inlet air temperature, atomizer rotational speed, feed flow rate, feed temperature and atomizer pressure were kept constant at 160 °C, 18,000 rpm, 15 ml/min, 25 ± 1 °C and 4.2 ± 0.1 bar, respectively. The results of powder production yield indicated that WPC was more effective than pectin as complementary drying aid. The bulk and tapped density of powders significantly decreased with an increase in WPC ratio. Moisture content, solubility, wettability, hygroscopicity and color parameters of the powders were also influenced by the carriers` type and their combinations. The microstructure of spray dried powders showed various particle sizes with spherical and irregular shapes (with shrinkages and dents on the surface). Taking into account all the parameters, 10% WPC in combination with MD was used which showed the best results in the economic production of powder with the highest yield (60.85%) and appropriate physical, flowability and functionality properties.