# Ohmic Heating in the Food Industry: Developments in Concepts and Applications during 2013-2020
## 5 Applications of Ohmic Heating  
Ohmic heating is an electric heating method and also known as Joule heating [48; 49], which is an advanced heat treatment, mainly used with food to be thermally processed as heating is more homogeneous [40] compared to other electrical heating techniques such as microwave and radio frequency heating [50]. This technique provides high-quality food and is also used in many applications such as pasteurization, sterilization, cooking, thawing, fumigation, extraction, and fermentation, in addition to the new trend for its use in military fields and food for long-term space missions [40]. Studies have shown that the use of this technique does not lead to significant effects on the nutritional, functional, and synthetic properties and sensory characteristics of food products compared to traditional techniques [51]. Figure 2 depicts factors and applications of ohmic heating in food processing. Many researchers have studied the effect of ohmic heating on fish, meat and its products, and compared to other traditional thermal methods used in melting, heating, and cooking for food quality, food safety, and flavor. In addition, this new technology has the ability to extend shelf-life. It is a favorable alternative for heat treatment due to the shorter heating time and non-heating of surfaces, in addition to the possibility of using lower temperatures [52]. Ohmic heating may have an effect on electrical, physical, and biological characteristics of the product, which has led to many research applications such as heating, fumigation, drying, extraction, wastewater treatment, melting, and cooking for different types of fish and meat and their products. Ohmic heating technology was also used to treat many other food products such as vegetables, juices, meat, seafood, soup, creams, and pasta, and to sterilize foods used in glass containers for ready-to-eat food, to produce low-acid, high-quality foods, and to reduce acidity of foods that depend on tomato sauces [53]. [PERSON] et al. [45] pointed to the possibility of using ohmic heating as a new method for baking without gluten and studied its effect on chemical and functional properties. Results indicated that ohmic-based baking without gluten improved qualities of size, stability, tissue, relative elasticity, pores, color, and starch gelatinization. The manufactured gluten-free (GF) bread using ohmic heating was significantly superior in its functional properties and characteristics compared to the traditional manufacturing methods. The values were 2.86-3.44 cm\({}^{3}\)/g, 45.05-56.83%, and 35.17-40.92% for specific volume, relative elasticity, and porosity, respectively. In contrast, conventional oven-baked GF bread resulted in 2.60 cm\({}^{3}\)/g of specific volume, 44.23% of relative elasticity, and 37.63% of porosity. [PERSON] et al. [33] also improved the mechanism of ohmic heating through a three stage application of electrical power: First using 2-6 kW for 15 s, followed by 1 kW for 10 s, and lastly 0.3 kW for 1-30 min. [PERSON] et al. [54] made ginger paste using an ohmic method with salt concentrations (0-2% w/w) on a laboratory level through a voltage of 5-13 V/cm. Temperature-dependent electrical conductivity was obtained at different time periods at (0, 5, 10 min) and at four temperature levels from (30-60 \({}^{\circ}\)C). The results indicated that there were bubbles on the surface of the product at temperatures above 70 \({}^{\circ}\)C, especially at higher voltage levels. The values of the electrical conductivity were in the range of 4.41-6.63 and from 3.75 to 5.87 S/cm, respectively. The study confirmed that the electrical conductivity of the ginger dough depended on the intensity of the temperature and the ionic concentration. Figure 2: Factors and applications of ohmic heating in food processing. An ohmic heating unit was designed on a 1 L laboratory scale by [55] for testing with papaya fruit whose conventional pasteurization yield suffered from rapid deterioration causing approximately 50% losses.