According to Goullieux & Pain (2005), the most used technique to ensure microbiological safety of processed foods are HTST pasteurization and UHT sterilization. But these processes have several disadvantages likeoverheating, loss of nutritional compounds, and sensory changes; moreover, the combustion of fossil fuels to generate heat causes economic and energy losses (Sakr & Liu, 2014). Ohmic heating can be used as the substitute of these methodology(Goullieux & Pain, 2005; Kaur & Singh, 2016; Sudhir, 2004; Varghese et al., 2014). Since the 19th century, ohmic heating is used in milk pasteurization, can not be considered as the new technique as a thermal treatment in food processing (De Alwis & Fryer, 1990).
Ohmic heating is known as a process in which electric current is passed through materials with the primary purpose of heating them through the conversion of electrical into thermal energy, resulting generally in a rapid and uniform 73 temperature increase within the food (Leizerson & Shimoni, 2005; Mercali et al., 2014). The most advantage comes from this technique as it provides the development of faster and more effective processes, ensuring greater nutrient retention capacity and sensory attributes (Guida etal., 2013; Pereira etal., 2008; Pereira etal.,2015).
Ohmic Heating and Food Safety:
Similarly as with traditional procedure, non-consistency heating could be seen in items, in spite of the fact that the warming is created legitimately in the item through the transformation of electric energy into thermal (Goullieux and Pain, 2005). This reality brings about locales of high temperatures (problem areas) and low temperatures (cold spots), which has been the Knowledge of the appropriation of the temperature profile as a basic point for food quality and sanitation (Jaeger et al., 2016). So remembering it is a significant advance to distinguish the unfavorable impact of cold spots in nourishment items situation related with cold spots (Tucker, 2014). Cold spots are connected by the most reduced electrical conductivity of individual portions presents in the nourishment creation, which is affected for instance, by lipid concentrations, ionic content and viscosity(Goullieux and Pain, 2005; Zareifard et al., 2014b; Jaeger et al., 2016). These zones can bring about a sub handling of the item, which legitimately influences its microbiological dependability (Jaeger etal., 2016). Then again, problem areas can be seen as the higher spherical conductivity of individual parts, however it doesn’t speak to a sanitation issue, in spite of the fact that it is a nourishment quality issue because of its over preparing (Tucker, 2014). The D and z esteems are another significant components for sanitation, because of their impacts in preparing on microbial inactivation and in the assurance of active parameters (USA-FDA, 2000; Knirsch etal., 2010; Park and Kang, 2013). Likewise, the extra non-thermal impact from electroporation in the microbial cell ought to be thought of and explored, because of the decrease in the motor qualities (D e z) of the microorganism. It could give a lower thermal force simultaneously, along these lines debasing less nourishing mixes without influencing the microbiological steadiness of the item (Goullieux and Pain, 2005; Jaeger et al., 2016). In this manner, the distinguishing proof of cold spots, the variables that influence the warming rates, the microbial inactivation and the instruments of inactivation are viewed as the key issues to guarantee the sanitation in OH process (Varghese etal.,2014).
Ohmic Heating and Intrinsic Quality Parameters in Dairy Processing:
The physicochemical and senaorial attributes of dairy items are significant for their quality and safeguarding appraisal, being affected by unique variables, for example, the sort and intensity of the treatment applied (Esmerino et al., 2015; Gaze etal., 2015; Morais etal., 2014). So as to assess the advantages of ohmic heating and to characterize the ideal procedure parameters, it is necessary to assess the impact of this method on quality and tactile elements of the item. A similar thermal procedure markers regularly utilized in ordinary medications can be utilized to decide the power of the ohmic heating procedure (Sastry and Barach, 2000). A few pointers are revealed in the writing, for example, lactulose, furosine and hydroxymethylfurfural (HMF), FAST record (fluorescence of cutting edge Maillard items and dissolvable tryptophan), carboxymethyllisine, glycoxidation items, protein denaturation and agglomeration (β-lactoglobulin), free unsaturated fats, among others (Claeys etal., 2001; González-Córdova and Vallejo-Cordoba, 2003; Meyer etal.,2011; Oldfield etal., 2005; Pereira etal.,2015; Schamberger and Labuza, 2006).
Ohmic Heating and Fouling in Dairy Processing:
Two significant instruments are answerable for fouling in dairy preparing plants: type A fouling, got from the totals framed by the nearness of whey protein (generally β-Lg and α-La) at 75 and 110 °C; and type B fouling, which happens at temperatures over 110 °C as an outcome of calcium phosphate precipitation (Bansal and Chen, 2006a; Visser and Jeurnink, 1997). Fouling causes numerous issues in dairy plants which incorporates thwarting the cleaning procedure, loss of value and decrease of the thermal move rates, in this way bargaining the microbiological soundness of the last item. As announced by (Van Asselt et al., 2005), about 80% of the expenses of dairy industry relates to cleaning procedure to forestall fouling. In addition, fouling prompts microorganism grip to the outside of the hardware, coming about in biofilm arrangement (Bansal and Chen, 2006b; Flint etal., 2000). Few researches showed that fouling is legitimately identified with the temperature increment; the higher the temperature, the more prominent the statement, advancing a “snowball” impact (Crattelet etal., 2013). Bansal and Chen , 2006b) assessed the impact of intensity recurrence (10 kHz and 50 Hz) and found that fouling can be definitely decreased at high frequencies. Moreover, a decrease of the present force at 50 Hz was watched, demonstrating that fouling may have changed the ohmic heating procedure parameters. To maintain a strategic distance from this change, new procedure conditions ought to be applied, for example, an expansion of the electric field quality. Therefore, numerical strategies were created to portray the conduct of the ohmic heating at various fouling levels (Fillaudeau etal., 2006). Moreover, the investigation detailed a few factors that can add to decrease fouling, for example, working in violent system to advance convection marvel, diminishing overheating of the cathode divider.
Ohmic Heating and Allergenicity of Dairy Foods:
Over 90% allergies are identified with 8 sorts of foods, with bovine milk included (Nowak- Wegrzyn and Fiocchi, 2009). The milk has a few proteins, where around 30 of them presents allergenic potential, where the casein and β-lactoglobulin are the proteins with the best allergenic potential in bovine milk (Shandilya et al., 2013). Casein causes provocative responses in the intestinal mucosa in celiac patients, where the αs1 portion is the most liable for the allergenic responses (Cabrera-Chavez and de la Barca, 2009; Miciński etal., 2013; Nowak Wegrzyn and Fiocchi, 2009). In connection of Whey proteins (0.6 w/w % milk arrangement), β-lactoglobulin (β-Lg) and α-lactoalbumin (α−La), present pertinent allergenic potential, which are liable for various sensitivity cases in bovine milk (Miciński etal., 2013). Around 80% of the populace has allergenic impacts related with β-Lg (Park and Nam, 2015). The basic role of the warmth treatment is the inactivation of microorganisms, which intends to ensure the microbiological consistency of the item (Nowak-Wegrzyn and Fiocchi, 2009). Be that as it may, the use of heating additionally advances a decrease in the allergenic capability of milk and their items, because of the loss of the tertiary structure, which prompts a protein denaturation and the development of totals (Shandilya etal., 2013). Being a warm innovation, the effect on the OH procedure in allergenicity of milk proteins can not be contrasted with the outcomes acquired from convectional process, considerably under same temperatures profiles, because of the outcome in nonthermal extra impact during the ohmic heating procedure. Power and procedure parameters, for example, recurrence and electric field, can impact casein micelles and protein conformational structures, which shows various outcomes contrasted with the regular heating framework (Jaeger etal., 2016). Due to the extra non-thermal impact in electroporation, the pace of warming may diminish during treatment, which brings about a decreased development of neoallergenics mixes from the Maillard reaction (Nowak-Wegrzyn and 453 Fiocchi, 2009; Jaeger etal., 2016).In complexity, with the decrease in the all out warm nourishment load, the treatment may advance less decrease on the allergenicity of proteins that would have been recently denatured by the treatment (Jaeger etal., 2016).
From several researches it is concluded that the the effect of ohmic heating on the intrinsic quality parameters and microbiological stability in dairy products. The main factors and necessary parameters for the application of this technology need to be monitored during processing of dairy products, considering its effects on products quality, microbial inactivation and fouling. There is a lack of studies on processed dairy products, such as chocolate-flavored milk, cheese, butter, fermented milk and others, which opens up a range of research opportunities in this are regarding instinct quality parameters .
M.Tech Scholar , Department of Dairy Chemistry, WBUAFS, Mohanpur, Nadia-741252
M.Tech Scholar , Department of Dairy Chemistry, WBUAFS, Mohanpur, Nadia-741252
B. Tech (Dairy Technologist), Production Supervisor,Cheese, Baladna Food Industry, Qatar