CC BY
9
Scientific Research of the Union of Scientists in Bulgaria - Plovdiv,
series B. Natural Sciences and Humanities, Vol. XVII, ISSN 1311-9192, International Conference of Young Scientists, 11 - 13 June 2015, Plovdiv
THE IMPACT OF HYGIENE OF HEAT EXCHANGER ON THE QUALITY AND HYGIENIC SAFETY OF DAIRY PRODUCTS Steve Veleska1* Prof. Dr. Vangelica Jovanovska2
University: St. Kliment Ohridski - Bitola, Republic of Macedonia Faculty of Biotechnical science - Bitola, Republic of Macedonia
Abstract
Heat transfer is a key operative unit within the framework of foodstuff (dairy) industry on which the key processes pasteurization and sterilization are based. Contamination of heat exchangers in dairy industry is a rather serious problem, both technically and economically. Hygiene of heat exchanger by using the CIP system and application of chemicals with higher concentration, at a higher temperature, provides safety, effectiveness and efficiency. This research comprises everyday hygiene with the following chemicals: soda (sodium hydroxide) and nitric acid in a higher concentration at a temperature of 70°C - 80°C through the CIP system which provides an efficient removal of the dairy deposit as a polluter of heat exchangers and it also contributes to high quality and hygienic safety of dairy products, and thus efficiency.
Key words: heat exchanger, hygiene, CIP system, detergents , quality of dairy products
Introduction
The microbiological quality of milk and dairy products is a result of the heat processing procedure up to 100°C the so-called pasteurization. Contamination is an undesirable formation of residues on the heat exchanger surface. It is a big problem in dairy industry because the decrease of pressure is increasing and the efficiency of heat transfer is reduced which affects the processing and the product's quality (Frajer P. J. and Kristijan G.K., 2005). Hygienic state of heat exchangers has a determining effect on quality and hygienic safety of dairy products (Thomas A., Sathian C. T., 2014).
Material and methods
As a research material in this study the following parameters are used: temperature and duration of pasteurization appropriate to the dairy product (sour milk products, cheese), type of heat exchanger, sections of heat exchanger, hygiene of heat exchanger, cleaning system and hygienic products for heat exchanger. The mentioned parameters were obtained as complete data based on a desk research conducted in Dairy Miki in Prilep, Republic of Macedonia.
Results and discussion
The French chemist Louis Pasteur first used the low thermal processing at a temperature of 50- 60°C in the period of 1860 - 1870 in order to provide a microbiological quality of wine and beer (Hudson A. et al.,2003). Thus, the term pasteurization is introduced in honour of this French chemist and pasteurization of milk was first used in 1882 by the International Dairy Federation (IDF). There are three types of pasteurization: vat pasteurization 63 - 65°C in a period of 30 min-
utes, high temperature short time pasteurization 71 - 74°C in the period of 20 - 40 seconds and ultra - pasteurization of 82°C in a period of 2 seconds (Presilski S., 2005). From the results, it is noted that in order to provide microbiological quality of dairy products produced in Dairy Miki it is used the necessary thermal processing method i .e. pasteurization in appropriation to the dairy product: high-temperature pasteurization of 95°C is used fon paoducCion on nour mhk products, pasteurization at a temperature of 82 - 883 °C is used fon production of cheese, especiatiy white soft chrrsr, ani for production of hard cheese it is used a temparature of 72°C Cor a rhort timf, which means that vat pasteurization is less used, bur in dairy iniurtries HTST method is more often used i.e. a high tempemature or pasteurization for a short time. In Graph 1. the temperature of pasteurization in appronriation to tha dairy peoduct in Dairy Mikiis shown,
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100 90 80 70 60 50 40 30 20 10 0
I Sour milk products White soft cheese i Hard cheese
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Chart 1. Temperature of pasteurization for production of dairy product in Dairy Miki
According io (Jovanovska V., 2007) the neoessary machine uced for heat transfer by an indeed method is called a hcal exchangee. In nlairy indushhes, the thermal procesfong oJT misk as asually perforated in plate heat exchangers. The plate heat exchangec (PHE) consisrs of stcinlesr steel psates which are set in a frame. In this frame, several sepaeate sections may be located, whero variance levels of processing take place, such ac preheating, heating, maintaining the temperate! for a certain time and coonine The heating medium io hot waten while the cooling medium is cold or ice waier, depending on the wanted temperarure far a certain product.1
The type (if hear exchanger in Daiey Miki is a plate one useo for heating milk, and a tubulaf ane foi cooling milk. Altogether the heat exchanger cansisns of 4 soctions, of which 2 are for heat-ting and 2 foo cooling. The firse one of the two heating seetioes is for pmeheating up to 45°C, and ahe senond one is for the mam heating i.e. until tire wanted temperature ohpasteieriiiation appropri-cte to the product ic reached (soua milk or cheese). Plate teat exchangers aire often used in dairy industries because of the opportunity for a good hean transfer nnd easy maintenance (Beuf M. and et al.,2003). Fraser P.J. amp Kristijan G.I0. (2005) j-,oint ouo the^ tire creation of deposit in heat exchangers can impaic the product's quatity through a ceots-contamination or through reproduction
00 misroorganisms in the deposit. (Alharthi M., 22010) concluded that the chemical composition mf milk: contains a chain of chemically unstable components such as proteins, fat and minerals which hinders i.e. complicates the hhgiene maintenance of heal exdoangers. The milk deposit that
1 http://www.tetrapak.com/usprocessing/Documents/Heat%20Exchangers Dairy%20Process-ing%20Hand%20Book.pdf
appears in the heat exchanger can be classified into two groups: type A (protein deposit) at a temperature between 75°C and 110°C, which is actually a white, soft milk film whose composition is 50 - 70% proteins mostly Mactoglobulin, 30 - 40% minerals and 4 - 8% fat and type B (mineral deposit) which is created at a temperature above 110°C and it is a solid granular structure with a grayish colour, and its composition is 70 - 80% minerals, mostly calcium phosphate, 15 - 20% proteins and 4 - 8% fat. Beta-lactoglobulin and alpha-lactalbumin are two major heat sensitive structural proteins, but beta-lactoglobulin is a rather sensitive and main polluter of heat exchangers. The milk deposit as a polluter of heat exchangerr necessitates their hygiene at least once a day, in order to provide a hygienic production with strict hygienic standatds. The most commonly used procedure of cleaning eguipment is with the CIP system.
The CIP system is rother developed and automated. The procedure of clcaning with the CIP system in industry includes ctrcularion ot chemicals at a Oigh tempetature through a closed system of pipes. This avoids the need for dismantling of equipment (Frajer P.J. and Kristijan G.K.,2005).
Chart 2. Temperature of soda and nitric acid as chemicals
In thSs context, an eveyydyy cleaning of heat exthnngers is applird in Daiyy Miki by using the CIP symtem, so that this system consists (if two tanks, where the first one is an acid tank (nitric acid) and the second one is a wster tank and this kind of cleaning is provided through a system gf pipes. The water itself can not remove milk deporit. The chemical agent musr provide dissolution of the milk deporit tFrajer P.J. and Kristijan G.K., 2005). According too (Thomas A., Sathian C, T., 2014) detergents i.e. chemical agenis ihat are used in the CIP sysSem can be alkaline and acidic. The most commonly used alkalino agents are: sodium hydroxide, potasrium fydroxide, sodium carbonate etc, while tht most commonly used acidic agents are: hydrochloric, nitric, phttphoric and citric acid. Alkaline agents for cleaninn are the ones that have e pH value above 7. Sodn i.e. sodium hydroxide is a veey rtrong alkaline ageni and it ir pretty often used in the CIP system owing to its low i.e. acceptable cast. It is usually used in a concentration of 0.°5% - 1,0% at a temperature of 70 -80°C for a period of 10 - 30 mimuies. It allows a perfectly rAidem nemomal rf protein deposit as well as fat deposit via saponification.
The reaction of srf ium hydroxide with the protein deposit includes hydrolysis of the; peptide bonds that bind amino arMs in the protein structure. The most common ocid detergene is the nitric acid whioh is used in a concentration of 0,5 - 1,0% at a temperature of 50 - 80°C, eor a period of 5 - 220 minutee. Many researches in the effectiveness tf toda and nitric acid, as cleaning agents o0 heat exchanger by using the CIP system, match with the rerults of this research i.e. their use and effectioeness in Dairy Miki. Soda as an alkaline agent and nitric acid as sour rgent are used in a cemcentratton of (1 - 3%). Cleaning with nitric acid is !n a concentration of 1 - r%, as a tempera-
ture of 70 - 80°C for a period of 20 minutes, and cleaning with soda is at the same temperature and in the same period, and then comes a rinsing with bacteriologically pure water at a temperature of 40°C for a period of 10 minutes.
According to (Jovanovska V. and et al., 2013) it can be noted that in all examined countries it is achieved a quality cleaning with the CIP system, but the duration is different, so that in Macedonia it takes the shortest, but at the expense of that, it has a faster flow and a higher temperature and concentration of the detergents in relation to other countries. The disinfection is a procedure by which the equipment is bacteriologically clean too. The used disinfectants are: hypochlorite and hydrogen peroxide. The main requirements of disinfectants are effectiveness, efficiency and safety. The effective and safe disinfection also achieves an economic efficiency if the disinfection agent can be rinsed easily, a lower energy consumption and not damaging the disinfected surface and the environment (Thomas A., Sathian C. T., 2014). According to the results, in this Dairy hydrogen peroxide is used as a disinfection agent in order to perform disinfection right after the cleaning. The disinfection with hydrogen peroxide is performed at a temperature of 40°C and after that comes the rinsing. Considering that it is evaporable and it can be rinsed easily, it provides an effective and safe disinfection and it doesn't damage the disinfected surface and the environment and it also contributes to efficiency.
Conclusion
Everyday hygiene of the equipment in a dairy industry (Dairy Miki) by using an automated CIP system and detergents (soda and nitric acid) with a higher concentration, at a higher temperature, a faster flow and for a shorter period and using an effective disinfection agent (hydrogen peroxide) it is provided a quality, effective and safe cleaning, for a shorter period, thus contributing to efficiency i.e. there is no additional energy and costs, and what is more important is that the quality and hygienic safety of milk and dairy products is on a high level.
References
Alharthi M. ( 2013). Fouling and cleaning studies of protein fouling at pasteurisation temperatures, A thesis submitted to the University of Birmingham for the degree of doctor of philosophy;
Beuf M., Rizzo G., Leuliet J.C., Muller-Steinhagen H, Yiantsios S., Karabelas A. and Benezech T. (2003). Fouling and cleaning of modified stainless steel plate heat exchanger processing milk products;
Frajer P. J. and Kristijan G.K., 2005 VTT Biotechnology, Finland,2005;
Hudson A. (2003). Pasteurisation of dairy products: times, temperatures and evidence for control of pathogens;
Jovanovska V. (2007): Machines and equipment for processing milk, University: St. Kliment Ohrid-ski, Faculty of Biotechnical science - Bitola, Republic of Macedonia - 75-80;
Jovanovska V., Sovreski Z., Sambevska K., Kocovska M. and Josheski D. (2013): Comparative analysis on the parameters of the cleaning in place system (CIP) designed to clean up the dairy industry;
Presilski S.( 2005): Milk and sour milk products, University: St. Kliment Ohridski, Faculty of Biotechnical science - Bitola, Republic of Macedonia 154-155;
Thomas A. and Sathian C.T.,(2014): Cleaning -in-place(CIP) System in Dairy Plant - Review, IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399.Volume 8, Issue 6 Ver. III (Jun. 2014), PP 41-44 www.iosrjournals.org
http://www.tetrapak.com/usprocessing/Documents/Heat%20Exchangers_Dairy%20Processing%20 Hand%20Book.pdf
