**8. Corrosion control**

Corrosion prevention and control require the application of appropriate methods and techniques from the early stages of design through the construction, erection and operation of the food processing plant.

Today, the main and fastest source of information on corrosion control of industrial equipment, plant and facilities is the Internet. Computer-based expert systems dealing with various aspects of corrosion prevention and control for many industries are listed in Roberge's Handbook. It is very important at the time to select an anti-corrosion material, ensure that we have investigated that the choice material is the most appropriate for the expected type of corrosive environment occurring in the plant (R. Nash, 2007).

Data on corrosion resistance of SS is displayed on NACE International's website (www.nace.org). Questions on corrosion prevention and control are answered in the NACE

In addition citric, tartaric, tannic, acetic and malic acids are also found in wines. SS is corrosion resistant to all of them in the concentration ranges in which they usually are found

The practice of preservation of vegetables and fruits by drying or salting can be traced to prehistory. Today, major processes for food preservations are cooling, freezing, dehydration, candying and canning. The main concern is for food quality, conservation and the prevention of spoilage. For cans fabrication is used tin one of the oldest available metals with a non toxic nature. The cans have been made from tin since 80 years ago when refrigeration of food was not easily available. According to their convenience the use of cans has been focused on food and beverages dispensers creating an intense competition between manufacturers not only for tinplate cans but also other materials, notably chromized steel,

Modern tinplate for cans is getting by continuous electrodeposition on steel strips, chemical conversion coating and finish polymeric coating. The manufacturing is made following three different types classified according to the methods of fabrication: a) The three piece can, b) The two piece draw/redraw (DRD), and c) The draw/wall ironed (DRW). In all of them the tinplate process is customized to economize and fulfill the requirements for

Aluminum cans are also widely used as containers for pressured beverages which are designed to have a minimum of material at the strength required for operation. The walls acquire rigidity by effect of the internal gas pressure from the content, but the bottom base

The processed fruits and vegetables are hermetically sealed and sterilized by heat and stored in glass jars and aluminum or coated steel cans. Sterilized canned food, include all types of vegetables under acidic or salty conditions and fruits in acidic, sweet syrup. The canning process consists of several stages: vegetable and fruit cleaning, filling the containers, closing and sealing, sterilizing the canned product, labeling and warehousing the finished goods. All these operation, carried out under excessive, humid conditions; require corrosion resistant equipment and machinery, currently fabricated from SS such as

Corrosion prevention and control require the application of appropriate methods and techniques from the early stages of design through the construction, erection and operation

Today, the main and fastest source of information on corrosion control of industrial equipment, plant and facilities is the Internet. Computer-based expert systems dealing with various aspects of corrosion prevention and control for many industries are listed in Roberge's Handbook. It is very important at the time to select an anti-corrosion material, ensure that we have investigated that the choice material is the most appropriate for the

Data on corrosion resistance of SS is displayed on NACE International's website (www.nace.org). Questions on corrosion prevention and control are answered in the NACE

expected type of corrosive environment occurring in the plant (R. Nash, 2007).

support and the top are made from thicker metal and formed into an internal dome.

in wine fabrication steps (B.J. Connolly, 1971 in ASM).

corrosion resistance, filling and mechanical properties.

**7.3 Canned food products** 

aluminum alloys and polymers.

S30400 and S31600.

**8. Corrosion control** 

of the food processing plant.

Corrosion Network. SS for food processing industry is reported by the International Association of Food Industry Suppliers (www.iafis.org).

The Nickel Development Institute (www.nidi.org) presents info on the use of SS and conducts workshops on related subjects. The SS Appeal (SSA), which groups SS equipment suppliers, launched a website (www.stainlessappeal.com) to promote the application of SS. The International Association of Milk, Food and Environmental Sanitarians (www.iamfes.org) provides food safety professionals worldwide with a forum for exchange of information on sanitation practices. Many producers of SS and fabricators of SS processing equipment are listed in the Stainless Steel World Buyer's Guide published in the SS World Journal, the Netherlands.

The National Sanitation Foundation (NSF) in the USA is best known for its role in the development of standards for equipment, primarily in the food service area. The NSF's materials and finishes guide refers to three zones: the food zone, the splash zone and the non-food zone. The NSF stipulates that the food zone "surface materials shall be smooth, corrosion resistant, non toxic, stable and non absorbent under use conditions. They shall not impart odor, color or taste, nor contribute to the adulteration of the food. Exposed surfaces shall be easily cleaned".

Corrosion control in the FI involves three different methods to reduce corrosion: design considerations, materials selection and protective coatings.

#### **8.1 Design considerations**

The variety of structures: tanks, heat exchangers, cooling systems, hygiene control systems, conveyors, cans, fillers, etc., used in the FI, should be designed to provide functional qualities along to all the process steps.

 It is necessary to avoid risks by underdesign or excessive costs due to overdesign considerations. Knowledge, technical information, and creative engineering principles must be used in an intelligent way to avoid corrosion. There are three important aspects in general to remember when designing a system for demanding service (P. Roberge, 2008, Avery et al., 1992):


Cathodic protection and corrosion inhibitors are also employed to protect some installations for water supply, cooling system and underground tanks and pipelines. Normally they are applied as a dual anti-corrosion system together with coatings, linings or paints.

#### **8.2 Materials selection**

Corrosion resistance is the main property to be considered in the choice of materials for such plant, but the final selection must be a compromise between technological and economic factors. It is sometimes more economical to use high-priced SS that will provide long and trouble-free service than to use a lower priced material that may require frequent maintenance or replacement.

Although the materials selection by trial and error frequently works, it does not always lead to an optimal or innovative decision. The evolution of computer and software has

Avery R.E., and Tuthill A.H., (1992) Guidelines for the Welded Fabrication of Nickel-

B. Valdez and M. Schorr, (2004) Stainless steels for corrosion control in the food

B. Valdez, J. Cobo, M. Schorr, R. Zlatev y L. Cota, (2008) Characterization of Materials and

B.J. Connolly, (2006) Australian. Corros. Eng., Vol. 15, No. 11, p. 23, 1971, ASM Handbook,

Buchanan R L et al., (2001) Moving beyond HACCP – Risk management and food safety

D.E. Talbot and J.D. Talbot., (2007) Corrosion Science and Technology, 2nd edition, USA,

H.S. Kathak, (1992) Corrosion of Austenitic Stainless Steel. Mitigation and Monitoring,

http://www.plunkettresearch.com/foodbeveragegrocerymarketresearch/industryandbusi

J. Beddoes, Introduction to Stainless Steel, 3rd ed. Materials Park, OH: ASM International,

J.T. Hola and R.H. Thorpe, (1990) Bacteria retention on cleaned surfaces, J. Appl.

Jellesen, M. S., Rasmussen, A. A. and Hilbert, L. R., (2006) A review of metal release in the

M. Schorr, B. Valdez, J. Ocampo and A. Eliezer. (2011) Corrosion Control in the

Oddy D J and Millar S (1985), Diet and health in modern Britain, pp. 148-147, London,

Pierre R. Roberge, (2008) Corrosion Engineering. Principles and Practice, McGraw Hill,

R.M. Davidson, T. DeBold and M.J. Johnson, (1987) Corrosion of Stainless Steels, Corrosion Metals Handbook, Vol. 13, 9th ed., ASM International, pp. 547-565. Rick Nash, (2007) Battling Corrosion in the Food Processing Industry, Pump & Systems, Food Processing Section, www.pump-zone.com, consulted on July 27, 2011. Ruiz-Capillas C, Jiménez-Colmenero F. (2009). Application of flow injection analysis for

S.H. Zhang and B. Monitz, (2006) Corrosion in the Food and Beverage Industries,

Pierre R. Roberge, (2000) Handbook of Corrosion Engineering, McGraw Hill, USA.

Desalination Industry, Desalination, Trends and Technologies, pp. 71-86

determining sulphites in food and beverages: A review. Food Chem. 112: 487-493.

Corrosion: Environments and Industries, Handbook Vol. 13C, 1th ed., ASM

food industry. Materials and Corrosion, Vol. 57, pp. 387–393.

Toronto, Canada: Nickel Development Institute (NiDI).

Corrosion: Environments and Industries, Vol. 13, USA.

USA.

131-136.

USA.

1999.

1985.

USA.

INTECH, India.

CRC Press, pp. 409 – 435.

Khlefa A. Esaklul, Vol. I. pp. 194-197.

Bacteriol., Vol. 69, pp. 599-608.

International, pp. 803-809.

nessdata/statistics, consulted on July 21, 2011.

Containing Stainless Steels for Corrosion Resistance Services. NiDI Report 11007.

371

processing industry, Stainless Steel World 2004, KCI Publishing BV, pp. 419-422,

Techniques used in Mexican Rock Paintings, Rock Art Research, Vol. 25, No. 2,

objectives, in Symposium abstracts IAFP 88th Annual Meeting, Minneapolis,

Handbook of Case Histories in Failure Analysis, ASM International, edited by

revolutionized the availability of data bases on materials characteristics and performance. These data bases are integrated in smart system as tools for the design operation improving the materials selection required for a specific environment. The methodology created by Michael Ashby integrates in this way the materials selection to the design process (M. Ashby, 2005). In this model the material has attributes such as density, strength, electrical properties, costs, etc., that must be compared with those of real materials to find the best match.

#### **8.3 Protective coatings**

The coating of surfaces is so ancient as well as rock paintings in caves dated to be thirty thousand years old. They were done on the surface of granitic rock; an igneous, hard rock with a coarse – or medium – grained texture, rich in quartz and feldspar. The ancient painters took advantage of the natural, exfoliated, rough surface, with diminutive cracks, voids and hollows for the mechanical anchorage of its mineral-based paint applied as a paste or as slurry (B. Valdez et al, 2008). Varnishes were used by the Egyptians, polychrome sculptures were realized by the Greek hundreds of years BC and Romans used coatings for protective and decorative purposes.

The organic coatings form an excellent physical barrier between possible corrosive environments and metallic surfaces protecting the material from degradation and corrosion. The organic coatings include paints, resins, lacquers and varnishes, while the inorganic comprise enamels, glass linings and chemical conversion coatings. They are used in the FI protect the interior of cans, water tank containers, and the exterior of installations made with carbon and galvanized steel, concrete or wood.

For best results in corrosion protection coatings are commonly applied as a system composed by several layers that are classified as follow:


#### **9. References**


revolutionized the availability of data bases on materials characteristics and performance. These data bases are integrated in smart system as tools for the design operation improving the materials selection required for a specific environment. The methodology created by Michael Ashby integrates in this way the materials selection to the design process (M. Ashby, 2005). In this model the material has attributes such as density, strength, electrical properties, costs, etc., that must be compared with those of real materials to find the best

The coating of surfaces is so ancient as well as rock paintings in caves dated to be thirty thousand years old. They were done on the surface of granitic rock; an igneous, hard rock with a coarse – or medium – grained texture, rich in quartz and feldspar. The ancient painters took advantage of the natural, exfoliated, rough surface, with diminutive cracks, voids and hollows for the mechanical anchorage of its mineral-based paint applied as a paste or as slurry (B. Valdez et al, 2008). Varnishes were used by the Egyptians, polychrome sculptures were realized by the Greek hundreds of years BC and Romans used coatings for

The organic coatings form an excellent physical barrier between possible corrosive environments and metallic surfaces protecting the material from degradation and corrosion. The organic coatings include paints, resins, lacquers and varnishes, while the inorganic comprise enamels, glass linings and chemical conversion coatings. They are used in the FI protect the interior of cans, water tank containers, and the exterior of installations made

For best results in corrosion protection coatings are commonly applied as a system

Primer. Is the first coating applied to the substrate and has adhesive affinity for it and to

 Intermediate coating. Is added when multiple thin layers are required. It is also called secondary coating when applied as top or final coat. Sometimes the intermediate is

 Topcoats. It is the final layer applied to extend the life of the previous coatings. This film is more dense and hydrophobic in order to avoid the penetration of moisture to the

Araújo C, Carvalho J, Mota D, Araújo C, Coelho N. (2005). Determination of sulphite and

Ashby, M.F., (2005) Materials Selection in Mechanical Design, 3rd Edition, Oxford, U.K.,

ASM News, http://www.asminternational.org/portal/site/www/NewsItem, consulted on

acetic acid in foods by gas permeation flow injection analysis. Food Chem. 92:

underlying coats. Commonly provides an aesthetic appearance to the surface.

provide if it is necessary a better adhesion for the subsequent coat layer.

match.

**8.3 Protective coatings** 

**9. References** 

765-770.

Elsevier.

July 27, 2011.

protective and decorative purposes.

with carbon and galvanized steel, concrete or wood.

composed by several layers that are classified as follow:

used to provide thickness to the coating film.


**20** 

373

 *Thailand* 

**for Canning Process** 

*Kasetsart University, Nakhon Pathom* 

**Computer-Based On-Line Assessment of** 

*Department of Food Engineering, Faculty of Engineering at Kamphaengsaen* 

**Sterilizing Value and Heat Distribution in Retort** 

Montip Chamchong, Vilasinee Sangsom and Nuttakorn Charoeamkitti

Heating process for food is of importance to the consumers since it is considered to be one of food preservation techniques. Under these techniques food can be stored or edible within a long period of time. One of them which require heat treatment is sterilization process. Thermal sterilization of prepackaged canned foods in retort has been the most widely used during the twentieth century. Typically this method consists of heating food containers in pressurized retorts at specified temperatures for prescribed lengths of times (Teixeira and

The process time for canned food is indicated based on the sufficient achievement of bacterial inactivation in each container in order to comply with public health standards or food safety. In addition it will minimize the probability of food spoilage. The traditional methods for thermal process calculations or validation such as Ball and Stumbo methods were developed and widely used ever since. However they required the off-line input of tables and consequently series of calculation steps which might be resulting in too-long or too short heating process. At present there are a lot of commercial software available which could be used either on-line or off-line analysis for sufficient heat treatment or process lethality (Fo) such as CAN-CALC, and CALSoft™ etc. Balaban (1996 cited by Teixeira et al., 1999) described that CAN-CALC software needed to get fh (heating rate factor) and jh (heating lag factor) from heat penetration test prior to be able to predict internal center product temperatures in response to any dynamic boundary temperature for products of any shape and size as shown in figure 1 and 2. Therefore if assumed that the selected can was at the slowest heating point of the retort, simulated system Fo for food products that heated by any combination of conduction or convection heat transfer also could be obtained. However, the software performance was emphasizing with its capability to deal with process deviation such as steam shutting off and back on. The CALSoft™ software (Anonymous, 2011) was designed specifically for conducting heat penetration and temperature distribution testing, evaluating the collected data, calculating a thermal process or vent schedule/come-up time, and evaluating process deviations. It was supposed to use with CALPlex™ data logger and claimed for the most widely used commercial thermal

**1. Introduction** 

Tucker, 1997).

processing software.

S.O. Jekayinfa, P.O. Okekunle, I.G. Amole, J.A. Oyelade, (2005) "Evaluation of corrosion cost in some selected food and agro-processing industries in Nigeria", Anti-Corrosion Methods and Materials, Vol. 52 Iss: 4, pp.214 - 218
