Scholarly article on topic 'Food safety hazards in Georgian Tushuri Guda cheese'

Food safety hazards in Georgian Tushuri Guda cheese Academic research paper on "Agriculture, forestry, and fisheries"

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Annals of Agrarian Science
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{"Case study" / "Tushuri Guda variety" / "Ewe milking and processing" / GMPs / GHPs}

Abstract of research paper on Agriculture, forestry, and fisheries, author of scientific article — Avtandil Korakhashvili, George Jeiranashvili

Abstract Scientific-research work provides a timely and valuable review of the progress being made in the greater understanding of the factors contributing to Tushuri Guda cheese making and how this experience may be applied to producing better and more consistent products with food safety HACCP system requirements. The HACCP study in this variety of cheese covers all types of food safety hazards, like biological, chemical and physical, but unfortunately it needs a more precise definition. It did not include clarification of cleaning and sanitation operations in accordance with modern standards, sanitation of grasslands and meadows. All of that are covered by the plant Good Manufacturing Practices (GMPs) procedures and Good Hygiene Practices (GHPs) for the obtaining of maximal food safety results.

Academic research paper on topic "Food safety hazards in Georgian Tushuri Guda cheese"



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Food safety hazards in Georgian Tushuri Guda cheese

Avtandil Korakhashvili a'*, George Jeiranashvili b

a Georgian National Academy of Sciences, 52, Rustaveli Ave., Tbilisi, 0108, Georgia b Agricultural University of Georgia, 240, David Agmashenebeli Alley, Tbilisi, 0131, Georgia



Article history: Received 12 June 2016 Accepted 25 July 2016 Available online xxx


Case study

Tushuri Guda variety

Ewe milking and processing

Scientific-research work provides a timely and valuable review of the progress being made in the greater understanding of the factors contributing to Tushuri Guda cheese making and how this experience may be applied to producing better and more consistent products with food safety HACCP system requirements. The HACCP study in this variety of cheese covers all types of food safety hazards, like biological, chemical and physical, but unfortunately it needs a more precise definition. It did not include clarification of cleaning and sanitation operations in accordance with modern standards, sanitation of grasslands and meadows. All of that are covered by the plant Good Manufacturing Practices (GMPs) procedures and Good Hygiene Practices (GHPs) for the obtaining of maximal food safety results.

© 2016 Agricultural University of Georgia. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (



In Georgia in recent years, there have been significant advances in our understanding of ewe milk and it's cheese systems, probably the most complex natural food available to man. At the same time, improvements in process technology of origin variety of Georgian Tushuri Guda cheese, have been accompanied by massive changes in the scale of ewe milk processing operations, and the manufacture a wide range of dairy and other related products. This research also introduces stamps of production on milk and milking action for ewe cheese making and maturation, packaging technology and transportation for cheese and the prediction and control of the overall manufacturing process for this brand of cheeses. A family-owned medium-sized cheese making groups has

been asked by local retail customers to provide a HACCP system principals for its main product-Tushuri Guda cheese [1].

In accordance with International Dairy Federation - IDF, 2015, world production of milk in 2013 is estimated at ~582 x 106 tones. Main producers are India/Pakistan, the Americas and Europe being the major producing regions. The proportions of total milk produced by cow, water buffalo, goat, ewe, camel and other are ~85.0, 12.3, 2.0, 1.3, 0.2 and 0.2, respectively. Cows' milk is the major milk used for cheese manufacture; however, significant quantities of cheese are also made from goat, sheep and water buffalo milks in some European Union (EU) countries, such as France, Italy and Spain. Based on an estimated yield of 1 kg cheese 10 kg-1 milk, the percentage of total milk used for cheese is ~25%, but varies widely from ~70-90% in some European countries (Italy,

* Corresponding author.

E-mail address: (A. Korakhashvili). Peer review under responsibility of Journal Annals of Agrarian Science. http://dx.doi.Org/10.1016/j.aasci.2016.08.005

1512-1887/© 2016 Agricultural University of Georgia. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (

France, Denmark and Germany) to ~0.5% in China. While cheese-like products are produced in most parts of the world, the principal cheese-producing regions are Europe, North America and Oceania [2,3].

Cheese production has increased consistently over the last two decades at an annual average rate of ~1.5%. As discussed in above, I this may be attributed to a number of factors including increases in global population (7,1bln) and per capita income, globalization of eating trends/habits, changing lifestyles, growth in use of cheese as an ingredient in the food service (in pizza-type dishes, cheese burgers and salad dishes) and industrial sectors (cordon bleu entrees, co-extruded products with cheese and gratins).

preparation of lactic acid bacteria, rennet, calcium chloride, salt. Processing technology represented in Fig. 1 - Generic flow diagram of Tushuri Guda cheese production.

Results and analysis

Product specifications and Microbiological Critical Points for Tushur iGuda depends from quality of raw ewe milk. Micro-bial contamination of milk can occur pre-milking as a consequence of sheep infection or during, or post-milking as a consequence of direct contact with bacteria in the environment or milk handling equipment.

Objectives and methods

Milking in the Field

For more than 30 century in Georgia ewe milk processing technology has sought to provide education and training in this dairy field, disseminating knowledge and fostering personal development through symposia and conferences, as well as by publications, and its International Journals of Agricultural Technologies provides a timely and comprehensive update on the principles and practices involved in this variety of cheese manufacturing. Principles of cheese manufacture is a concentrated protein gel, which occludes fat and moisture. Its manufacture essentially involves gelation of cheese milk, dehydration of the gel to form a curd and color. Technology of Cheese making treatment of the ewe milk curd (e.g. dry stirring, texturisation, salting, moulding, pressing, obtaining characteristic appearance). The moulded curd may be consumed fresh (shortly after manufacture, for example within 6 week) or matured for periods of ~12 weeks to 2 years to form a ripened cheese.

The increase in consumption has been paralleled by a greater emphasis on improved quality and consistency with respect to the levels of particular nutrients (fat, protein, calcium-Ca2+ and sodium-Na+), physical properties (texture and cooking attributes), sensory characteristics and processing ability (size reduction attributes, such as shred ability; ability to yield processed cheeses or other cheese products, when subjected to secondary processing). Consequently, this has necessitated an increase in the quality and consistency of all inputs (milk composition/quality, enzyme activity/purity, starter cultures characteristics, for example, acid productivity, phage resistance, autolytic properties and flavor-imparting characteristics, sources of contaminants) and standardization of the manufacturing process [4].

Tushuri Guda cheese is the most popular white brine matured cheese in Georgia and some other countries around the Black Sea. Last 6 years by this brand from Georgia it exported in some EU countries and USA. It is a traditional Georgian cheese (Protected Designation of Origin) and it is produced by pasteurizedewe milk by very original technology, starter culture, microbial rennet and salt, the curd is cut and strained, put into sheep fell with hair and matured for a minimum period of six months and above. Here is diagram of processing:

Ingredients of this variety or milk composition is Ewe milk (cheese not contain goat's milk at all), starter culture

Raw Ewe Milk Tanks


Pasteurization 72°C / 15-20 seconds

Cooling in field

Addition of starter


Addition of rennet

and salt (NaCl)


Curd cutting

Transferring to molds

Dry Salting

Maturation (18°C/60 days)

Ripening (<4°C)

Packaging in sheepskin bag

Storage (3-5 C)

Fig. 1 - Diagram of Georgian ewe cheese-Tushuri Guda production.


Starter cultures are central to cheese production as they give the product its individual characteristics. The amount of starter culture is approximately 0.5%-2.0% of the milk volume, depending on the type of cheese being produced. At this stage the cheese milk can also be acidified to influence its flavor, maturation and texture [4].

The enzyme rennet is then added to the milk (25 g-40 g rennet per 100 l cheese milk) to form the curd. The next process is syneresis (release of whey from the curd). The majority of the whey is removed and the remaining soft curds are passed in to a cotton bag. Curd is distributed using an automatic distributor, before being pre-pressed into a cheese "cake" and the remaining whey drained off. The cheese cake is then cut into bags, for final pressing in cheese moulds before being transferred for cooling, brining and ripening.

Ewe milk safety or public health (pathogens including Mycobacterium tuberculosis, Brucella spp., toxic residues, and contaminants) Directive 92/46 (EU, 1992) specifies that raw milk must come from healthy animals and should not endanger human health by way of infectious diseases or foreign substances that are communicable to human beings through the milk. The pathogens reported as the most common agents implicated in milkborne disease include Salmonella spp., Campylobacter spp. and Escherichia coli (E-coli), but others found in milk could also have public health implications, such as Mycobacterium tuberculosis and Listeria mono-cytogenes. These microorganisms may enter the mammary gland and thus the milk, from the external environment through the teat orifice during the milking process or during the interval between milking process [5].

Main factors affecting the quality of milk for cheese manufacture is quality of ewe. The quality of milk for Tusuri Guda cheese manufacture is affected by five key parameters, namely composition, microbiology, SCC, enzymatic activity and levels of residues/contaminants.

Ewe milk composition in our several studies have shown seasonal variations in composition of milk. The gross composition of cheese milk, especially the concentrations of protein, casein and fat, has a major influence on several aspects of cheese manufacture, including rennet coagulability, gel strength, curd syneresis, cheese composition, yield and quality.

In high mountains grasslands, the original cheese place suffered from a lack of space, traditional old technology and the need for manual lifting of heavy loads during cheese production; also, it could not be feasibly expanded because of a lack of available space in the herder's building. Usually, this process take place in open fields, sometimes with wing weather. By the point of safety carried out lab analyses show microbiological data below in Table 1.

Raw ewe milk intended for cheese making should not be stored for longer than 24 h and always at low temperature, at least <8 °C to avoid psychrotroph bacteria growth. It's not possible in mountain conditions make tests for: a) antibiotics, b) mycotoxins, c) pesticides, d) microbiological tests e) total acidity and pH. Storage time always less than 12 h at natural temperature (8-12 °C, average). Antibiotics should be absent. In south Caucasian countries and especially in Georgia the maximum tolerance limit for Aflatox in M1 (AFM1) in milk is 50 ng/kg (in dairy products like cheese, it is 250 ng/kg). Raw

Table 1 — Microbiological critical points.


Absence in 25 g Absence in 1 g <1 x 102 <1 x 103 <1 x 102 <1 x 103 <1 x 104 <1 x 105

1 Listeria monocytogenes 3 0

2 Salmonella spp. 3 0

3 Staphylococcus aureus (cfu/g) 3 2

4 Esherichia coli (cfu/g) 3 2

5 Coliforms (cfu/g) 3 2

n is number of sample units comprising the sample. m is the threshold value for the number of bacteria. M is maximum value for the number of bacteria. c is number of sample units where the bacteria count may be between 'm' and 'M'.

sheep's milk intended for the manufacture of heat treated milk based products must meet the obtained standards. Compliance with the standard must be checked by random sampling, either on collection at the production holding or on acceptance of the raw milk at treatment or processing establishment [6,7].

Among of microbiological and chemical hazards, to physical hazard have to pay special attention and filtration avoid milk from foreign materials. Mechanical filtration through stainless steel mesh with tangential flow of the milk, or a filter cloth in smaller plants is used to remove particulate contaminants. Daily cleaning and visual inspection of the integrity of the filter is necessary. Tushuri Guda cheese producers this presses are using at least 3 times.

Pasteurization is the most important step of the manufacturing process for Tushuri Guda cheese regarding microbiological safety. Temperature and time control is very significant, alkaline phosphatase test and occasional microbiological test for coliforms. Pasteurized milk for this kind of cheese must show a negative (pH) reaction to the phosphatase test and a positive reaction to the peroxidase test. The pasteurization vessel should be checked daily before use using the Swab test, and after cleaning it. Occasional microbiological test of the final rinse water for the presence of coliforms. It's not easy to keep all of above mentioned actions for the processing of cheese, but requested.

Before processing, frequent microbiological test of the vessels is needed using the Swab test. If jacketed vessel is used, then temperature can be adjusted to 32 ± 1 °C at this step. Else the temperature will keep dropping and will reach the desirable by the next step. Cooling at 37 °C requested.

For the Addition of starter culture and calcium chloride 0.5% to milk processors have to have Commercial starter culture preparation of the rmophile and mesophile lactic acid bacteria (Lactobacillus bulgaricus, Streptococcus thermophilus, Lactococcuslactis) 3-3.5% v/v is added to the pasteurised milk and it is incubated at 32-34 °C until the pH drops to 4.7. The prepared culture must be used within 24 h [8].

During Addition of rennet and NaCl 0.01%/Coagulation for 1 h the coagulation process step in according with Good Manufacturing Practice (GMP) must be applied, mainly cleaning and sterilization of the coagulation vessels and checking that the temperature stays at 32 ± 1 °C. Microbial cross contamination must be controlled as possible (in mountain indoors). On the next stage, curd is cut and after 10 min the strained curd is transferred into the mould. For the

Table 2 — Controlling of CCPs in the processing of Tushuri Guda cheese.

Process Steps Hazards Checking Frequency Critical points

Raw Milk in casserole Biological Control Milk According to a program established pH 6.3—6.7

Physical Acidity for a certain collection areaa max 500,000 cfu/g

Aerobic <40C



Chemical Antimicrobial Absence


Filtration Biological Any extraneous Every day Absence

Physical Material

Pasteurization Biological Temperature Every batch 75 °C for 15min

Addition of starter culture Biological Temperature Every batch 32—34 ° C

pH 4.8

Maturation 18 °C/15days Biological pH Continuously 4,3 < pH < 4,7

Temperature Continuously 17—18 °C < T < 23 °C

Storage 4 °C/45days Biological Temperature Every batch <5 °C



a Mixing of different batches of raw milk should be avoided, in order to avoid cross contamination.

Transferring to moulds, Good Manufacturing Practice must be applied, mainly cleaning and sterilisation.

Dry salt is added to the Tushuri Guda cheese. It influences cheese ripening, controls microbial growth and activity, controls enzymes activity and causes syneres is of the curd and thus reduction of moisture. In this time physical hazard must be controlled by visual inspection for foreign materials, like stones, metals, etc.

For the maturation at 18 °C/15 days (CCP) the pH value plays one of important roles in Tushuri Guda cheese making. It has a major impact on texture and microorganism control. Guda should be cooled after pH has reached at least 4,6. Guda cheese matures for at least two months in two steps. First at 17 - 18 °C for one day followed by 5 - 15 days in 6% NaCl at the same temperature (final pH = 4,6 - 4,7) and Second, at 4 °C in 8% NaCl until the two-month time period is reached. At the first step, general hygiene and temperature control is essential since temperature higher than 21 °C can be hazardous due to growth of E. coli which may be present [9].

Packaged in sheepskin bags and maturation in cool places or in refrigerator 4 °C/45 days Critical Control Points (CCPs) continues at 4 °C in 8% NaCl until the two-month time period is reached, after transportation by horses from mountains to usual basements in villages of Tusheti. The temperature should be constantly monitored, as well as combination of factors such as salt content, pH and the storage temperature interact to render Tushuri guda cheese microbiologically safe from pathogenic bacteria which may be present as aresult of cross contamination (B. melitensis, E. coli, Y. enterocolitica, A. hydrophila) (see Table 2).

Milking equipment on the farm should be designed and maintained to minimise frothing, foaming or agitation, thereby reducing physical damage to the milk fat and the development of FFA. It is important that all of equipment must be treated by steam, even in pasture conditions. The Quality of Milk for Cheese depends even from weather development. The most effective means of reducing lipolysis due to psychro-trophic bacteria is firstly by hygienic milk production to reduce

bacterial numbers and secondly by minimising milk storage time between milking and processing.

The processors also has a responsibility in ensuring minimal agitation, cavitation effects and temperature changes in milk during collection, transportation and Processing. They have to take in consideration that milk from sheep in late lactation has a higher FFA level than that from sheep in early lactation. This may be due to changes in milk and MFGM integrity at that time or mechanical damage of the MFGM due to excessive mixing of air into relatively small volumes of milk, particularly at evening milkings, within a seasonal milk production system [10-13].

Furthermore, other sources of contaminants to milk include cleaning and disinfecting agents (trichloromethane (TCM), iodine) and compounded animal feeds (mycotoxins). Antibiotics and Antimicrobial drugs are administered to treat bacterial infections or employed prophylactically to prevent spread of disease. All antimicrobial drugs administered to dairy sheep enter the milk to a certain degree, and each drug is given a certain withdrawal period, during which time the concentration in the tissues declines and the drug is excreted by the animal. The most frequently and commonly used antimicrobials are antibiotics, employed to combat mastitis-causing pathogens. Other infectious diseases such as lami-nitis and respiratory diseases are also treated with antimicrobial agents, but are of relatively minor importance. The occurrence of residues of antimicrobials in milk has both economical and technological impact on the sheep cheese industry. Antimicrobial residues can lead to partial or complete inhibition of acid production by starter cultures, inadequate ripening and ageing of cheese and cause defects of flavor and texture of Tushuri Guda cheese or similar cheese [14].


Georgian Farmers are producing various hard and semi-hard Tushuri Guda cheeses, which are matured for periods from

six weeks right up to 48 weeks to imbibe different trade color, flavors and characteristics. Flavors such as caraway are also incorporated into the cheese for certain varieties. Above 6 varieties include similar quality Georgian and Mild family cheeses. Special flower and color ply significant role for cheese variety. Nutritional values are as usual about 283 Kcal/100 g, Proteins: 19, 5%, Fat not less than 20%, Shelf life is more one year. Consumers are General public, ages between 20 and 70 mainly. Tushuri Guda cheese can accompany all Caucasus meals, it's also used in cooking for traditional Georgian delicious food. Basement keeping at refrigeration <4-5 °C in vacuum packed containers or in films with libeling for export.

Tusheti is one of Northwest region of Georgia with high mountain seasonal pastures in subalpine conditions. In an overall context, milk quality and safety systems (ISO, HACCP) for cheese manufacture may be defined as its suitability for conversion into cheese and deliver cheese of the desired quality and yield. The current article examines ewe milk quality for special variety of Georgian Tushuri Guda cheese manufacture and the factors affecting it, together with broad-based strategies for improving quality, safety and consistency by more precise definition of food safety block-schemes of this cheese variety.


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[2] Worldwide Regulations for Mycotoxins in Food and Feed in 2003, FAO, Rome, 2004.

[3] A. Korakhashvili, D. Kirvalidze, et al., Research of cinnamonic calcareous soil fertilizing systems for pastures of akhaltsikhe district, Commun. Soil Sci. Plant Analysis, Taylor Francis, U. S. A. 42 (7) (2011) 768—796.

[4] technology/milk.htm.

[5] Codex Alimentarius, FAO/WHO Food Standards. Pesticide Residues in Food, Maximum Residue Limits; Extraneous Maximum Residue Limits http://www.codexalimentarius. net/mrls/pestdes/jsp/pest_q-e.jsp.

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[8] P. Walstra, Dairy Technology: Principles of Milk Properties and Processes, USA-UK-Australia, 1999, p. 752.


[10] Commission Regulation 1881/2006 of 19 December 2006, Setting maximum levels for certain contaminants in food stuffs, Off. J. Eur. Union L 364 (2006) 5—24.

[11] Council Directive 92/46/EEC of 16 June1992 Laying Down the Health Rules for the Production and Placing on the Market of Raw Milk, Heat treated milk and milk based products. Off. J. Eur. Union L. 268: 1—40.

[12] A.A. Korakhashvili, New growing technologies of legumes in Georgia, Ann. Agrar. Sci. 1 (2003) 11—13.

[13] T.G. Andronikashvili, T.F. Urushadze, A.A. Korakhashvili, Developed agriculture as a guarantee of the independence, Ann. Agrar. Sci. 1 (2013) 8—12.

[14] S. Mortimore, Wallace CIn: HACCP — a Practical Approach, second ed., An Aspen Publlication, ISBN0412754401, 1198, pp.46—81.