Muhsin Mutlu; Gokhan Kurşad Incili; Mehmet Calicioglu

doi:10.19080/JDVS.2023.15.555913

Research Article

A Traditional Cheese That Has Fallen into Oblivion: Tomas

Muhsin Mutlu*, Gokhan Kurşad Incili and Mehmet Calicioglu

Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Firat University, Elazig, Turkey

Submission:January 27, 2023; Published:February 20, 2023

*Corresponding author: Muhsin Mutlu, Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Firat University, Turkey

How to cite this article: Muhsin Mutlu, Gokhan Kurşad Incili and Mehmet Calicioglu. A Traditional Cheese That Has Fallen into Oblivion: Tomas. Dairy and Vet Sci J. 2021; 15(3): 555913.DOI: 10.19080/JDVS.2023.15.555913

Abstract

Cheese, which is one of the animal foods, is rich in calcium and phosphorus, as well as protein, fat, minerals and vitamins, and its nutritional value is quite high. In addition to cheeses that are usually produced commercially, many traditional cheese varieties are produced in different geographical areas. Tomas is a type of Tulum cheese produced in Bingol, Tunceli, Elazig, Erzincan, Mus and Malatya provinces in Türkiye and known as Tomas, Dorak or Serto according to the region where it is made. Sheep or goat’s milk is mostly used in the production of Tomas, and Tomas production usually starts in May-June and continues until September-October. While a lot of research has been done on cheese varieties, there is very little research related to Tomas cheese. In this review, the definition of cheese, its nutritional value, its production and consumption, as well as general information about Tomas cheese and the studies carried out are presented as a summary.

Introduction

Cheese is the general name for a group of fermented milk-based food products produced worldwide in a wide variety of flavors and shapes. Although the primary purpose of cheese making is to preserve the main components of milk, cheese has become a highly nutritious culinary dish with its epicurean qualities as well as being highly nutritious. Properties related to the moisture content of the cheese in terms of texture, such as very hard, hard, semi-hard, semi-soft, soft, etc., are the most common criteria for the classification of cheeses. While many dairy products are biologically, biochemically, chemically and physically very stable if properly produced and maintained, cheeses are biologically and biochemically dynamic and naturally unstable. Cheese is believed to have evolved in the region known as the “Fertile Crescent”, that is, from the Tigris and Euphrates rivers to the Mediterranean coast in today’s southern Türkiye, about 8.000 years ago, when certain plants and animals were domesticated as food sources during the so-called agricultural evolution. Nowadays, in addition to cheeses that are usually produced commercially, many traditional cheese varieties are produced in different geographical areas, especially in mountainous areas [1]. According to the Turkish Food Codex Cheese Communique, the definition of cheese is “made by coagulating the raw material using a suitable coagulant and separating the whey from the curd or coagulating after separating the permeate of the milk, in different hardnesses and fat contents, in brine or salted with dry salting or unsalted. means dairy products with characteristic features specific to the variety, produced in accordance with the technique, with or without the use of starter culture, with or without boiling the curd, with or without seasoning [2]. Although cheese is a very important dairy food, the use of approximately 30% of the world’s raw milk production in cheese making makes cheese important [3]. Cheese is a rich calcium and phosphorus content, rich in protein, fat, minerals and vitamins [4]. In this review, information is given about the nutritional value of cheese, the production and consumption of cheese, general information about Tomas cheese and the studies carried out.

Nutritional Value of Cheese

Cheese contains a high concentration of essential nutrients relative to its energy content. The nutritional content of cheese is affected by the type of milk used (type, lactation stage, full-fat, low-fat, skim), mode of production and to a lesser extent the degree of ripening. Although cheese is a milk-based product containing high amounts of protein and fat, it has wide uses in the food industry, as it is considered an ideal food due to its high nutritional value, ease of digestion, good texture and flavor variety [5,6]. Cheese contains a high level of biologically valuable protein. Cheese contains protein between 3-40%, depending on the variety. During traditional cheese production, most of the whey proteins pass into the whey. Whey proteins make up only 2-3% of the total protein in cheese, and the remainder is casein, which is in small amounts of sulfur amino acids. Therefore, the biological value of cheese protein is slightly lower than the total milk protein. If the essential amino acid index of total milk protein is given a value of 100, then the corresponding value of proteins in cheese varieties ranges from 91-97. Since the ripening stage of cheese production involves the progressive breakdown of casein into water-soluble peptides and free amino acids, cheese protein is almost 100% digestible.

Most of the lactose, the main carbohydrate in milk, is lost in the whey during cheese production and therefore most cheeses contain only small amounts of carbohydrates. In addition, the lactose remaining in the cheese curd is usually fermented into lactic acid by the starter bacteria, so that the cheeses can be consumed unharmed by people with lactose intolerance and β-galactosidase deficiency. This is important as approximately 70% of the adult population is highly lactose intolerant. The fat content of cheese varies considerably depending on the milk used and the production method. Fat affects the hardness, stickiness, mouthfeel and flavor of cheese. Free fatty acids and their catabolites are important flavor components in some cheese varieties. From a nutritional point of view, the digestibility of fat in different cheese varieties is in the range of 88-94%. Most cheeses are potentially important sources of dietary fats. Cheese fat generally contains about 66% saturated, 30% monounsaturated and 4% polyunsaturated fatty acids. Therefore, cheese is an important dietary source of both total fat and saturated fatty acids [7]. Cholesterol content of cheese is a function of fat content and varies between about 10- 100 mg/100g depending on the variety. Generally, most cheeses are a good source of vitamin A, riboflavin, vitamin B12 and, to a lesser extent, folate. Cheese also contains a small amount of vitamin C [7]. Cheese is an important dietary source of various minerals, primarily calcium, phosphorus and magnesium. There is about 800 mg of calcium in 100 g of hard cheese, but acid-cured cheeses such as Cottage contain significantly less calcium than rennet-cured cheeses. The bioavailability of calcium in cheese is equivalent to that in milk, and cheese has an extra potential role in providing highly bioavailable calcium. Dairy products, including cheese, contain very little dietary iron [7].

Cheese Production and Consumption

Many governments have had to restrict the movement of raw materials between countries and locally, or stop production due to a lack of raw materials by producers. Due to the impact of COVID-19, trade restrictions have been experienced, supply chains have been interrupted, and the cheese production market has experienced great difficulties in 2020 due to the bans imposed by governments globally. The result of the COVID-19 measures implemented around the world was also reflected in the production, and in 2021, world cheese production increased by 1.5% compared to the previous year and amounted to 24.7 million tons. While the International Diabetes Federation (IDF) did not include the processed cheese production amount in the calculation of the total cheese production in the world, it only considered cheese made from cow’s milk, which represents 90% of the total cheese production; did not include the amount of cheese obtained from buffalo, goat and sheep milk and the amount of home-made cheese consumed in the household on the farm. The world’s largest cheese producers are the European Union (EU), which transfers most of the raw milk production to cheese production and represents 44.3% of the world’s total cheese production, and the The United States (USA), which represents 24.8% of the world’s total cheese production. Despite the stagnant milk production in the EU in 2021, cheese production increased by 0.9% to 10.7 million tons, with the opening of several new cheese factories partially producing cheese in the food processing industry, in the same year production in the USA increased by 2.4% compared to the previous year to 6.1 million tons [8].

According to OECD-FAO Agricultural Outlook 2021-2030 data, cheese production in 2022 is expected to increase by 1.5% compared to 2021 and reach 25 million tons. As in other dairy products, world cheese trade is estimated to increase (1.7%) to 3.4 million tons in 2022 [9]. Cheese consumption will remain strong, in part due to consumer popularity for cheeses designated under Geographical Indication status, and it is assumed that the hotel, restaurant and tourism industry will continue to be key components driving cheese consumption and that the cheese industry will recover from the COVID-19 crisis in 2022 [8]. Most of the cheeses in Türkiye (95%) are made from cow’s milk. Total cheese production in Türkiye decreased by 0.5% in 2021 compared to the previous year and was calculated as 763 thousand tons. In 2022, total cheese production in Türkiye is expected to increase by 3.8% and reach 792 thousand tons [8]. One of the most consumed dairy products in Türkiye is cheese. The cheese variety with the highest market share, with an increase in consumption in parallel with cheese production over the years, is white cheese. With a calculation that includes the amount of milk production excluding cow, sheep, goat and buffalo milk collected by Turkish National Dairy Council (TNDC) integrated dairy enterprises and cheese import and export, the annual cheese consumption per capita in Türkiye in 2019 is calculated as 17.5 kg [10]. Cheese production of some countries around the world is given in Table 1.

Consumption of processed dairy products varies by region. The level of consumption of dairy products per capita varies widely around the world. The per capita income of the country and the effect of regional preferences are important factors that drive this consumption difference. The general consumption of dairy products, especially cheese, is also affected by changes resulting from local preferences, dietary restrictions and the level of urbanization. The second most important dairy product consumed in terms of dairy products is cheese. High-income countries predominantly consume processed dairy products, including cheese. Cheese is consumed the most in Europe and North America in 2021, as in previous years, and consumption is increasing in both regions. Cheese consumption tends to increase worldwide in 2021. EU (20.4 kg), USA (17.9 kg), Canada (15 kg) and Australia (11.8 kg) take the first place among the countries with the highest cheese consumption per capita [8]. Cheese consumption per capita in some countries is given in Table 2.

Although cheese is a dairy product, its production, consumption and variety are increasing day by day as it is produced and consumed with pleasure in all countries of the world [11]. Cheese making has evolved greatly over time, with the rich diversity of cheeses produced worldwide and the culture and resources that have shaped production in each region. Today, consumer demand is increasing for high-quality products with excellent sensory properties and at the same time cost-effective. According to the latest estimates, global cheese consumption is expected to increase by 13% from 2016 to 2025 [12]. Since cheese can be eaten alone, used as an ingredient in meals, and having many options and varieties, it has become the most consumed dairy product in many countries. According to Duncan (n.d.), approximately 10 million tons of different types of cheese are consumed in EU countries. The EU consumed about nine and a half million metric tons of cheese in 2020, exceeding consumption figures elsewhere in the world. USA consumed approximately 6 million metric tons of cheese in the same year [13]. The high variety of cheese is one of the indicators of the cultural richness of a country. In every country, there are cheese varieties that are similar to each other but have different names and structures according to the region where they are made [14]. Cheese is a nutritious, versatile dairy product, and a wide variety of cheeses are available to meet specific consumer needs and provide ease of use [7]. Since Türkiye is the center of East-West culture, there are different types of cheeses in different shapes, structures and flavors in each region. Many factors such as the type of milk, whether the milk has been heat-treated, clot formation method, salt ratio, fat ratio, structure, additives and ripening time are effective in the emergence of cheese diversity [15]. The cheese varieties produced all over the world are about 1000, and this variety is constantly increasing according to the preferences of the people and the cultures of the region [1]. In recent years, efforts have been made to transfer the production method of many traditional products to medium and small scale industrial production in order to contribute to the regional economy by increasing the product variety in many countries and to increase product safety [16- 18]. In Türkiye, the realization of the flavors of local cheeses as a result of migration from rural areas to big cities in the last 20 years has enabled cheese to be recognized by a wide public. The fact that the sales prices of these cheeses are reasonable has led to an increase in demand [19]. Traditional cheeses in Türkiye are generally produced in small dairy or family businesses, and they are products that are limited to the region where they are located and that have a limited place in the national and international markets because they are not known [20]. Türkiye, with its geography and cuisine with a rich historical and cultural heritage, is an important country where approximately 130 kinds of cheese are produced [21]. Since Türkiye has an important potential in terms of domestic cheese varieties [22], it has a rich variety in terms of both local and industrial type cheeses [23]. Examples of this rich variety are common and widely produced cheeses such as feta cheese and cheddar cheese, and very different traditional cheeses such as tulum cheese, herbed cheese, curd cheese, pottery cheese and cubed cheese [21]. The flavor and texture of these cheeses are different from each other [24]. Local cheesemaking is typically characterized by small-scale production in limited volumes by individual producers. These cheeses are affected by geography, climate, cultural and economic conditions. Producers of this type of cheese argue that the use of raw milk provides various organoleptic and sensory properties to cheeses, as it is the source of high bacterial diversity and microflora [25].

Tomas Cheese

Tomas cheese; It is a Tulum cheese variety that is produced in the provinces of Bingol, Tunceli, Elazig, Erzincan, Mus and Malatya in the Eastern Anatolia Region of Türkiye and is known as Dorak, Tomas or Serto according to the region it is made [26]. Tomas cheese is mostly made from sheep’s or goat’s milk and its production usually begins in May-June and continues until September-October. In accordance with the traditional production process, yoghurt is first made from pasteurized milk, then yoghurt is turned into buttermilk by adding water. Buttermilk is produced by subjecting it to the churning process. The remaining fat-free buttermilk is heated to boiling temperature to make precipitate. After the heating process, buttermilk is cut and oil-free precipitate is obtained. Afterwards, the precipitate is cooled, filtered and packed into leather bags/coveralls. Sufficient amount of whole milk, milk cream and yoghurt are placed in a leather bag and mixed thoroughly at least once a week. This procedure is repeated for at least 3-4 months. The cheese is then packed in leather bags/ skins and left to ripen in a cool place. Tomas cheese acquires its unique taste and aroma as a result of the physical, chemical and microbiological changes that occur during this ripening process [27]. In short, while the fat in the yoghurt used in cheese making is initially removed, the fat is gradually increased during the ripening process of the cheese. Since Tomas cheese is produced in small family businesses, the absence of a control mechanism causes low quality problems in cheese and poses a risk in terms of food safety [28]. While a lot of research has been done on other cheese varieties, there is very little research on Tomas cheese, which is the subject of this research. For this reason, the number of researches on Tomas cheese should be increased and healthy products of appropriate quality should be produced (Figure 1).

Studies on the microbiological and chemical properties of Tomas cheeses are summarized below: Kurt et al. [29], in a study in which they examined the chemical and microbiological properties of 20 tomas cheeses collected from the province of Bingol, its districts and villages; water 52.5%, dry matter 47.49%, protein 22.56%, fat 18.3%, non-fat dry matter 29.37%, fat in dry matter 38.18%, salt 3.05%, ash 3.42%, and acidity (SH) 102.5%.

Gunduz [28], in a study in which Tomas cheese produced by using yoghurt culture (Streptococcus thermophilus+Lactobacillus bulgaricus+Lactobacillus acidophilus) and Penicillium roqueforti Thom strain in laboratory environment, examined in terms of sensory, physical, chemical and microbiological analysis, the average total number of mesophilic aerobic bacteria in cheese samples 2.61x108, lactic acid bacteria 1.87x108, proteolytic bacteria 6.47x107, Candida lipolytica 1.33x108, P. roqueforti 9.99x108, Lactobacillus plantarum 1.21x108, Lactobacillus bulgaricus 6.46x107, Streptococcus lactis 5.66x107, S. cremoris 2.91x107, S. thermophilus was determined as 2.71x107 cfu/g.

Korucu [30], investigated some physicochemical and microbiological properties of 16 home-made Tomas cheeses produced in Elazig and offered for sale in local markets. Dry matter 42.45±0.08%, fat 18.97±0.23%, salt 4.42±0.1%, ash 5.9±0.1%, acidity 1.34±0.07%, protein 16.34±0.16% and finally pH results were determined as 4.9±0.04. Mean total mesophilic aerobic bacteria (TMAB) count was 7.60±0.68, yeast-mold count 7.28±0.87, coliform group bacteria count <10, Lactobacillus spp.7.46±0.75 and Lactococcus spp. and the number was determined as 7.74±0.75 log10 cfu/g. Kurtulgan & Dikici [31], in a study in which they determined some physico-chemical and microbiological properties of Tomas/Serto (Dorak) cheeses available in the market in Tunceli and Elazig provinces, the average physico-chemical analysis results of the samples, moisture rate 53.24%, ash content 4.24%, dry matter 46.76%, lactic acid content 1.08%, salt content 2.93%, fat 17.66%, oil-free dry matter ratio 25.56% and pH value 4.67 and microbiological analysis results are total aerobic mesophilic bacteria (TAMB); 7.0, coliform; 2.3, yeast; 4.6, mold; It showed 5.5 log10 cfu/g. Lactococcus species; 6.8 and Lactobacillus species were determined as 6.1 log10 cfu/g.

Coskun & Korucu [32], investigated some properties of 16 Tomas cheese samples collected from different regions of Türkiye’s Elazig province and identified the lactic acid bacteria isolated from tomas cheese in their study, dry matter, fat, salt, ash, protein, titratable acidity, ripening index and pH values were respectively, 39.70-46.01%; 16.20-21.56%; 3.31-4.95%; 4.41- 6.90%; 11.80-23.83%; 0.9-1.8%; 13.18-42.04% and it is stayed that is between 4.5-6.03. Total aerobic mesophilic bacteria, yeastmold and lactic acid bacteria (Lactobacillus and Lactococcus) counts were respectively, 6.67-9.01; 5.30-8.39; 6.25-8.91; and varied between 6.56-9.01 log10 cfu/g. Coliforms were determined as <1 log10 cfu/g in all samples.

Conclusion and Recommendations

Studies should be carried out to increase the value of the product in terms of production standardization, increase the quality, potential to obtain geographical indications, and improvements in promotion, marketing and branding related to Tomas cheese. In order to protect the production and life styles and natural and cultural assets in the villages; It is necessary to support areas such as traditional production of villages, products with geographical indications, initiatives and collaborations that will carry the traditional production and storage knowledge of agricultural and food products to future generations. As a result, Tomas cheese and other local cheeses provide the expected contribution to the country’s economy; production in a safe, standard quality and chemical composition and putting it on the market depends on fighting against imitations as a result of effective marketing and promotion activities. While most of these are produced/consumed in quantities to meet the demand in the region where they are produced, some of them are known throughout the country and provide added value by being converted into a commercial product. In this sense, Tomas cheese, which has sunk into oblivion, should be classified by taking into account its different characteristics, its production technologies should be developed and standardized and introduced to the world. There is a need for more research on Tomas cheese in this regard.