INTRODUCTION

Faster living, stress, poor eating habits, irregular meals, overusing antibiotics and other environmental as well as genetic factors contribute to disturbances in the composition and function of the gut microbiota^1-2. Appropriate and balanced nutrition as well as diversity of products in the daily diet at every stage of life unquestionably precondition the growth and development of the organism and improve the quality of life^1,3.

The interest in fermented milk products has increased lately^4-5. These products are produced globally using a wide range of resources and microorganisms as well as various techniques⁴. Fermented milk products are products that have been treated with bacteria. They belong to particularly valuable dietary components due to their diversified composition, the source of essential building blocks and regulatory elements, low content of energy and sodium as well as relatively low fat content. Fermented milk products are rich in phosphorus and potassium. Also, they are sources of magnesium, manganese, cobalt, zinc and vitamins B. Moreover, a significant content of easily assimilated calcium is worth emphasizing^2-3.

Their mechanisms of action include strengthening of the natural intestinal barrier, immune system modulation, production of beneficial metabolites and enhancing enzymatic activity⁶. Furthermore, they interact with the host cells to provide anti-inflammatory, antioxidative and antibacterial action⁷. They exert pleiotropic effects on global health, for instance by preventing various metabolic disorders and chronic diseases (e.g. diabetes mellitus type 2) as well as stroke or hyperlipidaemia. In addition, they reduce blood cholesterol levels and decrease blood pressure⁸. Moreover, probiotics as dietary supplements enhance the absorbability of nutrients, participate in vitamin synthesis (group B vitamins: thiamine, riboflavin, niacin, folate), improve immunity and exert anticancer effects⁹.

Growing consumer awareness and high nutritional value of fermented milk products result from the developing dairy market. There is greater requirement for functional food that not only has an appropriate nutritional value, but also offers additional health-related benefits¹⁰. Yoghurt is included in the group of these foods^8,11.

At present, the value of the fermented milk product market, including yoghurt, is estimated at 46 billion Euro. The milk kefir market is worth 78.7 million Euro¹². Fermented milk products are both a consumer trend and a challenge for the development of functional foods^7,12. Fermented milk products include: such as yoghurt, ymer, kefir, ayran, cultured buttermilk, filmjölk (Scandinavian sour milk), cultured cream, koumiss (a product based on mares’ milk), labneh and kurut¹³. The markets of different countries offer various products of this type.

Some of the determinants that influence food choice include biological factors (hunger, appetite, taste), economic factors (cost, income, availability), physical factors (access, education), social factors (culture, tradition, family, peers, meal patterns), psychological factors (mood, stress, quilt), attitudes, beliefs and knowledge about food¹⁴. Considering these facts, it was aimed to present fermented milk products intake by Turkish and Polish students, as well as estimation of the products consumption, assessment of factors, which have an influence on the purchase and verification if there is any difference in fermented milk products intake, knowledge about them and consumer preferences between Polish and Turkish students of dietetics.

MATERIAL AND METHODS

RESULTS

Participants

Out of the 651 sampled students from two universities, 343 students (162 Polish and 181 Turkish students) responded voluntarily. 90.70% of Polish students and 87.80% of Turkish students were female (Figure 1).

Figure 1. Participant selection scheme 

DISCUSSION

In this study, plain yoghurt is the most frequently selected out of all fermented milk products. In the study of Kardas et al. (2016) addressing milk and dairy product intake in the region of Upper Silesia in Poland, the most frequently selected product was fruit yoghurt (over 65% of respondents)³. Similar results were obtained in the studies Najgebauer-Lejko and Sady (50%) (2015)¹⁵. These products are more frequently selected by the Turkish students. It should be remembered, however, that fruit products are poorer sources of calcium, phosphorus and protein than their plain equivalents, while they deliver more carbohydrates and energy¹⁶. O’Brien et al. (2017) concludes that fermented milk products are usually characterised by a high sensory value, but most consumers prefer less acidic products¹⁷. The SUM students are as eager to consume plain yoghurt as sour kefir. The IKCU students, however, choose plain products as well, but select flavoured ones or those that are less sour. According to Nergiz-Unal et al. (2017), this selection reflects changes in the nutrition of the younger population of Turkey, which in the future may lead to chronic metabolic diseases¹⁸.

In a study addressing the consumption of beverages in Turkey, products most frequently selected by young respondents were carbonated non-alcoholic beverages followed by ayran¹⁹. Middle-aged and older people selected ayran followed by black tea. By contrast with the younger generation, older participants prefer healthy traditional products¹⁹. Nearly 97% of the IKCU students in our study declare ayran consumption. Despite the availability of this product in Poland, it is still not popular, and its consumption is declared only by 7% of the SUM students.

Dried form of yoghurt or ayran is called "Drying yoghurt (Kurut)". Kurut, is made with plenty of milk generally in summer seasons and consumed in winter in eastern and southeastern region at villages and small towns, which is one of the dense consistencies of dairy products. Kurut is known to be used particularly in Turkish cuisine, regional cuisine in Eastern Anatolia²⁰. Kurut, in turn, is not consumed at all by the SUM students and only by few IKCU students. In Poland, this product is very rarely available, while in Turkey it is characteristic of the Anatolia region. The IKCU is in İzmir, in the Aegean region, where kurut may be less available.

The SUM students have fermented milk products for breakfast (61.11%), while the IKCU students for dinner (50.28%). Similarly, Selçuk et al. (2003) and Tarakçı et al (2015), concluded that Turkish students generally prefer to consume fermented milk products with meals^21-22. In the research of Kardas et al. milk or dairy products were most often consumed between meals (39.5%), and the lowest percentage of people (6.0%) consumed them to lunch³. From the other hand, Nergiz-Unal respondents consumed them to lunch, and rarely as a snack¹⁸.

Milk and fermented milk product intake is lower than recommended in both the Polish and Turkish students. Similarly, in the study of Şahinöz et al. (2017), it was determined that 30.0% of university students did not consume milk²³. According to the Turkish Guideline (2016), milk and dairy products should be consumed every day by people at all ages¹. Adults should have 3 servings of milk and dairy products a day, while children, adolescents and pregnant, breast-feeding and postmenopausal women should have 2-4 servings a day¹. Turkish guidelines as a one portion of products treats: 200mL of yoghurt, 240mL of home-made yogurt, 350mL of ayran, and 240mL of kefir. In contrast, Polish standards are: yogurt in a small package 50-125g, medium package 150-175g, large package 400-500g, and kefir small packaging 200g, large 400g²⁴. In the study, 140g of product was taken as a portion. Both Polish and Turkish students responded by consuming 1 portion of the product (140g) per day. Their consumption is too low and will not provide the body with all the necessary nutrients in the right amounts. The Turkish Guideline (2016) has stated the mean intake of fermented milk products. The respondents who consumed a lower amount than that covering calcium requirement according to the EAR had 57g of yoghurt, which constitutes 0.3 of a serving. Individuals who consumed the amount of the product covering the calcium level according to the EAR had 191g of yoghurt, i.e. 0.8 of a serving¹. Both the data from the present study and from other Polish and Turkish investigations indicate that the intake of fermented milk products is too low.

Furthermore, weekly intake is also insufficient. In spite of the fact that the IKCU students more frequently than the Polish students consume fermented milk products weekly, the guidelines mention daily intake, which is not observed in the studied population. Most of the SUM students consume fermented milk products 2-3 times a week, while the IKCU declare their intake 4-5 times a week. The Turkish Guideline, on the other hand, refers to statistical data according to which 62.5% of respondents consume fermented milk products every day or 5-6 times a week, 16.6% every other day, 14.5% once a week and 6.4% once or twice a month or never¹. Occasional intake is declared by 6.17% of the SUM students and 7.70% of the IKCU students. A Croatian study using a frequency questionnaire showed that the consumption of dairy products was also rare. 12% of women declared consumption of these products less than once a month²⁵. The knowledge and awareness of the important role of the products, is expected from dietetics students. Unfortunately, less than 30% of IKCU students and less than 22% of SUM students consume fermented milk products every day. Considering the frequency and amount of fermented dairy products consumed, it can be concluded that too low intake may not cover the calcium requirement.

The students who avoid consumption of some fermented milk products said that the reason is their taste (74.2% for SUM and 69.4% for IKCU), sometimes also price (36.3% for SUM, 25.9% for IKCU) or feeling unwell after consumption (less than 15% in both groups). Similarly, in the study of Yabancı Ayhan et al. (2018), dislike to drink milk is the most common cause with a rate of 54.1%²⁶. This is not a proper nutritional habit. A decision not to consume fermented milk products may result in deficiencies of important nutrients, such as high-quality protein, calcium, phosphorus, zinc and vitamins B, A, D, E and K⁴.

Almost 40% students of SUM (n_SUM=64), and less than 20% students of IKCU (n_IKCU=32) do not feel the beneficial effect of consuming fermented milk products. Most of respondents (47.53% for SUM and 64.64% IKCU) noticed favorable changes in the functioning of the digestive system. Indeed, regular consumption of fermented milk products helps shorten intestinal transit and maintain the beneficial composition of the intestinal microflora, as well as lower the pH in the large intestine, which inhibits the development of putrefactive and invasive pathogenic bacteria, preventing intestinal infections^8,10. Polish students observe the lowest impact on the appearance of the skin, and Turkish students on the faster weight loss process.

The most common products selected by the SUM students were those without colour additives and preservatives. Owing to the development of the food industry, the use of preservatives for improving shelf life has increased. The Turkish food code does not allow any preservatives in yoghurt even though this fermented milk product is characterised by short shelf life. Turkish students should follow their Polish colleagues’ example and check for the presence of added preservatives since, despite the prohibition, some manufacturers do use e.g. natamycin (colourless, tasteless, flavourless and almost insoluble in water) as a preservative to prevent the development of yeast and moulds in yoghurt. Yeasts are commonly used in yoghurt production, but an increase in lactic acid bacteria induces pH reduction, thereby contributing to an increase in the count and development of yeasts that cause the product spoilage²⁷. Bilgic Alkaya and Karalomlu (2016) have demonstrated that 28 yoghurts found in Turkish supermarkets contained natamycin, which is unacceptable as per the Turkish food code²⁷.

Despite of decision to be a student of faculty related with health and its protection, 30% of Turkish students do not read product labels and give the lack of interest as the reason. Students leading a healthy lifestyle and, above all, paying attention to it, set a good example for their patients and are more credible to them. Respondents who declared the habit of reading labels constituted a group of 148 among SUM students and 128 respondents among IKCU students. The factor that Polish respondents pay the most attention to is the presence of added substances, while Turkish respondents pay the most attention to the energy value of the product. The least important factor in both groups is the amount of carbohydrates. In the European profile of nutrients, the WHO (1995) has specified the upper limit of sugar content in yoghurt at 10g per 100g of the product²⁸. In light of this information, the fact that students of nutrition choose natural products with low carbohydrate content seems positive. However, they should be paying more attention to their composition while reading the labels.

In order to get to know the factors deciding about purchasing of fermented milk products, the respondents were requested to rank the following factors like: composition, quality, flavour, recommendation by health associations, price, manufacturer, packaging and advertisement. The rank was done by assiging specific point values from 1 to 8, where 1 was the most important factor and 8 the least. A given point value could be assigned once. For SUM students, the most important factor is the composition of the product, followed by: quality, taste, health organization recommendations, price, manufacturer, packaging and advertising. IKCU students put price first, followed by quality, packaging, manufacturer, product composition, health organization recommendations, taste and advertising. Polish and Turkish students awarded the same point value for product quality (2^nd place) and advertising (8^th place). As for the assessment of price and availability of fermented milk products, the opinions of the SUM and IKCU students vary. The students in the two groups agree in terms of the quality of fermented milk products, and consider it to be good. Also, both groups believe that advertisement is present to a moderate degree.

The Shapiro-Wilk test found that the distribution does not meet the assumption of a normal distribution (p<0.05), and the differences between the answers of SUM and IKCU students are statistically significant. Only in the case of the responses “health organization recommendations” and “price” there are no statistically significant differences.

There are limitations associated with web based research. These include limitations in participation and methodological issues.

CONCLUSIONS

In conclusion, plain yoghurt is a frequently chosen product by both the SUM and IKCU students. Typical Turkish fermented milk products are more popular amongst the Turkish respondents. Flavoured yoghurts are more often chosen by the Turkish respondents than by the Polish ones. Their “bio” equivalents are less popular than their basic versions in both groups. There were differences between the respondents in terms of times of the day, amount and types of consumed fermented milk products. Moreover, factors preconditioning their selection vary between the two groups. Cultural differences concerning fermented milk products are reflected in eating habits and consumer preferences.