Journal of Food Processing and Preservation

In this study, the effects of homogenization (0 and 20 MPa) and milk type (sheep and sheep/cow mixture) on the kinetic changes of selected minerals (Ca, Mg, K, Zn, and Fe) in winter yoghurt samples stored at 4°C for 90 days were investigated.Mineral composition changes were determined using an inductively coupled plasma-optical emission spectrometer (ICP-OES) at various storage times (0, 7, 15, 30, 60, and 90 days).A first-order kinetic model, exhibiting R 2 values ranging from 0.9165 to 0.9994, was determined to be the best fit for the mineral contents of the winter yoghurt samples.Changes in mineral concentration were primarily dependent on storage time, whereas homogenization and milk type exhibited mineral-specific effects.These findings provide insights into the stability and kinetic behavior of minerals within winter yoghurt during storage. | IntroductionYoghurt is a widely consumed fermented dairy product produced through lactic acid fermentation of milk using specific starter cultures.Among fermented foods, it is considered one of the most popular worldwide, with particularly high levels of production and consumption in Mediterranean regions, several Asian countries, and Central Europe.Although the precise origin of yoghurt remains uncertain, historical evidence suggests that it was first developed in the Middle East [1].Yoghurt was first produced by the Turks during their presence in Central Asia, and the product was named “yogurt.”Today, yoghurt has achieved international recognition under this name, although in many countries it is commonly spelled as “yoghurt” [2, 3].The widespread popularity and high consumption of yoghurt can be attributed to its rich nutritional value and the beneficial effects of starter cultures during fermentation.The shelf life of yoghurt is relatively short, typically limited to 1 day at 25°C-30°C, 5 days at 7°C, or up to 10 days at 4°C according to the Turkish Standards for plain yoghurt.To overcome this limitation, various traditional and technological approaches have been developed in Türkiye, such as water removal by straining or sun-drying yoghurt [2].In Türkiye, various types of traditional strained or concentrated yoghurts, including kurut, torba yoghurt, tulum yoghurt, peskuten, and winter yoghurt, are widely consumed.These products, prepared from different milk sources, are considered significant dietary sources of minerals such as phosphorus, calcium, magnesium, selenium, and zinc compared with conventional yoghurts and whey-based products.[4].Most sheep milk produced worldwide is processed into cheese.Although some sheep milk yoghurt is made in Greece, fresh sheep milk is rarely consumed.Therefore, when referring to the quality of sheep milk, emphasis is primarily placed on its ability to be converted into high-quality dairy products and its capacity to yield substantial quantities of these products per liter.This characteristic, commonly referred to as the processing performance of milk [5], is primarily attributed to the inherently higher protein, fat, and total solids content of sheep milk compared with cow or goat milk.In Eastern Anatolia, this is reflected in the production of winter yoghurt and strained yoghurt, typically made from sheep milk; however, when supply is