## 1 Introduction  
There is currently an upsurge of interest in functional foods as consumers become more conscious of their health and seek dietary choices that offer additional benefits beyond basic nutrition. Functional foods consist of a variety of components, including vitamins, essential fatty acids, antioxidants, prebiotics and probiotics. Foods enriched with probioticmicroorganisms are considered the main part of the functional foods market. Defined by the FAO/WHO as \"microorganisms (bacteria or yeasts) which, when administered in adequate concentrations, provide health benefits to the host\", probiotics are gaining increasing scientific and industrial interest [1]. In recent years, there have been numerous reports on the biological effects exhibited by probiotics, including their role in digestion, production of immune-modulating bioactive compounds, detoxification of toxins, and influence on the activity of the gut-brain axis [2]. To confer health benefits, probiotic foods should contain high cell loads able to survive during gastrointestinal tract (GI) passage and colonize the gut epithelium. According to the International Probiotic Association (IPA), the recommended cell levels in the foods are 10\({}^{7}\) cfu/g at the time of consumption in order to achieve a daily dose of 10\({}^{9}\) cells, considering the consumption of 100 g product. However, maintaining such high cell loads during food processing and storage consists of a real bottleneck for the food industry. Hence, cell immobilization is recommended as an alternative solution to overcome such obstacles, as it has been reported that it may enhance cell survival rates and ensure cell stability [3; 4]. In addition, considering that the food industry favors dried products due to their prolonged shelf life, ease of storage and transportation, and cost-effectiveness resulting from the elimination of refrigeration needs, freeze-drying is commonly employed for delicate ingredients that require special care [5]. The selection of a suitable food carrier is of great importance, as it has a significant impact on the adhesion of cells and their ability to colonize the gut effectively [6], along with the sensory properties. Prebiotics, as non-digestible compounds that stimulate the growth or activity of beneficial bacteria in the gut, such as dietary fibers, seems a promising option. Pistachio nuts (_Pistacia vera_ L.) contain dietary fibers, and their administration to diabetic rats resulted in functional modulation of gut microbiota [7] and beneficial alteration in fatty acids profile [8]. Dairy products and especially cheese, have been commonly served as food vehicles for probiotics to the human gut due to their chemical and physical attributes, such as a low pH value and high tittatable acidity, contributing to enhanced transit tolerance of bacteria and facilitating the effective delivery of probiotics to the GI tract [9]. Katiki Domokou, also known as Tsalafouti, is a traditional soft cheese manufactured in the Domokos area in Greece from goat's and ewe's milk and has been recognized as a Protected Designation of Origin (PDO) since 1994. The process begins by pasteurizing and cooling the milk at temperatures 27-28 \({}^{\circ}\)C. Coagulation is then achieved with or without the addition of rennet, followed by a resting period at temperatures ranging from 20-22 \({}^{\circ}\)C. The resulting curd is subsequently filtered and placed into cloth sacks to allow drainage. Notably, during cheese manufacturing, no commercial starter cultures are usually employed. Instead, the manufacturing process relies mainly on the natural acidification of the milk, accomplished by inoculation with fresh product. Thus, the indigenous microflora is enhanced, contributing to the milk's acidification during the ripening phase. This practice helps to establish a desired microbial population that promotes the development of specific flavors and textures in the cheese as it matures.