# Effect of Sea Buckthorn (_Hippocampae rhamnes_ L.) Mousse on Properties of Probiotic Yoghurt
## 1 Introduction  
Dairy products, and in recent years, yoghurt in particular, are important components of the human diet. For this reason, manufacturers of dairy products are making an effort to meet the needs and expectations of the contemporary consumer by offering a growing assortment of products [1, 2]. Consumers increasingly consider the quality of fermented milk products [3, 4, 5], and expect a high level of innovation. Chemically, yoghurt is a complex gel system incorporating protein, lipids, and polysaccharide in its structure. According to the definition given by the FAO/WHO, yoghurt is milk that has been fermented and coagulated using _Lactobacillus delbrueckii_ subsp. _bulgaricus_ and _Streptococcus thermophilus_ bacteria [6]. Itshould be mentioned that _Str. thermophilus_ bacteria primarily produce lactic acid, while _L. delbrueckii_ subsp. _bulgarcius_ are responsible for the aroma of yoghurt [7; 8; 9]. Lactic acid fermentation is one of the oldest and most widespread methods for preserving milk. Among the food, yoghurt most frequently contains probiotics [10], which are defined as \"live microorganisms, which when administered in adequate amounts confer a health benefit on the host\" [11]. Lactic acid bacteria, mainly from the genera _Bifidobacterium_ and _Lactobacillus_, are widely recognised as probiotics, as they commonly possess probiotic characteristics. These genera are usually assigned the generally-recognised-as-safe (GRAS) status, which indicates low or no health risk to the host upon consumption, with positive health effects [10; 12; 13]. Probiotic bacteria that are added to yoghurts colonize the human gut, thereby increasing immunity, reducing the effects of lactose intolerance, and protecting against diarrhoea and constipation. They also facilitate the absorption of minerals (iron and calcium) and vitamins [12; 14]. Yoghurt is recommended for children, people with allergies or digestive disorders, the elderly, and patients undergoing antibiotic treatment [12; 14; 15; 16]. The human body digests yoghurt three times faster than milk [17]. Producers increasingly often meet the expectations of consumers and enrich fermented milk beverages with plant additives. The application of additives primarily affects the sensory features of the final product, i.e., flavour, aroma, colour, and consistency, as well as texture and storage capacity. According to the idea of functional food, a plant additive also increases the content of bioactive compounds. When assessing the perceived quality of fermented dairy products, the most important are consumer quality attributes, i.e., sensory characteristics, mainly flavour, as well as availability, especially packaging and convenience of use, which determine the purchase decision. Healthiness, including product composition, is becoming increasingly important, especially among more informed consumers, taking into account not only the basic nutritional value, but also the content of biologically active ingredients positively influencing the human body. Therefore, fermented milk drinks enriched with plant additives may be more attractive to consumers, also contributing to increasing the market offer [2; 4]. In the recent years, it has been reported that fortification of yoghurts using natural resources (fruits, vegetables, cereals, nuts, seeds, oil, botanical or herbal extracts, fibre from fruits or vegetables, fruit processing wastes, and whey protein isolates) is necessary to improve its quality and bioactivity, including nutrient intake with minimal health side effects [2; 18; 19; 20]. However, the base is natural, plain yoghurt, which should be of good quality. In our research, we proposed sea buckthorn (_Hippocampae rhamnoides_ L.) as a new yoghurt additive. Sea buckthorn was known already in ancient Greece, where it was used as a medicine for horses. Its Latin name comes from Greek (hippos-horse, phao-shine).