## 1 Introduction  
Fruit wine brewing is a complex microbial metabolic process in which the intermediate and final products generated during fermentation play a crucial role in determining the aroma, flavor, and overall quality of the wine [1]. In addition to the chemical composition of the raw materials, the yeast species and their metabolic characteristics also profoundly influence fruit wine quality [2]. During fermentation, various compounds from the raw materials are released and transferred into the wine, with many key aroma compounds being formed under the metabolic activity of yeast [3]. Currently, _Saccharomyces cerevisiae_ is widely employed in fruit wine production due to its excellent fermentation performance and strong ethanol tolerance [4]. However, in the production of high-acidity fruit wines (pH 2.5-3.0), the growth of _S. cerevisiae_ is inhibited below pH 3.0, resulting in reduced -fermutation activity and a decline in wine flavor complexity and sensory quality [5]. Consequently, under high-acidity conditions, the fermentation performance of _S. cerevisiae_ may be restricted, ultimately affecting the final quality of the fruit wine. Therefore, screening and selecting yeast strains with superior acid tolerance has become a critical research focus for improving the flavor and quality of high-acidity fruit wines. In recent years, the selection and application of acid-tolerant non-_Saccharomyces_ yeasts have emerged as an effective strategy for optimizing the production of high-acidity fruit wines. Non-_Saccharomyces_ yeasts have garnered increasing attention due to their ability to enhance flavor complexity and modulate aroma profiles [6; 7; 8]. Different non-_Saccharomyces_ yeasts typically exhibit distinct metabolic advantages. For instance, _Torulaspora delbrueckii_ and _Metschnikowia pulcherrima_ are known for their capacity to regulate ester and higher alcohol metabolism, thereby enhancing fruity and floral characteristics [9; 10]. Among these, _Pichia kudriavzevii_ has been identified as a highly adaptable non-_Saccharomyces_ yeast that can maintain robust growth activity under acidic conditions (pH 3.2-4.0) [11]. Studies have demonstrated that _Pichia kudriavzevii_ optimizes the flavor profile of fruit wines through specific metabolic pathways [12], promoting the accumulation of esters such as ethyl acetate and ethyl hexanoate, while reducing higher alcohols (e.g., isoamyl alcohol, phenylethanol) and volatile acids (e.g., acetic acid, hexanoic acid), thus contributing to a more balanced and harmonious wine profile [13; 14]. In fruit wines, ester compounds are crucial determinants of their aroma and flavor profiles [15; 16]. Non-_Saccharomyces_ yeasts can influence ester synthesis and degradation by regulating the expression of esterases or acetyltransferases [17; 18]. In white wine and cider systems, non-_Saccharomyces_ yeasts such as _Hansenispora warum_ and _Starmerella bacillus_ have been shown to enhance the production of key esters, including ethyl acetate, ethyl octanoate, and phenethyl acetate, thereby intensifying fruity and floral characteristics [19; 20]. Moreover, fermentation strategies such as co-fermutation and sequential fermentation can shape distinct metabolic pathways and flavor profiles. For example, using non-_Saccharomyces_ yeasts during the initial fermentation stage to promote ester synthesis, followed by _S. cerevisiae_ to complete sugar consumption, can effectively balance fermentation efficiency and the accumulation of aroma compounds [21; 22; 23]. Although _Pichia kudriavzevii_ has gradually gained applications in the food and beverage industries, research on its use in high-acidity fruit wines remains limited, particularly regarding its influence on aroma metabolism under extreme fermentation conditions. Sea buckthorn wine, known for its nutritional value and unique sensory characteristics, often suffers from excessive tartness and astringency due to its high acidity, which negatively impacts consumer acceptance and market potential.