## 1 Introduction  
Fermented milk products, such as yogurt, cheese, and kefir, have played a pivotal role in human nutrition and culture since ancient times. These foods are the result of milk fermentation by beneficial bacteria and yeasts. This process not only enhances longevity and safety by inhibiting spoilage and pathogenic microorganisms but also improves nutritional value and digestibility [1, 2]. Throughout the world, around 400 generic names are applied to traditional and industrialized fermented milk products, underscoring their deep entwinement with regional culinary traditions. Despite the diversity in nomenclature, these products often share core characteristics, leading to a more concise classification based on the type of milk used, the dominant microbial flora, and their principal metabolites. Such classifications include lactic fermentations, yeast-lactic fermentations, and mold-lactic fermentations [2]. The art of fermenting dairy milk has been honed over centuries, with the role of lactic acid bacteria (LAB) in this process thoroughly characterized by the scientific community. However, as the world pivots towards plant-based diets, the intricate molecular characteristics of fermenting plant-based beverages remain little explored. Current trends indicate a shift in consumer preference towards plant-based dairy alternatives. This shift is partly attributed to considerations of dairy farming's environmental impact, ethical concerns,and health issues such as lactose intolerance [3]. While plant-based options are becoming more popular, they still face challenges in mimicking the sensory and textural qualities of traditional dairy products. The global dairy alternatives market, valued at USD 26.01 billion in 2022, is projected to grow at a robust CAGR of 12.6% from 2023 to 2030. This growth is propelled by evolving consumer preferences, with an increasing demand for plant-based options such as soy, almond, and rice beverages. The market is also witnessing a surge in demand for nutritional dairy alternatives, driven by consumers seeking low-calorie, high-protein, and vitamin-rich options. This shift towards dairy alternatives is not only a result of changing diets and eating patterns but also reflects a growing interest in sustainable and ethical food choices [4]. Fermented milk products are esteemed not only for their nutritional richness but also for their distinctive sensory properties, of which aroma plays a crucial role in consumer acceptability. This attribute is predominantly determined by a variety of volatile compounds, often at low concentrations, which are the result of intricate biochemical transformations of carbohydrates, lipids, and proteins conducted by the action of starter bacteria. For example, fermented milk has been suggested to contain over 100 different volatile compounds, with specific cultures producing signature flavors, such as acetaldehyde in yogurt or diacetyl in butter and buttermilk [5; 6]. The volatile composition of such products is influenced by multiple factors, including the milk source, fermentation by specific bacterial species, and the subsequent processing and storage conditions. The volatile aroma compounds of dairy yogurts have been studied extensively during the last decades through gas chromatography-mass spectrometry (GC-MS). In contrast, research on plant-based fermented dairy alternatives has been more limited, primarily focusing on texture and potential probiotic properties [7; 8; 9; 10]. A comparative study has shown that ketones were the main volatile flavor compounds across dairy, soy, and oat-based yogurts. The volatile profiles of dairy and oat-based yogurts were relatively similar, whereas soy-based yogurt was distinctly different, with high odor activity values of hexanal, 1-octen-3-one, 1-octen-3-ol, and 2-octenal [11]. Rice beverages fermented using different LAB strains showed 47 different volatile compounds, including acids, aldehydes, esters, furan derivatives, ketones, alcohols, benzene derivatives, hydrocarbons, and terpenes [12].