Physicochemical hazes that appear during storage of clear apple-based beverages are a concern for producers. Since the turbidity are among determinant quality parameters of this beverage, there is a need to better understand the aggregation phenomena that lead to the formation of visible aggregates. Among apple-base beverages, pommeau is a traditional mistelle obtained by adding apple spirit to apple must, subject to haze formation. Pommeau is also a good example of polyphenols and ethanol rich system but poor in proteins and polysaccharides and, in these respects, similar to Port wines. The effect of thermal stress was first investigated on turbidity of Pommeau. Samples were subjected to temperature drop-jump cycles and studied by DLS. Results showed that the formation of Pommeau haze was reversible upon heating, revealing a non-covalent nature of the interactions. The composition of pommeau haze was analysed in order to determine which families of compounds are responsible for their formation. The results revealed that procyanidins were the main polyphenols quantified in pommeau hazes [1]. A part of the haze remained unexplained by the analyses. However, several markers of the oxidised polyphenols were identified in haze suggesting that oxidation of phenolic compounds contributes to its formation in pommeau. Model solutions were designed to mimic pommeau hazes in order to decipher the mechanisms by which oxidised phenolic compounds contribute to the formation of haze [2]. Oligomeric procyanidins alone have the ability to self-aggregate after oxidation in model solution and the reversibility upon heating was very similar to that observed for real pommeau. The degree of polymerization as well as the level of oxidation determine the kinetics of aggregation. Chemical markers of procyanidins oxidation were also investigated in the model system using LC-MS analyses revealing that both intra and intermolecular oxidative coupling were involved in the formation of aggregates. These findings allowed to support the dominant role of oxidized phenolic compounds in formation of haze in Pommeau, and probably in other similar drinks [3]. This knowledge has been also used to improve curative or preventive treatments for colloidal instability. [1] Millet M., Poupard P., Le Quere J.-M., et al., Journal of Agricultural and Food Chemistry, 65, 6404- 6414, 2017. [2] Millet M., Poupard P., Guilois-Dubois S., et al., Food Chemistry, 276, 797-805, 2019. [3] Bauduin R., Poupard P., Cottereau, P., et al., Innovations Agronomiques, 79, 49-59, 2020.