Li-Cor de Oro (or Gold Liqueur; LO) is a traditional alcoholic beverage produced in Chiloé island, Chile. LO is made by mixing milk, alcohol (usually aguardiente, a distilled alcohol from wine) and sugar at a ratio of 1.0:1.0:0.7, along with lemon juice and other spices (such as vanilla, cloves and saffron), leading to a phase separation. The mixture is stored up to 2 wk and then filtered to obtain a product with a yellowish-transparent appearance, sweetness and acidic taste, milky and alcoholic notes and slightly viscous. The principle used to make LO is based on the destabilization of caseins (CN) due to the presence of alcohol in acidified milks. The lack of information regarding LO processing, mainly in the amount of acid added to the mixture, leads to products with high variability on their quality. The objective of this study was to evaluate the effect of milk acidification on the physicochemical and sensory properties of LO. Independent batches of raw milk (1 L) were acidified using 25% (vol/vol) citric acid to 6 different pH values: 6.7 (control), 6.0, 5.3, 4.6, 3.9 and 3.2. Each milk treatment was then mixed with 1 L of aguardiente (50% vol/vol ethanol), 700 g of sucrose and other minor ingredients (vanilla and almond extracts, cloves, and saffron). The mixtures were then filtered using filter paper after 2 wk of storage and the filtrates (LO) were further analyzed for composition, viscosity, turbidity and descriptive sensory analysis (12 trained panelists). As expected, a decrease of milk pH led to LO with higher levels of acidity (P < 0.05). LO obtained at pH 6.7 and 6.0 exhibited higher (P < 0.05) levels of total protein than other treatments, leading to a higher turbidity and viscosity (P < 0.05) when determined by instrumental and sensory analysis, which could be attributed due to the presence of CN as confirmed by protein analysis using HPLC. In contrast, treatments made at pH ≤5.3 had a typical transparent appearance of LO, because CN were not detected. These results suggest that a combined ethanol and acid concentration in milk is necessary to destabilize CN and obtain a desired appearance and composition on LO.