Investigation of Microbiological Quality and Chemical Properties of Ready-to-Eat Milk Jam

Milk jam (dulce de leche) is a dairy product obtained by boiling milk with sugar, characterized by high sugar concentration and low water activity. Consumption of this product, which has unique color, taste, and consistency, has been increasing in Türkiye in recent years. However, scientific studies examining the microbiological and chemical quality of milk jam are quite limited. This study aimed to determine quality parameters of milk jams on the Turkish market, evaluate results against relevant standards and provide comprehensive information about current product quality. Twenty packaged milk jam samples from different brands were analyzed. Chemical analyses included pH value, acidity in terms of lactic acid, dry matter content, fat content, reducing sugar, total sugar, and sucrose. Microbiological analyses included counts of Total Mesophilic Aerobic Bacteria (TMAB), psychrophilic bacteria, yeast-mold, lactic acid bacteria, Enterobacteriaceae, coliform bacteria, and proteolytic bacteria. Relationships between obtained data were evaluated by Pearson correlation analysis. Chemical results showed pH 7.54 ± 0.63 (6.70–8.99), acidity 0.49 ± 0.19%, dry matter 62.42 ± 8.85%, and fat 1.51 ± 1.50%. Sugar analyses revealed reducing sugar 17.25 ± 6.16 g/100 mL, total sugar 37.88 ± 8.67 g/100 mL, and sucrose 19.59 ± 8.74 g/100 mL. Microbiological analyses detected TMAB in 50% of samples (4.51 ± 1.91 log CFU/g), yeast-mold in 45% (3.92 ± 1.26 log CFU/g), Enterobacteriaceae in 30% (3.15 ± 1.26 log CFU/g), coliforms in 25% (3.63 ± 1.06 log CFU/g), and proteolytic bacteria in 55% (4.21 ± 1.57 log CFU/g). Positive correlation was found between pH and sucrose (r = 0.466, p ≤ 0.05), and strong negative correlation between dry matter and proteolytic bacteria (r = −0.732, p ≤ 0.05). Significant standardization deficiencies and microbiological quality problems were identified in milk jam samples. High pH values and the presence of hygiene indicator microorganisms indicate the need for HACCP system implementation and increased hygiene controls in production.