Evaluation of a Lactobacillus biopreservative on milk cake quality: Effects on physicochemical, microbiological, and flavor properties

This study investigated the effectiveness of preservation films derived from two Lactobacillus biopreservatives in maintaining the freshness of milk cake. The biopreservatives, fermented whey and its cell-free supernatant (CFS), were produced synergistically by high-exopolysaccharide (EPS)-producing Limosilactobacillus fermentum A51 and high-phenyllactic acid (PLA)-producing Lactobacillus plantarum L3. Both biopreservatives, rich in EPS (412.91–429.33 mg/L) and PLA (69.24–70.55 mg/L), showed strong antioxidant and antibacterial activity. EPS formed a stable protective film on milk cake surfaces, effectively retarding declines in pH, moisture, texture, and lightness, while inhibiting acidity and color changes during storage. Sensory shelf life extended from 21 to 28 days. After 28 days, total viable counts were significantly lower in treated groups (6.65–6.69 Log CFU/g) than controls (6.94 Log CFU/g), with yeast/mold also reduced. Spoilage genera ( Pseudomonas , Mucor ) and off-flavors (2-propanol, acetic acid) were suppressed. Therefore, this Lactobacillus biopreservative provides an effective and natural method for preserving the freshness of milk cake.