Valorization of second cheese whey for lactic acid production via mixed microbial culture fermentation

Lactic acid (LA) is a valuable compound with rising demand, particularly for biodegradable plastics production. Conventional LA production relies on lignocellulosic feedstocks, which are costly and require intensive pretreatment. In this respect, second cheese whey (SCW), a byproduct of ricotta production, may represent a sustainable and underexploited alternative. This study explores LA production from raw SCW using its indigenous microflora, without external inoculum or nutrient addition. Anaerobic batch fermentations were conducted at 39 °C and pH 5, 6, and 7. The highest LA yield (0.75 g/g carbohydrates) was achieved at pH 6 after 48 hours. These results confirm the feasibility of LA production from dairy byproducts and support sustainable fermentation strategies within circular bioeconomy frameworks