Aerobic Cultivation of Mucor Species Enables the Deacidification of Yogurt Acid Whey and the Production of Fungal Oil

Abstract

As the Greek-style yogurt market continues to experience prosperous growth, finding the most appropriate destination for yogurt acid whey (YAW) is still a challenge for Greek yogurt manufacturers. This study provides a direct alternative treatment of YAW by leveraging the abilities of Mucor circinelloides and Mucor genevensis to raise the pH of YAW and to produce fungal biomass with a high lipid content. Aerobic cultivations of these species were conducted in YAW, both with and without the addition of lactase, at 30 °C, and 200 rpm agitation. The density, pH, biochemical oxygen demand (BOD), biomass production, lipid content, fatty acid profile, and sugar and lactic acid concentrations were regularly measured throughout the 14-day cultivations. The data showed that M. genevensis was superior at deacidifying YAW to a pH above 6.0—the legal limit for disposing of cultured dairy waste. On the other hand, M. circinelloides generated more fungal biomass, containing up to 30% w/w of lipid with high proportions of oleic acid and γ-linolenic acid. Additionally, the treatments with lactase addition showed a significant decrease in the BOD. In conclusion, our results present a viable treatment to increase the pH of YAW and decrease its BOD, meanwhile generating fungal oils that can be further transformed into biodiesel or processed into functional foods or dietary supplements.

Effect of Yogurt Acid Whey on the Quality of Maize Silage

“…The increased demand for strained yogurt creates a considerable volume of acid whey, as for every 100 L of milk used, 70 L of yogurt acid whey is produced [20] that must be either disposed of or repurposed. Recent research has focused on alternative uses for yogurt acid whey in food processing [21][22][23] and in microbial cultivation [24]. Given the main ingredients of yogurt acid whey, including lactose (40 g/kg), organic acids (lactic acid, 6.5 g/kg, citric acid 1.8 g/kg) functional proteins (e.g., β-lactoglobulin, α-lactalbumin, lactoferrin) and minerals (potassium, >1500 mg/kg, calcium, >1200 mg/kg and phosphorus, >600 mg/kg), with pHs of 3.5-4.5 [21,25], its use as a silage additive/component merits investigation.…”