Using Kluyveromyces marxianus for biotechnological valorization of goat milk whey

Abstract

Whey is one of the most polluting substances in the World. Several studies have focused on using whey to generate single-cell protein, especially in cows. This study aimed to determine the effect of adding Kluyveromyces marxianus to raw and pasteurised goat whey on the pH and the gross chemical composition after 48 hours of incubation. Two bottles (500 mL) of goat whey were collected for three consecutive days to get three technical replicates. Every day, one bottle was autoclaved at 120 °C and 1 bar for 15 minutes and stored at 4 °C for 24 hours (pasteurised goat whey). The other bottle was immediately stored at 4 °C for 24 hours (raw goat whey). After this time, both bottles were inoculated with 40000 CFU of Kluyveromyces marxianus fragilis B0399® per mL and incubated at 35 °C for 0, 6, 24 and 48 hours. After this time, both pasteurised and raw goat whey were seeded on Brain-Heart Infusion (BHI) and Sabouraud Dextrose (SB) agar and incubated at 35 °C for 24 hours. After seeding, the pH of both was measured and the gross chemical composition determined. A two-way interaction was observed for the microbiological on the BHI (P=0.005) and SB (P<0.001) agars. Microbiological growth was higher in the raw goat whey than in the pasteurised goat whey in both culture media. A two-way interaction was observed for the pH (P<0.001). The pH was higher in the pasteurised goat whey than in the raw goat whey. Fat percentage was affected by treatment (P=0.004) but was not affected by incubation time (P=0.312). Fat percentage was higher in the pasteurised goat whey than in the raw goat whey. Neither protein, solids not fat nor total dry extract percentages were affected by treatment (P>0.107) and incubation time (P>0.368). In summary, adding K, marxianus to both raw and pasteurised goat whey lowers the pH after 48 hours of incubation, without altering its chemical composition. This study contributes to the potential use of K. marxianus to goat whey to generate single-cell protein for animal feeding. Thus, this study set the path for future research on the field.