Applicability of Lactococcus hircilactis and Lactococcus laudensis as dairy cultures

• Published in: International journal of food microbiology 2018-04, Vol.271, p.1-7
• Main Authors: Tidona, Flavio, Meucci, Aurora, Povolo, Milena, Pelizzola, Valeria, Zago, Miriam, Contarini, Giovanna, Carminati, Domenico, Giraffa, Giorgio
• Format: Article
• Language: English
• Subjects: Acetic acid; Acetoin; Antioxidants; Bacteria; Carbon sources; Cheese industry; Cheese starters; Citric acid; Dairy products; Dairy technology; Diacetyl; Ethanol; Exopolysaccharides; Flavor; Flavors; Folic acid; Galactose; Lactic acid; Lactococcus hircilactis; Lactococcus laudensis; Lactose; Milk; Phenotypes; Product testing; Proteolysis; Starter cultures; Strain characterization; Sugar
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2018.02.015

The aim of this study was to evaluate whether Lactococcus hircilactis and Lactococcus laudensis can be used as starter cultures. To this end, the two lactococci were characterized for traits of technological and functional interest. Tests in milk included growth at 20, 25, 30, and 37 °C, flavor production, antioxidant (AO) activity, folate and exopolysaccharide (EPS) production. At 30 °C, which resulted the best growth temperature for both strains, Lc. hircilactis and Lc. laudensis lowered the pH of the milk to 4.8 and 5.5, respectively, after 24 h of incubation. Sugar and organic acid composition indicated a higher lactose utilization, coupled with a higher lactate accumulation, by Lc. hircilactis, while galactose was completely consumed by both species. Both strains showed a Cit− phenotype after growth in a selective medium containing citrate as the sole carbon source. Nevertheless, a small amount of citrate was used by both lactococci when grown in milk. The two strains were characterized by a different flavor production, showed high AO activity, and produced small amounts of EPS (~30 mg/L). Lactococcus laudensis showed a weak proteolytic activity while Lc. hircilactis was able to accumulate folate at levels four times higher than uninoculated milk. When the two lactococci were tested as starter cultures in small-scale cheesemaking trials, cheeses resulted of satisfying quality and contained amounts of ethanol, acetic acid, diacetyl and acetoin higher than controls, obtained using a commercial culture. The application of Lc. hircilactis and Lc. laudensis as aromatic cultures in cheesemaking is proposed. •Search for dairy cultures with expanded technological properties to increase product quality and diversification.•Selection of starter lactic acid bacteria within wild strains and applicability of new lactococcal species in dairy products.•Lactococcus hircilactis and Lactococcus laudensis show phenotypic features of potential interest for a dairy application.•Testing of Lactococcus hircilactis and Lactococcus laudensis as acidifying and/or flavoring cultures in cheesemaking.