Yacon juice as culture and cryoprotectant medium for Latilactobacillus sakei and Staphylococcus vitulinus autochthonous strains

Abstract Yacon is mainly constituted of water and carbohydrates [single sugars and fructooligosaccharides (FOS)], thus being an excellent alternative for the growth and preservation of bacterial culture. Latilactobacillus sakei ACU-2 and Staphylococcus vitulinus ACU-10 comprised the autochthonous starter culture SAS-1 designed for the manufacture of dry sausages. This study evaluated the use of yacon juice as a potential growth medium and cryoprotectant for these bacteria. The growth medium was prepared with yacon juice supplemented with peptone and dipotassium phosphate. After growing, cells were resuspended in yacon juice (5, 10 and 25 mL/100 mL) and lyophilized. Viable cells were count before, immediately after lyophilization, and along 6 months of refrigerated storage. Both bacteria grew in every yacon concentration tested; however, juice concentration affected their growth. Latilactobacillus sakei grew at μ = 0.256 ± 0.01 giving the highest bacterial density at 10 mL/100 mL (Log DOmax 0.33 ± 0.01). While 5 mL/100 mL yacon juice provided the best conditions for S. vitulinus growth (μ = 0.215 ± 0.016; Log DOmax 0.32 ± 0.01). After lyophilization, the survival rate was 91.1% for L. sakei and 65.8% for S. vitulinus. Throughout storage, high cell counts suggested good stability of both bacteria. Results revealed that yacon juice comprises a nutritive substrate for the growth and cryopreservation of tested strains from the genus Latilactobacillus and Staphylococcus. Resumo O yacon é constituído principalmente por água e carboidratos (açúcares simples e fruto-oligossacarídeos), sendo uma excelente alternativa para o crescimento e a preservação da cultura bacteriana. Latilactobacillus sakei ACU-2 e Staphylococcus vitulinus ACU-10 compuseram a cultura starter autóctone SAS-1, destinada à fabricação de embutidos secos. Este estudo avaliou o uso do suco de yacon como potencial meio de crescimento e crioprotetor para essas bactérias. O meio de crescimento foi preparado com suco de yacon suplementado com peptona e fosfato dipotássico. Após o crescimento, as células foram ressuspensas em suco de yacon (5, 10 e 25 mL/100 mL) e liofilizadas. As células viáveis foram contadas antes e imediatamente após a liofilização, e ao longo de seis meses de armazenamento refrigerado. Ambas as bactérias cresceram em cada concentração de yacon testada; no entanto, a concentração de suco afetou seu crescimento. Latilactobacillus sakei cresceu a μ = 0,256 ± 0,01, dando a maior densid