Lactobacillus plantarum IN DEVELOPMENT OF ARTISANAL GOAT’S MILK CHEESE FLAVOUR FROM SANTIAGO DEL ESTERO, ARGENTINE

N. TABOADA, M. MOLINA, MEDINA R.B. , S. LÓPEZ ALZOGARAY

Tucumán

Simposio; III SIMPOSIO INTERNACIONAL DE BACTERIAS LÁCTICAS; 2009

rtisanal goat’s milk cheeses are elaborated with raw milk, artisanal rennet and without starter cultures. However these cheeses present typic organoleptic characteristics than are acceptably by customers.  Flavour development in cheese results from the metabolic activities of cheese bacteria, by glycolysis, proteolysis, lipolysis and citrate metabolism.  Lactobacillus plantarum was the most frequently isolates species from artisanal goat’s milk cheese. The purpose of the present work was to determine biochemical properties of lactobacilli, which are relevant to development cheese flavour. A total of 10 L. plantarum strains were screened for biochemical properties relevant to flavour production, acidification ability in powder skimmed milk, proteolytic activity, citrate utilization and diacetyl-acetoin production in milk. The enzymatic profiles were obtained with the system API Zym. The acidification curve for miniature scale cheesemaking with each strain was obtained according to previous protocols, the strains were inoculated at 1%, animal rennet F= 1:10000, was used.         APY Zym test showed the lactobacilli strains exhibited important esterase (C4) (10-20 nM of chromophore released, CR) and esterase-lipase activities (C8) (20-30 nM CR). High levels of the aminopeptidases of leucine, valine, cystine (30-40 nM CR) were observed for all lactobacilli. The strains degraded phosphates in acid medium (acid phosphatase and phosphohydrolase activities, 30-40 nM CR) and metabolized lactose (β-galactosidase, 20-40 nM CR). Trypsin and α-quimotrypsin (5-10 nM CR) and lipase (0-10 nM CR) presented low or null average values. The presence of weak proteinases, high peptidases and esterases-lipases are the desirable traits for the use of these strains in production of cheese flavorings. Cheese starter with low proteinase and strong peptidase activities are also useful in reducing bitterness. “Soapiness” defect acused by the accumulation of long-chained fatty acids can be removed by using strains with strong estearase and lipase activities. All strains were able to utilize citrate in solid medium. The diacetyl and acetoin production in milk was observed for all strains. Lactobacillus plantarum  243 and 186 exhibited low proteolytic activity.  Strains 213 and 243 are considered slow variants, however they exhibited fast goat milk acidifying ability, they have acidified and decreased goat’s  milk pH ~ one unit after 5 h at 40 °C. Other strains did not exhibited fast goat milk acidifying ability.  These biochemical properties would allow that L. plantaum strains may be usefull as adjunct cultures. The results show that these lactobacilli possesses a metabolic potential to contribute in the development of cheeses flavour.Additional studies are required for a complete characterization of these autochthonous Lactobacillus plantarum strains.