Microbiological and Technological Characteristics of Natural Whey Cultures for Argentinian Hard-Cheese Production

Abstract

Samples (29) of natural whey starters used in the Santa Fe (Argentina) area for hard cheese production were examined. The microbial composition (including lactic microflora identification) and technological characteristics (acidifying and proteolytic activities) were determined. The cultures consisted mainly of thermophilic lactic acid bacteria belonging to the genus Lactobacillus. L. helveticus (66% the total strains) and L. delbrueckii subsp. lactis (33%) were the dominant species. In every sample, yeasts appeared as the only natural contaminants, at variable contents. The samples showed high acidity levels (1.2 to 1.4% lactic acid) with a mean pH value of 3.3. The acidifying and proteolytic activities were high at temperatures ranging from 37 to 50°C and negligible at 55°C.

Adventitious dairy Leuconostoc strains with interesting technological and biological properties useful for adjunct starters

“…Seven of the analyzed samples were derived from cheesemaking ingredients (WPC, pasteurized milk and whey cream), whereas seven samples were soft Cremoso Argentino cheeses with a blown defect. LAB were enumerated on milk plate count agar (Reinheimer et al 1995) and on de Man, Rogosa and Sharpe (MRS) agar (Biokar, Beauvais, France) and incubated at 32°C for 48 h in a microaerophilic atmosphere. In addition, nonspecific gas-producing bacteria were enumerated on MRS broth (Biokar, Beauvais, France) tubes (limit dilutions) containing Dürham tubes for gas visualization, after incubation at 32°C for 5 days.…”

“…Washed cells were then inoculated (2% v/v) into sterile, reconstituted (10% w/v), commercial dry skim milk (RSM, Milkaut, Santa Fe, Argentina) supplemented or not with casein hydrolysate (0.25%). Milk acidification kinetics were assessed by measuring the pH with a model SA 720 pH meter (Orion, Beverly, MA, USA), at the beginning of the assay and after 3, 5, 7, 8 and 24 h of incubation at 32°C (Reinheimer et al 1995). In addition, the acidity developed (24 h, 32°C) was measured by titration with 0.1 mol L −1 NaOH to pH 8.4, and it was expressed as percentage of lactic acid.…”

Perfil de ácidos grasos libres y características sensoriales de quesos reggianito elaborados con diferentes fermentos

“…Por esta razón, se han desarrollado numerosos estudios tendientes a preservar las ventajas de los fermentos naturales por un lado y minimizar sus efectos negativos por otro lado. En este sentido la inclusión de cepas seleccionadas en estos fermentos se ha empleado como una posible vía de solución al problema (Botazzi et al, 1999;Hynes et al, 2003;Reinheimer et al, 1995Reinheimer et al, y 1996.…”

“…Se elaboraron quesos control empleando suero fermento natural (SFN) y tres tipos de quesos experimentales con suero fermento natural, libre de microorganismos, inoculado individualmente con tres cepas de bacterias lácti-cas seleccionadas (Lh 133, Lh 138 y Lh 209) (Reinheimer et al,1995(Reinheimer et al, y 1996.…”

Free fatty acid profiles of Reggianito Argentino cheese produced with different starters

“…These starters, composed mainly of Lactobacillus helveticus and L. delbrueckii subsp. lactis, have some disadvantages such as variations in their microbiological composition and the presence of undesirable contaminants, mainly moulds and yeasts (Reinheimer, Quiberoni, Tailliez, Binetti, & Sua´rez, 1996;Reinheimer, Sua´rez, Bailo, & Zalazar, 1995). In order to avoid the disadvantages of natural whey cultures, but preserving the typical technology, the addition of single and mixed cultures of selected strains of L. helveticus grown in whey, has been proved in our laboratory (Candioti et al, 2002;Perotti, Bernal, Meinardi, Candioti, & Zalazar, 2004).…”