Growth of Debaryomyces hansenii on a bacterial surface-ripened soft cheese

Abstract

Experimental cheeses were prepared in triplicate from pasteurized milk inoculated with Debaryomyces hansenii under aseptic conditions. Three cheesemaking replicates, with efficient control of environmental parameters (temperature, relative humidity, atmospheric composition) showed similar ripening characteristics. Deb. hansenii grew only on the cheese surface, where its oxygen demand was satisfied, especially during the first 24 h (mean generation time, 5·8 h). Salting in a sterile saturated brine solution reduced its growth and decreased viability. Growth was slower after 48 h because of the decrease in ripening temperature (mean generation time, 94 h). The total count of Deb. hansenii was maximum (≈3×107 yeasts/mm2) after 6 d ripening and its viable cell concentration was ≈2×106cfu/mm2. This difference was due to the ‘non-viability’ of part of the population. The viable Deb. hansenii concentration was highly correlated (r2>0·95) with the lactate concentration in the inner part and with the surface and inner lactose concentrations, up to day 10 of ripening. This emphasized the importance of the diffusion of carbon substrate from the inner part to the surface of the cheese during ripening. The pH of the inner part depended significantly on the lactate and lactose concentrations. Surface pH was significantly related to inner lactate concentration, temperature and relative humidity. This also demonstrated the controlling role of carbon source diffusion.

Contribution of several cheese-ripening microbial associations to aroma compound production

“…Conversely, B. linens growth occurred latergenerally after 5 d of culture -and reached a plateau after d 10 or more, depending on the yeast it was associated With [24,25]. Lactose and lactate also exhibited similar degradation patterns to those observed during cheese ripening [23][24][25]. The starter used in this experiment -which is extensively used in soft cheese-making -is mostly composed of homofermenters, which explains the high quantity of lactate detected [12,13].…”

“…Prior to analysis, each culture suspension was thawed and mixed with 20 mL of distilled water. The mixture was homogenised (Ultra-Turrax ® , 25 000 rpm, 30 sec) after incubation at 50 °C for 1 h. The resulting homogenates were subsequently treated for either lactate or sugar measurements by HPLC as previously described [23].…”

The Composition of Camembert Cheese-Ripening Cultures Modulates both Mycelial Growth and Appearance

“…Because of its ability to grow adequately in a cheese matrix and to assimilate lactose, lactate, citrate, and galactose, D. hansenii is considered to be a good ripening yeast for the production of some cheese varieties (12,39,41). The first impact of adding D. hansenii, which is well known to accelerate pH increases through lactate and citrate catabolism, was faster alkalinization of the rind (9,20,21,31,39). The presence of this strain also affected the growth of P. camemberti, G. candidum, and K. lactis, as reflected by the reduction of the rind density at the surface of the SCMC, which was visually and qualitatively evaluated.…”

“…Because D. hansenii is ubiquitous and highly salt tolerant, it may be present at the surface of manufactured cheeses, even in cases where the yeast is not added deliberately. In those cases, D. hansenii originates from the dairy environment, particularly from milk or brine (1,21,35,40).…”

Evaluation of proteolytic and physicochemical changes during storage of fresh Panela cheese from Queretaro, Mexico and its impact in texture

“…Organic acid production was quantified by high performance liquid chromatography according to the method described by Leclercq-Perlat, Oumer, Berge`re, Spinnler and Corrieu (1999). Cheese suspensions from day 1 to day 15 were prepared by mixing 10 g of finely ground cheese and 10 mL distilled water.…”