Controlled production of Camembert-type cheeses. Part I: Microbiological and physicochemical evolutions

Abstract

A holistic approach of a mould cheese ripening is presented. The objective was to establish relationships between the different microbiological and biochemical changes during cheese ripening. Model cheeses were prepared from pasteurized milk inoculated with Kluyveromyces lactis, Geotrichum candidum, Penicillium camemberti and Brevibacterium linens under aseptic conditions. Two cheese-making trials with efficient control of environmental parameters were carried out and showed similar ripening characteristics. K. lactis grew rapidly between days 1 and 6 (generation time around 48 h). G. candidum grew exponentially between days 4 and 10 (generation time around 4 . 6 d). Brevi. linens also grew exponentially but after day 6 when Pen. camemberti mycelium began developing and the pH of the rind was close to 7. Its exponential growth presented 3 phases in relation to carbon and nitrogen substrate availability. Concentrations of Pen. camemberti mycelium were not followed by viable cell count but they were evaluated visually. The viable microorganism concentrations were well correlated with the carbon substrate concentrations in the core and in the rind. The lactose concentrations were negligible after 10 d ripening, and changes in lactate quantities were correlated with fungi flora. The pH of the inner part depended on NH 3 . Surface pH was significantly related to NH 3 concentration and to fungi growth. The acid-soluble nitrogen (ASN) and non-protein nitrogen (NPN) indexes and NH 3 concentrations of the rind were low until day 6, and then increased rapidly to follow the fungi concentrations until day 45. The ASN and NPN indexes and NH 3 concentrations in the core were lower than in the rind and they showed the same evolution. G. candidum and Pen. camemberti populations have a major effect on proteolysis ; nevertheless, K. lactis and Brevi. linens cell lysis also had an impact on proteolysis. Viable cell counts of K. lactis, G. candidum, Pen. camemberti and Brevi. linens were correlated with the environmental conditions, with proteolytic products and with carbon substrate assimilation. NH 3 diffusion from surface to the cheese core during ripening was highly suspected. Interaction phenomena between microorganisms are discussed.

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

“…This fast growth in the first 10-15 d of incubation in our cheese-based medium corresponds to the development pattern usually reported for K. lactis [24] and D. hansenii [25] in soft cheese. 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].…”

“…Camembert-type experimental cheeses were prepared under aseptic conditions, in a sterilised 2-m 3 pilot-scale cheese-making chamber as previously described [25].…”

Cooperative Coevolution for Agrifood Process Modeling

“…One of its principal activity is the fermentation of lactose (noted lo) [14,15] (curd de-acidification by lactose consumption). Three dynamics are apparent in the timeline of K. marxianus growth [38,39]. Firstly, there is an exponential growth during about five days that corresponds to a decrease of lactose concentration.…”

“…One of its principal activi-ties is the consumption of lactate (noted la). Three dynamics are apparent in the timeline of G. candidum growth [38,39]. First, there is a latency period of about three days.…”

“…In such a process, human experts operators have a decisive role. Relationships between microbiological and physicochemical changes depend on environmental conditions (temperature, relative humidity ...) [39] and influence the quality of ripened cheeses [27,38]. A ripening expert is capable of estimating the current state of some complex reactions at a macroscopic level through its perceptions (for example, sight, touch, smell and taste).…”