This chapter discusses the most important groups of secondary flora, the species found in cheeses, the properties used in their selection, and the form and use of these cultures as adjuncts. The secondary and adjunct cultures involved include yeasts—for example, Geotrichum candidum, Debaryomyces hansenii, moulds, e.g., Penicillum camemberti, P roqueforti , and bacteria—for example, Corynebacterium, Staphylococcus, Micrococcus, Propionibacterium sp. , and heterofermentative lactobacilli and are involved only in cheese ripening. Except for Propionibacterium and the heterofermentative lactobacilli , the secondary cultures grow mainly on the cheese surface. They are called secondary cultures to distinguish them from the primary acid-producing starters and are as important as the primary ones in those cheeses in which they are found. The yeast flora contributes directly or indirectly to the appearance of cheese. For example, G. candidum varies considerably from slimy cream to velvet mould-like depending on the strain. Consequently, the growth behavior of G. candidum is of great importance in choosing the correct strain for the type of cheese being produced. The yeasts encountered on the surface of cheese show varied abilities to metabolize sugars, lactate and citrate. Because Kluyveromyces marxianus and Debaryomyces hansenii are able to ferment lactose, their use as adjuncts is very common. G. candidum assimilates galactose and lactate, which is of paramount importance in the ripening of mould and bacterial smear-ripened cheese.

Secondary and Adjunct Cultures

Changes in selected biochemical and sensory parameters as affected by the superficial inoculation of Penicillium camemberti on dry fermented sausages.

Thermodynamic modeling of CO2 and H2S solubilities in aqueous DIPA solution, aqueous sulfolane–DIPA solution, and aqueous sulfolane–MDEA solution with electrolyte NRTL model

Ball-lens laser-induced fluorescence detector as an easy-to-use highly sensitive detector for capillary electrophoresis application to the identification of biogenic amines in dairy products

Equilibrium temperatures for liquid–liquid and solid–liquid
transitions of systems containing sulfolane and propan-1-ol,
butan-1-ol, octan-1-ol or tetradecan-1-ol
were measured by a dynamic method. From butan-1-ol, the mixtures
show an upper critical solution temperature, which increases with the length
of the alcohol. It may attributed to a decreasing of the effective dipole
moment of the alkan-1-ol which markedly decreases the interactions
between unlike molecules. The coexistence curves become shifted to the high
molar fractions of sulfolane in solutions with longer alkan-1-ols,
probably due to size effects. Binary systems of sulfolane with cycloalkanes, n-alkanes,
benzene or toluene, CCl4 or alkan-1-ols were analyzed
in terms of a purely physical model, DISQUAC. The corresponding interaction
parameters are reported. DISQUAC represents fairly well, over a rather wide
range of temperature, a complete set of thermodynamic properties: liquid–liquid
equilibria, LLE, solid–liquid equilibria, SLE, vapor–liquid equilibria,
VLE, molar excess Gibbs energies, GE, molar excess enthalpies, HE
and natural logarithms of activity coefficients at infinite dilution, ln γi∞.
Deviations observed for LLE are typical for mean field theories as calculations
are developed assuming that thermodynamic properties close to the critical
points are analytical. Experimental data show that sulfolane may play the
role of an almost inert diluent, because of the steric hindrance of its globular
nature.

Thermodynamics of mixtures containing a very strongly polar compound.Part I. Experimental phase equilibria (solid–liquid and liquid–liquid)for sulfolane + alkan-1-ols systems. Analysis of some mixturesincluding sulfolane in terms of disquac

Thermodynamic and physical behavior of binary mixtures involving sulfolane. Excess volumes and dielectric constants of sulfolane-nitrobenzene mixtures

The results of an accurate thermal analysis on highly purified samples of 2-methylpropan-2-01 supply evidence for the supposition of the existence of three Crystalline phases, which we indicate as crystal I (mp 25.62 "C), crystal I1 (mp 25.00 "C), and crystal I11 (mp 21.66 "C). A two-slde transltlon: crystal I G I1 has been observed at 14.1 O C . Crystal 111, by cooling, undergoes a sluggish transltlon Into crystal 11 at 9 OC. Cryoscopic behavior of solutions of carbon tetrachloride, n-heptane, and sulfolane is consistent with the above results. Metastable equilibria may be detected owlng to the fact that the freezing points of the three crystalline phases fall withln a narrow temperature range. The cryoscopic constants of the three solid phases have been calculated and fusion entalpies derived. Negative conclusions are drawn concerning the use of 2-methylpropan-2-01 as a reliable solvent in cryoscopy. From thermodynamic data only crystal I1 Is suspected, possessing some globular character.

Alberto Azzi

Papers

Thermodynamic and physical behavior of binary mixtures involving sulfolane. Excess volumes and dielectric constants of sulfolane-nitrobenzene mixtures

Thermodynamic study of phase transitions in 2-methylpropan-2-ol

Activity coefficients of water and sulfolane from the solid + liquid phase diagram

Relationship between the content of biogenic amines and the deterioration of mould-ripened cheeses. II

Van der waals' volumes from densities and vaporization enthalpies