Predicting fungal growth: the effect of water activity on Penicillium roqueforti.

The effect of water activity on the colony growth of Penicillium roqueforti is studied by predictive modelling techniques. Measured colony diameter growth curves are fitted to estimate the growth rate and lag phase of the curves. The colony growth rate was modelled by a quadratic function of transformed water activity (a(w)) values, as suggested by Baranyi et al. (Food Microbiol. 10 (1993) 43-59). The lag time was modelled as a function of water activity, by means of the sum of a constant term and a hyperboloid function of a(w) raised to the second power. The lag-phase of Penicillium roqueforti was found insensitive to the water activity in the range of its higher (a(w) > 0.92) values.

Growth of Staphylococcus aureus in pasta in relation to its water activity.

Water activity (aw) of pasta decreased linearly with time during drying. A strain of Staphylococcus aureus isolated from commercial pasta began multiplying immediately after inoculation but decreased in number when aw was reduced to below 0.93. Another strain of S. aureus appeared to multiply until the aw was below 0.86. The results are discussed in relation to practices for pasta production.

[Metabolism of iodine iodophor in the thyroid gland]. / Die Verwertung des Jodophoriodes in der Schilddrüse.

As evidenced by animal experiments (Wistar rats), the iodophore iodine of the commercial product Jodonal-M is bound by the thyroid gland, if administered with the drinking water. When drinking water containing 2 mg/l iodophore iodine was given, the thyroid glands of the experimental animals bound 1.19%; and those of the control animals, 4.68% 131I. When drinking water containing 1 mg/l iodophore iodine was administered, the thyroid glands of the experimental animals bound 1.90%; and those of the control animals, 6.77% 131I. It is concluded that the iodophore iodine which passes over to the milk during teat disinfection is bound by the thyroid glands in a similar manner and takes part in the formation of the thyroid hormones just as the "native" iodine of the milk.

[Retention of several vitamins during ultra-high temperature sterilization of milk]. / Retention von einigen Vitaminen während der Ultrahocherhitzung von Milch.

Four independent studies were conducted in the course of two years to determine the retentions (or the losses) of vitamin A, beta-carotene, vitamin B1, vitamin B6, nicotinic acid and pantothenic acid during the ultra-high temperature sterilization of pre-pasteurized milk (85 degrees C without hold-up time) by means of the Alfa-Laval-Vtis-C apparatus (140 degrees C, 3-4 s, direct heating with subsequent expansion). The following retentions (or losses) were stated: vitamin A, 97.2% (2.8%); beta-carotene, 93.9% (6.1%); vitamin B1, 82.2% (12.0%); vitamin B2, 97.6% (2.4%); vitamin B6, 92.7% (7.3%) nicotinic acid, 96.0% (4.0%); and pantothenic acid, 96.4% (3.6%).