Water activity and temperature effects on growth of Eurotium amstelodami, E. chevalieri and E. herbariorum on a sponge cake analogue

Eurotium is a widespread storage fungal genus that has been frequently isolated from bakery products. The objective of this study was (i) to obtain a method for studying the growth of xerophilic fungi on bakery products, and (ii) to determine the effects of water activity (aw), temperature, isolate and their interactions on mycelial growth of Eurotium spp. on an analogue medium of sponge cake. Statistical analysis showed that there were intra-isolate differences (P<0.001) due to aw, temperature, isolate, and two- and three-way interactions. Optimum growth of all isolates over aw×temperature range tested showed optima at 0.90 aw and 30°C, with an interval of growth rate of 3.8–5.1 mm·d−1. At 0.75 aw, growth was less than 0.15 mm·d−1, if there was any.