Fungi Associated with Pure Maple Syrup Packed at the Minimum Recommended Reheating Temperature ¹

In a study on container storage and syrup stability, when pure maple syrup was heated at the traditional minimum packing temperature of 82°C, 6.9% of syrups in all types of containers were surface-contaminated with a fungal mat; Penicillium and Aspergillus species predominated. Fungal growth was not found in syrups stored at 4°C for 12 months, only in syrups stored for the same length of time at 24 and 30°C. In a second container study, heating the maple syrup before packing at 93°C resulted in no detectable fungal growth. This higher-than-recommended reheating temperature successfully minimized the effect of cold ambient temperatures during syrup packing, so that the reheated syrup was hot enough to sterilize the container and the air space between syrup and cap.