Preventing mould in packed maple syrup

Preventing mould in packed maple syrup can be a challenge. Cold-packing syrup usually guarantees mould will grow in bottled containers and can impart off-flavour in the syrup. The commercial maple industry has requested to the provincial government that hot packing be made mandatory for producers and regulated to prevent mould, to ensure food safety and to uphold the reputation of Ontario maple syrup as a quality product.

Maple researchers at the University of Maine and at Carleton University in Ontario are investigating whether current hot packing recommendations require refinement to preserve quality and prevent mould in syrup.

Mould growth often forms at the surface of the syrup (Figure 1) in unopened containers that are improperly hot packed. Mould can also develop in maple syrup after the sealed container is opened and is not refrigerated during consumption. Always refrigerate maple syrup after opening sealed containers.

Mould growth often forms at the surface of the syrup

Figure 1

Fresh maple syrup is usually filtered immediately after being drawn off the evaporator while it is still hot. Immediately after filtering to remove sugar sand, the syrup is either hot packed at 85 °C into bulk food-grade containers, or the syrup is hot packed at 85 °C into new small containers of various sizes for direct market sales.

When bottling maple syrup into small containers for direct marketing, the syrup should be hot packed at a temperature of 85 °C. Securely cap each container as it is filled and then place the container on its side (Figure 2) or upside down for 5 to 10 minutes to ensure the hot maple syrup contacts and kills all spoilage organisms that may be present in the top neck and inner lid surface of the bottle, jug or can. To ensure mould-free syrup, each sealed container should be held at the hot temperature of 85 °C for at least 5 minutes.

Securely cap each container as it is filled and then place the container on its side (Figure 2) or upside down for 5 to 10 minutes to ensure the hot maple syrup contacts and kills all spoilage organisms

Figure 2

Many syrup producers compete locally at annual fairs and industry meetings to be selected for producing the best maple syrup, maple candy, maple butter and granulated sugar. Here, Canadian and U.S. winners are highly respected at the annual International Maple Syrup conference (Figure 3).
Photo showing rows of bottled maple syrup entered in a competition.

Figure 3

All syrup containers that are intended for direct market sale must be made of brand new material that has not been previously used. Containers for syrup are made of glass, metal cans or plastic jugs and should be clean, free of any hazard inside and ready for hot-packing. Proper containers are available from reputable maple equipment suppliers. Do not use containers or lids that cannot tolerate the recommended hot-pack temperature of 85 °C. Containers must be filled to a minimum of 90% of the container volume.

Glass containers need to be preheated prior to hot packing otherwise the syrup and glass will cool down too quickly to provide adequate sterilization of the pack. Pre-heating is particularly important in smaller glass bottles that do not hold enough mass of hot syrup to remain hot long enough. Some producers have had good results where glass containers are preheated in hot water or in a warm oven. Protective gloves made of silicon, or heavy-duty rubber will provide a better grip on preheated bottles as they are filled with hot syrup.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca