Jam is an interesting food from a biological perspective because it is highly resistant to microbial contamination. This relates to the way the sugars within the jam prevent bacterial growth due to the osmotic potential they create across the cell walls of bacteria. The high sugar content draws water from the cells and this desiccates the cell, killing the organism. This phenomenon is the reason that jam was used as a way of storing fruits before the time of refrigeration, where during the winter, access to the benefits of these fruits were still available. In particular, the types of fruits used in jams are high in antioxidants and vitamin C and this can provide an important source of these nutrients during the winter, improving immunity and reducing the risk of disease and death. Of course the high sugar content is detrimental if jam is overconsumed, but historically this was not a problem because the diet as a whole was much lower in energy and the work performed by individuals was much harder physically.
Eat Well, Stay Healthy, protect Yourself
RdB
