What is the primary effect of high humidity on hygroscopic substances?

High humidity has a significant impact on hygroscopic substances, which are materials that can absorb moisture from the environment. When the humidity levels are high, these substances tend to draw in excess water, which can lead to various problems.

One primary effect is that the additional moisture can promote microbial growth, such as mold and bacteria, which can lead to spoilage of food products. This is particularly critical for food items that are susceptible to rotting, as higher moisture levels encourage conditions that are favorable for microbial action. The risk of spoilage increases because the extra water can alter the texture and taste of food, rendering it less desirable or even unsafe for consumption.

The other options are less relevant to the primary effects of high humidity. For instance, high humidity does not enhance the flavor of baked goods or improve the nutritional quality; rather, it could negatively impact baked products' texture by making them soggier. Similarly, hygroscopic substances do not become less effective at attracting water when humidity is high; on the contrary, they may absorb even more moisture. Thus, the most direct consequence of high humidity on hygroscopic substances in a food context is the increased likelihood of spoilage.