HMF stands for Hydroxymethylfurfural, which is an organic compound formed by the dehydration of reducing sugars. It is a white low-melting solid that is highly soluble in both water and organic solvents. HMF is classified as a food improvement agent and is primarily used in the food industry as a biomarker and a flavoring agent for food products. It is also produced industrially on a modest scale as a carbon-neutral feedstock for the production of fuels and other chemicals. HMF can be converted into other more useful compounds, such as 2,5-furandicarboxylic acid, which has been proposed as a replacement for terephthalic acid in the production of polyesters, and 2,5-dimethylfuran, a liquid that is a potential biofuel with a greater energy content than bioethanol.

HMF is also present in all heat-processed sugar-containing foods and is considered a neo-forming contaminant that can have both detrimental and beneficial effects on human health. It can be converted to a non-excretable, genotoxic compound called 5-sulfoxymethylfurfural, which is harmful to human health. However, recent studies have shown that HMF has a wide range of positive effects, such as antioxidative, anti-allergic, anti-inflammatory, anti-hypoxic, anti-sickling, and anti-hyperuricemic effects.

It is important to note that HMF has another meaning in the context of shipping. In this context, HMF stands for Harbor Maintenance Fee, which is a fee collected by the U.S. Customs and Border Protection (CBP) services for shipments that are imported via ocean. The fee is normally assessed and indicated in accordance with the value of the shipment, and it takes up 0.125% of the value of cargo declared on the commercial invoice of goods only imported via ocean.