Scientists at the University of Illinois have developed new hybrids of purple corn containing different combinations of phytochemicals that may fight obesity, inflammation and diabetes, a new study in mice indicates.
The pericarp—or outer layer—of purple and other brightly colored corn kernels also may provide an alternative source of colorants for food products, giving corn producers another value-added product from their crop. Researchers published their findings recently in the journal Food Chemistry.
From a strain of maize called Apache Red, researchers bred 20 genetic varieties of purple corn, each with a unique combination of anthocyanins, the nutritious, natural pigments that give the pericarp its vibrant color.
Widely found in plant tissues, phenolic compounds tend to be aromatic and contribute to the color, flavor and acidity of fruits. Anthocyanins are one class of phenols, and studies have associated the consumption of anthocyanin-rich foods with reduced risks of cardiovascular disease, Type 2 diabetes and certain types of cancer.
Scientists extracted the anthocyanins from the pericarp of the corn kernels, creating anthocyanin-rich water extracts. While analyses of the extracts showed that the pericarp is an abundant source of anthocyanins and phenolic compounds, the concentration varied significantly among the varieties.
To examine the impact of anthocyanins on obesity-induced inflammation researchers combined fat cells—called adipocytes—from mice with large immune cells called macrophages.
They observed that the phenolic compounds in the extracts altered the cells’ development, reducing the adipocytes’ fat content from 8%-56%, depending on the differing phenols used.
To study the compounds’ impact on insulin resistance, the metabolic dysfunction associated with diabetes, the scientists used a cell-signaling protein to induce insulin resistance in the mouse fat cells, then treated the cells with the anthocyanin compounds and monitored their glucose uptake.
A key marker of insulin resistance decreased by 29%-64%, they found, and the cells’ glucose uptake decreased by 30%-139%, depending on the chemical composition of the anthocyanins used.
Another advantage corn is that it could serve as natural pigments for the food industry, satisfying strong consumer demand for alternatives to synthetic dyes. Corn is shelf-stable, providing an economical substitute for the perishable fruits and vegetables that manufacturers also currently use to color many foods and beverages
Qiaozhi Zhang et al, Relationship of phenolic composition of selected purple maize (Zea mays L.) genotypes with their anti-inflammatory, anti-adipogenic and anti-diabetic potential, Food Chemistry (2019). DOI: 10.1016/j.foodchem.2019.03.116