Enhancing Shelf Life of Pearl Millet Flour

Pearl millet grains are used for food purpose in Asia and Africa. The whole grains are consumed either as grits or in the form of flour and its products. These grains are rich in fat, vitamins, and minerals. However, the shelf life of milled flour is limited due to high fat content and active lipolytic enzymes that come in contact with their substrates during milling. Moreover, moisture and oxygen availability further accelerate oxidative rancidity, rendering flour unacceptable for consumption after 10–15 days. Various processing techniques are applied either to physically separate different fractions of the grain or to inactivate the lipolytic enzymes in order to enhance shelf life. Decortication, pearling, and defatting are used to remove lipid-rich aleurone layer and germ from grains, while extrusion, fermentation, and malting are used to reduce lipid content and lipolytic enzyme activity. Thermal treatment is a common method used to inactivate lipolytic enzymes before milling. Apart from conventional techniques like dry heat and hydrothermal treatment, novel thermal processing techniques like microwave and infrared heating were also experimented with. Non-thermal processing methods like gamma irradiation and high-pressure processing are effective for controlling insect infestation and microbial load, respectively. Processed flour stored in laminated packaging and the modified atmosphere was found to be effective in extending shelf life. Efforts to develop low rancid genotypes have focused mainly on screening germplasm, inbred lines, varieties, and hybrids. Processing technologies in combination with targeted breeding through marker-assisted selection and genome editing are discussed in this chapter, which might help in developing low rancid pearl millet varieties with better keeping quality of flour.