Food is a necessity, people need it to survive, therefore the demand for food is likely to be unresponsive to a change in price because people still have to buy food reguardless of the cost or they will die. There is no alternative for food so the quantity demanded of food will remain the same despite a change in the price.
A reduction in the price pf food may not lead to a huge increase in quantity demanded as food is seen as a necessity meaning people purchase the same amount of food reguardless of price.