They are carefully balanced to produce a high quality product that will not spoil. Fat increases tenderness and enhances keeping quality. Large amounts decrease volume. Then sugar depresses the yeast action. Sugar contributes to a soft texture, flavor, and a brown crust.
Salt inhibits yeast fermentation, improves texture, has a slight toughening effect, and adds flavor.
Less fat may reduce keeping time. Less sugar may either slow down or speed up the rate of fermentation. Rolls may not brown as quick- ly. Texture may not be as tender or as moist. Less salt may speed up fermentation of yeast and cause poor texture.