I’ve noticed large bottles of Mexican vanilla at an inexpensive price in my grocery store. Can I substitute this type of vanilla for regular pure vanilla extract? What is the difference in taste? —K.F., Trinidad, ColoradoMexican vanilla extract has a smooth, rich flavor with a hint of spice. Unfortunately, some Mexican-processed vanilla extracts may contain an ingredient that is added to stretch the vanilla flavor. This ingredient is a potentially toxic substance that has been banned by the Food and Drug Administration. Check labels to find Mexican vanilla that is processed in the United States and is guaranteed pure; this type is safe and can be substituted for regular vanilla.