Green Bell Pepper Characteristics (IBMP) IBMP (3-Isobutyl-2-methoxypyrazine) is the main compound responsible for the “green bell pepper” aroma in wine.  In a white wine such as Sauvignon Blanc, the compound adds an often desired “grassy” character. In red wines however, this flavor is largely unpopular. Excessive IBMP levels in red wines, typically Cabernets or Cabernet-based blends, can lead to disappointing ratings and mixed success in the marketplace.  The “green bell pepper” flavor in wine depends primarily on IBMP levels in harvested grapes. Once grapes have been picked, IBMP levels are not easily altered by standard winemaking processes. Testing and Application The intensity of “green bell pepper/grassy” characters in wines can be predicted by measuring IBMP in grapes right before harvest. Grape screening of IBMP helps identify “problem” vineyards or blocks.  Since IBMP decreases during grape maturation,