Starch digestibility and predicted glycaemic index (PGI) in starchy foods consumed in Mexico

Different starchy foods are frequently consumed in the Mexican diet. Some of them were developed by Pre-Columbian Mesoamerican civilizations. Until today, common beans (Phaseolus vulgaris), tortillas made with maize (Zea mays) and related maize-based products are some of the main staple foods. Additionally, wheat-based foods are also important starch sources, incorporated in different dishes. This review deals with the in vitro digestibility of the starch fraction in foods commonly consumed in Mexico, paying attention to the addition of unconventional, natural raw materials, such as flour and starch from unripe banana, mango dietary fibre and common legumes. These ingredients enhance potential health-beneficial properties of the diet in cases of non-communicable diseases, particularly those related to obesity and glycaemic homeostasis. Since Mexico is among the countries with greatest indices of overweight and obesity, this paper reviews the in vitro starch availability features, including predicted GI, of variousMexican foods. Attention is also paid to the effect of cold storage conditions on starch digestibility. As an example, starch digestibility in bluemaize tortillas (58%) is lower than in white tortillas (70-89%) and a maize tortilla/boiled bean composite dish ranks as a food with low predicted GI (pGI - 51). Received: September 10, 2012 Revised: December 5, 2012 Accepted: December 13, 2012.