Subjecting pulses to heat for varying periods of time (i.e., toasting and roasting) is a widely practiced method of pulse processing. Roasting pulses by subjecting them to high temperatures for a short time has been practiced in Asia, the Middle East, and South America for many years.
Roasted chickpea, called leblebi, is widely enjoyed as a traditional snack in Turkey, the Mediterranean region, and the Middle East, though the method of preparation can differ from country to country. In general, leblebi production begins with rehydrated chickpeas being subjected to heat treatment in several stages. They are then allowed to rest for several hours before being roasted. Large-seeded chickpeas are preferred for leblebi. It is generally produced using traditional methods by small-scale manufacturers.
Selection of Raw Materials
Cleaned chickpeas are graded according to size and subjected to heat in several stages. Raw and roasted chickpeas can undergo substantial structural changes during processing (Coskuner & Karababa, 2004). The raw chickpea is tightly packed and contains no air pockets. A large number of air pockets are, however, formed in the cotyledon of the roasted chickpea (Coskuner & Karababa, 2004). This change is believed to be the result of the chemical and physical changes that the chickpea undergoes during processing. As noted, after the heat treatment, water is added to increase the moisture content of the chickpeas.
During the roasting process, this water changes from a liquid into vapor inside the chickpea. The chickpea expands, likely the result of the steam generated from the water vapor that then pushes on the compact structure of the chickpea. Because the majority of the starch granules do not gelatinize during roasting, researchers consider the amount of water as a major factor in swelling and gelatinization (Coskuner & Karababa, 2004).
A study on roasting lentils demonstrated that temperatures as high as 257 °F (125 °C) were attained in the lentils during processing. This enables the superheated steam to create voids in the cellular matrix. At the later stages of roasting, the steam exits and the starchy matrix is dehydrated, causing a porous and slightly extruded-like structure.
Raw and roasted chickpeas also differ significantly in color. Roasted chickpeas have a darker color with more yellow and red than raw chickpeas. These changes in color are indicative of chemical browning reactions during roasting. Color is an important consideration in food products as the color and appearance of foods are generally the first impressions consumers have of a specific product. The darker color of roasted chickpeas is generally preferable to that of raw chickpeas.