C: Food Chemistry JFS C: Food Chemistry Changes in the Functional Properties and Antinutritional Factors of Extruded Hard-to-Cook Common Beans ( Phaseolus vulgaris, L. ) KARLA A. BATISTA,SANDRA H. PRUDˆ ENCIO, AND K´ ATIA F. FERNANDES ABSTRACT: The biochemical and functional properties of 2 hard-to-cook common bean cultivars (Phaseolus vul- garis, L.) were investigated after the extrusion process. Beans of BRS pontal and BRS grafite cultivars were milled and extruded at 150 ◦ C, with a compression ratio screw of 3 : 1, 5-mm die, and screw speed of 150 rpm. Extrudate flours were evaluated for water solubility (WS), water absorption index (WAI), oil absorption capacity (OAC), foaming ca- pacity (FC), emulsifying activity (EA), antinutritional factors, and in vitro protein and starch digestibility. Results indicated that the extrusion significantly decreased antinutrients such as phytic acid, lectin, α-amylase, and trypsin inhibitors, reduced the emulsifying capacity and eliminated the FC in both BRS pontal and BRS grafite cultivars. In addition, the WS, WAI, and in vitro protein and starch digestibility were improved by the extrusion process. These re- sults indicate that it is possible to produce new extruded products with good functional and biochemical properties from these common bean cultivars. Keywords: extrusion, functional properties, hard-to-cook, heat–moisture treatment Introduction B eans are legumes that supply a significant amount of protein for a great part of the world population, especially in poor countries where the consumption of animal protein is relatively low. Their high content of protein, carbohydrates, fibers, some min- erals and vitamins make the beans a good source of nutrients. Unfortunately, the antinutritional factors present in the beans re- duce the activity of some enzymes, the biological action of several chemical compounds and the absorption of metabolites (Rocha- Guzm´ an and others 2006). In spite of its excellent nutritional profile, the common bean (Phaseolus vulgaris, L.) presents some disadvantages. It may be de- teriorated as a consequence of time and conditions of storage, par- ticularly under high temperature and high humidity, characteristics that are prevalent in tropical countries (Ruiz-Ruiz and others 2008). The main observed alterations are deterioration of texture and fla- vor and an increase of the cooking time due to the hardening of the bean grains, a characteristic known as Hard-to-cook (HTC) phe- nomenon. The HTC phenomenon inhibits cell separation during the cooking process, which affects the texture of the cooked seeds and limits the protein availability due to the physical restriction for the access of digestive enzymes, lowering the nutritional contribu- tion of the seeds (Alonso and others 2001). A number of alternative technologies have been proposed for the use of the hard-to-cook bean such as dry and wet fractionating, alkaline thermal treatment and extrusion. In recent years, the ex- trusion method has been widely used for cereal processing, pro- MS 20090887 Submitted 9/9/2009, Accepted 1/15/2010. Author Batista is with Escola de Agronomia e Engenharia de Alimentos, Univ. Federal de Goi´ as, CP 131, 74001-970 Goiˆ ania, GO, Brazil. Author Prudˆ encio is with Dept. de Ciˆ encia e Tecnologia de Alimentos, Univ. Estadual de Lond- rina, Paran´ a, Brazil. Author Fernandes is with Laborat´ orio de Qu´ ımica de Prote´ ınas, Dept. de Bioqu´ ımica e Biologia Molecular, Inst. de Ciˆ encias Biol´ ogicas, Univ. Federal de Goi´ as, CP 131, 74001-970 Goi ˆ ania, GO, Brazil. Direct inquiries to author Batista (E-mail: krlbatista@hotmail.com). duction of food and food ingredients such as precooked flour, in- fant food, breakfast cereals, meat and cheese analogues, snacks, and modified starches (Alonso and others 2001; Drago and others 2007; Ruiz-Ruiz and others 2008). The extrusion-cooking has good potential for the production of desirable forms of beans economically available in developing countries. Nontraditional methods of processing, such as thermal extrusion, are needed for expansion of the utilization of hard-to- cook beans (Rocha-Guzm´ an and others 2006). Heat, water, and high pressure in an extrusion process may induce desirable chem- ical changes in the material. The main reported benefit effect of extrusion is the reduction in activity of antinutritional factors such as trypsin and α-amylase inhibitors, lectins, and phytates concomi- tantly with an improvement of the digestibility of proteins and starch (Mant´ ın-Cabrejas and others 1999). The aims of this study were to determine the effect of the extru- sion method on the Hard-to-Cook common bean from the culti- vars of BRS pontal (carioca) and BRS grafite (black) on the basis of chemical composition, functional properties, and activity of antinutritional factors as well as to evaluate the alterations in the digestibility of starch and protein. Materials and Methods Flour bean preparation and extrusion The common HTC beans (Phaseolus vulgaris, L.), from the cul- tivars of BRS pontal (carioca) and BRS grafite (black), were pro- vided by EMBRAPA (Goi´ as, Brazil). The grains were ground in a Tecnal mill-grinder to pass a 0.420-mm mesh. The extrusion pro- cess was carried out in a single-screw extruder (Ceraltec Intl. CT- L15), with a compression ratio of 3 : 1, 5-mm die and screw speed of 150 rpm. The central temperature and moisture content were fixed in 150 ◦ C and 20g/100g of dry weight, respectively. The extrudates were cooled at room temperature (25 ◦ C), ground to pass a 0.420- mm mesh screen, sealed in plastic bags and refrigerated at 4 ◦ C. C286 JOURNAL OF FOOD SCIENCE—Vol. 75, Nr. 3, 2010 C  2010 Institute of Food Technologists R  doi: 10.1111/j.1750-3841.2010.01557.x Further reproduction without permission is prohibited