Submitted to: International Journal of Food Properties
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/11/2008
Publication Date: 3/3/2010
Citation: Onwulata, C.I., Thomas, A.E., Cooke, P.H., Phillips, J.G., Carvalho, C.P., Ascheri, J.R., Tomasula, P.M. 2010. Production of extruded barley, cassava, corn and quinoa enriched with whey proteins and cashew pulp. International Journal of Food Properties. 13(2):338-359. Interpretive Summary: Consuming certain foods such as puffed corn snacks containing mostly starch is reported to raise blood sugar rapidly, and overconsumption of high starch foods may lead to storage of excess calories as fat in the body. Inclusion of whey proteins and fiber reduces the amount of starch in snacks, and also reduces the glycemic potential, a number that measures how quickly blood glucose rises after the consumption of starchy foods. We designed new puffed, reduced starch snacks from barley, cassava and quinoa, by using whey protein concentrate and fiber from cashew fruit pulp. The products were compared to corn products made with the same ingredients. Adding whey protein concentrate and cashew pulp fiber reduced the glycemic potential in corn, barley and quinoa, but raised the value in cassava. Adding whey protein alone reduces the glycemic potential, but combining whey protein with cashew pulp fiber reduces the value even more. Using barley and quinoa with whey protein concentrate and cashew pulp fiber is a good way to lower the glycemic potential of snack products.
Technical Abstract: Well-formulated snacks can play a positive role in enhancing health by providing essential nutrients, such as increased protein and fiber, that mitigate metabolic syndrome associated with obesity. Adding whey protein concentrate (WPC80) and cashew pulp (CP) to corn meal, a major ingredient in extruded snacks in the US, or whole grains such as barley and quinoa, or cassava, can increase the amount of protein and fiber, and reduce overall carbohydrate content. In this study, barley, cassava, corn meal and quinoa were blended with WPC80 (12.5 wt%) or with CP (12.5 wt%) and formed into half-products (partially cooked) in an extruder at a terminal melt temperature of 60 deg C. The half products were later fully cooked by baking at 205 deg C for 24 min, or frying at 190 deg C for 60 s. The products were analyzed for water absorption (WAI) and solubility (WSI), viscosity, gelatinization, and glycemic potential, rapidly available glucose, RAG (20 min), and slowly available glucose, SAG (120 min). The physical characteristics of the extruded half- and finished-products depended on the carbohydrate source. Extrusion increased solubility of cassava and corn, but not quinoa half-products. WAI increased only for all products. Extrusion increased peak and breakdown viscosity for quinoa and cassava, but adding WPC80 reduced them moderately. Combining WPC80 and CP reduced viscosity most significantly (p<0.05). Adding WPC80 and CP improved viscosity properties while extrusion decreased viscosity. Gelatinization temperatures ranging from 100 to 160 deg C resulted in varying gelation, for cassava (90.3%), quinoa (57.9%), corn (52.0%), and cassava (42.0%). The glycemic potential of different products was dependent on the properties of its starch and the effect of adding WPC80 with or without CP varied. The products’ rapidly available glucose values or potential glycemic index were: quinoa (70%), barley (61%), corn (54%), and cassava (48%). Adding WPC80 with or without CP improved the RAG values for barley and quinoa, but not for cassava which increased from 61 to 77%. Adding WPC80 or CP had no effect on corn products. Overall, SAG was not significantly changed.