Vegetal burgers of cashew fiber and cowpea: formulation, characterization and stability during frozen storage

This work aimed to obtain a vegetable burger from the cashew juice production residue (fiber) and cowpea that are two abundant materials in Northeast Brazil. Fiber was washed and pressed in an expeller for five times. Cowpea was soaked in water and, after skin removal, ground to obtain a paste. Hamburgers were made by mixing the cashew fiber, the cowpea paste, and the ingredients used in traditional burger recipes, then shaped and frozen. Four sensory tests were performed to define: (1) the need of cooking the cowpea paste with the other ingredients; (2) the fiber/paste proportion; (3) ingredients to enhance the sensory characteristics; (4) burger acceptance. The resultant formulation had 29.3% of cashew fiber, 29.3% of cowpea paste, 25.1% of tomato, 6.8% of onion, 5.3% of sweet pepper, 1.3% of garlic, 0.1% of black pepper, 0.2% of dehydrated parsley, 1.2% of salt and 1.4% of corn oil. The sensory acceptance was 7.8 in a 9-point hedonic scale. Proximate composition was 71.08% moisture, 2.07% ashes, 4.86% proteins, 1.19% lipids and 20.79% total carbohydrates. Stability was evaluated during frozen storage (-18 oC) for 180 days. In this period, acidity increased and pH and ascorbic acid decreased. As to color, a* and b* values increased, indicating that the burgers became more orange/brown. The burger was considered microbiologically safe and shelf-stable for at least 6 months.