A comparative evaluation of processing of yellow peas (Pisum sativum L.) with hot air and superheated steam

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Brar, Navjot Kaur
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The present study was undertaken to evaluate the effect of hot air (HA) and superheated steam (SS) processing methods on the functional and nutritional properties of yellow peas. Moisture content, drying characteristics, hydration capacity, cooking characteristics, dehulling efficiency, protein content, peak starch gelatinization temperature, and microstructure of peas affected by SS and HA were investigated. Three temperatures (120, 135, and 150°C) for 10 minutes processing at one velocity of 1 m/s for both HA and SS were used. The processing conditions significantly affected (p<0.05) all measured properties of processed peas except starch. Moisture content was observed to decrease from 20% to 8.4% and 6.3% for HA and SS, respectively at 150°C. Hydration capacity of peas after SS and HA processing ranged from 12.6-27.7% and 5.8-12.3% at 120 to150°C, respectively. Peas processed with HA resulted in decrease in protein content by 1.20, 2.16, and 2.38% than the peas processed with SS, in which protein content was decreased by 0.38, 0.44 and 0.75% at 120, 135, and 150°C, respectively. An increase of 19.1, 20.0, and 35.0% in porosity was observed in SS processed peas in comparison to HA at 120, 135, and 150°C, respectively. Dehulling efficiency of HA processed peas ranged from 83.5-88.2% whereas for SS it ranged between 85.4-89.9% at 120-150°C. In regard to cooking characteristics, SS processed peas needed less extrusion force than HA for all cooking times tested (5, 10, and 15 minutes). Additional experiments were conducted for SS processing of high initial moisture content (26, 40, and 54%) yellow peas at varying temperature (120, 135, and 150°C) and time. The soaking step was eliminated before cooking peas for 5, 10, and 15 minutes. Decrease in the extrusion force of peas was observed from 1012.2 N (at 26% initial moisture content) to 587.5 N (at 54% initial moisture content) after 15 minutes of cooking. Superheated steam processing of peas at 135°C, 54% initial moisture content and 5 minutes cooking was deemed as the optimum processing condition. This study demonstrated that SS is an effective processing method that decreases overall cooking time without compromising functional and nutritional properties of yellow peas.
Hot air, Superheated steam, Yellow peas, Protein, Cooking, Dehulling