Processing of Sugar‐Coated Red Kidney Beans ( <i>Phaseolus vulgaris</i> ): Fate of Oligosaccharides and Phytohemagglutinin (PHA), and Evaluation of Sensory Quality

Abstract

ABSTRACT: The present study was undertaken to expand the uses of red kidney beans beyond traditional products such as sugar‐coated beans—a popular snack food in many Asian countries. Beans were soaked for 12 h (initial temperature 77 °C, end temperature 24 ± 1 °C) and then cooked in boiling water (approximately 99.3 °C) for 14 min. Finally, the cooked beans were sugar‐coated by dipping in 20%, 35%, or 50% sugar syrup (w/w) for 45 min at 70 °C and excess syrup was drained at the end of the process. Beans were analyzed for oligosaccharides (raffinose and stachyose) and lectins, as phytohemagglutinating (PHA) activity, at predetermined intervals during processing. A 105‐member consumer panel evaluated bean quality for texture, color, sweetness, flavor, and overall acceptability. Most of the weight (81.1% of total) was gained during the 1st h of soaking. There was a significant reduction in raffinose (80.8%) and stachyose (83.4%) after 12 h of soaking. Cooking, which further reduced raffinose for a combined total of 95.8%, had no effect on stachyose. The lectins decreased by about 90% in cooked beans, with over half of inactivation occurring during soaking. On a hedonic scale of 1 to 9 (1 = dislike extremely, 9 = like extremely), all 3 bean samples scored above 5 for all the sensory attributes tested. Beans coated with 50% sugar syrup were rated best overall, with a score of 6.1. Frequency distribution of overall acceptability scores showed that 59% to 70% of the panelists rated different bean samples at a score of 6 or higher.