title: Effects of Hull Scratching, Soaking, and Boiling on Antinutrients in Japanese Red Sword Bean (Canavalia gladiata).
abstract: The effects of hull processing, soaking, and boiling on the content or activity of antinutrients in the red sword bean (RSB; Canavalia gladiata) were investigated. RSB seeds were compared with kidney bean (KB; Phaseolus vulgaris) seeds that are starch based and often used as processed products in Japan. RSB seeds had higher weight, thicker hull, and higher protein content, but lower moisture content compared with KB seeds. Because of the strong and thick hull, the relative water absorption of untreated RSB seeds was very low after soaking. Seeds were soaked after dehulling, scratching, and roasting. The results showed that hull scratching was the optimal method for increasing water absorption during soaking compared with dehulling and roasting. After soaking, the water used for soaking was discarded, since it had a high content of polyphenols and bitter taste, and RSB seeds were boiled in fresh water for 20, 40, and 60 min. The results showed that polyphenol and tannin contents, antioxidant activity, and hemagglutinating activity, as well as maltase, sucrase, and trypsin inhibitor activities in scratched RSB seeds decreased significantly after boiling compared with those in raw seeds, whereas amylase inhibitor activity showed no significant change. Overall, it was concluded that the combination of hull scratching, soaking, and boiling in fresh water can reduce thermal-stable or sensitive antinutrients in RSB and thus, significantly improve its nutritional value.
authors.affiliation: Shujitsu Junior College, 1-6-1 Nishigawara Okayama, Okayama, 703-8516, Japan. une@shujitsu.ac.jp.
authors.forename: Satsuki
authors.initials: S
authors.lastname: Une
authors.affiliation: Osaka Prefecture Univ, 6-7-30 Habikino, Osaka, 583-8553, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nonaka
authors.affiliation: Kibi Intl. Univ, 8 Iga-cho Takahasi, Okayama, 716-0018, Japan.
authors.forename: Junich
authors.initials: J
authors.lastname: Akiyama
mesh_terms: D000681:Amylases / Q000032:analysis; D000975:Antioxidants / Q000032:analysis; D032449:Canavalia / Q000737:chemistry*; D005511:Food Handling / Q000379:methods*; D065089:Glycoside Hydrolase Inhibitors / Q000032:analysis; D006388:Hemagglutinins / Q000032:analysis; D006358:Hot Temperature; D006801:Humans; D007564:Japan; D009753:Nutritive Value; D059808:Polyphenols / Q000032:analysis; D012639:Seeds; D013213:Starch / Q000032:analysis; D013393:Sucrase / Q000032:analysis; D013634:Tannins / Q000032:analysis; D014357:Trypsin / Q000032:analysis; D014361:Trypsin Inhibitors / Q000032:analysis; D014867:Water
chemical_list: D000975:Antioxidants; D065089:Glycoside Hydrolase Inhibitors; D006388:Hemagglutinins; D059808:Polyphenols; D013634:Tannins; D014361:Trypsin Inhibitors; D014867:Water; D013213:Starch; D000681:Amylases; D013393:Sucrase; D014357:Trypsin
keywords: antinutrients; boiling; nutritional value; protein content; red sword bean