title: Evaluation of bioactive compounds and bioactivities of soybean dried by different methods and conditions.
abstract: Soybean has attracted significant research and commercial interests due to its many health-promoting bioactive compounds, especially isoflavones (β-glucosides, malonyl-β-glucosides, acetyl-β-glucosides and aglycones). Isoflavones possess antioxidant activity and α-glucosidase inhibitory activity, which has proved effective in the treatment of type 2 diabetes mellitus. Prior to its use, however, soybean needs to be dried to extend its storage life and to prepare the material for subsequent food or pharmaceutical processing. The present study investigated the effects of drying methods and conditions on the drying characteristics, isoflavones, antioxidant activity and α -glucosidase inhibitory activity of dried soybean. Hot-air fluidized bed drying (HAFBD), superheated-steam fluidized bed drying (SSFBD) and gas-fired infrared combined with hot air vibrating drying (GFIR-HAVD) were carried out at various drying temperatures (50, 70, 130 and150°C). The results showed that higher drying temperatures led to higher drying rates and higher levels of β-glucosides and antioxidant activity, but to lower levels of malonyl-β-glucosides, acetyl-β-glucosides and total isoflavones. At the same drying temperature GFIR-HAVD resulted in the highest drying rates and the highest levels of β-glucosides, aglycones and total isoflavones, antioxidant activity as well as α-glucosidase inhibitory activity of dried soybean. A drying temperature of 130°C gave the highest levels of aglycones and α-glucosidase inhibitory activity in all cases. The relationships between all the studied parameters were monitored and simple correlations between them were determined.
authors.affiliation: Center for Petroleum, Petrochemicals and Advanced Materials, Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, 50 Ngam Wong Wan Road, Chatuchak, Bangkok 10900, Thailand. Electronic address: fengcdni@ku.ac.th.
authors.forename: Chalida
authors.initials: C
authors.lastname: Niamnuy
authors.affiliation: Faculty of Engineering, Mahasarakham University, Khamriang, Kantarawichai, Mahasarakham 44150, Thailand.
authors.forename: Mali
authors.initials: M
authors.lastname: Nachaisin
authors.affiliation: Faculty of Engineering, Mahasarakham University, Khamriang, Kantarawichai, Mahasarakham 44150, Thailand.
authors.forename: Juckamas
authors.initials: J
authors.lastname: Laohavanich
authors.affiliation: Department of Food Engineering, Faculty of Engineering, King Mongkut's University of Technology Thonburi, 126 Pracha u-tid Road, Tungkru, Bangkok 10140, Thailand.
authors.forename: Sakamon
authors.initials: S
authors.lastname: Devahastin
keywords: Antioxidant activity; Gas-fired infrared drying; Isoflavones; Superheated steam drying; α-Glucosidase inhibitory activity