Effects of different carriers on the production of isoflavone powder from soybean cake.

The objectives of this study were to use soybean cake as the raw material for the production of isoflavone powder and compare the effects of different carriers as well as drying methods on the powder quality. Results showed that with spray drying, a level of 40% maltodextrin as carrier produced the highest yield (mass) of isoflavone powder, followed by 10% gelatin and 1% sodium alginate. However, a reversed trend was observed for the isoflavone content. With 1% sodium alginate, freeze drying generated the greatest yield of isoflavone powder, followed by vacuum drying and spray drying. The isoflavone content also exhibited the same tendency. With poly-gamma-glutamic acid (gamma-PGA) as carrier, all six levels studied (0.57, 0.28, 0.14, 0.028, 0.014 and 0.003%) were capable of forming powder containing high amounts of total isoflavone, which was comparable to that using 1% sodium alginate by freeze drying. Both high- and low-molecular-weight gamma-PGA showed similar effects in terms of powder yield and isoflavone content.