Low molecular weight carbohydrates released from Okara by enzymatic treatment under high hydrostatic pressure

- LMWC of Okara are studied with a new HPLC-ELSD method.
- Combined enzymatic and HHP treatment decreases MW of LMWC.
- There is a synergy between Ultraflo® L or Viscozyme® L under HHP.
- Combined treatment could increase the prebiotic effect of Okara.

Okara is an abundant, inexpensive and rich in dietary fibre by-product from soybean with potential prebiotic effect, although an increase in soluble dietary fibre (SDF) and low molecular weight carbohydrates (LMWC) would be desirable. Therefore, a simultaneous treatment with food-grade enzymes (Ultraflo® L or Viscozyme® L) and high hydrostatic pressure (HHP) was used to improve LMWC profile. Release of LMWC from Okara was monitored and estimated using a newly calibrated and validated HPLC method with an ion-exchange column and evaporative light scattering detection (HPLC-ELSD). Both enzymes improved the effect of the HHP treatment. Treatment at 600 MPa, 40 °C for 30 min achieved a decrease in the average molecular weight of polysaccharides from 12.74 ± 3.97 kDa to 3.85 ± 1.33 or 1.59 ± 0.40 kDa when Ultraflo® L or Viscozyme® L were used, respectively. Ultraflo® L (15 min) and Viscozyme® L (30 min) at 600 MPa, were the most effective treatments.Industrial relevanceUsing industrial by-products as a source of nutraceuticals is interesting from an economical point of view. The content of low molecular weight polysaccharides of Okara has been maximized to increase its value as a prebiotic. An industrial adapted treatment with high hydrostatic pressure assisted by food-grade enzymes has been employed. In addition, a new HPLC-ELDS method has been calibrated for monitorizating the process.

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