SHELF-LIFE STABILITY OF OAT GROATS PROCESSED WITH SUPERHEATED STEAM D. Head 1, S. Cenkowski 1, S. Arntfield 2 K. Henderson 3 1 Biosystems Engineering, UofM, Winnipeg, MB 2 Food Science, UofM, Winnipeg, MB 3 Can-Oat Milling, Portage la Prairie, MB Presentated at the CSBE/SCGAB 2008 Annual Conference Vancouver, BC, July , 2008

Oats are heat processed to enhance stability (high lipid content, 5-7%) to develop characteristic flavour Routine industrial process includes : Roasting, steaming and drying to inactivate the fat splitting enzymes Roasting at  C for min (up to 80% inactivation) then steaming at  C for 8-10 min Grain is dried and…processed to Commercial products (flour, bran, rolled oats)

Limiting factors for storage and handling Degradation of lipids via enzymatic hydrolysis followed by oxidation leading to rancidity and off-flavours development Prevention: –Hydro-thermal inactivation of the lipolytic enzymes –The kiln drying operation is difficult to control, lengthy and not energy efficient –Risk of grain cross-contamination with microorganisms present in the air used for cooling of the grain after kiln drying Superheated steam drying and processing is an attractive technology offering variety of advantages over the kiln drying

Objective to determine the shelf-life stability of oat groats processed with the optimum superheated steam parameters and stored at 21  C Optimum SS processing conditions were established in previous studies: steam temperature of 110  C steam velocity of 1 m/s processing time of 10 and 14 min

Materials and methods Groats standard kilned at a commercial plant A and B SS processed groats at 110  C at 1m/s for 10 and 14 min (SS10 and SS14) Storage at 21  C for 6 months+ and measured: –Moisture content –Pasting viscosity at 64  C (Rapid Visco Analyzer) –Hexanal and free fatty acids content –Sensory evaluation (flavour: oaty, toasted, raw, bitter, rancid) –Color determination (L, a, b values)

Results Fig. 1 Storage time effect on the final viscosity (at 64  C (commercial plant A & B) or processed with superheated steam (SS) Storage at 21  C Commercial plants 110  C, 10min and 14 min Plant A Plant B

Fig. 2 Moisture content of oat groats processed commercially (Plant A and B) or with SS at 110  C and 1 m/s for 10 and 14 min. Storage at 21  C Commercial plants 110  C, 10min and 14 min

Storage at 21  C Fig. 3 The effect of storage time on free fatty acids content of oat groats processed commercially or with superheated steam (SS) at 110  C Commercial plants 110  C, 10min and 14 min

Fig. 4 The effect of storage time on level of hexanal released from oat groats processed commercially (Plant A and B) or with superheated steam (SS) at 110  C Commercial plants 110  C, 10min and 14 min Storage at 21  C

Fig. 5 The effect of storage time on intensity of oaty flavour of oat groats processed commercially or with superheated steam (SS) at 110  C Commercial plants 110  C, 10min and 14 min

Commercial plants 110  C, 10min and 14 min Storage at 21  C Fig. 6 The effect of storage time on intensity of toasted flavour of oat groats processed commercially or with superheated steam (SS) at 110  C

Commercial plants 110  C, 10min and 14 min Storage at 21  C Fig. 9 The effect of storage time on intensity of rancid flavour of oat groats processed commercially or with superheated steam (SS) at 110  C

Fig.10 The effect of storage time on L value (lightness) of oat groats processed commercially or with superheated steam (SS) at 110  C Commercial plants 110  C, 10min and 14 min Storage at 21  C

Summary The shelf-life stability of oat groats processed with superheated steam at 110  C for 10 and 14 min, and stored at 21  C was acceptable and exceeded the intended storage time period of 6 months