150 likes | 265 Views
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.
E N D
SHELF-LIFE STABILITY OF OAT GROATS PROCESSED WITH SUPERHEATED STEAM D. Head1, S. Cenkowski1, S. Arntfield2 K. Henderson3 1Biosystems Engineering, UofM, Winnipeg, MB 2Food Science, UofM, Winnipeg, MB 3Can-Oat Milling, Portage la Prairie, MB Presentated at the CSBE/SCGAB 2008 Annual Conference Vancouver, BC, July 13 - 16, 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 88-115C for 90-104 min (up to 80% inactivation) • then steaming at 100-104C 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 21C Optimum SS processing conditions were established in previous studies: • steam temperature of 110C • 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 110C at 1m/s for 10 and 14 min (SS10 and SS14) • Storage at 21C for 6 months+ and measured: • Moisture content • Pasting viscosity at 64C (Rapid Visco Analyzer) • Hexanal and free fatty acids content • Sensory evaluation (flavour: oaty, toasted, raw, bitter, rancid) • Color determination (L, a, b values)
Results Commercial plants Storage at 21C 110C, 10min and 14 min Plant A Plant B Fig. 1 Storage time effect on the final viscosity (at 64C (commercial plant A & B) or processed with superheated steam (SS)
Storage at 21C Commercial plants 110C, 10min and 14 min Fig. 2 Moisture content of oat groats processed commercially (Plant A and B) or with SS at 110C and 1 m/s for 10 and 14 min.
Storage at 21C Commercial plants 110C, 10min and 14 min Fig. 3 The effect of storage time on free fatty acids content of oat groats processed commercially or with superheated steam (SS) at 110C
Commercial plants 110C, 10min and 14 min Storage at 21C 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 110C
Storage at 21C Commercial plants 110C, 10min and 14 min Fig. 5 The effect of storage time on intensity of oaty flavour of oat groats processed commercially or with superheated steam (SS) at 110C
Commercial plants 110C, 10min and 14 min Storage at 21C Fig. 6 The effect of storage time on intensity of toasted flavour of oat groats processed commercially or with superheated steam (SS) at 110C
Commercial plants 110C, 10min and 14 min Storage at 21C Fig. 9 The effect of storage time on intensity of rancid flavour of oat groats processed commercially or with superheated steam (SS) at 110C
Commercial plants 110C, 10min and 14 min Storage at 21C Fig.10 The effect of storage time on L value (lightness) of oat groats processed commercially or with superheated steam (SS) at 110C
Summary • The shelf-life stability of oat groats processed with superheated steam at 110C for 10 and 14 min, and stored at 21C was acceptable and exceeded the intended storage time period of 6 months