SHELFLIFE STABILITY OF OAT GROATS PROCESSED WITH SUPERHEATED STEAM

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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
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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 88-115?C for 90-104 min (up to 80
  inactivation)
• then steaming at 100-104?C for 8-10 min
• Grain is dried andprocessed to
• Commercial products (flour, bran, rolled oats)

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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

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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

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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)

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