The work presented here explores the effect of storage on chemical and other
characteristics of dry, free of added chemicals and pest-free barley and canola grain. This
was achieved by measuring the changes in a number of variables of grain stored at
different temperatures under laboratory conditions and in commercial storage. The
following measurements were carried out: Viability, moisture contents (mc), oil contents
(oc), whole grain colour, spectrophotometry of grain extracts, hydroxy methyl furaldehyde
(HMF), changes in storage atmospheres, organic sulphide levels, tocol concentrations
(vitamin E), Iodine Value (IV), Thiocyanogen Value (TV), Peroxide Value (PV),
p-Anisidine Value (p-AV) and Acid Value (AV).
The mc of canola and barley were within the range considered safe for storage. Oil content
of canola did not change significantly with storage. Viability of canola stored at 4 and
25 °C did not change noticeably, but higher storage temperatures resulted in seed death.
Barley maintained high viabilities at low temperatures, but was more susceptible to high
temperatures than canola. Colour changes of whole barley grain in storage were
pronounced and temperature dependent. Colorimetry of whole barley grain showed
potential as a tool for monitoring quality changes in storage. Absorption spectra of grain
extracts reflected chemical and physiological changes in storage. HMF, an indicator of
Maillard browning, accumulated in short to medium term storage at 45°C and in long term
storage at 25 and 35°C. Measurement of HMF was considered useful for monitoring
quality changes of stored cereal grain.
In a study of storage atmospheres, changes in the concentrations of carbon dioxide, carbon
monoxide, oxygen, carbon disulphide and carbonyl sulphide were shown to be useful
indicators of quality loss of grain in storage. Gas concentrations usually depended on
storage temperature and time and reflected the storage history of the commodity. They
indicated loss of carbohydrates and lipids by respiration, oxidative damage and
deterioration of sulphur containing amino acids and other compounds.
Oil quality indicators were consistent with oxidative damage to canola lipids in storage.
IV, TV, and p-AV of canola oil did not correlate with quality of commercial samples.
However, a relationship between increases in PV and high storage temperatures in canola
was shown and AV increased in storage dependent on storage temperature and time. In
barley and canola, the concentration of anti-oxidant tocol species (vitamin E) decreased at
35 and 45°C storage dependent on storage time. The overall tocol content as well as
vitamin E activity decreased with storage decreasing the nutritional value of the
commodities and indicating oxidative damage to lipids.
It was concluded that the storage of dry, pest-free whole barley and canola grain at
moderate temperatures (25-45°C) resulted in chemical and other changes. The
consequence of these changes was a measurable reduction in the freshness of grain
relevant to the nutritional, food technological and commercial quality of grain.
| Identifer | oai:union.ndltd.org:ADTP/219289 |
| Date | January 1999 |
| Creators | Reuss, Rainer, n/a |
| Publisher | University of Canberra. Applied Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright Rainer Reuss |
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