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 Grain Quality

• Introduction
  The development of oat varieties with improved quality is required to maintain current oat production and expand into new markets. Milling quality oats attract a premium of between $15 and $30 per tonne and oats for feed are a major end use for this crop.

  Both domestic and export markets trade on grain quality. Attributes such as hectolitre weight, screenings percentage, groat yield, grain size, protein, oil, and b -glucan are all measurements used to characterise the grain quality of oat varieties and determine suitable end uses. They are divided into physical and chemical characteristics. The Grain Quality Laboratory for the National Oat Breeding Program is located in Perth and also develops new tests for oat quality.
  

PHYSICAL GRAIN QUALITY TESTS
Measurements carried out by the Oat Breeding Program located at SARDI include hectolitre weight, grain weight, and screenings percentage.

• Hectolitre weight
  Hectolitre weight is a measure of grain density. Grain is poured into a container of known volume from a set height. The container filled with grain to a set level is weighed and hectolitre weight, expressed as kg/hl is calculated. High hectolitre weight is preferred and varieties must pass a cut off level before being classed as milling quality.
  
  
• Grain weight
  Grain weight is a measure of grain plumpness. Using a grain counter, 1000 seeds are counted and then weighed. Grain weight is expressed in grams per 1000 seeds. High grain weight is preferred.
  
  
• Screenings percentage
  Screenings percentage is a measure of seed size. 50g of seed is shaken for 20 seconds on a series of sieves using a Sortimat. Grain which is less than 2mm in size is weighed. Screenings percentage is then calculated as percent less than 2mm. Low screenings percentage is preferred and varieties must pass a cut off level before being classed as milling quality.

NIR TESTING
Development of NIR calibrations to predict protein, oil, groat percent and Minolta L, a and b have meant that screening of varieties for these parameters can now occur from the third generation of seed tested by the Oat Breeding Program. This has been crucial in the development of tests that allow selection for improved quality parameters from very early in the breeding program. These measurements are carried out by the Oat Breeding Program located at SARDI.

• Protein
  NIR calibrations were developed using the Dumas method to measure nitrogen content. Protein content is then calculated by multiplying nitrogen content by 6.25 and is expressed as percent as received. High protein is desirable for both milling and feed varieties.
• Oil
  NIR calibrations were developed using an automated soxhlet system. Oil content is expressed as percent dry basis. A low oil content is preferred for milling quality oats and high oil content for feed oats.
• Groat yield
  NIR calibrations were developed using a Codema Laboratory Dehuller. Groat yield is expressed as percent and is the percentage of the whole oat which remains after the husk is removed. High groat yield, which relates to commercial milling yield, is a high priority with processors and the highest priority in the selection of milling varieties.
• Grain Brightness
  High values for this trait are generally desirable for feed oats. For milling oats it is more important that the grain has a golden colour. Grain brightness is measured using a minolta colour meter, which gives three values. The Minolta L value is the total reflective brightness of the grain, whilst the Minolta a and b values give an indication of the colour of the grain.

OTHER TESTS

The Oat Breeding Program is constantly developing techniques to maximise the throughput and number of tests performed to characterise the quality of all breeding lines tested. Accurate and fast tests ensure as many samples as possible are tested as soon as possible in the breeding cycle.

The program also works with industry to determine the most suitable tests for characterising oats for different end uses. The Uncle Tobys Company has a co-operative project to determine the most important sensory tests for characterising suitable tasting milling quality oats.

• b-glucan
  b -glucan is determined by using flow injection analysis. A high b -glucan content is preferred for milling quality oats due to its medicinal properties and low b -glucan content is preferred for feed oats.
• Hull Lignin
  The amount of hull lignin is of importance to feed oats. Low levels are desirable as hull lignin reduces the feed quality or digestibility of the oat grain. Unfortunately low hull lignin levels are strongly associated with reduced grain brightness, resulting in low lignin lines being discarded from material selected for milling end use. Hull lignin is measured by immersing hulls in an indicator solution, observing the colour change and is reported as either a high or low lignin level.
• Digestibility
  Digestibility is a measure of how digestible the grain is when fed to human livestock. It is measure as % dry matter digestibility (% DMD). Digestibility is an important indicator of the feeding value of the variety.
• Digital imaging
  Digital imaging is one technique currently being used to determine the uniformity of whole kernels by measuring parameters such as size, shape, screenings and hectolitre weight. This method also measures brightness and colour, an important measurement for the horse industry.

Hay Quality

Quality is an important marketing tool for export oaten hay. Quality standards delimit payments for oaten hay delivered to processors and the continued growth of this industry is dependant on meeting the quality specifications of more discriminating export and domestic markets. Development of varieties which meet these standards form an important part of the oat breeding programs hay work. Currently varieties are tested using NIR calibrations for the following:

Preference is a key issue for which there is currently no measurement available to easily assess the number of lines tested by the program. Research is underway to link preference to more easily measured characteristics and this will be implemented when the results become available.

Mills and Grinders

The National Oat Breeding program is gradually increasing its mill and grinder collection used for reducing grain and hay samples ready for various quality testing analyses. Currently we have a Retsch ZM 200 Mill capable of milling grain to a fineness of 1.0mm and 0.5mm, a Foss Cyclotec 1093 Mill also capable of milling grain but which is mainly used for grinding dried hay samples to a fineness of 1.0mm and for initial reduction of dried hay, we have a Thomas Wiley Mill (Model 4) with a 4mm screen.