Although durum wheat production is minor compared with wheat (Triticum aestivum), and its area is very localized (the traditional region extending from the SE to the SW of the province of Buenos Aires), representing an attractive option for producers??.

 

Because of the specific conditions under which most durum wheat is produced, where farmers and industries agree on a contract, the samples were requested from the industries receivals, obtaining 27 composite samples.

They were organized according to their origin region, mainly in the Sub regions NOA,? IV and V South.

Composite samples were sent to Bahía Blanca and Buenos Aires Arbitration Chamber Laboratories, where the commercial analysis (grade), ash and weight per 1,000 kernels were performed.

Afterward, composite samples were referred to Grain Quality Laboratory of Chacra Experimental Integrada Barrow to carry out grinding in a Buhler 202 D mill. In the semolina obtained, Falling Number, Gluten, Colour and Farinogram were analyzed.

 

The evaluation of the industrial quality of durum wheat is based on grain characteristics, milling, behavior in milling, gluten quality, semolina colour and rheological properties of dough.

Some traits like protein content and vitreous kernels percentage are affected by agricultural and weather conditions. Percentage of hard vitreous kernels is an important grading factor in durum wheat. Industry prefers vitreous kernels because of theirs high correlation with protein content, semolina yield and cooking quality.

On the other hand, gluten quality (measured as Gluten Index), semolina colour and rheological characteristics, are strongly influenced by genotype.

The reasons why durum wheat produces good quality pasta are the following:

- Su Its yellow pigment content doubles the wheat (Triticum aestivum).

- Durum gluten is stronger and more cohesive than wheat (Triticum aestivum).

- Due to its kernel hardness, semolina yield is superior to other wheats. Durum semolina has many advantages with regard to wheat flour in the manufacturing of pasta: it requires less water to form a dough; consequently, drying cycle is cheaper.

- The main difference between durum and wheat (Triticum aestivum) is that pasta elaborated with durum semolina has more stability when cooked, doesn’t disintegrate when boiling and stands overcooking.

Methodology for durum wheat includes some of the tests regularly used for wheat (Resolution SAGPyA 557/97) plus the following specificiones:

GRAIN

Vitreous Kernels Percentage (Resolution N° 1075/94 – Standard XXI - Ex. SAGyP)

Percent in weight of vitreous kernels present in the sample, being vitreous the ones that are completely translucid, without points, opaque stains or bleached grains.

MILLING (Experimental Milling Buhler 202-D)

Grain is dampered to 15.8 % humidity and tempered during 20 hours. Semolina yield (Particle size between 125- 355 microns) is reported.

SEMOLIN

Color (Minolta Chromameter CR-310, Manufacturer’s Method)

Spaghetti color is due to a balance between pigment content (carotenes and xanthophylls) and lipoxigenasic activity which destroys color.

Lightness (L), redness (a) and yellowness (b) of Hunter data are determined using the tristimulus method, with Minolta CR-310 reflectance colorimeter.

Gluten Index (Glutomatic Perten 2200). Manufacturer’s Registry.

Once the wet gluten test is done, the centrifuge forces the gluten to pass through a sieve that has been specially designed. The amount of gluten that goes through the sieve is a measure of gluten characteristics.

This method is done as follows: both fractions, the one that passes through the sieve, and the one which is retained in it, are gathered and weighed, obtaining, thus, a percentage.

FARINOGRAM (Brabender’s Farinograph)

The method in use is described by Irvine, Bradley and Martin’s technique (Cereal Chemistry, Vol 38, Nº 2, 1961), using fixed water absortion (45 %), fixed time of kneeding (8 min) and small stainless steel bowl (50 g).
The following data are reported:
*Dough development time (min)
*Energy Level= Max Height (UF) / 20+ Area (cm2)
*Tolerance Index (%)= Max Height - Final Height / Max Height.