|Milling / Baking Lab
Description of Durum Semolina Quality Factors
1. DURUM WHEAT ANALYSIS
- Moisture % - Water content in the wheat is inversely related to the amount of dry matter. Dry wheat can be kept for years if properly stored, but wet wheat may deteriorate dramatically.
Protein % (12% MB) - Ranges from 6% to 20%, depending on variety, class, environmental conditions and cultural practices during growth. Rainfall during kernel development results in low protein, whereas dry conditions during development usually results in high protein. 1 to 1.5% of protein is lost when the wheat is milled into flour.
Ash % - Mineral content in the wheat. Bran has higher ash content than flour. Small or shriveled kernels have more bran on a percentage basis and therefore more crude fiber and ash than large, plump kernels and consequently yield less flour. Wheat usually contains 1.4 to 2% ash at 14% moisture basis.
Test Weight (lb/bu) - Wheat weight per unit volume. Most widely used and simplest criteria of wheat. Rough index of flour yield.
Wheat Hardness (NIR) - A means of determining hard and soft wheat kernels. The higher the hardness the higher the absorption.
1000 Kernel Wt. (g) - Function of kernel size, shape, dryness, purities and density and also an index of potential milling yield.
HVAC (Hard Vitreous Amber Color) - Vitreousness is that characteristic which gives the wheat kernels a hard, glossy appearance, and is usually related to protein content. The best milling quality will be found in those wheats of highly vitreous kernels.
Kernel Size Dist. (g) - Percentage of large, medium, and small kernels in a durum wheat sample.
2. SEMOLINA ANALYSIS
- Moisture % - Flour Moisture content is usually in the range of 12-15.
Protein % - 1 to 1.5% of protein is lost when the wheat is milled into flour.
Ash % - A highly significant correlation is found between ash content and the brightness of semolina. For any given wheat, higher extraction produces darker semolina with higher ash content.
Falling Number (Sec) - A measure of the a-amylase activity (starch liquefied enzyme). With more a-amylase, degradation of starch is greater and starch viscosity decreases, giving a decreased falling number. A falling number of 300 and above is desirable.
Wet Gluten % (14%MB) - Determined with the glutomatic instrument using 10 grams of semolina and with results expressed on a 14% moisture basis.
Dry Gluten % (14%MB) - The remainder from wet gluten test is completely dried by placing doughball in a heat press (Glutork) for 4 minutes and then weighed.
Speck - The number of bran specks per 10 sq. in. area of semolina. A test of the milling efficiency.
Color "b" Value - The intensive yellowness of pasta color. The color measured by Minolta Chromameter; the higher the value the more yellowness of the semolina or pasta.
3. EXPERIMENTAL MILLING
- Total Extract - Percentage of flour and semolina from 100% tempered durum wheat.
Semolina Extract - Percentage of semolina from 100% tempered durum wheat. Must not contain more than 3% flour through a #100 US sieve.
4. PASTA ANALYSIS
Color - A spaghetti sample with a color score 9.0 or greater is good, 8.0 to 8.9 is fair, and below 8.0 is a poor sample as far as color characteristics.
Cooked Weight - This test is best used in conjunction with firmness values to determine the cooking qualities of a spaghetti sample. A 10 gm spaghetti sample (precooked weight) is used for this test. A good spaghetti sample will have a high cooked weight with a high firmness value. A poor quality spaghetti sample will have a high cooked weight with a low firmness value. Generally a cooked spaghetti sample will weigh three times (30 gm) its pre-cooked weight. AACC method 16-50.
Cooking Loss - To determine the amount of solubles lost during cooking using AACC method 16-50. A spaghetti sample with a cooking loss below 6.0 is good, 6.0 to 6.9 is fair, and 7.0 or above is a poor sample.
Firmness - AACC method 16-50 modified by using two strands of spaghetti for the firmness measurement. A spaghetti sample with firmness 6.0 and above is good, 5.0-5.9 is fair, and below 5.0 is a poor sample.
- Analysis of dough strength.
W - Surface of the recording curve linked to the energy required to rupture the dough bubble.
P/L Ratio - Measure of resistance and extensibility.