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3.11.1 WATER ABSORPTION CAPACITY (WAC)

Water absorption capacity was determined by using the method of Adebowaleet.al. 2005. In this method 10 ml of distilled water was added to 1 gram of sample (flour) in a beaker. Then suspension was stirred using magnetic stirrer for 3 minutes. The suspension we get after stirring then centrifuged at 3500 rpm for 30 minutes, after this the supernatant we obtained measured in a graduated cylinder of 10 ml.Now the water absorbed by flour was calculated as the difference between the initial volume of sample and volume of the supernatant.

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WAC (%) =weight of water absorbed*density of water*100/weight of sample

 

5.1.1.2 SEDIMENTATION VALUE TEST (SDS)

The degree of sedimentation of a durum wheat meal suspended in a lactic acid-sodium dodecyl sulfate (SDS) medium during a standard time of settling. The SDS-value depends on the protein quality providing an indication of durum wheat gluten strength.

The sodium dodecyl sulphate (SDS) sedimentation volume of flour samples is estimated according to the method of Axford (1978). Flour (5g, 14% moisture basis) is added to water (50ml) in a cylinder, a stopclock is started and the material dispersed by rapid shaking for 15s. The contents are re-shaken for 15s at 2min and 4min. Immediately following the last shake, SDS-lactic acid reagent (50ml) is added, and mixed by inverting the cylinder four times before re-starting the clock from zero time. The SDS-lactic acid reagent is prepared by dissolving SDS (20g) in distilled water (1L) and then adding a stock diluted lactic acid solution (20ml; 1 part lactic acid plus 8 parts distilled water by volume). Inversion (four times) is repeated at 2, 4 and 6min before finally starting the clock once again from zero time. The contents of the cylinder are allowed to settle for 40min before reading the sedimentation volume.

5.1.1.3 SEDIMENTATION VALUE (ZELENY TEST)

The degree of sedimentation of a flour suspended in a lactic acid solution during a standard time interval is taken as a measure of baking quality.

Take 3.2gm flour suspended in 50ml water in a glass cylinder. The cylinder is shaken a few times to moisten the flour particles properly.Then 2ml of a water solution of lactic acid and iso propyl alcohol is added and cylinder is shaken again.The protein of flour start to swell immediately place cylinder in upright position and let stand for exactly 5 min.Then the volume of volume of sediment is read off the cylinder scale giving the sedimentation volume.

 

5.1.1.4  ALKALINE WATER RETENTION TEST (AWRC):

An important property of wheat flour is the amount of water it absorbs, what is often measured, the amount of water it retains against centrifugal force.

This test is made exactly as described above exactly that 0.1N sodium bicarbonate solution replaced the distilled water. Alkaline water retention capacity (AWRC) was determined according to the AACC 56–10 method. Flour (1 g) was suspended in 5 ml of 8.4 g/l NaHCO3, hydrated for 20 min and centrifuged at 1000 × g for 15 min at room temperature. The sediment obtained was weighed and the AWRC was calculated. All determinations were made in triplicate.

AWRC= (Final weight – Initial weight/ Initial weight)* 100

 

5.1.1.5  SOLVENT RETENTION CAPACITY (SRC)

Lactic acid SRC is associated with gluten protein characteristics. Sodium carbonate SRC is related to levels of damaged starch and sucrose SRC with pentosan components. Water SRC is influenced by all water adsorbing components in flour.

Prepare four solvents: deionized water, 50 percent sucrose, 5 percent sodium carbonate, and 5 percent lactic acid. Weigh 5 grams of flour in a 50 milliliter conical bottom polypropylene centrifuge tube for mixing with each solvent. Add 25 grams of a solvent and cap tube. Shake vigorously for 5 seconds to suspend flour. Shake for 5 seconds at 5, 10, 15, and 20 minutes. Centrifuge for 15 minutes without braking. Invert tube and drain for 10 minutes. Weigh tube with residue. Repeat steps 2 through 8 for each solvent.

5.1.1.6  TEXTURE ANALYZER TEST:

The most appropriate indicator of the freshness of the product is compression, for instance, the way in which a loaf of bread recovers after compression is indicative of its quality. If it retains a good amount of springiness it can be proven to be fresh, whilst crumbliness is a sign of excess loss of moisture. The deformability can be tested through FMBRA compression testing. Many textural properties like cohesiveness, springiness, hardness and fracturability can be assessed by squashing solid and self-supporting samples. This method can also be used for conducting the texture profile analysis of the breadcrumb texture.To test the firmness of bread, large size cylinders are pressed into the center , while small balls, cylinders, cones and needles are penetrated into the surface of the sample to replicate the biting action.

The changes in the crispness and hardness of bakery products can be tested through penetration and puncture testing, which helps in assessing new formulations, or how different conditions affect shelf-life.

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