How to measure and analyse the texture of food, cosmetics, pharmaceuticals and adhesives.

Tuesday, 6 September 2016

Noodle quality testing: a range of texture analysis methods for a wide variety of noodle types – Part 5

TEXTURAL QUALITY OF COOKED NOODLES [3]

Spaghetti/Noodle Tensile Rig
Tensile testing of Cooked Noodles

Suitable for: Only straight cooked noodles that are not thin and fragile to handle as single strands
 

Another test on cooked noodles uses a Spaghetti/Noodle Tensile Rig (right) which performs tension tests on samples to assess elasticity and breaking strength in tension see the example graph and table  which compare tensile properties of three noodle types (cooked to manufacturers' recommended times). These properties give another indication as to how a sample holds together upon cooking or when transported, for instance, within a ready meal.
The cooked sample is located through slots and is wound round parallel friction rollers two or three times, to reduce any slippage and also to anchor the sample ends. The rollers ensure that the sample is not split or cut during the test and that the break occurs along the extended region of the sample. The maximum stress value obtained gives an indication of the sample's resistance to break and the 'distance to break' indicates the extensibility of the sample.

The Spaghetti/Noodle Tensile Rig is suitable for samples that have already been cut and prepared for the consumer.  In the case of noodles or pasta ribbons, the dough sheet will have been cut to specific ribbon width and length. Whilst testing of this sample is possible on the Spaghetti/Noodle Tensile Rig the test setup is simplified if the sample is available in sheet form and cut into a circular piece for ease of mounting on the Noodle Tensile rig.

Cooked Noodle Surface Stickiness Determination – Straight Noodles

Suitable for: Cooked Straight Noodles or Sheeted Cooked/Uncooked Noodles that are not too fragile to handle as separate strands/sheets


Another parameter in evaluating the quality of cooked noodles is surface stickiness. This parameter is readily differentiated by sensory analysis but a rapid instrumental method, using a small sample size, has long been sought. The main reason pasta stickiness has received so little attention is that it is difficult to quantify. Instrumental measurement of stickiness is complicated by a number of factors of which meaningful sample comparisons can only be made if these factors are controlled. 


The apparent Stickiness of a given sample is strongly influenced by the amount of unabsorbed water associated with the cooked pasta/noodles following drainage, the length of time between drainage and testing, and the relative humidity of the testing area. Research has also shown that stickiness is influenced by cultivar, wheat class, raw material granulation and protein content.

A repeatable method developed at Stable Micro Systems, for evaluating surface stickiness of cooked pasta/noodles, uses an adhesive test with a Pasta Firmness/Stickiness Rig (as shown below). This consists of a rectangular aluminium probe which is attached to the load cell of the Texture Analyser. Samples are centrally aligned under the probe on a raised platform and are retained by a plate with a hole, on top of the strands. The probe then applies a suitable compression force to the sample to achieve a good probe:sample contact before withdrawing at maximum speed to measure the sample stickiness. 


Pasta Firmness/Stickiness Rig
Stickiness is defined as the maximum peak force to separate the probe from the sample's surface upon probe retraction (the higher the force value, the stickier is the sample). The total tensile work (area under the curve) required to separate the probe from the sample's surface is also applicable.

Also shown is a typical graph highlighting the key parameters obtained from a stickiness test. An example of the use of this test is shown in the table highlighting the difference of noodle sheet stickiness depending upon the hardness of the cooking water. Some researchers have demonstrated that as cooking water becomes harder (CaCO3 increases) cooked noodles become stickier. Others have reported that processing noodles under high temperature drying conditions may partly overcome cooked noodle stickiness. 


Effect of water hardness on pasta stickiness
Although water hardness does not affect cooked noodle firmness, it has a marked effect on surface stickiness; therefore prepared water of constant hardness and pH should be used for standard cooking tests and should be considered when distribution of pasta/ noodles to soft water areas is inevitable. See graph and table (right) for details.



We can design and manufacture probes or fixtures for the TA.XTplus texture analyser that are bespoke to your sample and its specific measurement.

Once your measurement is performed, our expertise in its graphical interpretation is unparalleled. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can also prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.

For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

TA.XTplus texture analyser with bloom jar The
TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.

No-one understands texture analysis like we do!

To discuss your specific test requirements click here...

Watch our video about testing of pasta productsDownload a published article covering methods for the testing of pasta products

Browse our range of pasta and noodle testing solutions





No comments:

Post a Comment

Note: only a member of this blog may post a comment.