Instrumental texture analysis emulates the sensory effect i.e.what happens with the foodstuffs in everyday life. Its biggest benefit: it removes all elements of subjectivity from the testing.
Benefits of instrumental testing at a glance:
- Conversion of sensory tests to objective values: Important test criterias such as freshness, crispiness, spreadability are determined objectively.
Small deviations can be measured and shown in values. By standardization of testing methods (Company Standards) different production sites can achieve the same product quality. This is very important in highly automated production lines, and for suppliers of semifinished goods, ingredients and food systems. All of this helps to avoid complaints at the outset by improving quality and consistency of the products. The tests deliver reproducible results. All results can be shown and interpreted in a graph and documentation of all results is easy. Proper documentation of product quality simplifies negotiations between suppliers, processors and customers.
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These dies are used mostly for penetrations tests to determine the hardness of foodstuffs. These tests are widely used and find their application with many foodstuffs.
Fundamental is the choice of the appropriate die: Cylindrical dies apply compressive stress by the surface and shear stressing by the edges and the outer surface area of the die. Whereas ball dies start with vertical forces. During the test more and more horizontal forces are added.
Zwick Roell offers penetration dies with various shapes, sizes and materials, also completely to your requirements.
Understood that also special dies for tests to Standard are offered:
For the determination of the bread firmness according to AACC74-09 a cylindrical die compresses defined bread slices up to 40% in two cycles. At a compression of 25% the CFV (Compression force value) is determined.
The gel strength according to Bloom (GME Monograph 2005, ISO 9665) is measured by many gelatin producers and fabricators. The gel strength in grams Bloom is the mass necessary to depress a standard plunger 4 mm into the gel. The method includes a comprehensive specimen preparation in special Bloom jars.
The Kramer shear cell simulates a single bite on foodstuffs and provides information about bite characteristic, crispiness and firmness. It is used for meat and fish products, small sized fruit and vegetables as well as for cereals and snacks like potato chips.
The 5 or 10 shear blades drive at a constant speed through the specimen material, compressing, shearing and extruding it through the slotted base. The test is made on a defined sample quantity. The multiple blades provide a measurement on several positions at the same time thus local texture deviations are compensated for with this method.
Warner-Bratzler Shear Device
In the Warner Bratzler test a blade cuts through a specimen. The shear behavior gives information about the toughness and tenderness of meat and fish products, the crunchiness of sausages as well as the bite characteristic of cakes and pastries.
The straight blade is mainly used for rectangular specimens and the notched blade for round specimens like sausages.
Because of the good reproducibility of the results, this test is widely used.
In a 3-point flexure test the specimen lies on two anvils and is centrally loaded with an upper anvil. The span is adaptable to the specimen.
This test is particularly suitable for brittle products, additionaly with same specimen sizes by production. For example waffles, cookies, chocolate bars or also noodle products are suited.
Flexure strength and breaking strength, fracturability and brittleness enable conclusions to be drawn for different recipes. Furthermore you can analyse the influence of moisture, baking time and temperature as well as packing and storage to the products characteristics.
In a compression test the specimen is smaller than the compression die. Also under compression the specimen should not extend over the edges of the die.
The compression test is made on brittle specimens to determine the brittleness, freshness and firmness, on specimens such as candies, coffee beans or fruits (for the determination of the stacking behaviour).
The test is carried out as a cyclic procedure on elastic specimens such as bread, cake, cheese, fish and marshmallows: The specimen is compressed twice to a certain degree and decompressed. The compression and recovery behavior shows firmness, stickiness, degree of ripeness and visco-eastic properties.
The OTMS cell (Ottawa Texture Measuring System) determines the firmness of products by compression and extrusion. This shows characteristics like ripeness, tenderness, crispiness or extrusion work on a defined sample quantity. This method is suited for products which are easy to extrude such as canned vegetables, cream cheese and pasties. But also for extrudates and cereals it can be used.
Various extrusion plates and reduction inserts for the reduction of the volume enable an adaption for different specimen materials. The measurement of pure compression forces is possible with the use of the sealing plate.
Multiple Back Extrusion Cell
Several working processes gradually break down the fat crystal network of fats like butter and margarine.This change of material is measured by the work softening or the remaining hardness.
The back extrusion die with multiple holes extrudes the fat in several cycles. The test determines the remaining hardness after a defined number of cycles or the number of cycles that is required to reach a defined remaining hardness.
With other test sequences the rig is also used for ice cream, fresh chees or cooked pasta.
The dough tensile test is a micro-scale tensile test: Only a small volume of flour or dough is sufficient. The test determines the processing characteristics, extensibility, elasticity and stickiness of dough and glutens.
This is useful for the comparison of different flours and baking ingredients as well as for the determination of their influence on the baked good. Various recipes, processing types- and times, as well as additives can be improved in order to have the optimal end product.
Alternatively the rig can be used for the determination of the elastic characteristics of chewing gum.
This test tool is used for the determination of butter firmness according to ISO 16305. In this test a stainless steel wire cuts through a defined cube of butter. This test is very dependant on temperature and is performed to a Standard method in a temperated water bath.
The butter cutter is also used for the determination of the cutting strength of cheese, eggs, vegetables and fruit.
The penetration test, also called „puncture test" or „force penetration", is used frequently to test the degree of ripeness of fruits and vegetables as well as of the skin strength.
The puncture needle is pushed into the specimen to a certain depth. Depending on the skin and the consistency of the pulp distinctive curves arise.
Hardness Test on Sausage Products and Fish
Zwick Roell has developed a range of hardness testers for fish, sausage and luncheon meat. A compression cylinder with a large surface area is used as penetrator to measure the hardness of sausage or the freshness of fish and obtain comparable quality control data.
Customized Test Tools & Fixtures
You have a product with singular properties and want to choose the most suitable test method? This requires a unique test tool or fixture. Zwick Roell develops and produces for you the most suitable tool for your product and your test method. And if required, you will receive a customer specific program which is a special software for your exact test sequence and your test results.
Temperature and Climate Chambers
Foodstuffs change their characteristics depending on the humidity and environmental temperature. According to the sensitivity of the product it may be necessary to precondition the specimens or test under defined, constant temperature. Examples for this are the testing of ice cream at a storage temperature of -20 °C, or the testing of pizza cheese at approx. +80 °C.
Zwick Roell developed a temperature chamber especially for these applications that fits on the zwicki texture analyzer. Also separate temperature or climatic chambers according to your requirements can be offered.
