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testing food packaging during trasnsport and storage ,as high temperature affect stability of the packaging materials, food taste, texture ,odor, and composition
Texture is a very important character of every food we eat or drink. To many people, it is even more important than taste! Think of all the ways we describe a food’s texture. The students in the class could probably come up with twenty or more words just to describe the foods in their lunchboxes. "Crunchy, chewy, crispy, juicy, squashy, runny, solid, hard, soft, soggy, firm, creamy, fatty" and so on.
The components and ingredients within foods plus the processes they go through determines their texture. Take the example of making a fruit smoothie, which is easy to make at home in a blender and found on many supermarket shelves. Depending on the type of fruit, how pulpy and pureed the fruit is and how much water is in there will determine how thick the final smoothie is. Most commercial products proudly claim to contain only fruit (and water), so all the texture comes from the fruit and the process. Different smoothies can vary in their thickness. If one is so thick that it requires a spoon to eat, then it is really more of a soft-solid type product than a drink.
In addition to sensory testing, food texture is also measured by special equipment in research laboratories and factory quality assurance (QA) labs. Texture analysers are machines that can press, pull, pierce, squash, twist and crush samples of food in a way which tries to mimic the end use as closely as possible. Special attachments have been developed to test for particular applications, especially in the meat area. Texture analysers measure food texture in a scientific, non-biased way that can be repeated to give standardized assessment methods. In many cases, these tests have been developed to try to mimic our senses to make the test as applicable to the product as possible, for example, to represent a biting action or a chewing action.
The texture analyzer above from Stable MicroSystems is used primarily for semi-solid or solid foods but more liquid foods can also be measured by machines called viscometers or rheometers. Rheometers are complex machines which have been developed to measure the rheological properties of materials in many industries, not just the food industry, and are often found in research organisations. More simple viscometers are also useful in factories and test kitchens to get quick indications of the product. You can think of viscosity as essentially the liquidness of a material, how "runny" or how thick it is. For older or more able students, there is a fuller explanation of rheology in the extensional section further down the page.
Suffice to say at this stage scientists have measured viscosities of many food materials as standards. For example, we now know that water is assigned a viscosity of1mPas at room temperature (20oC). The unit "mPas" is called the milli-pascal-second but you do not need to worry about that at this stage, just that for water it is measured to be1 unit. Olive oil is about100 times thicker at20oC (its viscosity is about100mPas) and golden syrup is about10000 times thicker! (or about10000 mPas). Just think of the differences when you try to pour water, olive oil and golden syrup out of a bottle. You can wait a long time for the syrup to make its way out of the bottle, especially if you have stored it in the fridge! Viscosity is greatly affected by temperature which is why it is always important to specify the temperature when talking about viscosity. Materials generally get thicker when they are colder and more liquid as they warm up.
Used in testing food packaging during transport and storage
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