LEC-4|PROPERTIES OF FOOD AND QUALITY EVALUATION| LEC-4|

Structure and physical properties of foods Physical properties of food are aspects such as colour, structure, texture, rheology and interfacial properties, and composition. We have a range of instrumental methods for objectively characterising and measuring food structure and physical properties. These are useful for applications such as new product development, benchmarking, reformulation and specification. Colour Consistent and accurate measurements of the colour and visual appearance of food products is extremely important. Various methods are available for colour measurement, allowing a wide variety of sample types to be measured. Colour measurement results are typically provided on the CIELAB scale. Others are available on request. Structure The structure of food influences texture. Examples include porous products such as aerated foods and bakery products where the bubble structure affects softness, and starch-based snacks where it affects crispiness. Food structure analysis using X-ray micro-CT X-ray micro-CT offers non-destructive imaging and structure measurement in 3D. Images and movies showing the internal structure of products can be generated. Measurements of porosity, bubble size distribution and structure thickness (wall size) can be performed. Texture Food texture is an important sensory attribute as it affects the way food tastes and how it feels in the mouth. The texture depends on the rheological properties of the food and evaluation involves measuring the response of a food when it is subjected to forces such as cutting, shearing, chewing, compressing or stretching. Rheology and interfacial properties The rheological properties of food materials are important in determining the texture as well as how they behave physically when subjected to physical forces and forced to flow. The rheological properties of raw materials, intermediate products such as batters and doughs as well as final products can be studied. Thermal analysis Thermal analysis techniques measure the physical and chemical properties of foods as a function of temperature or time. Compositional mapping Many food products have a non uniform distribution of composition. For example, fried products have a higher fat content near surfaces, and baked products have a higher moisture content in the centre of the product. Compositional mapping techniques allow these gradients to be measured and visualised. Food Quality Evaluation 988 Words Food quality evaluation is important to ensure proper control of quality in food industry, lesser prices, longer shelf life and good taste of the food. Human perception is manipulative and accurate. Hence, there is a need for machine perception since it’s a robust and reliable method. For food quality evaluation, sample images with some problem in quality are chosen. Some of the commonly evaluated foodstuffs include:

[1] Non-vegetarian foods like eggs and sea food

[2] Crops and seeds

[3] Fruits and vegetables

[4] Chocolate chip cookies Quality evaluation for chocolate chips will depend on number of chips, size of chips with respect to full cookie, area of chips and their distribution throughout the cookie.