Lesson 07 : Determination of quality of foods- objective methods
Texture : Texture refers to those qualities of a food that can be felt with fingers, tongue, palate, or teeth. Foods have different textures, such as crisp crackers or potato chips, crunchy celery, hard candy, tender corn, creamy ice cream etc. Texture is important in determining the eating quality of foods and can have a strong influence on food intake and nutrition. Perceived texture is closely related to the structure and composition of the food, and both microscopic and macroscopic levels of structure can influence texture. A complete description of food texture can only be achieved using sensory methods, but difficulties associated with such methods have led to the development of rapid, inexpensive but less satisfactory instrumental methods. New techniques based on instrumental measurement made on human subjects during chewing promise to open up new understanding of food texture.
Perception of texture can be sometimes misleading. When one of two identical samples of gravy is thickened with a tasteless starch or gum, many will judge the thicker sample to have the richer flavor. This can be entirely psychological. However, the line between psychological and physiological reactions is not always easy to draw. Our taste buds respond in a complex fashion not yet fully understood. Many chemicals can affect taste response to other compounds. It is entirely possible for texturizing substances to influence taste and flavor in a fashion that is not imaginary. If a thickener affects the solubility or volatility of a flavor compound, its indirect influence on the nose or tongue could be very real.
Colour : Color may be the most important sensory attribute of food and as such holds a preeminent position in overall food quality. It affects consumer judgment of other sensory characteristics such as flavor, sweetness and saltiness as well as being an important predictor of non sensory quality attributes like moisture content, over-processing and pigment content. Colour terms can bedivided into the subjective and objective. The subjective i.e psycho sensorial, are brightness, lightness, hue saturation, chroma and colorfulness. Colorfulness, a more recently introduced is that aspect of visual sensation according to which an area appears to exhibit more or less chromatic colour.
Flavour : Flavor is a combination of both taste and smell and is largely subjective and therefore hard to measure. This frequently leads to differences of opinion between judges on quality. This difference of opinion is to be expected since people differ in their sensitivity to detect different tastes and odors, and even where they can detect them, people differ in their preference. In Some cultures, strong smelling fish is desirable, whereas in others such fish would be unacceptable.
The flavor of a given food is determined by both the mixture of salt, sour, bitter, and sweet tastes and by the endless number of compounds which give foods characteristic aromas. Thus, the flavor of a food is quite complex and has not been completely described for most foods. Adding to this complexity is the fact that the same food is often perceived differently by different individuals. This difference. is due to cultural and biological differences between people.
Last modified: Thursday, 16 February 2012, 7:58 AM