SENSORY CHARACTERISTICS OF FOOD
Millions of flavor sensations are experienced in a lifetime. Flavor is an important attribute of a food. It involves the complex integration of sensations from the olfactory center in the nasal cavity, the taste buds on the tongue, tactile receptors in the mouth, and the perception off pungency, heat, cooling, and so on when a food is placed in the mouth. However, much of what we call flavor is a blending of taste and aroma. Other sensory factors may also effect our total experience with food, including its visual appearance and even the sounds of crunching crisp foods such as raw carrots and celery and the sizzle of faitas when they are brought to the table.
Taste and Aroma
Sometimes the words flavor and taste are used synonymously. In a strict sense, however, taste is only one part of flavor. Taste involves the sensations produced through stimulation of the taste buds on the tongue. It is generally accepted that there are only five primary taste sensations: sweet, sour, bitter and salty, umami. But the perceived flavor of a food involves, to a considerable extent, the sense of smell along with the taste sensations. It is influenced by other senses as well.
Taste buds are found in small elevations, called papillae, on the surface of the tongue. The actual taste sensations are produced when bitter, salty, sweet, or acid substances in a solution contact taste receptors in the taste pore leading to the taste bud. A message is sent to the brain from the taste cells by way of nerve fibres with endings in the taste cells. The brain interprets and identifies the specific taste.
The olfactory center is found at the top of the nasal cavity. To stimulate the olfactory center, substances must be in gaseous form. The gaseous molecules enter the nose as food is placed in the mouth and are drawn toward the olfactory center where they stimulate nerve endings.
Flavor a blend of taste, smell and general touch sensations evoked by the presence of a substance in the mouth
1) Olfactory : having to do with the sense of smell
2) Tactile : having to do with the sense of touch
3) Pungency : a sharp, biting quality
4) Taste : sensations perceived through stimulation of taste buds on the tongue; primary tastes are sweet, salty, sour and bitter
5) Aroma : an odor detected by the olfactory sense
6) Papillae : small, nipple like projections of various shapes on the surface of the tongue
7) Taste receptor : tiny ends of the taste cells that come in contact with the substance being tasted
8)Taste pore : a tiny opening from the surface of the tongue into the taste bud
9)Taste bud : a group of cells including taste cells, supporting cells and nerve fibres
10)Umami : Umami was first identified by Oriental Cooks 1200 years ago, it was’nt until the turn of this century that scientists isolated glutamate and other substance which convey this distinctive flavour.
Glutamate is an aminoacid that is found throughout the human body. Its also naturally present in protein- rich foods such as cheese,meat, fish and human milk. When present in its free form in foods - not bound together with other amino acids in protein - glutamate exerts its umami flavor effect.
MSG added to foods provides similar flavouring function on the “free” glutamate that occurs naturally in foods. It is often used to flavour meats, poultry, sea food, soups, stews, sauces and gravies.
The physical properties of foods, including texture, consistency, and shape, involve the sense of touch or feeling, also called the tactile sense. When food is contacted, pressure and movement receptors on the skin and muscles of the mouth and tongue are stimulated. Sensations of smoothness, stickiness, graininess, brittleness, fibrous qualities, or lumpy characteristics may be detected.
Texture is the term used to describe the characteristics of a finished food product. The order in which the ingredients are added, the way of mixing and the method of cooking affect the resulting product.
A good cook should not only be able to distinguish between on texture and another but also be able to produce what he or she wants. Only by observation, experience and perseverance will a person be able to know what the correct texture of a particular product should be. A brief description of some commonly found textures and their correct occurrence is given below, but it must also be borne in mind that the difference between one texture and another is very fine.
Firm and close: The air bubbles made by the raising agents are many but small, and the mixture is not in the least spongy. The fat included prevents the mixture from being too hard, e.g., in biscuits or plain short pastry.
Short and crumbly: This is similar to firm and close, but more fat is added. Eg.in shortbread or nankhatais.
Spongy : A soft and elastic texture showing inclusion of air, e.g.Swiss rolls, sponge cakes and idlis.
Light and even :
Holes are plentiful and of a fair size. The food is firm but not hard or tough. It is neither so short as pastry nor as spongy as sponge cakes, eg. Madeira cake, Queen cake.
Flaky: This is caused by the method of adding fat. Thin crisp layers are formed, separated by air pockets. The flakes themselves should not be tough, eg. .flaky and puff pastry, chiroti, etc.
Coarse:Holes are large and uneven, and the food is sunken in the centre. This brought about by the addition of too much raising agent or too little liquid.
Tough:Coarse mixtures are also tough. Toughness is caused by too much liquid or through incorrect mixing. This will also result if too little fat is added.
Hard: A bad fault brought about by the addition of too much liquid or too much pressure while mixing. Hard mixing. Hard mixtures are usually heavy since the air enclosed in driven off.
Basic forces of eating
There are five basic forces involved with eating. These are :
Compression : the deforming of a food using force, such as between the tongue and palate.
Adhesiveness – the attraction between the food and an external surface, such as food sticking to the palate.
Tensile : the extending of foods under force, such as the effects of the muscles on the bolus as it travels through the pharynx.
Shear : the cutting of a food into pieces by forces that are not directly opposing, such as the lateral movement of the molars during chewing.
Fracture : the breaking of the food directly opposing forces, such as the incisors biting through a cookie.