Engineering Properties of Biological Materials and Food Quality 3(2+1)

Lesson 13. Introduction to Food Quality

Food Quality:

The four principal quality factors in food are the following:

1. Appearance, comprising colour, shape, size, gloss, etc. is based on optical properties and visual manifestation of size and shape.
2. Flavor: comprising taste (perceived on tongue) and odour (perceived in the olfactory centre in the nose), is the response of receptor in the oral cavity to chemical stimuli.
3. Texture, is the response of the tactile senses to physical stimuli that result from contact between some part of the body and the food
4. Nutrition  Cost, convenience and packaging are also important but not considered quality factors. Of the above listed the first three are termed as “sensory acceptable factors” because they are perceived by the senses directly. Nutrition is a quality factor that is not an acceptability factor as it is not perceived by the senses.

As consumers, these four attributes typically affect us in the order specified above, for example we evaluate the visual appearance and color first, followed by the taste, aroma, and texture. The appearance of the product usually determines whether a product is accepted or rejected; therefore this is one of the most critical quality attributes. Nutritional value is a hidden characteristic that affects our bodies in ways that we cannot perceive, but this quality attribute is becoming increasingly valued by consumers, scientists, and the medical profession Kramer (1965).

Food Texture:

The importance of texture in overall acceptability of foods varies widely, depending upon the food

1. Critical: Those foods in which texture is the dominant quality characteristics, eg. Meat, porato chips

2. Important: Those foods in which texture makes a significant but not a dominant contribution to the overall quality, contributing, more or less equally, with flavor and appearance eg. Most fruits, vegetables, bread, candy.

3. Minor: Those foods in which texture makes a negligible contribution to the overall quality, eg most beverages and thin soups.

Table 1 Most frequently used Texture words

 

USA	Japan
crisp dry juicy soft creamy crunchy chewy smooth stringy hard	hard soft juicy chewy crunchy crisp creamy slippery viscous greasy
78 words	406 words

Japanese use 406 descriptive words whereas in USA people use 78 descriptive words to describe food texture.

Definition of texture:

Texture means those perceptions that constitute the evaluation of a food’ s physical characteristics by the skin or muscle senses of the buccal cavity, excepting the sensations of temperature or pain (Matz, 1962).

By texture we mean those qualities of food that we can feel with fingers, the tongue, the palate or the teeth. (Potter, 1968).

Texture is the attribute of a substance resulting from a combination of physical properties and perceived by the senses of touch, sight and hearing. Physical properties may include size, shape, number, nature and conformation of constituent structural elements (Jowitt, 1974).

Texture: all the rheological and structural attributes of a food product perceptible by means of mechanical, tactile and when appropriate visual and auditory receptors (International Organization for standards, standard 5492/3, 1979)

Texture of foods has the following characteristics:

1. It is a group of physical properties that derive from the structure of the food.
2. It belongs under the mechanical or theological subheading of physical properties.
3. It consists of a group of properties, not a single property.
4. Texture is sensed by the feeling of touch, usually in mouth, but other parts of body may be involved (hands).
5. It is not related to chemical senses of taste or odour.
6. Objective measurement is by means of functions of mass, distance and time only.

Table 2 Relationship between textural properties and popular nomenclature

Mechanical characteristics	Secondary parameters	Popular terms
Hardness Cohesiveness Viscosity Elasticity Adhesiveness	brittleness chewiness gumminess	soft→firm→hard crumbly→crunchy→brittle tender→chewy→tough short→mealy→pasty→gummy thin→viscous plastic→elastic sticky→tacky→gooey

 

Geometrical characteristics		examples
Particle size and shape		Gritty, grainy, coarse, etc.
Particle shape and orientation		Fibrous, cellular, crystalline etc.
Other characteristics Primary parameters	Secondary parameters	Popular terms
Moisture content
Fat content	oiliness	Dry→moist→wet→watery
	greasiness	oily
		greasy

 

Other definitions:

Kinesthetics: Those factors of quality that the consumer evaluates with his sense of feel, especially mouthfeel.

Body: The quality of food or beverage, relating either to its consistency, compactness of texture, fullness, flavor or to a combination thereof (American Society for Testing and Materials, standard E253-78a).

Chewy: Tending to remain in the mouth without rapidly breaking up or dissolving, Requiring mastication.

Haptic: Pertaining to the skin or to the sense of touch in its broadest sense

Mealy: A quality of mouthfeel denoting a starchlike sensation. Friable.

           Possessing the textural property manifested by the presence of components of different degrees of firmness or toughness.

Mouthfeel: “The mingled experience deriving from the sensations of the skin in the mouth during and /or after ingestion of a food or beverage. It relates to density, viscosity surface tension, and other physical properties of the material being sampled.

Getaway: the textural property perceived as shortness of duration of moutfeel.

Consistency: “All the sensations resulting from stimulation of the mechanical receptors and tactile receptors, especially in the region of the mouth, and varying with the texture of the product”.

Hard: “ As a texture characteristics, describes a product which, displays substantial resistance to deformation or breaking”.

Soft: “As a texture characteristics, describes a product which displays slight resistance to deformation”

Tender: “As a texture characteristics, describes a product which, during mastication, displays slight resistance to breaking”

Firm “ As a texture characteristics, describes a product which, during mastication, displays moderate resistance to breaking”.

Body-Texture Interactions:

The properties of texture and viscosity are perceived by the human senses. Hence in order to understand texture and viscosity, it is necessary to understand how human body interacts with food.

Some definitions:

Masticate: To chew, grind or crush with teeth and prepare for swallowing and digestion.

Bolus: a mass of chewed food in mouth.

Deglutition: The act or process of swallowing food.

Teeth Lips Cheeks Tongue Palate Gums Salivary gland Upper jaw (maxilla) Lower jaw (mandible) Oral cavity  Pharynx Other (neck, arm, shoulder muscle)

Reasons for mastication of food:

•  Gratification

•  Comminution

•  Mix with saliva

•  Temperature adjustment

•  Release flavor

•  Increase surface area

References:

Bourne, M. C. 1982. Food Texture and Viscosity: concepts and measurement, Academic Press, USA

Sahin S. & Sumnu, S. G. 2006. Physical Properties of Foods. Springer, USA

Barrett, D. M., Beaulieu, J.C. and Shewfelt, R. (2010). Color, Flavor, Texture, and Nutritional Quality of Fresh-Cut Fruits and Vegetables:  Desirable Levels, Instrumental and Sensory Measurement, and the Effects of Processing, Critical Reviews in Food Science and Nutrition, 50: 5, 369-389.