Lab 2 Flashcards
What are the 5 primary mechanical characteristics of food?
Hardness Cohesiveness Viscosity Elasticity/Springiness Adhesivesness
Describe hardness
Force necessary to attain a given deformation
Descrive cohesiveness
the extent to which a material can be deformed before it ruptures
Describe Viscosity
the rate of flow per unit force, the force required to slurp a liquid from a spoon over the tongue
Describe elasticity/springiness
there rate at which a deformed material returns to unperformed after the deforming force is removed.
Describe Adhesiveness
the work necessary to overcome attractive forces between surface of food and surface of other material.s
What are the 3 secondary mechanical characteristics of food?
Fracturability
Chewiness
Gumminess
Describe fracturability
the force in which material fractures, such as a food crumbling or cracking or shattering. Is a result of a high degree of hardness and low degree of adhesiveness.
Describe Chewiness
energy required to masticate a solid food to a state ready for swallowing. Product of hardness, cohesiveness and elasticity. Is also a producer of hardness, cohesiveness and springiness.
Describe Gumminess
the energy required to disintegrate a semi-solid food ready for swallowing. A product of low hardness and high cohesiveness.
What factors are considered in the selection of foods to be used as a standard?
1) Major brands of good quality control.
2) Products requiring minimum amount of preparation to eliminate recipe variables.
3) Products that do not change radically with small temperature variation.
The evaluation of mechanical characteristics are both _____
qualitative and quantitative.
How do standard rating scales work?
- Devised for each mechanical characteristic to provide a quantitate method of texture evaluation.
- Specific examples for each point so proper reference standards are available to measure intensity of each characteristic.
- Reference standards are compared to establish intensity parameter.
What are the 3 discriminative (difference) tests?
1) Duo-Trio Test
2) Triangle test
3) Paired comparison test
Why do we perform discriminative tests?
to determine whether or not a difference can eb detected between samples.
What are discriminative tests useful for?
Detecting sensory variations in food resulting from alterations in ingredients, processing or storage conditions.
Explain the Duo Trio Test
Employs three samples, two are the same and one is different.
One sample is designated as the reference,is presented first.
Two coded samples follow .. one is identical the reference.
Panellist is required to identify the sample which is either same or different from the reference, probability is 50%
What is the advantage of the duo trio test?
Less tasting required, particular advantage when strong tasting samples are being evaluated.
Explain the Triangle test
Employs three samples, two the same and one different. No sample is designated as the reference! Panelist must determine which one of the three samples is different. Probability of choosing the odd same is 1/3.
What us the triangle test used for?
Industrial quality control, and also in selecting panelists.
Explain the paired comparison test.
Employs two samples. Judge must determine which same has the greatest amount of a particular characteristic. Probability of selecting correct sample is 50%. Ranking test is an extension of this test.
Which tests require forced choice?
All 3 of them.
Define mechanical characteristics
those related to the reaction of food to stress
Define geometrical characteristics
those characteristics related to the arrangement of physical constituents of food.
describe “others” characteristics
properties related to the moisture and fat content of foods.
List the 2 primary ‘other’ characteristics
- Moisture content
- Fat content
List the 2 secondary ‘other’ characteristics
- Oiliness
- Greasiness
The fracturability scale is divided in to what three terms ?
1) Crumbly
2) Crunchy
3) Brittle
Define crumbly
Samples with low resistance to force (low hardness) and very low deformation before fracturing (low cohesiveness)
Define crunchy
samples that have fairly HIGH resistance for force (moderate hardness) and very low deformation before fracturing (low cohesiveness)
What the major difference between crumbly and crunchy
crumbly = LOW resistance to force (low hardness) crunchy = HIGH resistance to force (moderate hardness)
What does crumbly and crunchy have in common?
Very low deformation before fracturing (low cohesiveness)
Degree is fracturability is measured by what
the horizontal force with which a food moves away from the point where vertical force is applied.
How is adhesiveness measured ?
Fore required to remove food from palette with tongue. Influenced by amount of saliva, ensure to rinse with water immediately prior to each evaluation.
How is viscosity measured ?
6 point scale, place spoon with standard directly in front of mouth and draw liquid from spoon over tongue by slurping. Degree of viscosity is measured as the force required to draw liquid over the tongue.
How is chewiness measured ?
3 point chewiness scales, (tender, chewy and tough), where degree is determined via number of chews to masticate.
