Food quality is evaluated by all
people either consciously or unconsciously. Evaluation of foods can be divided
into 2 major categories: Objective and Subjective.
I. Objective Evaluation
Definition: the measurement of physical
properties of a food by use of mechanical devices.
Goal: to obtain highly reliable data on
food characteristics that are amenable (comparable) to physical testing
Physical methods – using various instruments to
measure specific physical characteristics, i.e., volume, moisture, texture,
viscosity, color, specific gravity/density.
Chemical methods – use of instruments or procedures
to measure changes in the chemical properties of a food, i.e., nutrient
analysis, pH, salt or sugar content, aroma, flavor compounds.
II. Subjective Evaluation
Definition: evaluation by individuals using a
scoring system based on various characteristics that can be judged using the
senses.
Goal: To evaluate food products using the
human senses of sight, smell, taste, and sometimes touch.
Also called Sensory Evaluation.
Sensory evaluation is not an exact science.
Sensory Evaluation
Individuals tend to perceive sensory
attributes of food in the following order:
- Appearance – visual analysis
- Color
- Size & shape
- Surface characteristics
- Interior appearance
- Clarity
- Carbonation
1. Odor/ Aroma/ Fragrance
Odor of a product is detected when food volatiles enter
the nasal passage and are perceived by the olfactory system. Volatility – related to the
temperature of the food and the nature of the compounds
2. Flavor
Sensory attributes resulting from a
combination of taste and aroma.
Includes
- aromatics – perceptions caused by volatile
substances released from a product in the mouth (lemon, mint, buttery)
- taste – perceptions caused by soluble
substances in the mouth (salty, sweet, sour, bitter)
- chemical feeling factors – compounds that stimulate nerve ends
in the soft membranes of the mouth and nasal cavity (spicy hot, cool,
metallic). These can include flavor enhancers or inhibitors.
3. Texture/ Mouthfeel
Evaluation by sensors in the mouth
other than taste and chemical feeling factors, Includes :
- viscosity – rate of flow of liquids under some
force such as gravity. This attribute can also be accurately measured using
objective methods.
- consistency – flow characteristics of solutions
that are very viscous to semi-solid
- texture – sensory manifestation of the structure
or inner make up of a food product (solids or semi-solids)
4. Noise
Sounds produced by a food during
mastication (chewing) or physical handling.
Includes : pitch – frequency
of sound, loudness – intensity of
the sound, persistence – endurance of sound over time
