Unit 10
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
卡片预览 (24 张)
A moisture sorption isotherm is a graph that plots the change in water content of a food sample against …… (acronym, two capital letters)
RH
Reduction of …… enhances the efficacy of the drying process due to the reduction of the boiling point of water
Pressure
…… is the process of soaking food in a sodium bisulfite and water solution for 10 to 30 minutes (one word, first capital letter)
Sulfiting
What affects the perception of the product by the client
Quality
What is food quality
the product meets (or exceeds) the expectations of the consumer
Difference between QC and QA
Quality control (QC) involves testing (representative samples) of the finished product to determine whether they meet the specifications that have been set for the product. Quality assurance (QA) involves taking measures to ensure that the processing steps are properly performed, which should ensure that the finished products are of consistent quality As mentioned at the beginning of this section, QC involves testing (representative samples) of the finished product to determine whether they meet the specifications that have been set for the product. QA involves taking measures to ensure that the processing steps (unit operations) are properly performed, which should ensure that the finished products are of consistent quality. Plant sanitation. Microbiological quality
Testing of the finished product to determine whether they meet the specifications that have been set for the product a. Quality assurance b. Quality control
B
Two quality characteristics
Sensory quality characteristics Hidden quality characteristics
Sensory characteristics can be divided into what categorizes
appearance attributes textural attributes flavor attributes
The consumer s initial perception of the quality of a product is largely based on appearance attributes such as:
Color: often an indicator of ripeness, spoilage, or storage history Size/shape: e.g., fruits & vegetables Wholeness: e.g., cookies, nuts Degree of damage: e.g., bruising of bananas Consistency (visual perception of thickness): e.g., ketchup Gloss: e.g., apples
Fat crystallization on the surface of the chocolate is called
Fat bloom
QC Measurement of Color
Human eye (comparison to colored tiles) A spectrophotometer (transparent liquids) A tristimulus colorimeter
What is a standard plate
QC generally uses color difference measurements to make color measurements more sensitive. For example, a standard plate is made to represent the desired color of the product.
We sense texture by
We sense by touch, tongue, palate, and teeth.
What texture we expect from liquids and pastes
Viscous (thick): e.g., tomato ketchup Non viscous (thin): e.g., water Smooth consistency: e.g., mayonnaise, yogurt Creamy: e.g., margarine, icing
What texture is expected for solids
Crisp: e.g., lettuce, chips Chewy: e.g., granola bars Crunchy: e.g., chips Soggy: e.g., crackers
What is rheology
Rheology: the study of the deformation and flow of matter.
What instruments are used to objectively measure fluidity of products
A Bostwick consistometer measures the time it takes for a viscous fluid product (e.g., ketchup, syrup) to flow down an inclined plane. Numerical measurements of viscosity can be made using various types of viscometers
What is the equipment to measure texture of solid and semi-solid products
Measuring texture is more complex than measuring viscosity. It is based on measuring the force required for deformation of a material. Common forces include compression (squeezing), shear (cutting), and tension (pulling) or combinations thereof (chewing).
What is universal testing machine
These instruments come with a wide variety of accessories: cutting devices, pulling devices, and plungers to mimic forces imposed on food products.
Examples how texture and viscosity can change
Meat becomes more tender with aging. Starches gelatinize with heat/moisture. Bread firms/stales over time (starch retrogradation). Crackers become soggy with exposure to humid conditions.
Some instruments do exist that can objectively measure some flavor related parameters:
Gas chromatography (measures volatile compounds associated with Conductivity measurements (salt concentration) pH meters (acidity) Refractometers (sugar concentration)
Do we still need to do taste panels
However, no instrument has replaced humans as of yet, so taste panels are commonly used to measure flavor as well as other quality attributes of foods: sensory evaluation Sensory evaluation is carried out routinely in most food companies for QC purposes or to compare products against those of competitors.
What are Non sensory (Hidden) Quality Attributes
For example, nutritional value has recently become much more prominent in consumers ’ perception of quality.