Sensory Science - Quality Control and Shelf Life
21 important questions on Sensory Science - Quality Control and Shelf Life
What are the three different product standards?
- Product standard: only for products wiht long shelf life/ingredients
- Mental standard: created by one one of several experts
- Written standard: decription of main attributes
What are the 5 methods for Sensory Quality Control?
- In/out
- Difference from standard
- Descriptive analysis
- Quality rating with diagnostics
- Quality rating with key attribute scale
What is 'in/out' method for Sensory quality control?
- Panellist are trained to recognise ' out-of-spec' products from 'normal' products.
- +: Quick decision making tool
- -: No diagnostic for failure, Bias riks of individual preference
- Decision: Panel
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What is 'Difference from standard' method for Sensory quality control?
- The panel rates for an overall degree of diffeernetn from the control product.
- Suitable for simple products with few sensory attributes
- Decision: Management
What is 'Descriptive analysis' method for Sensory quality control?
- Intensity rating of individual sensory attributs by a trained panel
- Mostly used for end-products
- Needs extensive panel training
- Not all sensory attributes are equally important, and some are allowed to vary more than others
- Direction for failure
- Decisions: Management/ panel leader
What is 'Quality rating with diagnostics' method for Sensory quality control?
- The quality scale is used for the most important sensory attributes
- Score 1,2 -> reject
- Score 3-5 -> Unable to ship, but might be improved/inspected again
- etc.
- Direction for failure
- Decisions: Management/ panel leader
What is 'Quality rating with key attribute scale' method for Sensory quality control?
- Similar as the ratings with diagnostics, but avoding 'rejection and acceptance'
- Can also be used most important different attributes
- Direction for failure
- Decisions: Management
What is the definition of sensory shelf-life?
What is the most common reason in shelf life loss?
How to define sensory shelf life?
- The length of time which the product does not significantly change its sensory characteristic
- Using discriminative test.
- The length of time which the product reaches the cut-off point of sensory perception
- Using line scales ( affective or descriptive test)
Sample design: What is Basic design?
- Sore a single large batch and test at various storage times
- For example, store steak at 2c, and evaluate at day) 0, 4, 8 etc
- Common method
Sample design: What is Reversed design?
- Evalute a set of samples with different strorage times all together.
- Bread stored at 20c for: 1, 4, 8 days. After recachtin the desired stroage times, bread were frozen.
Basic vs Reversed design: advantages and disadvantages
- Adv: Direct measures, no effect of in between storage
- Dis: Bias in sensory evaluation( no randomisation possible)
Reversed:
- Adv: Randomisation in sensory evaluation, time efficient
- Dis: Strorage conditions needed to minimise deteriatation
Overal, Reversed design seem to be more time efficient and appropriate, if you can find storage conditions that minimise deterioration.
Which basis sensory test can be used to evaluate shelf life?
- Discrimination
- Descriptive -> comparing means/medians, select main sensory attributes that affect storage
- Affective -> comparing means/medians
What is survival analysis ?
- Reflection of acceptance or rejection whem they have the prodcut at home, or buy the product
- "Would you normally consume/buy this product?" Yes/No
Affect of sellers and buyers risk in shelf life?
- Sellers risk: Retrieving an acceptable product from the market
- Unacceptable products at the marktet-> diminish consumer confidence -> Buyers risk
- Cut off point inscrease/decrease these risk. If you decrease sellers risk, you increase the buyers riske and vice versa.
What is the effect of using instruments in shelf life testing?
- Much quicker and cheaper
- Instrumetn could replace human perception in some case when shelf life is determined by texture and color
- Difficult to replace hmans for odor and flavor perception
Which conditions minimise bias, improve precision and reduce variation?
- Individual test booths
- Labelled with random numbers
- Randomised order
- Standardized temperature, volume, spacing in time
How to reduce variation of human response?
- Control experimental conditions
- apporpirate sample size calculation
- appropriate statistical analysis
- Train your panel
Human could be seen as 'heterogeneous', dispite screening and training
What is Internal validation?
- Relates to experiment itself
- Alternative explantions? Time of day, type of partcipants, improper experimental design
What is External validation?
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