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Week 5: Shelf life of Foods - Coggle Diagram
Week 5: Shelf life of Foods
Determine Shelf Life :check:
Reasons
To determine shelf life of existing products
To study effect of changes in processing parameters, ingredients, storage conditions and packaging materials on product shelf life
To determine shelf life of new products
Methods
End point study: Determine product quality through lab testing on samples purchased from retail outlet
Good estimation since products went through the actual supply chain
Turnover Time: Monitor the sales and determine the average duration that products stay on the retail shelf
Limitation: Estimate only the “required” shelf life at retail outlets rather than “true” shelf life.
Accelerated Shelf Life Testing (ASLT): Accelerate the deterioration rate by modifying the known environmental conditions
Literature Study:
Published literature e.g. books on shelf life of foods
Limited data and applicable to commodity-type of foods
Factors Affecting Product Shelf Life :check:
Environment where products are exposed (extrinsic factors)
Properties of packaging
Product formulation or processing parameters (intrinsic factors)
Packaging Properties & Product Shelf Life
Water Vapour Transfer & Shelf Life
Moisture loss
Moisture gain
Key
𝑚_(𝑒 )=𝐸𝑞𝑢𝑖𝑙𝑏𝑖𝑟𝑢𝑚 𝑚𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑐𝑜𝑛𝑡𝑒𝑛𝑡 𝑜𝑓 𝑓𝑜𝑜𝑑 𝑒𝑥𝑝𝑜𝑠𝑒𝑑 𝑡𝑜 𝑒𝑥𝑡𝑒𝑟𝑛𝑎𝑙 𝑝𝑎𝑐𝑘𝑎𝑔𝑒 𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 ℎ𝑢𝑚𝑖𝑑𝑡𝑦
𝑚_(𝑖 )=𝐼𝑛𝑖𝑡𝑎𝑙 𝑚𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑐𝑜𝑛𝑡𝑒𝑛𝑡 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑜𝑜𝑑
𝑚=𝑚𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑐𝑜𝑛𝑡𝑒𝑛𝑡 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑜𝑜𝑑𝑠 𝑎𝑡 𝑡𝑖𝑚𝑒 𝑡
𝑝_𝑜=𝑣𝑎𝑝𝑜𝑢𝑟 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑜𝑓 𝑝𝑢𝑟𝑒 𝑤𝑎𝑡𝑒𝑟 𝑎𝑡 𝑡ℎ𝑒 𝑠𝑡𝑜𝑟𝑎𝑔𝑒 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 (𝑛𝑜𝑡 𝑡ℎ𝑒 𝑎𝑐𝑡𝑢𝑎𝑙
𝑣𝑎𝑝𝑜𝑢𝑟 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑜𝑢𝑡𝑠𝑖𝑑𝑒 𝑡ℎ𝑒 𝑝𝑎𝑐𝑘𝑎𝑔𝑒)
𝑊_𝑠=𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑑𝑟𝑦 𝑠𝑜𝑙𝑖𝑑𝑠
𝜃_𝑠=𝑆ℎ𝑒𝑙𝑓 𝑙𝑖𝑓𝑒
Permeability formula
Accelerated Shelf Life Testing (ASLT): increases the rate of deterioration making the assumption that chemical kinetics can be applied to quantify the detrimental effects of extrinsic factors (e.g. temp, RH, gas and light)
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Problems associated with ASLT
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Errors associated with sensory evaluation or analytical testing
Change in phase (e.g. solid fat to liquid) as temp. increase that could accelerate certain reactions
2 reactions with different 𝑄_10 might result in reaction with higher 𝑄_10 to predominate at higher temperature which may be the other way under normal storage temperature
Increase temp can cause Aw of dry foods to increase resulting in increase in reaction rate for products with low Aw inside sealed package
Gas solubility (esp. oxygen in fat/water) decreases by approx. 25% for every 10℃ increase in temp
Foods packed in low barrier package may have higher moisture loss if stored under high temp/low humidity chamber
High temp. may cause protein denaturation which might increase/decrease reaction rate
ASLT Procedures
:check:
Identify the microbiological safety and quality parameter
Determine Indics of failure (IoFs) and tests (e.g microbial, sensory) to be conducted during trial
Select the package. Typically several packaging materials are tested in order to choose the most cost effective material
Select the extrinsic factors to be accelerated.
Determine duration of storage using the hypothetical shelf life plot or conduct open-ended ASLT (𝑄_10 𝑣𝑎𝑙𝑢𝑒 𝑛𝑜𝑡 𝑘𝑛𝑜𝑤𝑛) using a minimum of 3 test temp
Determine test frequency.
Tabulate the total samples (including control) to be stored in each test condition
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Common date marking :check:
Best Before Date:
Foods may still be acceptable (safe to eat) as long as they are not damaged/deteriorated but their quality may have deteriorated
Usually for canned, dried, ambient and frozen foods e.g. cereal, biscuits
However, in Singapore for the purpose of Food Regulations, “BEST BEFORE” has the same meaning as “Use By
Use By / Expiry Date
Foods must be discard by the date. Unsafe to consume after the date
Usually storage condition is stated
Illegal to sell foods after “Use-by” or “Expiry date”
Usually for foods that are highly perishable from microbiological point
