Food Shelf Life Quiz

Packaged Product Quality and Shelf Life

• Packaged product quality and shelf life is a guide for the consumer, indicating the period of time food can be kept before it deteriorates, assuming proper storage conditions.
• Shelf life begins when the food is prepared or manufactured and depends on various factors.
• Key factors influencing shelf life include ingredients, manufacturing processes, packaging types, and storage methods.

Contents

• The presentation covers an introduction to shelf life, factors which affect it, and methods to measure shelf life and food spoilage.

What is Shelf Life?

• Shelf life is the timeframe within which a food product retains its quality and safety.
• Important considerations include when to evaluate shelf life, the parameters defining the end of shelf life, and the relationship between shelf life and food safety.

Introduction to Shelf Life

• Shelf life is a guide to the customer for keeping food safe and quality, during a defined period.
• Stated storage conditions must be observed.
• Shelf life is dependent on many factors.
• These factors include ingredient types, manufacturing process, type of packaging, and food storage method.

Introduction...cont

• Shelf life is communicated with date markings on the product.
• Date marking is critical to the consumer, retailers, and manufacturers.
• For consumers, shelf life ensures product safety and quality meets expectations.
• For retailers, product quality must meet or exceed customer expectations.
• Manufacturers must justify the shelf life assigned.

Introduction...cont (When to conduct shelf life study)

• Shelf life studies are conducted for new product launches, new packaging, ingredient changes, and QA/QC program aspects.
• Validating shelf life information requires data collection.

Introduction...cont (End of shelf life parameters)

• An acceptable shelf life allows desired characteristics (sensory, functional, chemical, microbiological, physicochemical) of products to be retained.

Is shelf life related to food safety?

• Shelf life is the period during which food will retain safety and quality.
• Shelf life considerations include the retention of desired sensory, chemical, physical, and microbiological characteristics.
• Nutritional data compliance is also a key factor within shelf life.
• A Hazard Analysis Critical Control Point (HACCP) system is a method for controlling food hazards.

What is HACCP?

• HACCP is a system to address food safety issues. Key principles include hazard analysis, identifying critical control points, establishing critical limits, creating monitoring procedures, establishing corrective actions, and finally making all food safe for consumption.
• Identifying hazards (microbiological, chemical, physical) is the first step.

Microbiological Hazard

• Microbiological hazards are bacteria, viruses, and protozoa that cause illness and grow on food.
• Examples include Campylobacter, Listeria, Salmonella.
• Giardia is an example of a food-borne protozoa.

Chemical Hazards

• Chemical hazards involve excessive or toxic amounts of substances like heavy metals, chemicals, pesticides, herbicides, insecticides, vitamins, minerals, preservatives, disinfectants, and cleaning compounds.

Physical Hazards

• Physical hazards include objects (glass, metal fragments, hair, or insects) that get into food.
• These contaminants might not pose a health danger but can still negatively impact the consumer experience and require management.

Determine critical control points

• Critical control points are points in the food processing chain where hazards can be controlled or removed.
• These are essential points for controlling hazards in the food processing chain that may not have later steps to establish further control.

Establish Critical Limits

• Critical limits (CL) are parameters that indicate whether a critical control point (CCP) is in or out of control.
• Factors that influence critical limit determination are temperature, time of processing, solid content, titratable acidity level, moisture, preservatives, water activity, salt concentration, etc.

Establish Monitoring Procedures

• Monitoring procedures involve measuring or observing critical control points (CCPs) for meeting critical limits.
• Procedures involve measurement for numerical critical limits and observation for attribute-based critical limits.

Creating corrective actions

• Corrective actions are required when critical limits (CL) are not met.
• Corrective approaches differ based on food types and production processes to prevent food that is no longer safe reaching consumers.

Establish Verification Procedures

• Comprehensive verification activities are key to a HACCP system.
• Verification activities include verifying the hazard evaluation, monitoring procedures, and corrective actions.

Establish Recordkeeping and Documentation Procedures

• Records document all CCP measurements and corrective actions and serve as traceability records for a food product.
• Records can be reviewed when questions arise about the product's safety.

Factors Affecting Product Quality and Shelf Life

• Factors affecting shelf life are intrinsic factors (product makeup) and extrinsic factors (environment of the product).

Intrinsic factors

• Intrinsic factors (product makeup) include water activity, pH, total acidity, type of acid, natural microflora and surviving microbiological counts in final product, availability of oxygen, natural biochemistry/chemistry of the product, added preservatives (salt, spices, antioxidants), product formulation, packaging interactions (tin pickup, migration).

Extrinsic factors

• Extrinsic factors (environment) include time-temperature profile during processing, temperature control during storage and distribution, relative humidity during storage & distribution, exposure to light (UV, IR) during storage and distribution, gas composition within packaging, and consumer handling.

Factors Influencing

• Manufacturers can influence the combination of intrinsic and extrinsic factors to affect shelf life.
• Factors include raw material selection and quality, product formulation, processing environment, and processing/preservation techniques; packaging, and product packaging effects on extrinsic factors

Factors influencing Shelf Life continued...

• The interaction between intrinsic and extrinsic factors can influence the number of changes that limit shelf life.
• These changes can be classified as microbial, chemical, or physical changes (i.e. moisture, temperature).

Physical and Physico-Chemical Processes

• Physical changes affecting shelf life arise from physical damage or underlying food chemistry.
• Physical damage can include vibration, compressive loads, sudden jolts and knocks.
• This damage is often product specific; thus, the product formulation must tolerate these forces to avoid product failure.
• For fragile products (cereals, biscuits) protection is needed from outer packaging.
• Packaging for products susceptible to bruising needs to withstand stacking, high and variable humidity
• The design considers the commodity properties, humidity, airflow, respiration rates, and susceptibility to bruising.

Physical and Physico-Chemical Processes (Insect damage)

• Insect infestation can occur during extended storage or shipment.
• Insect infestations can be classified into penetrators and invaders.
• Penetrators bore through packaging layers, and invaders use existing openings, including poor seals.

Physical and Physico-Chemical Processes (Moisture migration)

• Hygroscopic foods need protection from moisture uptake.
• Moisture uptake can cause a loss of texture (bread, biscuits).
• The use of proper packaging materials is crucial in the avoidance of water loss in chilled and frozen products, which can cause quality loss due to the higher monetary values of products sold by weight.
• Rates are dependent on vapor pressure differences and air speed.
• A small percentage moisture loss will cause food to wilt.

Physical and Physico-Chemical Processes (Barrier to odor pick-up)

• Storage or distribution with other strong smelling commodities is important.
• Improper packaging can allow odors of products to transfer, leading to flavor contamination.
• Products like chocolate are sensitive to this effect.

Physical and Physico-Chemical Processes (Flavor scalping)

• Flavour is lost when chemical components present in food have high affinity for packaging materials.
• This loss does not result in a direct health risk.
• However, scalping reduces the flavour of the product.

Physical and Physico-Chemical Processes (Physical changes in food)

• Physical changes, like bruising in fruits and vegetables, affect quality during harvesting.
• Moisture uptake in products like cookies, or ice cream recrystallisation from temperature fluctuations are similar issues.

Chemical/Biochemical Processes (Oxidation)

• Chemical components reacting with oxygen affect color, flavor, nutritional status, and occasionally the physical characteristics of food.
• Using packaging to exclude, or control oxygen is key.
• Increased amounts of fat lead to oxidative rancidity.
• This is particularly relevant to unsaturated fats.

Chemical/Biochemical Processes (Antioxidants)

• Natural or added antioxidants slow the rate or extend the lag time to onset of oxidation and rancidity
• Oxidation of fatty acids occurs through three routes:
  • Free radical formation (metal catalysts such as iron, or heat or light)
  • Photo-oxidation (photosensitizers affect the oxygen energetic state)
  • Enzymatic route catalyzed by lipoxygenase
• Oxidation of unsaturated fatty acids produces hydroperoxides.

Chemical/Biochemical Processes (Oxidation) Continued...

• Decomposition of hydroperoxides produce further substances, leading to "stale", "rancid", or "cardboard" flavors, often associated with lipid oxidation.

Chemical/Biochemical Processes Continued...

• Reducing oxygen concentration by below 1% and use of antioxidants are strategies to extend shelf life when rancidity is the limiting factor. UV light can also affect shelf life.
• Vitamins A, B2, B6, B12 and folic acid; are particularly susceptible to light - inducing color and flavor changes.

Measuring Shelf Life and Spoilage of Food

• Perishable foods (less than 30 days shelf life) commonly have issues with high-temperature abuse during storage
• Semi-perishable foods (over 30 days, but less than 6 months)
• Long shelf-life foods (over 6 months) or non-perishable foods.

Measuring Shelf Life and Spoilage of Food

• Any packaged food with a shelf-life less than 2 years must be marked with a dated label.
• There are two marking options:
  • Use-by date: used for highly perishable products susceptible to safety risk
  • Best-before date: used for products other than highly perishable ones, thus it is not illegal to sell them after the best-before date is met.

Measuring Shelf Life and Spoilage of Food

• Food products are diverse, complex, and active systems, with simultaneous reactions (microbiological, enzymatic, physicochemical).
• Shelf-life evaluations require understanding all the relevant food disciplines.
• Important disciplines include food engineering, food chemistry, microbiology, analytical chemistry, physical chemistry, polymer science, and food regulations.

Measuring Shelf Life and Spoilage of Food (testing)

• Shelf life testing methods involve:
  • Selection of quality characteristics that most rapidly deteriorate
  • Mathematical modeling of quality change
  • Professional judgment, regarding the particular product being evaluated.
• No one test can measure all deterioration events.
• Multiple tests provide a more reliable evaluation of the condition that determines shelf life.

Measuring Shelf Life and Spoilage of Food (additional tools)

• Methods for gathering shelf-life data include literature reviews, checking distribution times, distribution abuse tests (supermarket locations), consumer use reviews, and accelerated shelf-life testing (ASLT).

Measuring Shelf Life and Spoilage of Food (Testing procedures)

• Methods are needed to define a clear index for food quality (sensory, chemical, microbiological, physical testing).
• Shelf-life is determined by using an objective method to define how long a food product can remain of acceptable quality/safety.
• Studying shelf life requires separate studies for each product.
• Approaches to shelf-life study are direct methods and indirect methods (ASLT).

Measuring Shelf Life and Spoilage of Food (Direct Method)

• Direct shelf-life testing involves storage trials under controlled conditions mimicking real-world storage, distribution, retail display and consumer conditions.
• The exact procedure depends on the product being evaluated.

Measuring Shelf Life and Spoilage of Food (steps to direct method)

• Identify food deterioration causes
• Identify what tests are needed
• Design and implement study
• Determine shelf-life
• Monitor shelf-life following market launch

Measuring Shelf Life and Spoilage of Food (Indirect Method)

• Indirect methods like accelerated shelf-life testing (ASLT) predict shelf-life without full-scale storage trials.
• This is useful for products with longer shelf-lives.

Measuring Shelf Life and Spoilage of Food (Accelerated Shelf Life Testing - ASLT)

• Shelf-life testing can be accelerated using controlled conditions to speed up deterioration.
• Valid kinetic models are necessary to predict shelf-life.
• ASLT tests for chemical, physical, biochemical, and microbiological deterioration.

Measuring Shelf Life and Spoilage of Food (ASLT Procedures)

• The procedures are outlined for evaluating microbiological safety, identifying biological/physicochemical reactions that impact shelf life (and are thus good indicators during evaluation), evaluating proper packaging and establishing storage temperatures.

Measuring Shelf Life and Spoilage of Food (ASLT Procedures continued...)

• Calculate time at different temperatures based on typical Q10 values, or establish multiple testing temperatures.
• Statistical measurements (at least six data points per storage condition) are needed.
• Plotting data can show reaction orders, and decide when to alter test frequencies.
• Determined reaction rate and order, create Arrhenius plot to forecast shelf-life for desired storage conditions.
• These calculations are based on approaches to ASLT and aim to produce reliable deterioration data in a short period.

Measuring Shelf Life and Spoilage of Food (Initial Rate Approach)

• Initial rate approach uses an empirically derived testing procedure.
• This technique uses a method to accelerate deterioration through a convenient kinetically active factor.
• This methodology is useful for cases where deterioration can be measured by an extremely sensitive method.

Measuring Shelf Life and Spoilage of Food (Kinetics Model Approach)

• Kinetics model approach is commonly utilized for accelerated shelf-life evaluations.
• Involves:
  • Choose appropriate kinetically active factors that accelerate product deterioration.
  • Kinetics study of deterioration at appropriate factor levels.
  • Extrapolate kinetic modeling data to normal storage conditions.
  • Use extrapolated data to predict the actual shelf-life for storage conditions.

Measuring Shelf Life and Spoilage of Food (Kinetics Model Approach Continued...)

• The methodology aims to identify/determine pertinent chemical and biological reactions that affect food quality/safety and use those reactions to forecast degradation based on kinetics modeling of reactions based on variables in food composition and environmental factors.

Measuring Shelf Life and Spoilage of Food (Kinetics Model Approach Continued...)

• The impact of environmental factors can be modeled into rate constant k (i.e. k(E;) ).
• The Arrhenius relation is important in kinetics studies, as it examines the effect of temperatures on reaction rate constants.
• Temperature affects reaction rates via activation energy.

Measuring Shelf Life and Spoilage of Food (Kinetics Model Approach Continued...)

• Water activity affects factors like kinetic parameters (KA, EA), reactant concentrations, and reaction order.
• Inverse relationship to activation energy is notable.
• Enthalpy-entropy compensation may explain this relationship.

Measuring Shelf Life and Spoilage of Food (QA Concept)

• QA concept is similar to Q10 concept, with a mathematical method to establish the effect of water activity (aw) on food stability.
• The QA value represents the effect of aw increase on reactivity/half-life (i.e., a greater QA value denotes larger effect on half-life).

Example Shelf Life Predictions

• Specific examples are provided for predicting shelf-life using established models and data (Ghee, aspartame-sweetened product, browning in fruit juice).

Test your knowledge about shelf life in food products. This quiz covers various factors that influence shelf life, methods of communication to consumers, and the timing of shelf life studies. See how much you know about maintaining food quality and safety!