MicrobiologicalShelf Life

EvaluationsHeather Smith

Research Microbiology Assistant Manager

heathers@abcr.com

Ivy ChoBusiness Development Director

ivyc@abcr.com

What does shelf life mean?

• It is the extent of time for which a food remains usable, acceptable for consumption, or saleable from manufacturing until reaching the “best before date”, “sell by date”, or “use by date”.– These terms all relate to

the quality of the foodMicrobiological Shelf Life Evaluations

Terms used to describe shelf life

• A "Sell-By" date tells the store how long to display the product for sale. You should buy the product before the date expires.

• A "Best if Used By (or Before)" date is recommended for best flavor or quality. It is not a purchase or safety date.

• A "Use-By" date is the last date recommended for the use of the product while at peak quality. The date has been determined by the manufacturer of the product.

• "Closed or coded dates" are packing numbers for use by the manufacturer.

Microbiological Shelf Life Evaluations

Shelf life influences

Growers/ Producers Other suppliers

Manufacturers

Retailers

Distributors

Consumers

Microbiological Shelf Life Evaluations

Factors that affect the shelf life

• Moisture• Water activity• Fat/oil content• Alcohol content• Flavor loss• Texture changes• Color changes• Acid content• pH• Light exposure• Microbial spoilage

Microbiological Shelf Life Evaluations

Real time shelf life evaluations

• Microbiological evaluations are applicable in refrigerated (and sometimes ambient) foods.

Microbiological Shelf Life Evaluations

• This is applicable in ambient, refrigerated, and frozen foods where the storage temperature is real time.

Real time shelf life

• Products are stored under normal conditions for the length of time desired by the client.  Manufacturer may wish to evaluate products for a time length greater than the expected shelf life to determine the deterioration point

Microbiological Shelf Life Evaluations

Microbial Quality Shelf Life Evaluation (refrigerated foods)

• Products analyzed for applicable quality indicators (product specific)– Aerobic Plate Count– Gram-negative Bacteria count– Lactic Acid Bacteria Count– Yeast & Mold Counts

• Assesses microbiological quality of a product (not safety)

• Results best understood by concurrent microbial and organoleptic quality evaluations

Microbiological Shelf Life Evaluations

Total plate count humor

Microbial Quality Shelf Life Evaluation (ambient foods)

• Microbiologically safe/stable foods– Organoleptic Quality Shelf Life

• -Microbiologically safe foods/not microbiologically stable under ambient storage conditions– Organoleptic Quality Shelf Life–Microbial Quality Shelf Life

Microbiological Shelf Life Evaluations

Types of Microbiological safety testing

1. Chemical testing2. Product Assessment3. Challenge study4. Growth studies5. Lethality studies

Microbiological Shelf Life Evaluations

1. Chemical testing

– Safety can often be addressed via minimal chemical testing, e.g.:• Water activity (aw)

• pH• NaCl

Microbiological Shelf Life Evaluations

2. Product Assessment

– Predictive modeling and safety assessment based on chemical parameters, storage temperature, shelf life, packaging, etc.

Microbiological Shelf Life Evaluations

3. Challenge Study

– Products inoculated with pertinent pathogens

– Inoculation level depends on study objective

– Storage temperature and shelf life mimic worst case scenario

Microbiological Shelf Life Evaluations

4. Growth studies       –Microbial levels monitored to detect

outgrowth or control of pertinent pathogens• Example: Listeria monocytogenes challenge

study in refrigerated deli products

Microbiological Shelf Life Evaluations

5. Lethality studies

– Verify target lethality (e.g., 5-log reduction) in pertinent pathogens• Example: 5-log reduction of acid-tolerant

pathogens in cold-packed, acidified hot sauce

Microbiological Shelf Life Evaluations

Questions?

For additional information, please contact us at 352.372.0436 or visit our website at abcr.com

Microbiological Shelf Life Evaluations