Shelf life extension is essential for commercially baked bread.

Shelf life extension is essential for commercially baked bread.

Shelf Life Extension

Also Known As Extended Shelf Life (ESL)


What Is Shelf Life Extension?

Shelf life extension is aimed to extend the period food stays at eating quality from a safety and organoleptic point of view.6 With advancements in technology, the shelf life extension of baked products have been made possible by improving texture and preventing microbial growth.

Beyond shelf life, products become:

  • Firm
  • Dry
  • Less resilient
  • Less flavorful

What factors influence shelf life?

Two main factors influence the shelf life of bakery products:

1. Microbial spoilage: This is the main factor against shelf-life extension. It is also the major cause of economic loss in the baking industry. Mold contamination occurs during cooling and packaging.1

2. Physical spoilage (e.g., moisture loss, staling): Bread staling falls into two categories: crust staling and crumb staling. Crust staling is generally caused by moisture transfer from the crumb to the crust, resulting in a soft, leathery texture. Crumb staling happens when hydrated starch reverts to the crystalline form.1

How can you extend shelf life?

To decrease mold spoilage:

  1. Use a mold inhibitor in the formulation. There are chemical mold inhibitors, like calcium propionate or potassium sorbate, and natural mold inhibitors, such as cultured wheat.1
  2. Decrease the pH of the final product
  3. Have good sanitation processes: follow HACCP (Hazard Analysis Critical Control Point). Mold spores cannot survive the baking process, therefore sanitation plays a critical role in controlling mold growth.
  4. Control water activity
  5. Use the right packaging method and materials. Modified atmosphere packaging (MAP) is used to increase the mold-free shelf-life of bakery products. Research is now undergoing to incorporate volatile antimicrobial substances from spices and herbs into packaging materials to prolong the shelf life of bread. This may provide an alternative way for bread preservation without the use of chemical preservatives.2

Decreasing starch staling and moisture loss

Emulsifiers
The function of an emulsifier is to get better dispersion of fat in dough and increase fat efficacy, so as to extend shelf life. Examples of emulsifier are mono-and diglycerides and sodium stearoyl lactylate (SSL).

Enzymes
Alpha-amylase, xylanase, and protease exhibit a significant antistaling effect. Alpha-amylase hydrolyzes starch molecules and releases dextrins and other oligosaccharides. This hinders the formation of amylopectin double helices, hence lowering the retrogradation of amylopectin.3 The use of alpha-amylases is not widespread because even a slight excess of alpha-amylase results in a sticky bread.3 Not all enzymes have a positive effect on staling.

Hydrocolloids
The function of hydrocolloids is to lower crumb moisture loss. Here are the factors to consider when choosing the right hydrocolloids: the capacity to make liquids denser (viscosity increase), water holding capacity, hydration rate, and the effect of temperature on hydration. For most hydrocolloids, viscosity will decrease with increasing temperature.2 Guar gum, xanthan gum, carrageenan, and hydroxypropylmethylcellulose (HPMC) have been used to lower crumb moisture loss.

Storage condition
Using a short freezing rate and avoiding temperature changes during frozen storage are preferred for frozen dough storage to increase the shelf life of bakery products made from frozen dough.2

Other methods
Bread produced with durum wheat flours with a higher protein content and higher water adsorption undergo lower moisture loss and firming in the crumb.2 Sourdough fermentation is also effective in delaying starch retrogradation.4

FDA Regulation

FDA does not require food firms to place “expired by”, “use by” or “best before” dates on food products, except infant formula.5 A principle of U.S. food law is that foods in U.S. commerce must be wholesome and fit for consumption. A product that is dangerous to consumers would be subject to potential action by the FDA to remove it from commerce regardless of any date printed on a label.5  In an effort to reduce food waste, the U.S. Department of Agriculture’s (USDA) Food Safety and Inspection Service (FSIS) have revised current guidelines for product dating on labels.7  

FSIS is changing its guidance to recommend the use of “Best if Used By” because research shows that this phrase is easily understood by consumers as an indicator of quality, rather than safety.7

References

  1. Galić, K., D. Ćurić, and D. Gabrić. “Shelf Life of Packaged Bakery Goods – A Review.” Critical Reviews in Food Science and Nutrition 49.5 (2009): 405-26.
  2. Jideani, V. A., and K. Vogt. “Antimicrobial Packaging for Extending the Shelf Life of Bread—A Review.” Critical Reviews in Food Science and Nutrition 56.8 (2015): 1313-324.
  3. Ľubomír Mikuš, Mária Kováčová, Ladislav Dodok, Alžbeta Medveďová, Lucia Mikušová, and Ernest Šturdí­k. “Effects of Enzymes and Hydrocolloids on Physical, Sensory, and Shelf-life Properties of Wheat Bread.” Chemical Papers 67.3 (2013): 292-99.
  4. Corsetti, A., M. Gobbetti, B. De Marco, F. Balestrieri, F. Paoletti, L. Russi, and J. Rossi. “Combined Effect of Sourdough Lactic Acid Bacteria and Additives on Bread Firmness and Staling.” Journal of Agricultural and Food Chemistry 48.7 (2000): 3044-051.
  5. “Did You Know That a Store Can Sell Food past the Expiration Date?” U.S. Food & Drug Administration. 04 Mar. 2016. www.fda.gov/AboutFDA/Transparency/Basics/ucm210073.htm. Accessed 14 Dec. 2016.
  6. Shelf life. (n.d.) In Oxford English Dictionary. Retrieved from http://en.oxforddictionaries.com/definition/shelf_life
  7. “USDA Revises Guidance on Date Labeling to Reduce Food Waste”  United States Department of Agriculture Food Safety and Inspection Service. 14 Dec. 2016. https://www.fsis.usda.gov/wps/portal/fsis/newsroom/news-releases-statements-transcripts/news-release-archives-by-year/archive/2016/nr-121416-01 Accessed 16 Dec. 2016