Lipid Oxidation

“Lipid oxidation causes rancidity that leads to loss of shelf life, product nutrition”

Raw and cooked meat and eggs can be freeze-dried. However, the freeze-drying process does not kill harmful bacteria that can cause foodborne illness (Penn State)

Fat does not freeze-dry well and can go rancid quick. Bacon that has been cooked well, drained, and mixed in with other ingredients has been successful. (Utah State Extension Office)

OXIDATION CHANGES AFFECTING ODOR AND FLAVOR OF FREEZE-DRIED MEATS

  • Off odors which rapidly develop when freeze drying meats related to oxidization is not a direct result of rancidity. However it is a result of oxidized deteriorating lipids that forms a stale putrid like odor by water soluble, non lipid components of the crude bound lipids.
  • Moisture levels of meat influence the rate of oxidization
  • Washed bound lipids envelop typical rancid odors
    • Washed raw freeze dried meats have the strongest foul odor once freeze dried
  • Crude bound lipid, amine-type, putrid odor from water soluble non lipid material.
    • Cooked meat that is freeze dried can produce an off smell.

For best stability and palatibility it is suggested that: a) meat should be freeze-dried to a moisture level of 1% or less;

  • b) the freeze-dried product should not, at any time, be exposed to oxygen, and should be kept under vacuum or in an inert atmosphere;
  • c) the product be stored at low temperature; and
  • d) that it be used as quickly as possible.

Lipid oxidation in meat and meat products—A review

  • Sodium chloride accelerates oxidation of the triglycerides
  • Protein denaturation and cross-linking may result from lipid oxidation in stored freeze-dried meat.
  • The meat pigment in the cured pink ferrous form does not promote the rapid oxidation undergone by cooked uncured meat.

Factors Affecting the Drying, Stability, and Rehydration Factors Affecting the Drying, Stability, and Rehydration of Freeze-Dried Chicken Meat1of Freeze-Dried Chicken Meat1

  • The advantages of freeze-dried meat can be lost in a few days if the dried product is ex- posed to oxygen.
  • suggested that poultry suitable for dehydration should contain some fat, but not excessive amounts which could possibly be very susceptible to rancidity
  • chicken deteriorated in quality if stored in ambient temperatures longer than 6 months.

Understanding Lipid Oxidation in Low-Moisture Food

  • Even the small amounts of naturally occurring phospholipids in raw ingredients can cause rancidity, a problem that is seen in nonfat dried milk and whey powder (Bassette and Keeney, 1960; Karagül-Yüceer et al., 2002).
  • (poultry fat oxidized faster than beef tallow), although they also found, surprisingly, that fat-free control treatments oxidized faster than their fat-containing counterparts.
  • Whole wheat flour is known to be more susceptible to rancidity development.
  • Lipid oxidation causes rancidity that leads to loss of shelf life, product nutrition, and ultimately, saleable product and profits. Strategies to postpone lipid oxidation are needed for both economic and consumer health, particularly because the healthier unsaturated fats are at greater risk for oxidation then saturated fats (Holman and Elmer, 1947; Buttery et al., 1961).

Meat Preservation and Processing

  • Lean meat is selected for lyophilization, to avoid the rapid rancidity to which it is prone