FREEZE‐DRIED MEAT. II. THE MECHANISM OF OXIDATIVE DETERIORATION OF FREEZE‐DRIED BEEF^a

Abstract

Dehydrated meats of good organoleptic quality and functional properties can be produced in the form of steaks, chops, roasts, and stew meat by the method of freeze-drying (3,13). Since the primary value of freezedried meat, especially for the military forces, lies in its storage stability a t elevated temperatures, studies of its mechanism of deterioration become important.The mechanisms of deterioration of freeze-dried meat may be conveniently divided into those of oxidative and those of non-oxidative deterioration. Since the oxidative deterioration of such dehydrated foods as meat, milk, and eggs can be prevented by commercial gas packing the mechanisms of this deterioration have not been completely investigated (2, 9, 11).Except for the work of the British, which has been recently reviewed by Sharp ( l l ) , the information available on oxidative deterioration of dehydrated meats is generally meager. I n precooked air and vacuum dehydrated pork, the oxidation of unsaturated fatty acids is known to play a dominant role. It has been recognized that the oxidation of the non-lipid fraction especially in dehydrated beef is also an important mode of oxidative deterioration. This mechanism of the non-lipid oxidative deterioration of dehydrated meat has not been investigated. Principally because of oxidative pigment changes, the oxidative deterioration of freeze-dried raw meat assumes greater significance than the oxidative deterioration of dehydrated meat which was produced at high temperatures.The rate of oxygen absorption, the effect of oxygen on the flavor, and changes in peroxide value of freeze-dried raw beef have been measured by the British workers (11). Available oxygen had a pronounced detrimental effect on flavor of freeze-dried beef held in storage at 37°C. and 15°C. The loss of the bright pink color of freeze-dried beef was noted. It was found that the large oxygen absorption and the corresponding deterioration could be prevented by tight packing of the minced freeze-dried meat in cans. This paper reports research directed toward establishing the mechanism of the oxidative deterioration of freeze-dried beef. It was found that the protein portion of freeze-dried beef was more oxygen labile than was heretofore expected. Oxidation of the non-ether-extractable lipids appears to a This paper reports research undertaken in cooperation with the Quartermaster Food and Container Institute for the Armed Forces, and has been assigned number 587 in the series of papers approved for publication.

Rate of Deterioration of Freeze‐Dried Salmon as a Function of Relative Humidity

“…As was observed by Tappel (1956) and by Karel et al (1966)) oxygen can also be absorbed by proteins. This can account for up to SO-SO% of the total oxygen absorbed, especially at high temperatures.…”

Composition of Dehydrated Protein Extracts From Poultry Bone Residue

“…Oxidative changes in freeze-dried meats have been shown to involve the oxidation of bound lipids, e.g., phospholipids (Chipault and Hawkins 1%5), followed by the oxidation of glycerides. Tappel (1956) also concluded that ether-extractable lipids in freeze-dried meat absorbed only a small proportion of oxygen compared to nonether extractable fat. Therefore, although 20-carbon polyunsaturated fatty acids are concentrated by the extraction process, lipid oxidation in this fraction precedes the oxidation of 18-carbon fatty acids.…”

The Effect of Storage at Elevated Temperature on Some Proteins of Freeze‐Dried Beefa

“…the compomids usually considered to be most susceptible to oxidation. Tappel (1956) EXPERIMENTAL reports also that potentially oxidizable In every instance the following basic canning procedure was followed. Freeze-dried slices taken was closed under 25 in.…”