Aging fresh and frozen chicken breast
Getting to the fundamentals of bioelectrical impedance analysis (BIA) reactance (capacitance)
Animal cells are very different from vegetable cells in that their metabolic processes are dependent on blood. Blood delivers oxygen and nutrients and transports carbon dioxide and waste from the cells. Once the flow of blood is stopped animal cells begin a slow death. The health or death of cells are a function of the dialectic properties (capacitance) of the cell membrane and is sensitive to environmental stress. All cells (animals and vegetables) are destroyed the moment they are frozen or cooked and never recover once they return to room temperature.
A whole “fresh” chicken breast (right and left sides) was purchased from a reputable market. The question was asked of the butcher “Has this chicken breast ever been frozen”. His answer was “No you’ll have to go down the street for that”. The truth of his answer requires knowledge of how the chicken was preserved at the packing house and the refrigerated truck temperature that delivered the chickens. Indeed, the results indicate that the chicken was never frozen.
The following experiment will measure resistance and reactance of two chicken breasts that came from the same chicken. One breast was measured immediately after purchase and the other was measured after it was frozen. Both chicken breasts were measured while refrigerated at 40 degrees F.
A second electrode array was constructed using the same 1-2-1 inch electrode separations. Instead of using tapered 1/8 inch penetrating electrodes, 3/8 inch stainless steel flat bottom electrodes were created for surface contact only that eliminated injury to to the chicken breast. The array was attached to a sturdy ring stand and placed in a small refrigerator set to 38 to 40 degrees F. The chicken breast was placed in the same Pyrex container used in other experiments and allowed to cool after being purchased. The electrode array was placed on the fleshy side of the chicken breast without regard to the skin and covered to keep from drying. The Quantum Desktop cable was located around the refrigerator door insulation and attached to the instrument that sat on top of the refrigerator. Sampling rate was set to 5 minutes and ran for more than 12 days. The second chicken breast was wrapped and placed in a home freezer. After the fresh chicken breast measurements were completed the frozen chicken breast was placed in the same Pyrex container and allowed to thaw for two days before taking measurements with the same surface electrodes.
The chicken breasts were large (not Amish) and probably fed typical growth products. However, they looked good and worth placing on a Weber grill.
The fresh chicken observations illustrate a slow death of living cells over 12 days. It might be possible to project the reactance values backwards and determine when the chicken was slaughtered. This would require having a freshly killed chicken to establish an absolute fresh baseline. The difference between fresh and frozen is significant, indicating cellular destruction after freezing.
Notice after twelve days the fresh chicken has a reactance greater than 4 ohms, while the thawed frozen chicken starts at 2.0 ohms and degrades to 1.0 ohms (probably due to temperature) and changes very little. If food products are frozen they should be eaten immediately after thawing because they can become a host for many kinds of bacteria and fresh (nonfrozen) products have a refrigerated life of a few days.
As a consumer it is very difficult to know if animal parts have ever been frozen, specifically fowl and fish. Indeed, feeling, smelling and asking the butcher are very subjective.