Glass transition values of muscle tissue

Reports of glass transition (Tg') values for frozen muscle tissue are not common and reported values are mostly much lower than would be expected. Tg' values for muscle tissue and isolated proteins were studied using differential scanning calorimetry. Apparent Tg's of mackerel, cod and beef were similar (ca -11 to -13 degrees C) and substantially higher than most published values (-15 degrees to -77 degrees C for tuna and beef), but in accord with expectations for substances of high molecular weight. Dialyzed insoluble and soluble protein fractions from mackerel yielded apparent Tg' values (ca -7 degrees C) that were similar, with both being higher than those for whole muscle. Apparent Tg' values of ca -7 degrees C were determined for aqueous sample of gelatin and collagen, but none was detected for zein.