Food Structure


The effects of addition of adipose tissue, rendered fat, rendered fat + the separated connective tissue and rendered fat + gelatin, respectively, were compared on the fat-holding properties of hamburgers upon heating. The fat losses on frying (175 °C, 3.5 minutes on each side) were substantially less than in the net test (cooking in a water bath at 77 oc for 35 minutes, followed by a centrifugation step). Fat losses during frying were governed both by the instability of the fat and the migration of the fat out of the product. The fat losses determined by the net test, however, reflected only the instability of the fat, as the effect of the migration of the fat out of the product was minimized, due to the centrifugation step. Fat-holding on frying was the best when fat was added in the form of fat cells and when an increased amount of connective tissue was added. On the contrary, fat-holding in the net test was be.st, when the fat was emulsified to smaller droplets with gelatin as an emulsifier. These observations suggest that the migration of the fat out of the hamburger is the most important factor, governing fat-holding in hamburgers on frying, whereas for the net test the instability of the fat per se seemed to be more essential.