Reduction of red blood spots in cooked marinated chicken breast meat by combined microwave heating and steaming

Abstract

One of the defects commonly found in cooked marinated chicken breast products is a red blood spot (RBS), which is caused by undercooked blood in vessels. This problem was alleviated by microwave (MW) pre-heating for 6 to 7 min, followed by steaming. RBS formation decreased when samples were heated to a core temperature of 80°C and were completely eliminated at a core temperature of 82°C and 85°C when a MW pre-heating step was applied for 7 min. Based on synchrotron-based Fourier transform infrared spectroscopy (SR-FTIR), blood remaining in the blood vessel had a lower α-helical content when samples were cooked by the combination of MW heating and steaming as compared with those prepared by steaming alone (P < 0.05). MW pre-heating decreased cooking time by 28 to 48% as compared with steaming alone. Heating regimes had no effect on cooking loss, pH, water-holding capacity, and shear force. MW pre-heating for 7 min followed by steaming to a core temperature of 82°C appeared to be an effective heating regime to reduce the occurrence of RBS, with acceptable cooking loss.

Keywords: blood denaturation; microwave heating; red blood spot; steaming; synchrotron radiation Fourier transform infrared spectroscopy.

Figure 1

Diagram of heating regime of microwave heating and steaming.

Figure 2

Temperature profiles of chicken breast subjected to steaming alone and the combination of microwave and steaming at various core temperatures. S80, S82, and S85 indicate steaming to core temperatures of 80°C, 82°C, and 85°C, respectively. W6S80, W6S82, and W6S85 denote microwave pre-heating for 6 min followed by steaming to core temperatures of 80°C, 82°C, and 85°C, respectively. W7S80, W7S82, and W7S85 denote microwave pre-heating for 7 min followed by steaming to core temperatures of 80°C, 82°C, and 85°C, respectively.

Figure 3

Representative micrographs of blood remaining in the blood vessels of raw meat (A) and samples cooked by the combined heating process to 82°C (B) obtained from a 36× objective microscope connected to a Synchrotron IR.

Figure 4

SR-FTIR spectra of cooked blood remaining in the blood vessels in situ and marinated chicken breast cooked by steaming alone to a core temperature of 85°C. Abbreviation: SR-FTIR, synchrotron-based Fourier transform infrared spectroscopy.

Figure 5

SR-FTIR spectra of blood remaining in vessels of chicken breast samples cooked to core temperature of 82°C by steaming and the combined microwave heating regimes. Spectra of cooked samples were subtracted from those of raw samples after baseline correction and vector normalization. Abbreviations of heating regimes are shown in Figure 2. Abbreviation: SR-FTIR, synchrotron-based Fourier transform infrared spectroscopy.