To investigate the gel properties of surimi-like materials (SLM) made from pig heart (PH), psoas major muscle (PM) and semimembranosus muscle (SM) of pigs, the three muscles were diced, chopped and washed with 25 mM sodium phosphate buffer (pH 7.0) to extract myofibrillar protein. SLM from SM had significantly (p<0.05) higher moisture content and lower crude protein content compared with PH and PM samples. The cooked SLM from PH was darker than that from PM and SM. Gel from PH had significantly (p<0.05) lower L* and hue values, and higher b* and chroma values compared to gels from PM and SM. The cooked SLM from PH had poor water-holding capacity (WHC) resulting in higher cooking loss. SDS-PAGE showed that the bands of myosin and tropomyosin/troponin had reduced staining intensity in the PH sample, and some unidentified bands that were not in PM and SM samples were observed in PH samples.

Gels were made from surimi-like pork (SLP) made from muscles obtained at 1, 24 and 72 h post-mortem. The SLP from pre-rigor muscle had higher pH and moisture percentage compared to in-or post-rigor muscles. Also, SLP from pre-rigor muscle showed higher concentration of water-soluble protein that was washed out during the process. Gel from post-rigor muscle exhibited higher a* and b* value, and also resulted in higher Chroma and lower hue values. The dark color of gel from post-rigor muscle was related to higher concentration of sarcoplasmic protein in SLP and denser structure in the gel matrix. SDS-PAGE showed higher intensity of the phosphorylase in the sarcoplasmic protein fraction from pre-rigor muscle. Gel from post-rigor muscle showed higher hardness and sensory firmness, and the greater firmness was related to higher concentration of protein in SLP, and a compact network with smaller pockets in the gel matrix.

MATERIALS AND METHODS Antigen preparationPorcine adrenocorticotropic hormone (ACTH) extracted from the pituitary (Sigma Chemical Co., Saint Louis, MO, USA) was conjugated to keyhole limpet hemocyanin (KLH) or human histone carrier using either 3-maleimidobenzoic acid N-hydroxysuccinimide (MBS) or glutaraldehyde, under a 2 × 2 × 2 factorial arrangement of treatments; main effects included hapten (ACTH vs none), carrier and crosslinker. The hapten-carrier conjugation using MBS was performed following the procedure of Liu et al. (1979). Briefly, 70 mg KLH or histone dissolved in 4.4 ml of 50 mM phosphate-buffered saline (PBS), pH 7.4, was mixed with 875 µl of 6.0 mg MBS/ml N, N-dimethyl formamide solution for 30 min on a rocker at room temperature. After removing free MBS on a P-6 disposable gel filtration column (Bio-Rad, Hercules, CA, USA), fractions corresponding to activated carrier were pooled and mixed with 13.2 ml PBS containing 70 mg dissolved ACTH or none for 3 h on a stirring plate. The hapten-carrier