CIE Color Values Research Articles

Influence of Turkey Meat on Residual Nitrite in Cured Meat Products

A response surface experimental design was employed to estimate residual nitrite level at various initial nitrite concentrations, percent turkey meat in the formula, and heat quantity (F) values using a typical wiener as the test system. Pork and mechanically separated turkey were used as the meat ingredients. Residual nitrite and pH were measured at day 1, 7 days, 14 days, and 49 days after processing. Protein, fat, salt, moisture, and CIE (L*a*b*) color values were also determined. Results showed that the effect of turkey meat on residual nitrite level was significant (P < 0.01). An increased amount of turkey meat in the formula resulted in lower residual nitrite levels at a fixed pH. The residual nitrite level was initially proportional to initial nitrite concentration, but it became a nonsignificant factor during longer storage time. Differences in heat quantity had a significant effect (P < 0.05) on residual nitrite level initially. Greater heat quantity decreased residual nitrite level in finished cured meat products at a fixed pH. However, this effect became nonsignificant during longer storage. Reduction of residual nitrite in wieners because of turkey meat addition at a fixed pH was due to characteristics of the turkey tissue, but the mechanism of action remains unknown. It was also established that commercial wieners had a higher pH if poultry meat was included in the formulation.

Phenylalanine ammonia lyase inhibitors control browning of cut lettuce

Inhibitors of the first enzyme in the phenylpropanoid pathway, phenylalanine ammonia lyase (PAL), were used to investigate the role of phenolic metabolism in browning of lettuce tissue. Excised 4×7-cm midrib segments were soaked for 1 h at 20°C in aqueous solutions of the PAL inhibitors, α -aminooxyacetic acid (AOA; 0.1–10 mM), 2-aminoindan-2-phosphonic acid (AIP; 50–100 μ M), and α -aminooxi- β -phenylpropionic acid (AOPP; 200 μ M). Browning of the cut ends and uncut surfaces was measured using a visual score, and CIE color values ( L *, a *, b *). Overall browning potential was measured as the absorbance at 340 nm of an aqueous extract of the tissue. The visual scores were more highly correlated with hue angle than with the a * and b * values; there was no correlation with the L * values. Ethylene applied at 5 μ l l −1 had no effect upon browning compared with the air treatments. AIP at 50 μ M and AOPP at 200 μ M effectively inhibited browning; AOA was less effective requiring 3–10 mM to reduce browning. These results confirm the view that for browning to occur in lettuce PAL activity is required to form phenolics that are subsequently oxidized and polymerized.