近红外光谱技术在评定肉类品质上的应用

本文介绍了近红外光谱技术的原理及其在评定肉类品质上的应用和发展前景,并简要介绍了应用近红外光谱技术在评定牛肉品质上应用实例。     

CARCASS CHARACTERISTICS, SENSORY PROPERTIES AND MINERAL CONTENT OF MEAT FROM BULLS AND STEERS

Thirty-three bulls and 22 steers were slaughtered and subsequent carcasses were evaluated for carcass characteristics. Longissimus muscle samples were analyzed for sensory properties and concentrations of Cu, Fe and Zn. Bulls produced carcasses with older maturity characteristics, larger ribeyes, less fat and produced longissimus steaks that were less tender and had more organo-leptically detectable connective tissue than steaks from steers. Zn concentration was significantly correlated to skeletal maturity, fat thickness, ribeye area, connective tissue and tenderness before adjusting for sex. After adjusting for sex, mineral content did not significantly correlate as well with many carcass or sensory properties as before adjusting for sex.     

EFFECTS OF ELECTRICAL STUNNING DURATION ON POSTMORTEM RIGOR DEVELOPMENT AND BROILER BREAST MEAT TENDERNESS

Experiments were conducted to determine the effect of electrical stunning duration on poultry breast meat postmortem biochemistry and texture. Broilers were stunned with 100 V AC for 0, 5, 10, 20, or 40 s, killed by conventional neck cut, and bled for 180 s to determine percentage blood loss. Breast fillets were removed from the carcass immediately after picking or following 24 h of aging in an ice-water bath. R-values and pH were determined at both deboning times and Allo-Kramer shear values were recorded after holding the samples for 48 h at 2 C. Stunning durations of 10, 20 and 40 s resulted in lower (P < 0.05) blood losses than birds stunned for 0 or 5 s. Stunning inhibited postmortem glycolysis as indicated by higher (P < 0.05) pH values and lower R-values at 15 min postmortem, but not after 24 h. Stunning had no effect on Allo-Kramer shear values. Stunning durations from 5 to 40 s at 100 V AC had no significant effect on postmortem rigor development, or meat quality.     

CALCIUM, PHOSPHOROUS AND NITROGENOUS COMPOUND CONTENTS OF CHICKEN BROTH FROM BROILER BREAST FRAMES AS AFFECTED BY VARIOUS ACIDULANTS

The effect of acidulants on the total nitrogen, pH, gelatin, calcium, and phosphorous contents of chicken broth was investigated. Acidulants used included: ascorbic, acetic, citric, lactic, and phosphoric acids. All acidulants at a 0.50% level increased (P<0.05) the calcium and phosphorous contents of the broth prepared from broiler breast frames. The highest calcium and phosphorous contents were produced in chicken broths prepared with 0.50% phosphoric acid, followed by citric, lactic, acetic and ascorbic acids. Phosphoric acid-treated broth showed the highest nitrogen and gelatin contents, followed by lactic, citric, acetic, and ascorbic acids, in that order. As phosphoric acid concentration increased from 0 to 0.05%, the total nitrogen and gelatin contents of the broth decreased. However, phosphoric acid, at a concentration as low as 0.025%, increased (P<0.05) calcium and phosphorous extraction. Results indicated that acidulants could be used for the processing of high calcium and phosphorous chicken broth from broiler breast frames.     

THE EFFECTS OF DELAYED PICKING AND HIGH-TEMPERATURE CONDITIONING ON THE TEXTURE OF HOT- AND COLD-BONED BROILER BREAST MEAT

Four trials were conducted to evaluate the effects of delayed picking for 30 min versus normal picking, high temperature conditioning at 32°C versus low temperature conditioning at 0°C, and hot boning versus cold boning on broiler breast meat tenderness, pH, sarcomere length and R-values. None of the treatments affected cold-boned shear values. Within the hot-boned group, delayed picking significantly increased shear value (14.5 kg) compared with normally picked samples (12.5 kg). Conditioning at 32°C significantly lowered shear values (12.5 kg) compared with 0°C (14.6 kg). High-temperature conditioning lowered muscle pH immediately after evisceration, but delayed picking had no effect. Following 24 h aging, treatments had no effect on muscle pH or R-value. These results indicate that 32°C conditioning temperature and early picking significantly reduced meat toughness, but not to a commercially practical degree.     

THE EFFECTS OF MEAT TYPE AND FORMULATION ON THE PHYSICAL PROPERTIES AND SENSORY CHARACTERISTICS OF NONSPECIFIC MEAT LOAVES

Processing and sensory characteristics of meat loaves prepared from CB, CBS, HB and HBS meats and formulated with varying levels of fat (30 and 40%) and added water (120 and 130%) were evaluated. Muscle pH values were observed to be the highest for HB raw materials and lowest for CBS materials. Loaves prepared from HB and HBS meats exhibited less cook loss. Higher levels of added water resulted in a greater amount of fat and moisture loss during cooking. Loaves formulated at the 30% fat level exhibited a more desirable color and were superior in sensory characteristics when compared with loaves formulated to the 40% fat level.     

COMPOSITION AND SENSORY CHARACTERISTICS OF HOT-BONED,TUMBLED, TURKEY BREAST MUSCLE1

Turkey breast muscles were processed conventionally and hot-boned. Hot-boned breasts were chilled or tumbled in ice or ice and solutions of NaCl or Lem-O-Fos. Tumbling tended to increase “moisture pickup” and cooking losses; chilling in an ice and Lem-O-Fos mixture tended to decrease cooking losses and increase percentage moisture in cooked samples. Panelists scored flavor of muscles marinated in NaCl as significantly saltier than other muscles. Firmness and cohesiveness of samples hot-boned with no additional treatment tended to be greater than of other treatments.     

PREDICTION OF INSTRUMENTAL AND SENSORY TEXTURAL CHARACTERISTICS OF MAHON CHEESE FROM ULTRASONIC MEASUREMENTS

Ultrasonic velocity was related to sensory and instrumental texture measurements. A semi-logarithmic model (Weber-Fechner) was used to relate the sensory and instrumental texture measurements. The ultrasonic velocity ranged from 1650 to 1723 m/s for the softest and hardest cheese, respectively. As expected from theoretical equations, the ultrasonic velocity was related to the square root of the instrumental measurements. The deformability modulus (r²=0.93) and the slope in puncture (r²=0.85) were the most closely related parameters. A model developed from the relationship between sensory and instrumental texture and the relationship between ultrasonic velocity and instrumental texture, was used to relate velocity to sensory measurements. Elasticity (r²= 0.84) and firmness (r²= 0.81) were the sensory attributes which best correlated with ultrasonic velocity. From the obtained results, it was concluded that ultrasonic velocity measurements could be used to assess instrumental and sensory properties of Mahon cheese texture nondestructively, and therefore could be used for grading purposes.     

TENDERNESS ANALYSIS AND CONSUMER SENSORY EVALUATION OF OSTRICH MEAT FROM DIFFERENT MUSCLES AND DIFFERENT AGING TIMES1

Six ostrich carcasses were split and aged for 1 h, 1 day, or 1 week, roasted to 75 C and evaluated for tenderness and sensory attributes. Shear values for aged ostrich meat were 10.1, 10.0, 10.0, and 14.1 kg/g for 1 h, 1 day, 1 week, and the beef control, respectively. The most tender ostrich muscles identified were: M. iliofibularis, M. iliofemoralis, and M. oburatorius lateralis. Tenderness was affected by fiber orientation of the meat after slicing. Shear values were higher (p<0.05) for the longitudinal fiber orientation (11.5 kg/g) compared with the transverse fiber orientation (7.4 kg/g). A 9–point hedonic scale and a consumer sensory panel were used to evaluate tenderness, flavor, and overall acceptance of selected cuts. Ostrich meat aged for 1 week provided higher (p<0.05) liking scores for flavor compared with lesser aged ostrich or the beef control. This study suggests that prepared ostrich meat provides a good alternative compared with a similar beef product.