PORK SOFTNESS ASSESSED SUBJECTIVELY AND OBJECTIVELY USING VACUUM-INDUCED CHANGES IN REFLECTANCE

Subjective assessments were made of softness and paleness in longissimus muscles of 382 sides of pork. Softness was correlated with paleness, (r = 0.57, P < 0.001). Softness was tested objectively in another 48 pork loins by applying a vacuum (to −2 kPa) across an elliptical area of longissimus. Reflectance from the meat surface measured by fiber-optics increased as the meat bulged outwards toward the vacuum. Pale pork was deformed to a greater extent than dark pork, and the initial slope of the reflectance-pressure relationship was correlated with initial reflectance before deformation and with maximum reflectance during deformation. At the maximum extent of deformation, there was a decrease in reflectance if the meat touched the fiber-optic light guide. By spectrophotometry of another 19 loins, the major difference between reflectance at 0 kPa and ≤−2 kPa was found at 470 nm.     

DIFFERENT PROPORTIONS AND TYPES OF MECHANICALLY RECOVERED PORK IN HAMBURGERS

The properties of hamburgers containing 10, 20, and 30% mechanically recovered meat (MRM) from backbones, 20% MRM from leg bones, and 20% MRM from ribs were studied using such parameters as composition, cooking loss, color, sensory analysis, and instrumental texture analysis. Adding more than 10% MRM increased the percentage of water retained during cooking. The presence of MRM caused a significant decrease in the L (lightness) value of the hamburgers and a significant rise in the a (redness) value, in an amount depending on the proportion and type of MRM. When MRM was added, the hardness and firmness of the hamburgers underwent a significant decrease. Sensory analysis indicated that, though adding MRM led to a certain “liver” flavor, a proportion of 10% MRM resulted in organoleptic properties superior to those of hamburgers made exclusively of hand-boned meat.     

EVALUATION OF GROUND PORK AND PORK SAUSAGE CONTAINING DIFFERENT FORMS OF APPLE PRODUCTS

Fat contents of ground pork were altered by reducing the amounts of fat trim incorporated and by the inclusion of different apple products (fresh, rehydrated, and sauce). Panelists could discriminate between ground pork containing 15% or 30% fat (without apples) and between ground pork with 0% or 15% apple (25% fat) but not between formulations with 15% or 25% fat and 10% apple (p<0.05). Incorporation of apple products (15% of total formulation weight) into reduced-fat pork sausage containing 15% fat yielded formulations with comparable flavor and preference scores to sausage with 30% fat, depending on the apple product. Total fat of cooked pork sausage can be reduced by approximately 35% by incorporation of apple products (15%) into reduced fat pork sausage. Inclusion of fresh or rehydrated apples did not significantly influence psychrotrophic bacteria populations or the color of pork sausage stored at 1–2C up to eight days.     

THE EFFECT OF OXYGEN SCAVENGERS ON THE COLOR STABILITY AND SHELF-LIFE OF CO, MASTER PACKAGED PORK

Pork chops were stored with and without O₂ scavengers in a modified atmosphere (50% CO₂/50% N, or 100% CO₂) master pack system at 0C for up to 21 days, At 7-day intervals, the chops were displayed at ca. 4.5C for 96 h. Color (L, a, b, hue and chroma); panelist assessments of color and odor; and drip losses were recorded. Oxygen scavengers reduced O₂ levels, resulting in chops that were generally as red as flesh, but tended to have higher hue angles at 0 h, and towards the end of display (P<0.05). Visually, chops packaged in 50% CO₂/50% N₂ were less acceptable than flesh (P<0.05). There were no odor differences between flesh and packaged chops. Fresh chops had lower drip losses than packaged (P<0.05). An acceptable display life was obtained for pork chops stored for up to 21 days in a modified atmosphere CO₂ master pack containing O₂ scavengers.     

CITRUS PRODUCT COLOR ENHANCEMENT USING EXTRACTS OF PEEL OF DIFFERENT VARIETIES

SUMMARY— Colored fractions ware extracted and concentrated from peel of most commercial orange varieties and used to enhance the color of orange juice products. These included Pineapple, Hamlin, Parson Brown, Valencia, blood orange and Dancy tangerine. The relative yields of crude pigment per kg of peel were compared between he different varieties. The color extracts were analyzed for tristimulus yellowness (Y) and redness (RI factors. Crude pigment yields ranged from .34 g (Hamlin) to 1.29 g (Dancy tangerine) per kg of peel. R factors were highest for Dancy tangerine, followed by Pineapple orange and Valencia, and lowest for Hamlin. Y factors were highest for Dancy tangerine, followed by Valencia and Pineapple and lowest for Hamlin. Most color extracts were effective at a dilution of 113500 parts in improving the color of orange juice products.     

2012美国色彩协会室内色彩设计作品赏析

这是一组由美国色彩协会（CAUS）会员单位提供的2012美国室内色彩设计的案例。三家室内设计公司根据不同的客户的设计要求．都采用以不同红色为主色调的设计方案。     

LIPID AND CHOLESTEROL OXIDATION,COLOR CHANGES,AND VOLATILE PRODUCTION IN IRRADIATED RAW PORK BATTERS WITH DIFFERENT FAT CONTENT1

An emulsion-type product was prepared to determine the effect of irradiation on lipid and cholesterol oxidation, color change, and volatile production in raw pork with different fat contents. Lipid oxidation increased with an increase in fat content or irradiation dose. Irradiated batters had higher cholesterol oxides than nonirradiated, and the major cholesterol oxides formed in irradiated pork batters were 7α- and 7β-hydroxycholesterol. Hunter color a- and b-values of raw pork batters were decreased by irradiation regardless of fat content. Irradiation increased the amount ofvolatiles significantly. Although lipid oxidation of high fat products (10 and 15% fat) was higher than that of low fat products (4%), high fat products did not always produce greater amount of volatiles. In summary, irradiation increased lipid and cholesterol oxidation, volatiles production and had detrimental effects on the color of raw pork batters under aerobic condition.     

EVALUATION OF BARLEY AND MALT QUALITY USING NEAR-INFRARED REFLECTANCE TECHNIQUES

A scanning near-infrared reflectance spectrophotometer was calibrated for the prediction of barley aleurone colour and malt moisture. The malt moisture was predicted on malt ground for the determination of malt extract (coarse grind) making the method suitable for moisture correction in malt extract estimation. Calibrations for the prediction of malt extract and endosperm modification from barley and malt were also attempted. A correlation (r= 0.851 n = 135) was found between malt hot water extract and the percentage of the endosperm estimated as being modified by microscopy following staining with Calcofluor. Probably because of this influence of modification on malt extract, the use of near-infrared reflectance to predict malt extract was most successful at predicting the malt extract values obtained following micro-malting in the absence of the additives, gibberellic acid and potassium bromate.     

DETECTION OF SPECIES ADULTERATION IN PORK PRODUCTS USING AGAR-GEL IMMUNODIFFUSION AND ENZYME-LINKED IMMUNOSORBENT ASSAY

Mixing undeclared species in meat products is illegal under food labeling regulations. This study compared the conventional agar-gel immunodiffusion (AGID) with the Enzyme-Linked Immunosorbent Assay (ELISA) for detecting species adulteration and assessed the species adulteration problem in raw ground pork products in Alabama retail markets. Forty-two ground pork and 87 fresh pork sausage samples collected throughout Alabama were examined by AGID and ELISA for four species: pork, beef, poultry and sheep. Using ELISA, 91 % of the ground pork samples were found to contain other meats while 71 % were found to be contaminated using AGID. Using ELISA, 54% of the sausage samples were found to contain undeclared species while none were found to be contaminated using AGID. The major adulterating species in the pork products was beef followed by poultry and sheep. Reliable analytical methods, such as ELISA, must be used as a regulatory tool to discourage the meat species adulteration problem in retail markets.     

IDENTIFICATION OF POULTRY MEAT FROM PORK AND BEEF ON THE BASIS OF THE TITIN PEVK REGION USING PCR

The possibility of distinguishing three kinds of meat species (chicken, porcine and bovine) alone or in two-component meat mixtures was investigated using the polymerase chain reaction. The contribution of each component in the meat mixtures ranged from 1 to 100%. The identification of meat was performed on the basis of the sequence coding the PEVK region of titin and by employing polymerase chain reaction. DNA was isolated from raw, fresh and chilled meat. The data presented in this study suggest that it is possible to detect chicken meat, pork and beef in meat mixtures on the basis of PEVK region by using PCR.

PRACTICAL APPLICATIONS

The polymerase chain reaction (PCR) is a precise and quick technique that has many practical applications. Using PCR with primer sets designed on the basis of the PEVK region present in titin can be a convenient tool for species identification, especially for chicken meat mixed with pork and beef meat in two-component meat mixtures. Reliable and sensitive methods for species differentiation can give consumers confidence about authentic meat product composition.     

ON THE INTERACTION OF MYOGLOBIN AND HEMOGLOBIN WITH MOLECULAR OXYGEN AND ITS LOWER OXIDATION STATES AND WITH CYTOCHROMEc

Ferrimyoglobin and ferrihemoglobin are oxidized to the ferry1 (+4) state by the xanthine-xanthine oxidase system under the same conditions under which the system causes rapid reduction of ferricytochrome c. Catalytic amounts of ferrimyoglobin exert an apparent inhibition of ferricytochrome c reduction by the system. Oxidation of ferrimyoglobin and ferrihemoglobin is most likely due to their reacting with products of xanthine oxidase reduction of oxygen, O⁻₂ (HO₂) and/or H₂O₂. The apparent inhibition of ferricytochrome c reduction is direct (interception of O⁻₂ by ferrimyoglobin) and/or indirect (reoxidation of ferrocytochrome c by ferrylmyoglobin). The latter mechanism is supported by spectral evidence of one-equivalent redox reactions (intermolecular electron transfers) between ferrylmyoglobin and ferrocytochrome c and between ferromyoglobin and ferricytochrome c. Both electron transfers have favorable redox potentials and therefore would be expected to occur from that standpoint. During autoxidation of oxymyoglobin O⁻₂ dissociation was not detected. This is consistent with theoretical arguments which indicate that O⁻₂ cannot dissociate during autoxidation although the conjugate acid (HO₂) can. If so, this would at least partially explain the known decrease in stability of the oxyheme complex as the pH of fresh red meat, meat extracts or oxyhemoprotein solutions is lowered. Mechanisms of autoxidation that are consistent with known pH and oxygen partial pressure effects and chemical reactions, as well as with available quantitative data and pertinent theoretical arguments are discussed.     

EFFECTS OF VARIOUS FRESH MEAT STORAGE METHODS ON THE COLOR OF COOKED GROUND PORK

The effects of microbial growth in raw materials on cooked pork color were investigated. In two trials with sow meat held aerobically at 2C for 3 weeks, microbial load reached spoilage levels (10⁷ cfu/g), pH increased to 6.46, and samples cooked to 71C had red exudate, shown by absorption spectroscopy to contain myoglobin and cytochrome c. Samples cooked to 82C also received high panel ratings for red color, due to red, flocculent precipitate in the exudate, but undenatured myoglobin levels were low. In sow meat held frozen or vacuum-packaged at 2C, pH after 3 weeks was 6.03 and 6.18, and plate counts were 10⁴ and 10⁷, respectively, but exudates after cooking were much less red. In five trials with fresh pork legs, total plate counts also reached 10⁷ cfu/g by 3 weeks storage, and pH increased to 6.37, but cooked samples were not red. Higher myoglobin levels in sow meat probably accounted for the red color and level of undenatured myoglobin remaining after cooking of high pH, spoiled samples.     

QUANTITATIVE DETERMINATION OF METMYOGLOBIN AND TOTAL PIGMENT IN AN INTACT MEAT SAMPLE USING REFLECTANCE SPECTROPHOTOMETRY

SUMMARY— A technique for determining the relative quantities of oxymyoglobin, metmyoglobin and total pigment concentration at the surface of on intact meat sample was developed. A Beck-man DK-2 spectrophotometer with reflectance attachment was used and spectra were recorded on the R_A scale. The sample port of the spectrophotometer was modified so that a uniform and high intensity light beam measuring 0.5 × 0.6 cm reached the surface being evaluated. A sample holder was constructed so that known proportions of oxygenated and oxidized meat could be exposed to the light beam. A family of curves representing varying known amounts of metmyoglobin and oxymyoglobin were obtained. The height of the peak at 632 nm (ΔR_A632) was directly related to the amount of metmyoglobin at the surface of the meat sample. For 100% oxymyoglobin, ΔR_A632 was at a minimum and equal to R_A750. For 100% metmyoglobin, ΔR_A632 was at a maximum and the height of the response depended upon the amount of total pigment present. A linear relation was obtained when ΔR_A362 was plotted against percent metmyoglobin or against total pigment determined by the Hornsey (1956) method. The method requires making two readings of the meat samples at a single wave length. One reading of the sample followed by one reading of the same sample after oxidation with K₃ Fe(CN)₆ provides a quantitative evaluation of the metmyoglobin concentration and the total heme pigment concentration. The accuracy of the method may be improved by making multiple readings.     

不同电压电击昏对猪肉品质的影响

30头品种、年龄、性别相同的杂交猪(体重120 kg±5 kg)随机分成3组,每组10头,分别用215、150、100V的电压在头部进行电击昏后屠宰.取背长肌测定各项肉质指标.结果显示:宰后45 min采用215 V电压电击昏组的猪肉pH值与150 V电压组差异显著(P<0.05),其它时间点差异不显著;215 V电压组与100 V电压组相比在45 min、1.5、2.5、24 h差异显著(P<0.05).150 V电压组与100 V电压组相比在1.5、2.5 h差异显著(P<0.05).击昏电压对宰后背长肌的色泽(L*和a*值)、滴水损失、蒸煮损失、嫩度、没有显著影响(P<0.05);宰后24 h 215 V组的细胞间空隙面积明显高于其它两个组.生产操作中建议击昏电压采用150 V电压.