Consumers associate meat color with quality. In some cases, especially in fresh and cured hams, the surface of a ham, whole, boneless or sectioned and formed displays a color gradient, which is unsightly and generally is considered of lower quality and must be discounted or processed different where color is less critical to the ultimate value of the resulting product. This disparity in color uniformity across fresh and cured products is sometimes known as two-toning and is most often found in the semimembranosus (SM) and associated muscles of fresh hams and is exacerbated with curing. The underlying color of fresh meat may be a function of postmortem metabolism or the underlying characteristics of those muscles involved. Therefore, the objective of this study is to determine the changes in underlying muscle type and postmortem metabolism in those muscles responsible for fresh ham color variation. Semimembranosus (SM) muscles of 15 mixed bred pigs were collected at 30 min and 1440 min postmortem, and muscle color was determined and muscles were collected and snap frozen for various energy metabolism analyses. Differences in color (L*, a* and b*) were noted across the face of the muscle by zone and time (P < 0.0001) but no differences were detected in pH and lactate, glucose, glucose-6-phosphate, and glycogen metabolisms. Glycolytic potential was also measured on a lactate basis and showed no differences across zone (P = 0.0746) but increased over time (P < 0.006). Lactate and pH were plotted and showed a linear relationship linear relationship (R2 = 0.928337) at 30 min (P < 0.0001) and at 1440 min (R2 = 0.161412; P < 0.0015). Muscle type characteristics showed no difference between zones and time. Buffering capacity showed a significant difference at pH 6 (P < 0.0359) and with time across all pH measured (P < 0.0001). These data suggest inherent differences, such as location and function, in the semimembranosus muscle may be more critical in developing fresh color than aberrations in postmortem metabolism. / Master of Science

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Titus O. Awokuse, Dept. of Food & Resource Economics. Includes bibliographical references.

As variation in pork tenderness has increased, identification of tenderness has become an industry need. This study consisted of 1208 pork loins randomly selected to test the efficacy of four automated grading techniques. Visible and near-infrared spectroscopy (VVNIR) (350-1830 nm wavelengths), bioelectrical impedance (EI) (resistance, reactance, phase angle, and partial capacitance), pH, and CIE L*, a* and b* color space values were used to predict chemical moisture and lipid, pH, Warner-Bratzler shear force (WBSF), and Slice shear force (SSF) on 13 d aged pork loins. The means and standard deviations for WBSF were (22.95 and 5.16) and SSF were (165.49 and 58.15). Prediction was based on stepwise linear regression and partial least squares regression. VNIR, pH, and color, when in combination, had the highest R^2 (0.19 and 0.21) for the prediction of WBSF and SSF, respectively. Partial least squares regression (PLSR) was used to remove autocorrelation between VNIR values. By using PLSR, with an R ^2 value of 0.49, 100 percent of the "tender" chops were correctly classified, 93 percent of the "intermediate" chops were correctly classified, and 92 percent of the "tough" chops were correctly classified into its category for WBSF. However, SSF was much lower (R^2 = 0.24) with only correctly placing 62 percent of the "tender" chops and only 48 percent of the "intermediate" and "tough" chops. Electrical impedance, alone or in combination with other technologies, either did not improve predictability of linear regression equations (increase R^2) or of PLSR models (increase R^2). Equations and models that included EI values had low R^2. When adding EI to the regression equation involving all variables, R^2 increased slightly from 0.19 to 0.21 in predicting WBSF, and from 0.21 to 0.25 for SSF. When pH or CIE L* color space values were included in linear regression or PLSR models to predict WBSF and SSF, R^2 values increased from 0.14 to 0.19 for WBSF, and 0.14 to 0.21 for SSF. pH played a large role in predicting WBSF and SSF, along with CIE L*. Thus, for an on-line situation, use of VNIR, pH, and color could be used to predict tenderness. Utilization of VNIR alone could be effective in predicting pork tenderness (WBSF). Using EI alone, or in combination with VNIR, would not provide acceptable prediction of WBSF or SSF. Use of VNIR with pH and color would improve the ability to predict tender and intermediate pork WBSF and SSF, but the additional improvement in accuracy may not be warranted based on the cost and additional time needed when using more than one technology.

Call number: LD2668 .T4 1944 H62 / Master of Science

Call number: LD2668 .T4 1964 W42 / Master of Science

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Current industry chilling practices with and without the application of 2 percent L-lactic acid were compared for their effectiveness at reducing levels of Salmonella, Yersinia enterocolitica, Campylobacter coli, and common indicator organisms used in industry (aerobic plate count APC, Escherichia coli, and coliforms) on pork variety meats. Pork livers, hearts, intestines, and stomachs were either inoculated individually with 1 of the 3 pathogens or not inoculated and subjected to 1 of 5 treatments: 1 (water wash + lactic acid spray + freeze), 2 (freeze), 3 (water wash + lactic acid spray + chill + freeze), 4 (chill + freeze), and 5 (water wash + freeze). Samples were analyzed between treatment steps and after 2 months, 4 months, and 6 months of frozen storage. Results of effects of the steps within treatments showed that reductions in levels of pathogens after the water wash and lactic acid spray were significantly different (P<0.05) across variety meats. Treatment of variety meats with water wash and lactic acid before chilling resulted in >/= 0.5 log CFU/sample (P<0.05) reductions when compared to chilling alone. Regardless of treatments, reductions in levels of Salmonella and Y. enterocolitica of 0.6-1.3 log CFU/sample were observed after freezing (0 degrees C) overnight. Freezing reduced C. coli by >/= 2.2 log CFU/sample regardless of previous treatment. Throughout 6 months of frozen storage, reductions were observed in levels of all microorganisms equal to or greater than 1.3 log CFU/sample. The greatest reductions were observed on samples treated with lactic acid (Treatments 1 and 3) (1.3-5.0 log CFU/sample) while the smallest reductions were reported for samples without any spray treatment (Treatments 2 and 4) (0.7-4.5 log CFU/sample). Large reductions were observed in levels of C. coli (2.9-5.0 log CFU/sample) for all treatments. The results of this study suggest that, while the application of a water wash followed by freezing reduced levels of pathogens by approximately 1 log CFU/sample, the application of lactic acid before chilling and freezing variety meats results in significantly larger (P<0.05) reductions in microorganisms. Results also show that aerobic plate counts, E. coli, and coliforms follow similar trends to the pathogens.

ABSTRACT The pig industry is one of the important industry for rural economy development in Taiwan¡CGross production value is about NTD 100 billion¡Awhich accounts for 51% and 16% respectively of animal husbandry and agricultural production value¡CIt is estimated around six hundred persons are engaged in related field of pig industry¡CTherefore¡Ain addition to proper rural economy¡Apig industry is also an important factor for social stability¡C Before foot-and-mouth disease outbreak in Taiwan in 1997¡Ait was a gold era for Taiwan pig industry¡Aas Taiwan export big amount of pork to Japan¡CHowever pork export suddenly stopped due to FMD outbreak¡Aswine producer suffered enormous economic losses¡C In order to enter WTO¡Ain 1998 Taiwan agreed to open pork import by the way of increasing quota progressively¡Aand then ¡Ain 2005¡Aopen pork import in all-round way¡C Because of high labor and land cost plus high cost to prevent environment pollution¡ATaiwan pork cost is generally higher than that in the main pork producer¡CFortunately¡Apeople in Taiwanese prefer warm body pork than imported frozen pork at present¡CImported pork is mainly used in pork processing industry¡Ait has not caused immediate threat to the domestic pork¡CImported pork only accounted for 7.2 % of total pork consumption till 2003¡C Facing the situation¡ACOA(Council Of Agriculture) has drafted a complete plan to support swine producer¡CIn this research¡Athree representative pig farms were choosed for depth interview, and than carry on questionnaire interview to 139 different scale swine farmers located in different area¡CThe result shows swine farmers think that the open of pork market in an all-round way will influence the industry development, but the majority does not cherish the pessimistic attitude¡CThey think except open of pork market¡Athere are many other factors¡Asuch as high morbidity of swine disease¡Bwaste water treatment¡Bgovernment¡¦s industrial policy etc¡Awill impact pig industry development¡C According to the survey results¡A43% of swine farmer have taken some actions to face the open of pork market, the major actions include to improve breed stock¡Bto create brand pork¡Bgood swine farm authentication¡Bto enter pig cooperative society and to raise black hair pig¡C Key Word ¡Gopen of pork market¡Apig industry

Fresh bone-in hams were sorted into "high pH" (5.6 or greater) and "low pH" (5.5 or less) groups and processed into spiral sliced, bone-in hams. Randomly selected hams from each group were evaluated for objective color and purge loss during a 75-day storage period and at a "holiday thaw" or 137-day storage date. At slicing, the "high pH" group displayed lower levels (P < 0.05) of fluid loss. When evaluated during the "holiday thaw" period, the "high pH" group had lower L* and higher a* values (P < 0.05), as well as lower purge loss values (P < 0.05). Boneless inside cushion muscles (M. semimembranosus) were sorted into four treatment groups: Control, Low PSE, Intermediate PSE, and High PSE. There were differences (P < 0.05) found between all treatments for fresh muscle pH. The Low PSE group had the lowest L* and highest a* values, whereas the High PSE group had the highest L* and lowest a* values as fresh muscles. The sorted muscles then were manufactured into 4x6 sliced ham, water added product. The Low PSE group displayed lower yield loss values during slicing. Randomly selected finished product was evaluated for objective color and purge loss during a 75-day storage period. The Low PSE and Control groups had lower mean L*, and lower mean purge loss values (P < 0.05). At day 45, consumer panel evaluations and textural measurements were collected. The Low PSE group had higher purchase intent ratings (P < 0.05) when compared to all other treatments. Fresh bellies were sorted into three treatments (Thin, Average, Thick) according to thickness. Information collected included processing and slicing yields, consumer panel sensory and visual characteristics, and proximate composition values. While the Thick treatment showed yield advantages during processing and slicing, the Thin and Average groups were clearly preferred (P < 0.05) when the consumer panel visually evaluated the slices. These data suggest that sorting for higher lean quality, if feasible, can be advantageous for ham manufacturing. In addition, thick bellies have proven to have an advantage during processing; however, consumers still prefer bacon that is visually leaner.