Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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This study examined the effectiveness of UV radiation in reducing numbers of naturally occurring aerobic psychotrophic bacteria, lactic acid bacteria, Campylobacter and surface inoculated E. coli on split, boneless, skinless chicken breasts and the effects the UV treatments had on the taste of the chicken. The objective of the study was to determine the UV dosage that gave the largest amount of microbial kill without adversely affecting the taste of the chicken. Two groups of 12 breasts were individually vacuum packaged. One group was surface inoculated with 1ml of a 2.0 X 106 CFU/ml culture of generic E. coli. The other group received no inoculation. Two breasts from each group were treated with one of six different UV radiation doses, 0 mW s/cm2 (control-no exposure), 34mW s/cm2, 101mW s/cm2, 202mW s/cm2, 504mW s/cm2 and 1008mW s/cm2. Within 24 hr of the treatments and again after seven days, one breast from each group and each treatment was enumerated for bacterial load. The results showed that bacterial load on the inoculated UV treated breasts were significantly reduced (p <0.05) at every treatment level by an average of 1.5 logs compared to the inoculated controls. There were however, no significant differences (p >0.05) between the inoculated breasts at any of the five different UV treatment dosages. The non-inoculated breasts showed no significant differences in the numbers of bacteria on the controls, as compared to the breasts treated with any of the five UV doses (p >0.05). Another set of 50 breasts were individually vacuum packaged and divided into six groups. Five groups contained five breasts each. Each group was treated with UV doses of 202mW s/cm2, 504mW s/cm2, 1008mW s/cm2, 2016mW s/cm2 and 3024mW s/cm2 respectively. The control group (n=25) received no exposure. Within 48 hr, and again seven days after treatments, triangle tests for difference were conducted to see if the taste of the chicken had been affected by the treatments. A sensory panel detected a significant taste difference between the untreated chicken and chicken treated at 504mW s/cm2 (p <0.05) two days after treatment, and between the control and chicken treated at 2016mW s/cm2 seven days after treatment (p <0.05). / Master of Science

Assessment of freshness and quality of meat and fish is a major activity of both food regulatory agencies and the food industry. Various methods are used for measuring fish and meat quality, each with its particular advantages and limitations. However, methods based on monitoring the products of proteolysis have received relatively little attention. The objective of the present study was to identify specific protein and peptide products of proteolysis as indicators of freshness and quality during chilled storage of fresh fish and meat. / Samples of meat and fish were subjected to chilled storage; at intervals of 0, 2, 4, 8, 12 and 16 days, samples were subjected to protein and peptide extraction, and separation of individual sarcoplasmic and myofibrillar proteins by SDS and native electrophoresis. These extracted proteins along with acid soluble nitrogen (ASN) were separated by RP-HPLC, fractions were collected and identified by electrospray ionization mass spectrometry (ESI-MS). / RP-HPLC separated at least thirty fractions from the ASN extract of fresh fish. ESI-MS revealed the presence of at least twenty-five polypeptides with molecular weights (MW) ranging from 2 to 32 kDa. The relative area % of the polypeptides with MW 32.8 kDa and 42.8 kDa decreased during the storage while polypeptides of MW of 10.9 kDa and 16.7 kDa increased during storage. Changes in polypeptides of MW 12, 34.2 and 42.8 kDa was also observed. The sarcoplasmic protein extracted from ground and whole meat contained at least 12 polypeptides with MW ranging from 11 to 42 kDa. The relative area % of polypeptide of MW of 35.7 kDa decreased during storage. The results suggest that changes in proteins and polypeptides of MW 10.9, 12, 16.7, 32.8, 34.2 and 42.88 kDa in fish and 35.7 kDa in meat could serve as indicators of spoilage.

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I declare that this is my own, unaided work. It is being submitted for the degree of Master of Science in the University of the Witwatersrand, Johannesburg. It has not been submitted before for any degree or examination in any other University. / Heat resistance and inactivation of processed meat spoilage lactic acid bacteria was investigated in vitro and by in-package pasteurization of South African vacuum-packaged vienna sausages. In vitro heat resistance of four lactic acid bacteria strains was low, since reductions of at least one log cycle in bacterial numbers occurred upon heating at 57, 60 and 63°C in quarter-strength Ringers solution for one minute. In vitro heat resistance data were used to calculate three in-package pasteurization treatments of increasing severity for vacuum-packaged vienna sausages. Depending on treatment, pasteurization in a water cooker at 67°C increased microbiological shelf life of sausages 10, 14 and 17 times that of control samples, during storage at 8'C. Although in-package pasteurization successfully decreased growth of spoilage lactic acid bacteria and increased product shelf life fit did not entirely prevent spoilage by pediococci. Since pasteurization also promoted growth of potentially pathogenic Bacillus and Clostridium, safety of pasteurized vacuum-packaged vienna sausages was compromised. / Andrew Chakane 2018

Thesis (Ph. D.)--Washington State University, December 2008. / Title from PDF title page (viewed on Feb. 12, 2010). "School of Food Science." Includes bibliographical references (p. 199-225).

No description available.

Extracts from medicinal mushrooms were prepared and tested for anti-microbial activity against food pathogens and food spoilage microorganisms. The inhibitory activity was measured using a disk diffusion assay and with optical density (OD). For OD, 7 fractions were collected using HPLC for 4 (A. blazei Murrill, G. lucidum, G. frondosa, I. obiquus) medicinal mushrooms and 6 fractions from L. edodes and 8 fractions from P. linteus. The results from disk diffusion assay showed that most mushrooms displayed significant inhibition compared to the ethanol. The exceptions were: A. blazei Murrill, I. obliquus, and L. edodes against E. coli O157:H7; I. obliquus against L. monocytogenes V7; I. obliquus against S. cerevisiae Y99; L. edodes against Z. bailii Y03; and I. obliquus against Z. bailii/bisporus Y108. Inhibition was more effective in yeasts than bacteria. The result from Bioscreen C showed that against L. monocytogenes V7, fraction 7 in A. blazei Murrill; fraction 1, 4 and 5 in G. lucidum; fraction 4 in G. frondosa; and fraction 4 and 5 in I. obliquus significantly inhibited the growth compared to ethanol. Against Z. bailii Y03, fraction 7 in A. blazei Murrill; all fractions from G. lucidum, G. frondosa, and P. linteus; fraction 1, 2, 3, and 6 from I. obliquus; and fraction 4 and 6 from L. edodes significantly inhibited growth compare to ethanol. The results indicated that there is significant antimicrobial activity against food pathogens and spoilage organisms in the medicinal mushrooms studied. / Ph. D.