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dc.contributor.advisorBekhit, Alaa El-Din
dc.contributor.authorWeerakoon, Linakshi Kekuli
dc.date.available2020-09-08T23:52:15Z
dc.date.copyright2020
dc.identifier.citationWeerakoon, L. K. (2020). Investigating the safety of meat co-products: Microbiology aspect (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/10277en
dc.identifier.urihttp://hdl.handle.net/10523/10277
dc.description.abstractMeat co-products (offal) are rich in protein and essential nutrients and have been consumed as delicacies worldwide. China, New Zealand’s largest red meat export market is a country where offal dishes are frequently consumed. As foodborne diseases are a major challenge faced by Chinese consumers, it is important to ensure the quality and safety of offal consumed in China. The objectives of the study were; firstly to investigate the presence of E. coli/ coliforms, Campylobacter jejuni, Salmonella, Clostridium perfringens, Listeria monocytogenes and determine the aerobic plate count (APC) of sheep offal (testes, skirt, liver, tripe, kidney, heart, tail and pizzle) purchased from New Zealand and China using conventional microbiology enumeration methods. Secondly, the distribution of microbial populations present in the sheep offal were investigated using metagenomics. Thirdly, the presence of mycotoxins, aflatoxin B1 (AFB1), deoxynivalenol (DON), zearalenone (ZEA), T-2 toxin and ochratoxin A (OTA) in sheep offal were investigated. Lastly, the decontamination efficiency of chitosan on meat co-products was investigated. Campylobacter jejuni, Salmonella, Clostridium perfringens, Listeria monocytogenes were not present in any of the sheep offal. APC counts obtained for testes, skirt, liver, tripe , kidney, heart, tail and pizzle were 1.85 ± 0.58, 1.65 ± 0.53,1.41 ± 0.28, 1.61± 0.51,1.53 ±0.97, 2.16 ± 0.18 and 2.35 ± 0.46 log CFU/g, respectively for the New Zealand sheep offal and 6.27 ± 0.25, 6.04± 1.53, 6.36 ± 0.72, 5.70 ± 0.92, 7.56 ± 0.58, 7.41 ± 0.56, 7.41 ± 0.45 and 7.44± 1.11 log CFU/g, respectively for the Chinese sheep offal. Coliforms were not present in the New Zealand sheep offal samples. However, in the Chinese sheep offal coliform counts of 4.67 ± 0.96, 5.10 ± 0.60 5.01 ± 1.02, 4.77 ± 0.52, 7.12 ± 0.16 log CFU/g were found to be present in testes, skirt, liver, tripe, and kidney respectively. There was no E. coli present in any of the sheep offal samples. The metagenomic analysis revealed that Proteobacteria, Fermicutes, Actinobacteria, Bacteroidetes and Fusobacteria were the predominant phyla in the investigated sheep offal. However, different abundance levels of these phyla were observed between the samples from the two countries. Community abundance at Genus level indicated the presence of psychrotrophic foodborne bacteria. All of the New Zealand offal were positive for AFB1. The highest and lowest AFB1 concentrations were present in skirt (13.77±7.55 μg/kg) and liver (0.88±0.76 μg/kg) samples respectively. In the Chinese samples only pizzle, kidney, tripe and liver were positive for AFB1. The highest concentration was detected in liver (0.83 μg/kg) and the lowest was in pizzle (0.51±0.15 μg/kg). T-2 toxin was only present in the kidney, heart and pizzle samples of New Zealand. The highest and lowest concentrations were present in skirt (3.512 μg/kg) and heart (1.37±0.15 μg/kg) respectively. In the Chinese samples T-2 toxin was present only in skirt samples (0.03±0.01 μg/kg). All offal types from New Zealand were positive for DON except the pizzle and tripe samples. In the Chinese samples, only liver, tripe and kidney were positive for DON. OTA and ZEA were not present in any of the sheep offal from either of the countries. Non-irradiated crab chitosan was used to treat sheep tripe samples inoculated with S. aureus and E. coli O157:H7. The E. coli count on tripe was significantly reduced (p<0.05) to 4.31 log CFU/g and 3.88 log CFU/g when treated with chitosan at 0.31 mg/ml and 1.25 mg/ml respectively from an initial count of 5.30 log CFU/g. A significant reduction (p<0.05) in E. coli count was observed only with the 1.25 mg/ml treatment. The S. aureus count on the tripe samples was found to be reduced (p<0.05) to 4.695 log CFU/g and 3.710 log CFU/g when treated with chitosan at 0.31 mg/ml and 1.25 mg/ml, respectively compared to the initial S. aureus count (5.34 log CFU/g). Keywords: Meat co-products, Foodborne pathogens, Mycotoxins, Metagenomics, Chitosan
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectMeat co-products
dc.subjectFoodborne pathogens
dc.subjectMycotoxins
dc.subjectMetagenomics
dc.subjectChitosan
dc.titleInvestigating the safety of meat co-products: Microbiology aspect
dc.typeThesis
dc.date.updated2020-09-08T23:05:41Z
dc.language.rfc3066en
thesis.degree.disciplineFood Science
thesis.degree.nameMaster of Science
thesis.degree.grantorUniversity of Otago
thesis.degree.levelMasters
otago.interloanno
otago.openaccessAbstract Only
otago.evidence.presentYes
otago.abstractonly.term26w
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