No abstract available / Thesis (DVSc)--University of Pretoria, 1948. / Includes bibliographical references. / Production Animal Studies / DVSc / Unrestricted

Examination of a more economical electrical method of reducing the number of micro-organisms on dairy utensils. / Master of Science

Recently interest has been aroused over the topic of acidity of milk in southwest Virginia. Certain manufacturers of skin milk powder have manufactured products, which upon being reconstituted have exceeded the government limits in titratable acidity to be classified as "Extra Grade." This is the highest grade and cannot exceed 0.15 per cent in titratable acidity. Normal milk when freshly drawn, will naturally be slightly acid in reaction. This acidity of milk has been shown by various workers to be due to the presence of natural constituents such as the phosphates, proteins, carbon dioxide, and citrates. Any increase in acidity upon standing is due to the action of fermenting bacteria, changing lactose to lactic acid. It has been proven that normal milk with a high natural acidity is not objectionable in the manufacture of dairy products. However a highly-developed acidity is undesirable and may cause serious economic losses if used to any great extent. It is the opinion of certain dairymen and dairy manufacturers in this locality that due possibly to some natural existing condition in this area (such as soil type), the fresh milk may have a higher natural acidity than milk produced in other sections of the country. Should this be the case, it would seem logical that the standards should be modified so as not to reject that milk exceeding 0.15 percent titratable acidity, if the acidity is entirely natural. The nature of this problem is to attempt to find out if the milk produced in this area has a higher natural acidity than is expected; and if so, what the factors are contributing to it. / Master of Science

The aim of this investigation is to determine whether there is a correlation between the sanitary condition of milk and dairy products dispensed in Sherman, Texas, and the plate counts, the morphology, and the Gram stain reaction of the organisms in predominant colonies from these.

A study was conducted to determine the break-even point of three comparative fluid milk casing and stacking operations. The first comparative models consisted of two filling machines with the processed cartons manually cased and stacked, compared with automated casing and stacking, on a cost basis. The second comparative models consisted of three filling machines with the processed cartons cased and stacked as in the first comparative models. The third comparative models consisted of four filling machines with the processed cartons cased and stacked as in the first and second set of models. The break-even point of the first comparative models was not reached within a 24 hour period based on 260 operating days per year. However, components of automation in the packing handling phase of the fluid milk plant operation were considered. The break-even point of the second comparative models was reached after 18-1/2 hours of operation. It is advisable for the operator of this combination of filling equipment to consider automation if he is operating the plant more than 18-1/2 hours per day. If this is not feasible, then those components of automation should be considered that would result in the greatest reduction in the packing handling costs of the processed milk. The break-even point of the third comparative models was reached at slightly over seven hours of operation. The operator will realize a savings by installing the automated equipment if it is operated at or above seven hours per day. / Master of Science

Thesis (M. Tech. (Environmental health)) - Central University of technology, Free State, 2013 / Introduction Dairy farms in central South Africa produce a substantial amount of milk, which is sold in Bloemfontein, Free State. Large volumes of unpasteurized (raw) milk is collected on the dairy farms, which undergoes further processing before it reaches the consumer at the end of the production line. There is a large proportion of the population that, in most cases unknowingly, consumes raw milk that has bacterial counts substantially higher than legal standards. Poor quality unpasteurized milk is either sold as fresh milk in the informal market, or as dairy products, such as cheese, manufactured from unpasteurized milk. Consumers are therefore, in most cases, unaware of the poor quality dairy products they consume. Milk quality is usually assessed in terms of bacterial content, which include Escherichia coli, coliforms and total bacterial count. The bacterial quality of milk is influenced by a number of factors, including farming practices, structural design of the milking shed, herd health and quality of water used in the dairy. If the highest level of hygiene practices is maintained, contamination of the milk by pathogenic microorganisms will be controlled, however, any drop in the vigilance of hygiene practices could result in unacceptable high levels of pathogenic microorganisms resulting in poor quality raw milk. Poor quality raw milk will inevitably result in poor quality pasteurized milk, containing unacceptably high levels of pathogenic organisms, which will eventually reach the consumer. Objectives The objectives of this study were to assess the quality of milk and influencing factors of milk produced on 83 dairy farms that supply milk intended for further processing to the greater Mangaung region, Central South Africa. Influencing factors investigated included, water quality and hygiene of milk contact surfaces, namely pulsator surfaces and milk pipeline surfaces. Methods Standard sampling procedures were followed when milk was sampled from bulk milk tanks, water at the point of use in the dairy, as well as collection of surface swabs. Escherichia coli, coliforms, total bacterial counts and somatic cell counts in milk were determined in terms of the regulations relating to milk and dairy products, and for water in terms of drinking water standards. These data were analysed and the factors that directly influence bacterial quality of milk were identified. Results 93% of the dairy farms displayed E. coli in their bulk milk containers, which did not comply with the legal standard. For coliforms, 86% of the milk samples did not comply with the legal standard. The total bacterial count of 85% of the milk samples did comply with the legal standard. The somatic cell count of 42% of the milk samples did not comply with the legal standard. The pulsator surfaces as well as the milk pipeline surfaces of 13% of the dairy farms displayed the presence of E. coli. 80% of the pulsator surfaces and 78% of the milk pipeline surfaces did comply with the legal standard pertaining to coliforms. The total bacterial count of pulsator surfaces revealed that 19% complied, whereas 29% of the milk pipeline surfaces complied with the legal standard. The water data further revealed that 31% of the dairy farms contained E. coli in the water used in the dairies. 63% of the dairy farms contained more than the allowable number of coliforms in their water. Chi-square tests revealed significant differences (p > 0.05) between the presence or absence of E. coli in milk and water; the presence or absence of E. coli in milk and milk pipeline surfaces; the presence or absence of E. coli in milk and pulsator surfaces and the presence or absence of E. coli in milk and the positioning of the cows in the milking shed. When milk quality indexes were calculated for all the farms, only four farms were classified with excellent milk, the remainder were all classified as producing poor quality milk. The hygiene quality indexes revealed that the hygiene practices on all the farms were not up to standard. Discussion and conclusion The study revealed that the milk produced for commercial processing and distribution in the greater Mangaung region of central South Africa was of poor quality. It is often mistakenly believed that the pasteurization process will remove all microorganisms from milk. As this is not the case, it is of major concern that milk delivered commercially is not of acceptable quality. Furthermore, it could be concluded that the quality of milk products from raw milk were also probably not of acceptable quality. The results further revealed that the possible contributing factors to the poor quality milk produced by the 83 commercial dairy farms were; poor quality water used in dairy sheds and contaminated milk contact surfaces. From this study it could be concluded that the overall status of milk production on the 83 commercial dairy farms studied, did not meet the standards required for milk quality, water quality and hygiene practices.

Thesis (M.Tech.: Food Technology)-Dept. of Biotechnology, Durban University of Technology, 2007 xiii, 100 leaves / There are many ways for milk and dairy products to develop flavour defects. Sensory evaluation, has been the traditional approach to characterize off flavours. The need for odour sensing devices becomes greater when volatile and semi-volatile organic compounds are present in the product in parts per billion or even in the parts per trillion concentration range that cause off flavours. Today, sophisticated, sensitive instrumental tests such as electronic nose technology coupled with gas chromatography are capable of detecting, identifying and quantifying the specific chemical agents responsible for off flavours. This study focused on the use of the electronic nose as a novel technology for the detection and monitoring of milk quality by testing the effects of heat treatment at 63˚C and shelf life. Microbiological testing, sensory evaluation and gas chromatographic analysis were carried out together with aroma profiling using the electronic nose to determine milk quality.

Thesis (M.Tech.: Food Technology)-Dept. of Biotechnology, Durban University of Technology, 2007 xiii, 100 leaves / There are many ways for milk and dairy products to develop flavour defects. Sensory evaluation, has been the traditional approach to characterize off flavours. The need for odour sensing devices becomes greater when volatile and semi-volatile organic compounds are present in the product in parts per billion or even in the parts per trillion concentration range that cause off flavours. Today, sophisticated, sensitive instrumental tests such as electronic nose technology coupled with gas chromatography are capable of detecting, identifying and quantifying the specific chemical agents responsible for off flavours. This study focused on the use of the electronic nose as a novel technology for the detection and monitoring of milk quality by testing the effects of heat treatment at 63˚C and shelf life. Microbiological testing, sensory evaluation and gas chromatographic analysis were carried out together with aroma profiling using the electronic nose to determine milk quality.

M. Tech. (Biotechnology, Department of Biosciences, Faculty of Applied and Computer Sciences), Vaal University of Technology. / The Organization for Economic Co-operation and Development (OECD) and the Food and Agriculture Organization (FAO) of the United Nations predict that milk production and the dairy sector will remain one of the fastest-growing agricultural subsectors over the coming decade. The global milk production is projected to expand over the 2011-2020 period at an annual rate of 2%. In South Africa alone, approximately 14 – 15 million litres of milk are wasted annually due to microbial spoilage. Therefore, the identification of the spoilage microorganisms in the milk products is necessary. This will contribute towards the design of appropriate measures to prevent wastage due to spoilage and in turn contribute towards sustainability of the sector. Accordingly, one hundred samples of spoiled full cream UHT milk were collected from two plants of each of the two largest milk processors. These samples were examined visually, and the pH was measured. A presumptive identification up to genus level was conducted by examining morphological features and conducting Gram-stain, catalase and oxidase tests. Species-specific identification was done by using the Analytical Profile Index and Biolog system. Molecular profiling was done by sequencing the rDNA genes. The main spoilage organisms identified in the samples were Pseudomonas, Micrococcus, Bacillus, Enterococcus and Lactobacillus. All organisms belonging to the five genera were psychrotrophs, which are commonly found in biofilms in UHT milk processing equipment. Therefore, according to the study, the spoilage bacteria apparently entered into the milk due to inadequate cleaning-in-place (CIP) processes. More importantly, further studies should be conducted in order to identify the spoilage microbes and how CIP processes can be improved.

No description available.