Frederick Tawi Tabit

Advantages and limitations of potential methods for the analysis of bacteria in milk: a review

Contamination concerns in the dairy industry are motivated by outbreaks of disease in humans and the inability of thermal processes to eliminate bacteria completely in processed products. HACCP principles are an important tool used in the food industry to identify and control potential food safety hazards in order to meet customer demands and regulatory requirements. Milk testing is of importance to the milk industry regarding quality assurance and monitoring of processed products by researchers, manufacturers and regulatory agencies. Due to the availability of numerous methods used for analysing the microbial quality of milk in literature and differences in priorities of stakeholders, it is sometimes confusing to choose an appropriate method for a particular analysis. The objective of this paper is to review the advantages and disadvantages of selected techniques that can be used in the analysis of bacteria in milk. SSC, HRMA, REP, and RAPD are the top four techniques which are quick and cost-effective and possess adequate discriminatory power for the detection and profiling of bacteria. The following conclusions were arrived at during this review: HRMA, REP and RFLP are the techniques with the most reproducible results, and the techniques with the most discriminatory power are AFLP, PFGE and Raman Spectroscopy.

The effects of wet heat treatment on the structural and chemical components of Bacillus sporothermodurans spores

The objective of this research was to study the rate of structural damage and survival of Bacillus sporothermodurans spores following treatment at high temperatures by determining the amount of Dipicolinic acid (DPA) and soluble protein leakage over time. A reference strain of B. sporothermodurans (DSM 10599) and a South African strain (UP20A) isolated from UHT milk were used. To determine the survival of spores at 130 degrees C, spores were heated for 4, 8 and 12min. To check the viability of spores plate counts were determined, while structural damage was determined using the Transmission Electron Microscopy. The filtrate of the heated spore suspension was analysed for the amount of DPA and soluble protein release due to heating. The amount of DPA released was quantified by HPLC analysis while the amount of soluble protein released from heated spores was quantified using the Bradford method. The log values of spore counts, released DPA and soluble proteins from triplicate experiments were analysed. The results of this study indicate that the inactivation of B. sporothermodurans spores during wet heat treatment is due to the penetration of hot moisture into the spore which then moistens the spore components, and inactivates enzymes, and because of the high water pressure, vital spore components such as proteins and DPA in solution leak out of the spore. Interestingly a vast majority of heated spores were inactivated before a significant amount of DPA was released. This research is the first to determine the effect of high temperature wet heat treatment on the structure of B. sporothermodurans spores and has given an insight regarding the mechanisms of destruction of B. sporothermodurans spores by wet heat.

Incidence and survival of Bacillus sporothermodurans during processing of UHT milk

Purpose – The presence of Bacillus sporothermodurans in retail UHT milk along with milk from different points of a processing line was determined. This paper aims to investigate the effect of chilling, pre‐heating, UHT, reprocessing and H2O2 individually and in combination on the survival of B. sporothermodurans in broth.Design/methodology/approach – Standard plate counts were conducted for all milk samples and isolates from UHT milk were characterised using PCR. BS vegetative cells and spores in broth were subjected to various stresses encountered, during UHT processing of milk. Survival counts were conducted after all treatments.Findings – B. sporothermodurans was detected in retail UHT milk packs from only one processor. UHT treatment at 140°C for 4s eliminated B. sporothermodurans in broth. The combination of chilling and UHT was more effective in eliminating B. sporothermodurans spores than UHT treatment alone. H2O2 was also effective in eliminating B. sporothermodurans spores after 15 min of exposur...

Phytochemical Constituents and Antioxidant and Antimicrobial Activity of Selected Plants Used Traditionally as a Source of Food

Many indigenous plants have also been used as a source of food and medicine in many African rural communities in the past. The study investigated the antimicrobial activity, phytochemical constituent, and antioxidant activity of selected traditional plants used traditionally as a source of food and medicine. The methanol and water extracts of different plant parts were analyzed for phytochemicals using standard phytochemical screening reagents while the broth microdilution assays were used to analyze antimicrobial activities. Alkaloids, phenols, flavonoids, saponins, tannins, and terpenes were found in one or more of the plant extracts, and all the plant extracts demonstrated scavenging activities. The back extracts of Sclerocarya birrea and the leaf extracts of Garcinia livingstonei exhibit the best antioxidant activities, while the water and methanol back extracts of S. birrea and G. livingstonei were the most active against all the tested foodborne bacteria.

Antimicrobial, Antioxidant, and Cytotoxicity Properties of Selected Wild Edible Fruits of Traditional Medicinal Plants

ABSTRACT The fruit pulp extracts of 12 wild edible fruits were investigated for their antimicrobial, antioxidant, and cytotoxic properties. Methanol extracts of the pulps were tested against five microorganisms (Salmonella typhi, Streptococcus pyogenes, Bacillus cereus, Klebsiella pneumonia, and Prevotella intermedia). The fruit pulp extracts of the wild edible plants exhibited different degrees of antimicrobial activity, with Adansonia digitata exhibiting considerable antimicrobial activity against Salmonella typhi. The fruit pulp extracts of A. digitata were also the highest in antioxidant activity. None of the fruit pulp extracts was toxic to humans. The results show the potential use of these fruit pulps for the development of functional foods with medicinal benefits.

Assessing the Food Safety Attitudes and Awareness of Managers of School Feeding Programmes in Mpumalanga, South Africa

The managers of school feeding programmes are responsible for ensuring the safety of the food which is provided to schoolchildren, but very few studies have been conducted on the food safety knowledge and awareness of these managers. The objective of this study is to evaluate the food safety attitudes and awareness of managers of the National School Nutrition Programme (NSNP) in schools in Mpumalanga, a province of South Africa. A cross-sectional survey study was conducted in which questionnaires were used to collect data from 300 NSNP food service managers. The majority of schools offering NSNP meals were located in informal settlements and most were found to lack basic resources such as electricity (power supplies to the food preparation facility) and potable tap water in their kitchens. No school was found to have implemented the hazard analysis and critical control points (HACCP) programme, and only a few staff had received food safety training. Food safety implementation is worst in informal schools in rural areas due to limited resources and infrastructure. The NSNP food service managers in some schools—especially those located in rural settlements—were found to have little knowledge and awareness of HACCP. These results indicate an urgent need to provide NSNP managers with food safety training and resources (potable water supplies, electricity, dedicated food preparation facilities), particularly in schools in rural settlements.