Chemical Modifications of Lipids and Proteins by Nonthermal Food Processing Technologies

A range of nonthermal techniques have demonstrated process efficacy in ensuring product safety, extension of shelf life, and in general a retention of key quality attributes. However, various physical, chemical and biochemical effects of nonthermal techniques on macro and micro nutrients are evident, leading to both desirable and undesirable changes in food products. The objective of this review is to outline the effects of nonthermal techniques on food chemistry and the associated degradation mechanisms with the treatment of foods. Oxidation is one of the key mechanisms responsible for undesirable effects induced by nonthermal techniques. Degradation of key macromolecules largely depends on the processing conditions employed. Various extrinsic and intrinsic control parameters of high-pressure processing, pulsed electric field, ultrasound processing, and cold atmospheric plasma on chemistry of processed food are outlined. Proposed mechanisms and associated degradation of macromolecules, i.e., proteins, lipids, and bioactive molecules resulting in food quality changes are also discussed

Effectiveness of a novel UV light emitting diode based technology for the microbial inactivation of Bacillus subtilis in model food systems.

peer-reviewedThe objective of this study was to assess the effectiveness of a novel UV multiwavelength light emitting diode (LED) based technology for the inactivation of B. subtilis in two model food systems. The LED based system was used to treat B. subtilis bacterial cultures using various combinations of UV wavelengths (285, 365, 405, 285/365, 285/405, 365/405, 285/365/405 nm) for different treatment durations (5 & 10 min). Bacterial enumerations, post-treatment analysis and SEM imaging were carried out. UV treatment at 285 nm was found to be the most efficient individual wavelength for inactivation resulting in > 6 log10 reductions. Treatments at other wavelengths investigated also resulted in bacteriostatic effects. Synergistic effects were observed for treatment at a 285/405 nm combination in one model system. Growth kinetics were carried out using a modified Gompertz model and model fit was assessed by root mean squared error, accuracy factor and bias factor. Experimental data showed good fit with model employed with RMSE values ranging from 0.01 x 10-2 to 1.367 x 10-2 for 5 min treatment, and 0.01 x 10-2 to 0.210 x 10-2 for 10 min treatment. Multivariate analysis was also carried out using principal component analysis and explained 100% of the variation observed for 3 principal components. This study shows that UV-LED technology is effective as bactericidal and bacteriostatic technology, depending on wavelength used

Effect of non-thermal plasma technology on microbial inactivation and total phenolic content of model liquid food and black pepper grains

pre-printThe objectives of this study were to investigate the effects of cold plasma technology on the growth and survival rates of vegetative cells and spores, and total phenolic content of black pepper grains. Plasma treatment was carried out using a non-thermal plasma jet system operating at 20 kHz using atmospheric air at a flow of 11 L/min. Two matrices were used, a model liquid food system and black pepper grains, both inoculated with Bacillus subtilis vegetative cells and spores. The samples were treated at 15 and 30 kV for 3–20 min. The plate count method was used to observe the colony-forming units at selected storage times i.e. at 1, 24 and 48 h post treatment at 4 °C. The highest log reduction was observed at 24 h post treatment, i.e. 2.92 log reduction. A 1 log reduction was achieved in the case of black pepper inoculated with spores for all selected storage times. No significant differences in total phenolic content were observed between treated and non-treated samples (p > 0.05). Optical emission spectroscopy was used to detect reactive species which could be responsible for cell death. Atomic oxygen, atomic nitrogen, hydroxyl radicals, nitrite oxide and nitrate were detected in light emitted from the plasma. Cell membrane damage caused by non-thermal plasma technology was observed using scanning electron microscopy. This study concludes that cold plasma technology has potential for industry application in food processing to reduce microbial loads in dried foods with limited impacts on food quality

Antimicrobial effects of airborne acoustic ultrasound and plasma activated water from cold and thermal plasma systems on biofilms

peer-reviewedBacterial bioflms are difcult to inactivate due to their high antimicrobial resistance. Therefore, new approaches are required for more efective bacterial bioflm inactivation. Airborne acoustic ultrasound improves bactericidal or bacteriostatic activity which is safe and environmentally friendly. While, plasma activated water (PAW) is attracting increasing attention due to its strong antimicrobial properties. This study determined efcacy of combined airborne acoustic ultrasound and plasma activated water from both cold and thermal plasma systems in inactivating Escherichia coli K12 bioflms. The application of airborne acoustic ultrasound (15 min) alone was signifcantly more efective in reducing E. coli counts in 48 and 72 h bioflms compared to 30 min treatment with PAW. The efect of airborne acoustic ultrasound was more pronounced when used in combination with PAW. Airborne acoustic ultrasound treatment for 15 min of the E. coli bioflm followed by treatment with PAW signifcantly reduced the bacterial count by 2.2—2.62 Log10 CFU/mL when compared to control bioflm treated with distilled water. This study demonstrates that the synergistic efects of airborne acoustic ultrasound and PAW for enhanced antimicrobial efects. These technologies have the potential to prevent and control bioflm formation in food and bio-medical applications.Science Foundation Irelan

The TED matriculation, higher grade, biology examination as an evaluator of educational objectives for effective biology teaching

A research project submitted to the Faculty of Science, University of the Witwatersrand, .Johannesburg, in part fulfillment of the requirements for the Degree of Master of Science. Johannesburg 1993.This study aims at providing some evaluation of the impact of the Transvaal Senior Certificate, Higher Grade, Biology Examination on Biology teaching in the Transvaal, It also looks. at the effectiveness of this exarnlnatlon as an assessment/evaluation instrument. A questlonnalre is used to secure the views qf practising Biology teachers, and teacher trainers, about the stated objectives of Biology teaching at senior high school level in terms of:- - their relative merit and importance. - their attainment through current teachinq practices. - their evaluation by the examination Board, The views of 63 teachers and 9 teacher trainers are analysed and the views of Transvaal and Natal teachers are compared to those of Teacher Trainers. Much consensus is found in the responses of all three groups of educators. They are well aware of modern trends and methodologies in the field of Biology Education but are pessimistic about the current achievement of many of the objectives they identify as being Important for effective Biology Teaching. They see the examination as one which focuses mainly on the assessment of Recall of Knowledge, The implications of these findings are discussed and several recommendations are made.AC201

Graduate Work-Readiness in Mauritius: A multi-stakeholder approach

Characterised by strong human capital dependency, Small Island Development States (SIDS) such as Mauritius depend largely on work-ready graduates to boost their economy. Yet, Graduate Work Readiness (GWR) and graduate unemployment feature prominently on the Mauritian government agenda. This paper investigates the previously unexplored issue of GWR in Mauritius through four key stakeholder lenses - those of the government, employers, universities, and undergraduates - before suggesting collaborative strategies to enhance graduate employability. The paper findings build on government and parastatal body interviews and qualitative survey responses from the Top 100 companies, higher education institution directors and final year undergraduates in Mauritius. Study results and recommendations are derived from a thematic content analysis of interview transcripts and qualitative survey data. Results indicate that there is a strong need to (1) strengthen stakeholder links, (2) enforce industry-centric university curricula, (4) improve graduate work experience, (4) hone graduate soft skills, and (5) their attitude to work. A Graduate Work Readiness Integrated Stakeholder Framework (GWRISF) supported by a National Work Integrated Learning Committee (NWILC) is then recommended. It is envisaged that proposed strategies will not only assist Mauritian stakeholders in better joining forces for GWR improvement but can also be useful to other comparable SIDS

Chemical Modifications of Lipids and Proteins by Nonthermal Food Processing Technologies

A range of nonthermal techniques have demonstrated process efficacy in ensuring product safety, extension of shelf life, and in general a retention of key quality attributes. However, various physical, chemical and biochemical effects of nonthermal techniques on macro and micro nutrients are evident, leading to both desirable and undesirable changes in food products. The objective of this review is to outline the effects of nonthermal techniques on food chemistry and the associated degradation mechanisms with the treatment of foods. Oxidation is one of the key mechanisms responsible for undesirable effects induced by nonthermal techniques. Degradation of key macromolecules largely depends on the processing conditions employed. Various extrinsic and intrinsic control parameters of high-pressure processing, pulsed electric field, ultrasound processing, and cold atmospheric plasma on chemistry of processed food are outlined. Proposed mechanisms and associated degradation of macromolecules, i.e., proteins, lipids, and bioactive molecules resulting in food quality changes are also discussed