One of the most important environmental parameters which affect the growth, biochemical activities and death of microorganisms in foods is water activity (aw). By appropriate adjustment of aw in the food system the food scientist can secure its extended preservation and minimize the possibility of a food-borne disease problem. This paper deals with the following subjects with respect to aw: the effect of aw on the growth and the biochemical activities of microorganisms; the parameters which affect the water requirement of microorganisms; the effect of aw on the survival of microorganisms at low and high temperature; the technology of aw adjustment in foods and its food safety implications and finally a discussion of some recent developments, trends and problems in the application of the aw principle in food preservation.

With 40% of the South African population experiencing moderate to severe food insecurity and climate change predicted to impact agriculture negatively, there is a future role for inland fisheries to help feed 60 million people. To support the expansion of inland fisheries, reducing the current postharvest losses of ~25% of fish requires improving the current preservation and storage techniques. This review aims to assess the potential benefits for Sub-Saharan Africa’s freshwater aquaculture and fisheries to utilise an emerging technology to reduce postharvest losses, using South Africa as a case study. We demonstrate the potential for plasma activated water (PAW) for preserving fresh fish. PAW offers non-thermal and non-toxic bacterial inactivation. Considered safe for human use, PAW is currently used in medical applications and has been investigated as a postharvest sanitiser for many fruits and vegetables, effectively increasing the shelf life of fresh food. The limited studies of PAW treatment of fresh fish show increased shelf life with some generally insignificant changes to quality. This novel treatment's success depends on the optimisation of application methods, including PAW-derived ice (PAWDI). To strengthen the value chain of the fresh fish industry, PAW/PAWDI could extend the shelf life of fish from origin to market. Investment in food supply chain development would preserve more harvested fish and improve the quality. Utilising solar power to produce PAW or PAWDI in situ potentially offers benefits for the small communities of inland fisheries to commercial production. This technology as well as changes to traditional preservation and transport chains could be utilised in other Sub-Saharan African nations. | The Australia Africa Universities Network. | https://link.springer.com/journal/12571 | hj2024 | Zoology and Entomology | SDG-02:Zero Hunger

Includes bibliographies

Diagrs., illus., tables. Includes bibliographies