Microbial diversity, nutritional value and antioxidant activity of the edible giant African bullfrog (Pyxicephalus Adspersus Tschudi, 1838) meat from Oshana region of Namibia
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Date
2022
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University of Namibia
Abstract
The seasonal, edible African Bullfrog Pyxicephalus adspersus, a notable indigenous food in Northern Namibia, is a good nourishment for human consumption and an alternative source of proteins. However, consumption of this species harvested after the first rain of the rainy season has been reported to be associated with severe dysuria. No study has been conducted to decipher its cause or consequent deleterious effects. Additionally, nutritional composition and the antioxidant properties of this meat species in Namibia have not been investigated.
This study is a preliminary attempt to reveal the nutritional composition including antioxidant activities as well as the bacterial diversity associated with this
species. Frog meat was analysed for crude protein, ash, crude fat and moisture content using standard analytical methods. Moreover, the antioxidant activity of methanol extract of the frog meat was evaluated using DPPH assay, nitric oxide as well as reducing power assay. The results showed that the highest crude protein recorded was 21±0.00%, ash was found to be 1.19±0.32%, crude fat was 1.65±2.71% while moisture content was 78.21±0.38%. Moreover, frog meat extracts exhibited antioxidant activity with the highest reducing power absorbance of 0.98±0.66 at 700nm, DPPH free radical scavenging of 51.13±18.26% inhibition, and a much lower nitric oxide inhibition of about 34.57±35.85%. Furthermore, metagenomics data reveal four phyla associated with Giant African Bullfrog meat, where Firmicutes is the most abundant accounting for nearly 90% of the total bacterial accumulation. In addition, metagenomics revealed a few pathogenic
species such as Lactococcus garvieae which is related to urinary tract infection in humans. Moreover, Lactococcus lactis which is highly studied in food fermentation research is one of the dominant species in this study. These findings endorsed the consumption of this species as a source of protein and antioxidants. The results indicated that frogs might have a valuable chemical composition as compared to other types of meat. Therefore, frog meat has the potential of attracting the attention of food technologists and dieticians as a healthy and valuable source of food based on its chemical composition.
Description
A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science (Microbiology)
Keywords
Edible African bullfrog, Nutritional composition, Antioxidant, Metagenomics, Dysuria