Strains of Lactobacillus plantarum in Grape Must are also Present in the Intestinal Tract of Vinegar Flies

Twenty-one lactic acid bacteria isolated from the intestinal tract of Drosophila simulans Stuvervant and nine from Merlot noir grapes were identified as L. plantarum by PCR with species-specific primers and 16S rDNA sequencing.The 30 isolates grouped into four clusters based on RAPD-PCR banding patterns, suggesting that they belong to at least four genotypic groups. Thirteen isolates from grape must and five from the flies yielded identical RAPDPCR banding patterns and grouped into one cluster, suggesting that they are descendants from the same strain.  Concluded from these results, L. plantarum (or at least descendants from a specific strain) has the ability to use vinegar flies as a host and vector to infect grape must. Further research is needed to determine the role of this specific strain in wine fermentations

Seasonal variation of citrinin in traditionally brewed African beer

A seasonal study on citrinin concentrations in traditional beer was conducted using a standardised enzyme-linked immunosorbent assay. Representative samples of indigenous South African beer were collected during the hot, mild and cold seasons from marginal-urban settlements in the Kimberley area, South Africa. The mean temperature and humidity readings were 37C and 29% for respectively summer, 19.4C and 7.1% for spring, and 16.3C and 6.5% for winter. Samples were analysed for the mycotoxincitrinin using a commercial Ridascreen (citrinin) ELISA kit, validated for the purpose of the study. The recovery level achieved for citrinin in beer samples using the kit was 117 + - 15%. The inter-assay and intra-assay variations were 17.8 and 14.8% respectively. Standard curves prepared using traditional beer samples were similar to the standard curves prepared using the kit standards. The mean citrinin concentrations found in the various samples were 257.6 ug/kg, 99.0 and 185.7 ug/kg for the summer, spring and winter seasons respectively and the levels ranged between 35.6 ug/kg (min) and 924.2 ug/kg (max). Statistically significant differences (p ?0.05) were found between the citrinin levels of the summer and spring samples and also between citrinin levels of the spring and winter samples (p ?0.001). The relatively high levels of citrinin in selected samples may, with prolonged exposure, have adverse impacts on the health of consumers. Thus further studies into the origin and levels of this mycotoxin should be a priority

The use of ultraviolet radiation as a non-thermal treatment for the inactivation of alicyclobacillus acidoterrestris spores in water, wash water from a fruit processing plant and grape juice concentrate

Alicyclobacillus acidoterrestris is a non-pathogenic, spore-forming bacterium that can survive the commercial pasteurisation processes commonly used during fruit juice production. Surviving bacterial endospores germinate, grow and cause spoilage of high acid food products. Fruit juices can be treated using ultraviolet light (UV-C) with a wavelength of 254 nm, which has a germicidal effect against micro-organisms. In this study, A. acidoterrestris was inoculated into water, used wash water from a fruit processing plant and grape juice concentrate. Ultraviolet dosage levels (J L−1) of 0, 61, 122, 183, 244, 305 and 367 J L−1 were applied using a novel UV-C turbulent flow system. The UV treatment method was shown to reliably achieve in excess of a 4 log10 reduction (99.99%) per 0.5 kJ L-1 of UV-C dosage in all the liquids inoculated with A. acidoterrestris. The applied novel UV technology could serve as an alternative to thermal treatments of fruit juices for the inactivation of Alicyclobacillus spores as well as in the treatment of contaminated wash water used in fruit processing.Department of HE and Training approved lis