MICROBIOLOGICAL CHARACTERISTICS AND PHYTOCHEMICAL SCREENING OF SOME HERBAL TEAS IN NIGERIA

Aims: The present study was undertaken to investigate the bacterial and fungal contamination of herbal teas in the Nigerian market with special reference to Benin City.Methodology And Results: Twenty-six (26) samples of five different types of herbal teas: antidiarrhoeal, antimalarial, antiobesity (slimming), antihypertensive and antidiabetic teas were analysed using standard microbiological procedures. All samples of the herbal teas were contaminated with both bacteria and fungi. The bacteria count ranged from 1.1x101 to 4.8x102cfu/g. The fungal count ranged from 1.1x102 to 4.5x105cfu/g. Bacterial isolates from herbal teas include: Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Pseudomanas flourecens, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcenscens, Salmonella typhimurium, and Escherichia coli. Fungal isolates were Aspergillus niger, Aspergillus flavus, Penicillium expansum, Rhizopus stolonifer and Fusarium solanii. Of all the bacterial isolates, Bacillus subtilis had the highest occurrence (100%) and the least was Salmonella typhimurium (3%). Among the fungi, Aspergillus niger had the highest occurrence (100%) and the least was Rhizopus stolonifer (10%). The bacteria isolates showed multiple resistace pattern to the antibiotics with all gram-negative exhibiting resistance to ampicillin. Phytochemical screening of the herbal teas revealed the presence of flavonoids, alkaloids, phenols, tannin and saponins.Conclusion, Significance And Impact Of Study: The presence of secondary metabolites justify the use of herbal teas.Good manufacturing practice and proper quality control is however needed for the continued use of the products to curtail antibiotic resistance

Survival of some food-borne pathogenic microorganisms in ozonated tropical fruits juices treated with chitosan

Enteric pathogens in non-pasteurized fruit juices can cause gastroenteritis. The ability of chitosan to inactivate food-borne pathogens in tropical fruit juices was investigated. Challenge studies was conducted with Salmonella typhimurium, Escherichia coli 0157:H7, Listeria monocytogenes and Staphylococcus aureus. Tropical fruit juices employed were orange, pineapple, watermelon and a mix of the three. Fruit juices samples (100ml) were dispensed into 150ml conical flasks. Chitosan powder was added directly to the juice to give a final concentration of 1000μg/ml, 1500μg/ml and 2000μg/ml respectively. For challenge testing, 0.1ml of 24h old broth cultures of the microorganisms were inoculated into the flasks at a level of ≤ 6.69Log10CFU/ml. The juices were then stored at 28oC and 4oC for 7-14 days and 20 days respectively. Chitosan concentration of 2000μg/ml was effective in killing Escherichia coli 0157:H7 in all fruit juices in 36 h irrespective of temperature of storage. Salmonella only survived up to 24h in pineapple and mixed fruit juices treated with ≥1500μg/ml chitosan. A greater killing occurred for Listeria monocytogenes with the application of concentration of 1500-2000μg/ml chitosan. At these concentrations Listeria monocytogenes counts were reduced from an initial challenge inoculum of 5.82log10CFU/ml to zero count in 12h to 24h in all fruit juices. The addition of 1500μg/ml or 2000μg/ml chitosan to the juices reduced Staphylococcus counts to zero in 18h in watermelon and orange juices. The ≥5log reduction of these pathogens by chitosan demonstrates its potential preservative power for unpasteurised fruit juices