Objective:
This study aims at investigating the antibacterial potential of ethanolic extract of
Camellia sinensis
(common name: Green tea) and
Azadirachta indica
(common name: Neem) leaves on methicillin-resistant
Staphylococcus aureus
(MRSA) and shiga-toxigenic
Escherichia coli
(STEC).
Materials and Methods:
Fresh leaves were processed and extracted by 99% ethanol and reconstituted with 50% ethanol before testing. Disk diffusion and broth microdilution methods were used to determine zone diameter of inhibition (ZDI) and minimum inhibitory concentration (MIC), respectively. Nutrient agar plate was used to estimate the minimum bactericidal concentration (MBC).
Results:
Maximum ZDI value was observed for green tea against MRSA (7.5 mm) and minimum for neem (4.9 mm). Moreover, the highest ZDI against STEC was also for green tea and the combination of green tea and neem (4.5 mm). The MIC values of green tea extract were 15.625 and 31.25 mg/ml against MRSA and STEC, respectively, whereas the MIC of neem was 31.25 and 125 mg/ml, respectively. The combination had similar MIC (46.87 mg/ml) against both organisms. Green tea showed the lowest MBC values, 31.25 and 62.5 mg/ml, against MRSA and STEC, respectively. However, MBC of neem and the combination against MRSA and STEC were found >250 mg/ml, >500 mg/ml and 93.75 mg/ml, >375 mg/ml, respectively.
Conclusion:
Green tea and neem leaves showed good antimicrobial effects and can be used to explore novel antimicrobial compounds against MRSA and STEC.
Rice bran is an undervalued/underutilized by-product of rice milling, rich in protein, lipids, dietary fibers, vitamins, and minerals. It is an inexpensive source of high-quality protein, fiber and lipids to be incorporated into value-added food products. The issue with rice bran is its susceptibility to rancidity and therefore measures must be taken to stabilize the bran in order for it to be fully utilized. Due to this susceptibility to rancidity, historically the bran has either been disposed and wasted or used as low-grade animal feed. As the nutritional value of the bran has been recognized, along with its potential to add value to food products, research has been increasing in volume in order to determine the most effective methods for stabilizing the bran and extracting the valuable nutrients from it. It's been reported that a free fatty acid content of over 5% is considered to render the bran unfit for human consumption (Tao, Rao & Liuzzo, 1993). Therefore, controlling this level of rancidity is imperative to being able to store and use rice bran over extended periods of time. In order to achieve control, stabilization procedures can be carried out on the rice bran to slow down the lipase activity within the bran and preserve the nutritional qualities that rice bran possesses. Stabilization of rice bran is particularly important for use over winter months in developing countries, where there may be no crops to harvest and therefore a supply of non-rancid rice bran could be extremely beneficial. This length of storage for stabilized rice bran could be up to a period of 6 months, where it can become important for value-added product development (Bagchi, Adak & Chattopadhyay, 2014). The present review will provide an overview of the traditional and innovation rice bran stabilization techniques, those have been a common interest in the research community, and the suitability of the process in terms of the energy consumption.
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