Screening of tropical medicinal plants for sporicidal activity

Bacterial spores have special significance in foods because they are much more resistant to physical and chemical antimicrobial treatment. Nowadays, there is interest in using natural products such as plant extract for food preservation. In this study, 26 of tropical medicinal plants and spices were screened for their sporicidal activity against the spores of Bacillus cereus. The spores of B. cereus was harvested after incubation at 30°C for 1 week and treated with various plant extracts using the method of Standard Operating Procedure for the AOAC (Association of Official Analytical Chemists) Sporicidal Activity. Glutaraldehyde was used as a positive control. Among them, Indonesian bay leaf (Eugenia polyantha Wight) inactivated more than 3 log of spores/ml of B. cereus (99.99%) at the concentration of 1% and completely killed B. cereus spores at concentration of 2.5%. These results suggest that Indonesian bay leaf extract has strong sporicidal activity against spores of B. cereus

In vitro antimicrobial activity of Cymbopogon citratus (lemongrass) extracts against selected foodborne pathogens

Microbial contamination in food system poses risk towards public health. The usage of synthetic and chemical preservatives to prevent the contamination has become a growing concern due to the presence of deleterious and harmful substances that can cause environment and health problems in prolonged exposure. Thus, there are needs to overcome this problem by using natural products as food preservatives. In this study, the antimicrobial activities of methanolic Cymbopogon citratus (lemongrass) extracts were tested against five foodborne pathogens, namely Bacillus cereus, Escherichia coli O157:H7, Klebsiella pneumoniae, Staphylococcus aureus and Candida albicans. The susceptibility test, minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) or minimum fungicidal concentration (MFC) were conducted using the broth microdilution techniques as described by Clinical and Laboratory Standard Institute (CLSI). C. citratus extract showed antimicrobial activity against all tested foodborne pathogens; B. cereus, E. coli O157:H7, K. pneumoniae, S. aureus and C. albicans with the inhibition zone of 12 mm, 7.5 mm, 11 mm, 10 mm and 9 mm, respectively. The MIC of C. citratus extract against B. cereus, E. coli O157:H7, K. pneumoniae, S. aureus and C. albicans was 0.08 mg/ml, 0.63 mg/ml, 0.04 mg/ml, 0.31 mg/ml, and 0.16 mg/ml, respectively, while the MBC or MFC was 1.25 mg/ml, 2.50 mg/ml, 2.50 mg/ml, 1.25 mg/ml and 1.25 mg/ml, respectively. Time-kill curves were determined to assess the correlation between MIC and bactericidal activity of C. citratus extract at concentrations ranging from 0× MIC to 4× MIC. The bactericidal endpoint for B. cereus, E. coli O157:H7, S. aureus and C. albicans was at 4× MIC after 2 h, 4× MIC after 2 h, 4× MIC after 30 min and 4× MIC after 4 h, respectively whereas K. pneumoniae was not completely killed after 4 hours of incubation at 4× MIC. The potent antimicrobial activity of C. citratus extract may support its usage as natural antimicrobial agent

Antibacterial activity of ethanolic Piper cubeba L. extract against Escherichia coli and its effect on microbiological quality of raw chicken meat during storage

Piper cubeba L. is traditionally recognised as flavouring ingredient in various types of foods and has been used to marinate meat. Scientifically, it has been reported to possess various valuable nutritional and pharmacological properties including antimicrobial potential. The aim of the present work was to determine the antibacterial activity of ethanolic P. cubeba L. extract against Escherichia coli and its effect on the microbiological quality of raw chicken meat during storage. Disc diffusion assay was done and resulted in 8.40 ± 0.10 mm of inhibition zone. The bacteriostatic and bactericidal effects of the extract were determined at 0.63 ± 0.00 mg/mL and 1.25 ± 0.00 mg/mL of concentration by MIC and MBC methods, respectively. The killing time was recorded at 2 × MIC (1.25 mg/mL) for 4 h. The application of the extract on chicken meat samples showed reduction in TPC and E. coli count with the observed optimum condition at 5.00% concentration stored at -18°C for 14 days based on the consistent reduction. Sensory attributes acceptability evaluation by 9-point hedonic scale showed acceptable score for colour, odour, texture and overall acceptability of the treated raw chicken meat samples. The findings implies that P. cubeba L. can be listed as one of the alternatives to reduce the bacterial load of raw chicken meat prior to cooking which is very important in ensuring food safety as well as reducing the occurrence of foodborne poisoning associated with chicken meat

Effects of extraction conditions on yield, total phenolic contents and antibacterial activity of methanolic Cinnamomum zeylanicum Blume leaves extract

Increase of foodborne diseases has promulgated the development of new natural food additive with high extraction yield to eliminate food pathogenic organisms. One such possibility is the use of plant product as antibacterial agents with non-conventional method to enhance the yield. In this study, cinnamon leaves (Cinnamomum zeylanicum Blume) were subjected to ultrasonic assisted extraction (UAE) using response surface methodology (RSM) to optimise extraction yield and total phenolic contents. The effect of two independent factors, extraction temperature (x1: 25-40°C) and extraction time (x2: 15-45 minutes) were investigated. Optimum extraction yield and total phenolic contents of cinnamon leaves were 27.49 ± 1.59% and 3987 ± 79.10 mg GAE/g which were closely as predicted using RSM (28.34%, 4048 mg GAE/g), respectively. The optimum condition of extraction yield (40°C and 45 minutes) showed the maximum zone of inhibition against all tested foodborne pathogens (7.33 ± 0.50 to 13.22 ± 0.44 mm), whereas optimum condition of total phenolic contents (33°C and 31 minutes) showed the lowest zone inhibition (6.78 ± 0.67 mm to 11.67 ± 1.41 mm). The minimal inhibitory concentration (MIC) values range from 97.65 to 6250.00 μg/mL and minimal bactericidal concentration (MBC) values from 6.25 to 50.00 mg/mL. These results indicated that UAE method is excellent in producing significantly the highest of extraction yield, total phenolic contents and act as a potential natural antibacterial agent even using low extraction temperature and short time

Effects of Myristica fragrans Houtt. (nutmeg) extract on chemical characteristic of raw beef during frozen storage

The objective of this study was to investigate the effect of nutmeg (Myristica fragrans Houtt.) extract at different concentrations on chemical characteristics of raw beef under frozen storage. Nutmeg extracts at concentrations of 0.25%, 0.65%, 1.25%, 2.50% and 5.00% (g/ml) were used to treat raw beef (2.5 × 2.5 × 1.0 cm; 4 ± 0.5 g) with dilution method. Treated samples were then individually packed in overwrapped trays and stored for 3 weeks at -18 ± 1°C. The effects of the extract on the chemical characteristics such as lipid oxidation, colour, pH, moisture, fat, and protein content of raw beef were evaluated at 0, 4, 7, 10, 14 and 21 days of storage. Lipid oxidation was evaluated based on thiobarbituric acid-reactive substance (TBARS) content. Colour of beef was observed by spectrophotometer in colorimetic parameters CIELabs. Values of pH were measured using pH meter. Moisture, fat and protein content were determined using method by Analysis Association of Official Analytical Chemists (AOAC). The result showed that extract at concentration of 1.25% inhibited TBARS value meaning that extract of 1.25% or more was able to maintain the oxidative stability of beef at -18°C. A 1.25% of extract was also able to maintain the redness (a*) of treated beef compared to untreated during frozen storage. The pH values of all samples beef decreased starting from 10th day of storage. Untreated samples (0.00%) showed the lowest pH values compared to other treated samples at the end day of storage. There was no significant different in term of protein content in all treated or untreated samples. However, fat and moisture content were significantly affected by the concentration of nutmeg extract. Treated beef was able to retain its moisture with only loss of moisture ranging from 0.2% - 2.00% while untreated samples had 5.00% loss of moisture. The fat content of untreated samples (0.00%) showed a reduction of 0.2% of fat content at the end of storage compared to all treated sample with only loss of 0.1% - 0.05%. Overall, nutmeg extract can be used to maintain the chemical characteristics of raw beef during storage for 3 weeks

Antifungal activity of Boesenbergia rotunda (temukunci) extract against filamentous spoilage fungi from vegetables

The filamentous spoilage fungi in vegetables can lead to significant impact in food and economic loss. In order to overcome this problem, chemical fungicide has been implemented in vegetable farming and processing but it causes problems towards environment and food safety. Thus, the utilization of natural products such as plants extracts, which exhibit antimicrobial and antifungal activity, is more acceptable to solve this problem. The aim of this study is to investigate the antifungal activity of Boesenbergia rotunda extract against ten filamentous spoilage fungi isolated from five vegetables. The extract was used to treat fungal isolates from vegetables; CRb 002 (Penicillium sp.), CHa 009 (Aspergillus sp.), TMa 001 (Geotrichum sp.), TMa 002 (Aspergillus sp), ONb 001 (Aspergillus sp.), WBb 003 and WBb 004 (Fusarium sp.) WBb 007 (unidentified), WBb 008 (Aureobasidium sp.) and WBb 010 (Penicillium sp.). The results showed that the yield of the extract of B. rotunda using ethanol (95%) was 11.42% (w/v). The 10% of B. rotunda extract exhibited antifungal activities against ten filamentous fungi after 5 days treatment with growth reduction of 41.56%, 30.68%, 86.20%, 50.62%, 26.67%, 47.44%, 50.74%, 36.39%, 42.86%, and 39.39% for WBb 008, WBb 004, WBb 007, WBb 003, CRb 002, WBb 010, CHa 009, TMa 001, ONb 001, and TMa 002, respectively. B. rotunda extract showed highest antifungal activity against fungi isolated from winged bean (WBb 007) with percentage reduction in growth was 86.20%, while the lowest activity was against fungi isolated from the carrot (CRb 002) with 26.67% reduction in growth. Generally, the TPC of fungi in the vegetable samples were reduced after treatment with 5% of B. rotunda extract at 5 min and 10 min of exposure time. The results suggested that B. rotunda extract has high potential to become natural food preservative which can reduce the fungi spoilage of vegetables

Cosmos caudatus Kunth. extract reduced number of microflora in oyster mushroom (Pleurotus ostreatus)

Nowadays consumer is more demand on natural foodstuff instead of synthetic product due to their concern on health. The objective of this study is to investigate the effect of C. caudatus extract on the number of microflora in oyster mushroom at different concentration of C. caudatus extract and exposure time using dilution method. The results showed that the number of microorganisms (Log10 CFU/g) in oyster mushroom in term of Total Plate Count (TPC), Bacillus cereus, Escherichia coli and Staphylococcus aureus were 6.13 ± 0.04, 6.15 ± 0.09, 5.97 ± 0.04, and 6.46 ± 0.00, respectively. The effect of C. caudatus extract on microflora in oyster mushroom at concentrations of 0.00%, 0.05%, 0.5%, and 5.0% with exposure time of 0, 5, 10, and 15 min demonstrated that the reduction number of microflora in oyster mushroom was dependent on the concentration of C. caudatus extract and exposure times. The number of TPC (Log10 CFU/g) in oyster mushroom was significantly reduced after treated with C. caudatus extract at concentration of 0.05% for 15 min; 6.13 ± 0.04 reduced to 2.62 ± 0.07. Moreover, B. cereus (Log10 CFU/g) in oyster mushroom was significantly reduced by treatment of C. caudatus extract at concentration of 0.05% for 5 min; 6.15 ± 0.09 reduced to 3.77 ± 0.15. Meanwhile, the number of E. coli (Log10 CFU/g) in oyster mushroom was significantly reduced at concentration of 0.05% for 10 min; 5.97 ± 0.04 reduced to 3.21 ± 0.13. Lastly, the survival number of S. aureus in oyster mushroom was significantly reduced after treated with C. caudatus extract at concentration of 0.05% for 15 min; 6.46 ± 0.00 reduced to 4.83 ± 0.07. In conclusion, C. caudatus extract has potentiality to be developed as natural sanitizer for rinsing raw food materials such as oyster mushroom

Effect of dried and extrudate of bitter gourd fruit on epithelial microflora in raw chicken legs meat

Plants have been used recently to eliminate bacterial growth in food products. This study was undertaken to test the in vitro sanitizing effect of crude extract from bitter gourd (BG) fruit on the growth of native microorganisms in raw chicken leg meat. Hot air dried BG and extrudate extracts at 1% concentration and exposure times of (5, 10 and 15 min) were used to treat the samples using dilution method. Results showed that BG extrudate had a slightly stronger bactericidal activity against the microflora than the B.G. hot air drying treatment, especially, on E. coli at all exposure time. Overall, there is no significant difference between the treatments; Total Plate Count (TPC), Escherichia coli, Bacillus cereus, Staphylococcus aureus. The best reduction time of microflora by hot air dried extract was at (15 min) except for B. cereus was at (5 min) and for extrudate extract was at (5 min) except for E. coli was at (10 min). In conclusion, bitter gourd extract could be used as an important natural sanitizer for rinsing raw food matrials such chicken meat

Increase in Polyphenolic Substances from Fermented Robusta Coffee Pulp (Coffea canephora L.) by Using Indigenous Actinomycetes

The fermentation of the coffee fruit processing into coffee beans leaves the fermented coffee pulp which still contains polyphenol secondary metabolites. This study aimed to analyze the total flavonoid content (TFC) and total phenolic content (TPC) of fermented robusta coffee pulp (Coffea canephora L.) by using indigenous Actinomycetes. The ability of fermented extracts to inhibit free radical DPPH (2,2-diphenyl-1-picrylhydrazyl) also were done. In this study, coffee cherries were fermented in the solid-state fermentation cultivation (SSF) using isolates HJ4.5b, P2b(b).3 and P2b(b).18 which in previous studies were reported to have cellulolytic and xylanolytic activities. Determination of molecular identification base on 16S rRNA gen showed the isolates HJ4.5b and P2b(b).3 have similarities to the genus Streptomycetes, while P2b(b).18 has a homologous base arrangement with a rare actinomycetes genus Micromonospora. Fermentation using P2b(b).3 on the 9th day of fermentation indicated the highest percentage increase in TFC (295.54%) with IC50 18.41 µl/ml and having an antioxidant activity index (AAI) value of 2.14 which was included in the very strong antioxidant activity category

Lignans from Phyllanthus niruri L. and Their Antifusarium Properties

In this study, two lignan compounds were isolated from acetone extract of Phyllanthus niruri L. nirtetralin B (1) and phyllanthin (2) using several chromatographic methods followed by molecular structure elucidation mainly based on 1D and 2D of 1H and 13C NMR spectrum. The isolated compounds were tested for their antimicrobial properties against the plant pathogenic fungus, Fusarium oxysporum, using the agar plate well diffusion method. The microdilution method determined the minimum inhibitory concentration (MIC) and the minimum fungicide concentration (MFC). In addition, the microconidia germination inhibition test was carried out using the agar diffusion method. As a result, compound 1 had MIC and MFC values of 4 and 16 μg/mL, respectively. While compound 2 showed the same MIC and MFC values of 16 μg/mL. Further testing on the inhibition of germination of F. oxysporum microconidia showed that compound 2 inhibited microconidia germination 100% at a concentration of 2 × MIC. In comparison, compound 1 at the same concentration was only able to inhibit germination by 29%. This study revealed that compound 2 is a potential new fungicide derived from local medicinal plants. However, further research is needed to identify the interaction mechanism between the test compound and the fungal pathogen F. oxysporum to develop new antifungal agents