• Food Science and Biotechnology
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• v.15 no.2
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• pp.260-263
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• 2006

In this study, we investigated the antimicrobial effect of 14 different herbal petal extracts on various foodborne and food spoilage bacteria. Herbal petal extracts were prepared with 70% ethanol followed by sequential hexane, chloroform, ethyl acetate, n-butanol, and water fractionation. Antimicrobial activity was highest in the ethanol fraction from roselle (Hibiscus sabdariffa L.) petals as determined by the paper disc method. The roselle ethanol extract retarded the growth of food spoilage bacteria in kimbap (rice rolled in dried laver). Foodborne microorganisms (e.g. Bacillus cereus and Clostridium perfringens), on the other hand, were most efficiently inhibited by the ethyl acetate fraction of the roselle petal extract as determined by growth inhibition curves. Our study shows that roselle petals harbor antimicrobial activity against foodborne and food spoilage microorganisms. The critical ingredient is highly enriched in the ethyl acetate fraction of the extract.

• Mycobiology
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• v.42 no.1
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• pp.66-72
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• 2014

Roselle (Hibiscus sabdariffa L.) family Malvaceae is an important crop used in food, cosmetics and pharmaceutics industries. Roselle is cultivated mainly in Upper Egypt (Qena and Aswan governorates) producing 94% of total production. Root rot disease of roselle is one of the most important diseases that attack both seedlings and adult plants causing serious losses in crop productivity and quality. The main objective of the present study is to identify and characterize pathogens associated with root rot and wilt symptoms of roselle in Qena, Upper Egypt and evaluate their pathogenicity under greenhouse and field condition. Fusarium oxysporum, Macrophomina phaseolina, Fusarium solani, Fusarium equiseti and Fusarium semitectum were isolated from the natural root rot diseases in roselle. All isolated fungi were morphologically characterized and varied in their pathogenic potentialities. They could attack roselle plants causing damping-off and root rot/wilt diseases in different pathogenicity tests. The highest pathogenicity was caused by F. oxysporum and M. phaseolina followed by F. solani. The least pathogenic fungi were F. equiseti followed by F. semitectum. It obviously noted that Baladi roselle cultivar was more susceptible to infection with all tested fungi than Sobhia 17 under greenhouse and field conditions. This is the first report of fungal pathogens causing root rot and vascular wilt in roselle in Upper Egypt.

• Journal of Dairy Science and Biotechnology
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• v.38 no.1
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• pp.37-44
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• 2020

The antimicrobial activity of the ethanol extract of Hibiscus sabdariffa L. (Roselle) powder against various food-borne pathogens was tested using the lawn diffusion assay. The results showed that the ethanol extract exhibited antimicrobial activities against Staphylococcus aureus (total inhibition), Salmonella enteritidis (partial inhibition), Listeria monocytogenes (partial inhibition), Escherichia coli (partial inhibition), Cronobacter sakazakii (partial inhibition), and Bacillus cereus (partial inhibition). Therefore, it is strongly recommended that Hibiscus sabdariffa L. (Roselle) should be considered for use as a natural food-grade additive for the inhibition of various food-borne pathogens, including both gram-positive and gram-negative pathogens, and the improvement of the overall quality of various dairy products, including milk.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.409-414
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• 2007

Antimicrobial and antioxidative effects of 14 different herbal flower extracts on skin microorganisms and oxidation were tested in this research. Herbal flower extracts were prepared with 70% ethanol. Among the herbal flower extracts, roselle (Hibiscus sabdariffa L.) flower extract showed the highest antimicrobial activity against Staphylococcus epidermidis as determined by a paper disc method. The seventy % ethanol extract of roselle flower was fractionated by sequential hexane, chloroform, ethyl acetate, n-butanol, and water fractionation. The growth of S. epidermidis, Streptomyces collinus, Streptomyces coeruleoprunus, Salmonella enteritidis, Vibrio parahaemolyticus, and Malassezia pachydermatis was most efficiently inhibited by ethyl acetate fraction of roselle flower extract as determined by a paper disc method and growth inhibition curves. In addition, the ethyl acetate fraction, water fraction and butanol fraction showed free radical scavenging and DNA cleavage inhibition activities. These results demonstrate that roselle flowers hold antimicrobial and antioxidative activities against skin microorganisms and oxidants.

• 한국약용작물학회:학술대회논문집
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• 2012.05a
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• pp.241-242
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• 2012

• Korean Journal of Plant Taxonomy
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• v.52 no.2
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• pp.123-126
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• 2022

Hibiscus sabdariffa L., (roselle) in the Malvaceae family is an erect subshrub known to be native to India and Malaysia. It is widely used as a food or tea material around the world, and its therapeutic effects have been widely studied. In this study, the sequencing of the complete chloroplast genome of H. sabdariffa was carried out. The result indicates a genome size of 162,428 bp, which is composed of a large single copy of 90,327 bp, two inverted repeats of 26,242 bp each, and a small single copy of 19,617 bp. Overall, a total of 131 genes were predicted, including 86 coding sequences, 37 tRNAs, and 8 rRNAs. According to a phylogenic analysis, it was clearly distinguished from outgroups such as other species of the genus Hibiscus used in the analysis.

• The Korean Journal of Food And Nutrition
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• v.30 no.2
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• pp.226-235
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• 2017

Roselle (Hibiscus sabdariffa L.) is a shrub which grows well in a tropical climate. There are large amounts of anthocyanins, organic acids and other compounds in roselle. Mostly, roselle is cultivated to use its red calyx. Its calyx is used as a natural food colorant and commonly consumed as a tea. This quality study was conducted to investigate the characteristics and antioxidant activities of Sulgidduck with roselle calyx powder. Four samples and a control were made with different ratios of added roselle calyx powder (0.5%, 1%, 1.5%, 2%). The moisture content of the 0.5%-sample was the highest as 40.60%, and that of the 2%-sample was the lowest as 37.37%. The pH of samples significantly decreased from 6.26 to 3.65 as the amount of roselle calyx powder increased (p<0.05). The L-value of samples also significantly decreased (p<0.05). In contrast, a-value and ${\Delta}E$ of samples significantly increased with elevated amounts of roselle calyx powder (p<0.05). The b-value of roselle calyx added Sulgidduck samples significantly increased compared to the control (p<0.05). Hardness and chewiness of Sulgidduck samples with added roselle calyx also significantly increased compared to the control (p<0.05). Cohesiveness of Sulgidduck samples with roselle calyx significantly decreased compared to control (p<0.05), with the exception of the 1% sample. There were no significant differences in springiness among samples. Total phenolic contents significantly increased when roselle calyx powder was added above a level of 1.5% (p<0.05). The flavonoid content of the control was the lowest as 0.73. ABTS radical scavenging activity significantly increased with increasing amounts roselle calyx powder (p<0.05). The 2%-sample got the lowest sensory preference scores in sweetness and overall acceptability. In contrast, the control and 1%-sample got the highest sensory preference scores. Based on these study findings, addition of 1% roselle calyx powder optimized the preparation of Sulgidduck and roselle calyx is therefore a useful natural colorant and antioxidant.

• Mycobiology
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• v.42 no.4
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• pp.376-384
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• 2014

Roselle (Hibiscus sabdariffa L.) is one of the most important medicinal crops in many parts of the world. In this study, the effects of microelements, antioxidants, and bioagents on Fusarium oxysporum, F. solani, and Macrophomina phaseolina, the causal pathogens of root rot and wilt diseases in roselle, were examined under field conditions. Preliminary studies were carried out in vitro in order to select the most effective members to be used in field control trials. Our results showed that microelements (copper and manganese), antioxidants (salicylic acid, ascorbic acid, and EDTA), a fungicide (Dithane M45) and biological control agents (Trichoderma harzianum and Bacillus subtilis) were significantly reduced the linear growth of the causal pathogens. Additionally, application of the previous microelements, antioxidants, a fungicide and biological control agents significantly reduced disease incidence of root rot and wilt diseases under field conditions. Copper, salicylic acid, and T. harzianum showed the best results in this respect. In conclusion, microelements, antioxidants, and biocontrol agents could be used as alternative strategies to fungicides for controlling root rot and wilt diseases in roselle.

• Journal of the Korean Society of Food Culture
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• v.28 no.4
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• pp.392-400
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• 2013

The purpose of this study was to determine the optimal amounts and mixing condition of skim milk powder (A), and roselle (B) for the production of yogurt prepared with roselle. The experiment was designed according to the central composite design for estimating the response surface method, which yielded ten experimental points, including two replicates for the skim milk powder and roselle. The physicochemical and mechanical analysis of each sample, including pH (P<0.001), titratable acidity (P<0.001), color (P<0.05), viscosity (P<0.001), showed significant differences. Antioxidant properties (total phenolic content, DPPH free radical scavenging activity) and viable cell counts of lactic acid were significantly different (P<0.05). The sensory measurements were significantly different in color, flavor, sourness, texture, and overall quality (P<0.05). The optimal formulation, calculated by numerical and graphical methods, was 7.82 g of skim milk powder and 2.09 g of roselle. From findings of this study, the roselle may be used in yogurt and can be applied for other food industries.