• 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.

• 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.

• 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.

• 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.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.4
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• pp.574-581
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• 2008

Two experiments, involving a total of 100 crossbred pigs (Hampshire$\times$Landrace$\times$Duroc) aged 5 weeks, were used to evaluate the effect of Roselle (Hibicus sabdariffa Linn.) calyx as an antioxidant and acidifier on growth performance. Experiment 1: growth performance response of pigs fed basal corn-soy diet was compared with that of pigs consuming diets that contained 4, 8 and 12% Roselle in powder form, 4 g/kg acidifier (Fra$^{(R)}$Acid Dry) or 100 mg/kg antibiotic (Aurofac$^{(R)}$). All diets were isocaloric and isonitrogenous. Twenty-four castrated male and twelve female pigs were randomly allocated into 6 treatments which comprised 3 replicates (2 male and 1 female) of 2 pigs each. The results demonstrated no beneficial weight gain and feed intake response among treatments at 7, 9 and 11 weeks of age (p>0.05). However, feed-to-gain ratios (FCR) of Roselle-fed groups were significantly different from the basal-diet group at 7 weeks of age (p<0.05). Pigs fed with 8% Roselle had the lowest FCR. Therefore, 8% was set as an appropriate level of Roselle in feed. Experiment 2 was conducted to determine antioxidant and acidifier properties. Pigs were fed similar diets to Experiment 1 except that Roselle was fed to only one treatment at the level of 8%. Sixty-four piglets, 32 castrated male and female each were randomly allocated into 4 treatments which comprised 4 replicates (2 male and 2 female) of 4 pigs each. Body weight was measured. At 7 and 9 weeks of age, four pigs from each treatment were randomly selected. The pH in their gastrointestinal tract, pepsin activity in stomach mucosa, trypsin activity in the pancreas and protein and fat digestibility in the ileum were measured to investigate acidifier properties. For antioxidant properties, malondialdehyde (MDA) and glutathione concentration in plasma and liver were used as parameters. The results showed no significant difference in weight gain, pH or pepsin activity among all treatments at both ages (p>0.05). Nevertheless, trypsin activity and fat digestibility of the Roselle-fed group were higher than the basal-diet group at 7 weeks of age (p<0.05). Glutathione in plasma was significantly different between antibiotic-fed and basal-diet groups (p<0.05). Significant differences were found only in some parameters and between the basal-diet group and the other groups. Therefore, it cannot be precisely concluded that Roselle in powder form has clear acidifier and antioxidant properties in postweaning pigs. Further studies should be undertaken to clearly confirm both properties.

• Journal of Dairy Science and Biotechnology
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• v.37 no.4
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• pp.247-255
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• 2019

The objective of this study was to evaluate the sensory profiles of market milk, yogurt, and kefir, supplemented with the powder of Hibiscus sabdariffa Linnaeus (Roselle) in 1% increments, ranging from 0% (control) to 4%. In this study, there was no statistically significant difference in titratable acidity and pH between the treated groups and the control group. All samples were evaluated in five categories by thirteen appraisers. Compared to the control group, the best sensory profiles were observed in the market milk sample supplemented with 1.0% of Hibiscus sabdariffa Linnaeus (Roselle) powder, in the yogurt samples supplemented with 2.0% and 3.0% of Hibiscus sabdariffa Linnaeus (Roselle) powder, and in the Kefir sample supplemented with 3% of Hibiscus sabdariffa Linnaeus (Roselle) powder. According to statistical analysis of the sensory profiles obtained in this study, there was a statistical difference in the taste, flavor, color, and overall acceptability of market milk; in the taste, color, texture, and overall acceptability of yogurt; and in the taste, color, and overall acceptability of Kefir, between the treated groups and the control group (p<0.05). In the future, when Hibiscus sabdariffa Linnaeus (Roselle) powder is used as a food additive for dairy products, studies on improvement of biofunctionality, as well as of sensory profiles in dairy products must be carried out.

• 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.

• 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.

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