Food Biotechnology
Ehsan Safari; Hassan Barzegar; Hossein Jooyandeh; Behrooz Alizadeh Behbahani; Mohammad Noshad
Abstract
Introduction
The addition of chemical preservatives increases the shelf life of food products, but prolonged and indiscriminate use of chemical preservatives increases the resistance of microorganisms and the health risks associated with theiruptake. Medicinal plants have a wide variety in the ...
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Introduction
The addition of chemical preservatives increases the shelf life of food products, but prolonged and indiscriminate use of chemical preservatives increases the resistance of microorganisms and the health risks associated with theiruptake. Medicinal plants have a wide variety in the world as well as in Iran. In recent years, the use of natural preservatives such as plant extracts and essential oils, due to their importance and role in controlling the growth of pathogenic microorganisms, has been proposed as an alternative to chemical preservatives. Black pepper is an aromatic medicinal plant. The specific properties of black pepper essential oil, such as its antimicrobial and antioxidant activity, have also been confirmed. Amphotericin B is one of the effective antibiotics for treating infections caused by pathogenic fungi. The mechanism of action of amphotericin B is to destroy fungal cells in such a way that by binding to ergosterol in the cell membrane of fungi, it creates pores and eventually destroys them. One of the most important and common antibiotics used in the treatment of infections caused by pathogenic bacteria is chloramphenicol. This antibiotic is effective against gram-positive and gram-negative bacteria due to its broad spectrum. The aim of this study was to identify bioactive functional groups, antioxidant potential, phenol and total flavonoid compounds and to evaluate the antimicrobial activity of black pepper extract against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus coagulans and Aspergillus niger.
Materials and Methods
In this study, the antimicrobial effect of black pepper aqueous extract was investigated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus coagulans and Aspergillus niger by disc diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration methods. Total phenol and flavonoid contents of the species were determined by Folin-Ciocalteu and AlCl3 assays, respectively. Three biochemical assays, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis 3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) free radical scavenging and β- caroten/linoleic acid activity systems, were used to evaluate antioxidant activity. Identification of functional groups as well as the structure of organic compounds in black pepper extract was also performed by Fourier transform infrared spectroscopy (FTIR). To evaluate the synergistic effect of black pepper extract in combination with amphotericin B and chloramphenicol antibiotics, Sub-MIC was used.
Results and Discussion
The peaks observed in aqueous black pepper extract confirmed the presence of O-H (3000-3500 cm-1), C-H (2800-3000 cm-1), C=O (1613.62-1633.52 cm-1) and C-O (100.57-1038.82 cm-1) functional groups of bioactive compounds. The total phenol and flavonoids content of the extract were 45.12 mg GAE/g extract and its flavonoid content was 29.66 mg QUE/g extract which had an important role in its antioxidant activity. The aqueous black pepper extract had remarkable DPPH free radical scavenging activity (IC50=32.37 μg/ml), ABTS free radical scavenging activity (IC50=28.45 μg/ml) and beta-carotene bleaching inhibitory effect (46.45%), revealing the electron/hydrogen donating ability of the essential oil. The results of measuring the antimicrobial activity of extract by disk diffusion and agar well showed that black pepper extract showed more antimicrobial effect on gram-positive bacteria Staphylococcus aureus and Bacillus coagulans than gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. This could be due to the difference in their cell wall structure. Aspergillus niger is the most sensitive species to aqueous black pepper extract. The minimum inhibitory concentrations of extract for Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus coagulans and Aspergillus niger were equal to 32, 16, 4, 8 and 4 mg/ml, respectively. The minimum bactericidal concentration of black pepper extract for two bacterial species, Escherichia coli and Pseudomonas aeruginosa was more than 512 mg/ml. Also, the minimum bactericidal concentration for Staphylococcus aureus and Bacillus coagulans was 128 and 256 mg/ml, respectively, and 128 mg/ml for Aspergillus niger. The results of interaction of black pepper extract with chloramphenicol antibiotic showed that the Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were synergistic, but antagonism was observed for the gram-positive Bacillus coagulans.
Faezeh Jamalizadeh; Mahdi Ghasemi-Varnamkhasti; Mehdi Ghasemi Nafchi; Mojtaba Tohidi; Majid Dowlati
Abstract
Introduction: Spices are the most valuable medicinal plants used in food and medical science industries and due to quality and price diversity between various species, distinction, classification and separation of them based on purity and quality degree have great importance. Spices are produced in different ...
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Introduction: Spices are the most valuable medicinal plants used in food and medical science industries and due to quality and price diversity between various species, distinction, classification and separation of them based on purity and quality degree have great importance. Spices are produced in different countries, including India, Pakistan, China, and East and South Asian countries. The difference in the percentage of aromatic compounds in various types of spices from different regions has led to a distinction between spices. Also, profitable individuals for economic purposes and more profit without regard to the general health of the community will lead to the creation of adulteration in different types of spices. The most important of these adulterations is the addition of volatile ingredients such as cubeb pepper and palm kernel powder in black pepper. Materials and Methods: In this study, an olfactory machine system based on eight metal oxide semiconductor sensors in combination with pattern recognition methods were used to classify and separate of black pepper samples based on geographic origin and also to detect cubeb pepper adulteration and palm kernel powder. The adulterated black pepper samples were tested with different adulteration levels (10, 20 and 30%).The fractional method was used to improve and optimize the electronic nose output signals before entering diagnostic methods. In order to analyze the extracted data from the sensor response signal, the principal component analysis method (PCA) was used. Based on the results, PCA with two main components of 96% for black pepper and 95% of cubeb pepper and palm kernel adulteration can be described from the variance of data. Also, three methods of linear separation analysis (LDA), Support vector machine (SVM) and decision tree (DT) were used to classify the samples. The use of the LDA method for black pepper showed a classification precision of 100%, and for adulterations, accuracy was 97.14%. Results and Discussion: The results showed that SVM with Gaussian function has the highest accuracy in classifying black pepper samples, cubeb pepper, and palm kernel adulteration Also, the success rate of the DT method in separating and categorizing black pepper, cubeb pepper, and palm kernel was 96.66% and 88.5% respectively.According to the results obtained, the machine olfaction system in combination with pattern recognition methods has the ability to detect and classify different black pepper samples from different geographical origin and the lowest level of adulteration.
Fahimeh Tooryan; Maryam Azizkhani
Abstract
Introduction: Nowadays, consumers are applicant to usage of natural replacements causing to side effects of synthetic preservatives such as carcinogenicity and teratogenicity. The tendency to use natural preservatives and replacing them with chemical preservatives has led to various studies of natural ...
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Introduction: Nowadays, consumers are applicant to usage of natural replacements causing to side effects of synthetic preservatives such as carcinogenicity and teratogenicity. The tendency to use natural preservatives and replacing them with chemical preservatives has led to various studies of natural compounds with antioxidant properties such as essential oils. Considering the environmental problems raised from current plastic packaging, edible and biodegradable coating could be developed and also be effective in controlling the chemical and microbial properties of food; especially if their effect be strengthened by adding natural antioxidant and antimicrobial agents like herbal essential oils. Various herbal compounds such as black pepper essential oils with antioxidant properties can be effective in combining with natural biodegradable coatings such as chitosan in oxidation control and enhance the effects or prevent or delay the chemical spoil. Safety and shelf-life of foods can be improved by using this technologies such as using natural preservatives. Adding essential oil, as a suitable source of antioxidant, for improvement the quality of the fish is the main purpose. Many fruits, especially orange, are rich in polyphenols. These materials are the most commonly existing phytochemicals in most fruits. Orange juice concentrate can be a good source of antioxidant and can be employed as a preservative in food products. Omega-3 fatty acid is used in daily healthy diet and plays an important role in prevention of disease. Being a considerably main source of Omega-3 fatty acid groups, fish preservation against oil oxidation and any other similar causatives seems quite necessary. In the present study, the effects of orange juice concentrate and chitosan coating enriched with black pepper essential oil on the chemical degradation of rainbow trout fillet stored in a refrigerator investigated.
Materials and methods: The chemical composition of black pepper essential oils were determined using a gas chromatography equipped with mass spectroscopy (GC/MS). GC-MS analysis of the essential oil was performed using Agilent-Technologies 6890N Network gas chromatographic (GC) system, equipped with Agilent Technologies 5975 inert XL Mass selective detector and Agilent-Technologies 7683 B series auto injector (Agilent-Technologies, Little Falls, CA, USA). Samples were stored at 4 ± 1 C° up to 12 days and evaluated periodically ( on days 0, 4, 8 and 12) for chemical and sensory characteristics. The samples were divided into 8 groups and assessed for PH-values, total volatile nitrogen (TVN), thiobarbituric acid (TBA), peroxide value (PV), free fatty acids (FFA) and sensory evaluation .The samples were also evaluated for antioxidant activity by measuring their scavenging abilities to DPPH radical (2,2 diphenyl-1-picril hydrazyl) and RP (Reducing power). Statistical analysis was performed using SPSS 20 software.
Results & Discussion: Results showed that More than 21 compounds were identified in oil, representing 97.75% of the total oil. The major constituents of essential oils obtained from the black pepper were β-caryophyllene (25.56%), Limonene (15.19%), Sabinene(12.2) , α-copaene(8.5) and beta –bisabolene (7.81) respectively. Results revealed that in comparison to the other treatments the control showed a significant increase in the trend of oxidative and sensory indexes and In the coated samples, the sample of fish coated with orange juice concentrate ,chitosan, and black pepper essential oil was the least amount of indexes than the rest (p<0/05) and showed lower indexes during the storage time .The radical scavenging DPPH, orange juice concentrate with a Brix 1/39 (66/9 %)and pepper essential oil 2% (64/1%) have more ability and had a greater antioxidant activity. In investigating corruption oxidation and sensory evaluation in all samples,chitosan coating with pepper essential oil and orange juice concentrate was higher(score:7/2) than other treatments and there were significant differences between treatment and control (p<0/05). Final peroxide value (meq O2/Kg oil) and tiobarbituric acid (m gr/kg oil MD) number using chitosan coating with pepper essential oil and orange juice concentrate in sample was 0.14 and 0.015, respectively. This significant deference was also observed when comparing to control sample (p<0.05)Minimum oxidative changes were observed in samples treated with orange juice concentrate,chitosan, and black pepper essential oil and had the best conditions in reduction of oxidative rancidity. The results obtained in this study showed that the chitosan coating enriched with black pepper essential oil with orange juice concentrate has a good potential to being employed as an active packaging to preserve food products. Overall, this study demonstrated that using concentrated juice incorporated with chitosan coating with pepper essential oil has a good effect on the quality of rainbow trout fillets and can keep on the sensorial attributes acceptably during 12 days storage time and present a good potential for their application in the food industry.
