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Trinetta V, Morgan MT, Coupland JN, Yucel U. Essential Oils Against Pathogen and Spoilage Microorganisms of Fruit Juices: Use of Versatile Antimicrobial Delivery Systems. J Food Sci 2017; 82:471-476. [PMID: 28071802 DOI: 10.1111/1750-3841.13614] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 12/01/2016] [Accepted: 12/12/2016] [Indexed: 11/30/2022]
Abstract
Essential oils (EO) are increasingly used as natural antimicrobial compounds, however the effect of delivery system to enhance their antimicrobial activity has not been widely studied. Limonene (0 to 10 μL/mL) was added to microbial suspensions (∼105 CFU/mL) of selected foodborne pathogens (Listeria monocytogenes Scott A, Salmonella enterica Typhimurium, Escherichia coli and Staphylococcus aureus), and spoilage microorganisms (Lactobacillus plantarum, Saccharomyces cerevisiae, and Candida albicans). S. aureus was found to be the most sensitive foodborne pathogen while Salmonella enterica showed continued growth under all concentrations. Stable nanoemulsions and solid lipid nanoparticles (SLN) (d ∼ 170 nm) were prepared using an alkane carrier oil (n-tetradecane and n-eicosane, respectively). Interfacial effects and homogenous distribution of limonene in nanoemulsions improved its (8 and 12 μL/mL) antimicrobial effect against S. aureus. Higher aqueous concentrations as a result of expulsion from SLN further enhanced the antimicrobial activity pronounced at higher limonene concentrations. Therefore, our findings confirm that the emulsion-based delivery systems are able to effectively distribute limonene inside a microbial suspension to improve its antimicrobial activity.
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Affiliation(s)
- Valentina Trinetta
- Food Science Inst., Kansas State Univ., 1530 Mid-Campus Drive North, Manhattan, Kans., 66506, U.S.A
| | - Mark T Morgan
- Dept. of Food Science and Technology, The Univ. of Tennessee, 2605 RiverDrive, Knoxville, Tenn., 37996, U.S.A
| | - John N Coupland
- Dept. of Food Science, The Pennsylvania State Univ., University Park, PA, 16802, U.S.A
| | - Umut Yucel
- Food Science Inst., Kansas State Univ., 1530 Mid-Campus Drive North, Manhattan, Kans., 66506, U.S.A
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52
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Joshi S, Howell AB, D'Souza DH. Blueberry proanthocyanidins against human norovirus surrogates in model foods and under simulated gastric conditions. Food Microbiol 2016; 63:263-267. [PMID: 28040178 DOI: 10.1016/j.fm.2016.11.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/21/2016] [Accepted: 11/30/2016] [Indexed: 01/04/2023]
Abstract
Blueberry proanthocyanidins (B-PAC) are known to decrease titers of human norovirus surrogates in vitro. The application of B-PAC as therapeutic or preventive options against foodborne viral illness needs to be determined using model foods and simulated gastric conditions in vitro. The objective of this study was to evaluate the antiviral effect of B-PAC in model foods (apple juice (AJ) and 2% reduced fat milk) and simulated gastrointestinal fluids against cultivable human norovirus surrogates (feline calicivirus; FCV-F9 and murine norovirus; MNV-1) over 24 h at 37 °C. Equal amounts of each virus (5 log PFU/ml) was mixed with B-PAC (1, 2 and 5 mg/ml) prepared either in AJ, or 2% milk, or simulated gastric fluids and incubated over 24 h at 37 °C. Controls included phosphate buffered saline, malic acid (pH 7.2), AJ, 2% milk or simulated gastric and intestinal fluids incubated with virus over 24 h at 37 °C. The tested viruses were reduced to undetectable levels within 15 min with B-PAC (1, 2 and 5 mg/ml) in AJ (pH 3.6). However, antiviral activity of B-PAC was reduced in milk. FCV-F9 was reduced by 0.4 and 1.09 log PFU/ml with 2 and 5 mg/ml B-PAC in milk, respectively and MNV-1 titers were reduced by 0.81 log PFU/ml with 5 mg/ml B-PAC in milk after 24 h. B-PAC at 5 mg/ml in simulated intestinal fluid reduced titers of the tested viruses to undetectable levels within 30 min. Overall, these results show the potential of B-PAC as preventive and therapeutic options for foodborne viral illnesses.
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Affiliation(s)
- Snehal Joshi
- The University of Tennessee-Knoxville, Department of Food Science and Technology, 2600 River Drive, Knoxville, TN 37966, USA
| | - Amy B Howell
- Marucci Center for Blueberry and Cranberry Research, Rutgers University, Chatsworth, NJ, USA
| | - Doris H D'Souza
- The University of Tennessee-Knoxville, Department of Food Science and Technology, 2600 River Drive, Knoxville, TN 37966, USA.
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Ben Jemaa M, Falleh H, Neves MA, Isoda H, Nakajima M, Ksouri R. Quality preservation of deliberately contaminated milk using thyme free and nanoemulsified essential oils. Food Chem 2016; 217:726-734. [PMID: 27664691 DOI: 10.1016/j.foodchem.2016.09.030] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 09/05/2016] [Accepted: 09/05/2016] [Indexed: 10/21/2022]
Abstract
The objective of this study is to evaluate the effect of either a solution of Thymus capitatus essential oil or its nanoemulsion on the quality of milk contaminated by bacteria. After 24h of S. aureus inoculation, bacterial growth reached 202×10(3)CFU/ml in the presence of the essential oil while it was limited to 132×10(3)CFU/ml when treated with nanoemulsion. The reduction of antioxidant capacity of milk treated with essential oil was higher when treated with nanoemulsion. Moreover, free essential oil was more efficient in protecting proteins from degradation than the nanoemulsion. For instance, after 24h of E. hirae contamination, 26% of the total proteins were consumed in the presence of nano-encapsulated essential oil, while only 14% of the initial content was consumed when free essential oil was added. Concerning milk acidity increase and the inhibition of peroxide production, no statistical differences have been recorded between the use of free essential oil or its nano-emulsion. In conclusion, bulk or nano-encapsulated T. capitatus essential oil preserve milk quality and can extend its shelf life.
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Affiliation(s)
- Mariem Ben Jemaa
- Laboratory of Aromatic and Medicinal Plants, Biotechnology Center of Borj-Cédria, BP 901, 2050 Hammam-lif, Tunisia; Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Hanen Falleh
- Laboratory of Aromatic and Medicinal Plants, Biotechnology Center of Borj-Cédria, BP 901, 2050 Hammam-lif, Tunisia.
| | - Marcos A Neves
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Hiroko Isoda
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Mitsutoshi Nakajima
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Riadh Ksouri
- Laboratory of Aromatic and Medicinal Plants, Biotechnology Center of Borj-Cédria, BP 901, 2050 Hammam-lif, Tunisia
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Sarkar P, Bhunia AK, Yao Y. Impact of starch-based emulsions on the antibacterial efficacies of nisin and thymol in cantaloupe juice. Food Chem 2016; 217:155-162. [PMID: 27664621 DOI: 10.1016/j.foodchem.2016.08.071] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 08/20/2016] [Accepted: 08/22/2016] [Indexed: 10/21/2022]
Abstract
The use of antimicrobial compounds to prevent foodborne pathogens from contaminating fresh-cut produce has received broad attentions; however, the applications of these compounds are hindered by their rapid depletion in foods. To prolong their efficacies, the use of delivery systems is essential. In this study, oil-in-water emulsions formed using starch octenyl succinate (starch-OS) were used to stabilize nisin and thymol in cantaloupe juice-containing fluid. Listeria monocytogenes V7 and Salmonella enterica serovar Typhimurium were used as model pathogens to evaluate the antimicrobial activities of nisin and thymol formulations in cantaloupe juice. The results showed that the emulsions had much greater capability to retain nisin and thymol over the storage and displayed much greater effect to inhibit Listeria and Salmonella than non-emulsion, aqueous formulations. Starch-OS based emulsions not only retained nisin and thymol activities separately, but also exhibited their cooperative antibacterial effects.
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Affiliation(s)
- Preetam Sarkar
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, West Lafayette, IN 47907, United States
| | - Arun K Bhunia
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, West Lafayette, IN 47907, United States
| | - Yuan Yao
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, West Lafayette, IN 47907, United States.
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Singh BN, Prateeksha, Upreti DK, Singh BR, Defoirdt T, Gupta VK, De Souza AO, Singh HB, Barreira JCM, Ferreira ICFR, Vahabi K. Bactericidal, quorum quenching and anti-biofilm nanofactories: a new niche for nanotechnologists. Crit Rev Biotechnol 2016; 37:525-540. [PMID: 27684212 DOI: 10.1080/07388551.2016.1199010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Despite several conventional potent antibacterial therapies, bacterial infections pose a significant threat to human health because they are emerging as the leading cause of death worldwide. Due to the development of antibiotic resistance in bacteria, there is a pressing demand to discover novel approaches for developing more effective therapies to treat multidrug-resistant bacterial strains and biofilm-associated infections. Therefore, attention has been especially devoted to a new and emerging branch of science "nanotechnology" to design non-conventional antimicrobial chemotherapies. A range of nanomaterials and nano-sized carriers for conventional antimicrobial agents have fully justified their potential to combat bacterial diseases by reducing cell viability, by attenuating quorum sensing, and by inhibiting/or eradicating biofilms. This communication summarizes emerging nano-antimicrobial therapies in treating bacterial infections, particularly using antibacterial, quorum quenching, and anti-biofilm nanomaterials as new approaches to tackle the current challenges in combating infectious diseases.
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Affiliation(s)
- Brahma N Singh
- a Pharmacognosy & Ethnopharmacology Division , CSIR-National Botanical Research Institute , Lucknow , India
| | - Prateeksha
- a Pharmacognosy & Ethnopharmacology Division , CSIR-National Botanical Research Institute , Lucknow , India
| | - Dalip K Upreti
- b Lichenology laboratory , Plant Biodiversity and Conservation Biology Division, CSIR-National Botanical Research Institute , Lucknow , Uttar Pradesh , India
| | - Braj Raj Singh
- c TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gurgaon , Haryana , India.,d Centre of Excellence in Materials Science (Nanomaterials), Z. H. College of Engineering and Technology , Aligarh Muslim University, Aligarh , Uttar Pradesh , India
| | - Tom Defoirdt
- d Centre of Excellence in Materials Science (Nanomaterials), Z. H. College of Engineering and Technology , Aligarh Muslim University, Aligarh , Uttar Pradesh , India.,e Laboratory of Aquaculture & Artemia Reference Center , Ghent University , Gent , Belgium
| | - Vijai K Gupta
- f Molecular Glyco-biotechnology Group, Discipline of Biochemistry , School of Natural Sciences, National University of Ireland Galway , Galway , Ireland
| | | | - Harikesh Bahadur Singh
- h Mycology & Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University , Varanasi , Uttar Pardesh , India
| | - João C M Barreira
- i Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança , Campus de Santa Apolónia , Bragança , Portugal
| | - Isabel C F R Ferreira
- i Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança , Campus de Santa Apolónia , Bragança , Portugal
| | - Khabat Vahabi
- j Biologisch-Pharmazeutische Fakultät , Institut für Allgemeine Botanik und Pflanzenphysiologie, Friedrich-Schiller Universität Jena , Jena , Germany
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57
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Marchese A, Orhan IE, Daglia M, Barbieri R, Di Lorenzo A, Nabavi SF, Gortzi O, Izadi M, Nabavi SM. Antibacterial and antifungal activities of thymol: A brief review of the literature. Food Chem 2016; 210:402-14. [PMID: 27211664 DOI: 10.1016/j.foodchem.2016.04.111] [Citation(s) in RCA: 404] [Impact Index Per Article: 50.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 03/27/2016] [Accepted: 04/25/2016] [Indexed: 12/22/2022]
Abstract
Thymol (2-isopropyl-5-methylphenol) is the main monoterpene phenol occurring in essential oils isolated from plants belonging to the Lamiaceae family (Thymus, Ocimum, Origanum, and Monarda genera), and other plants such as those belonging to the Verbenaceae, Scrophulariaceae, Ranunculaceae, and Apiaceae families. These essential oils are used in the food industry for their flavouring and preservative properties, in commercial mosquito repellent formulations for their natural repellent effect, in aromatherapy, and in traditional medicine for the treatment of headaches, coughs, and diarrhea. Many different activities of thymol such as antioxidant, anti-inflammatory, local anaesthetic, antinociceptive, cicatrizing, antiseptic, and especially antibacterial and antifungal properties have been shown. This review aims to critically evaluate the available literature regarding the antibacterial and antifungal effects of thymol.
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Affiliation(s)
- Anna Marchese
- Microbiology Unit, IRCCS-San Martino-IST and DISC, University of Genoa, Italy
| | - Ilkay Erdogan Orhan
- Department of Pharmacognosy, Faculty of Pharmacy, Gazi University, 06330 Ankara, Turkey
| | - Maria Daglia
- Department of Drug Sciences, Medicinal Chemistry and Pharmaceutical Technology Section, University of Pavia, Italy
| | - Ramona Barbieri
- Microbiology Unit, IRCCS-San Martino-IST and DISC, University of Genoa, Italy
| | - Arianna Di Lorenzo
- Department of Drug Sciences, Medicinal Chemistry and Pharmaceutical Technology Section, University of Pavia, Italy
| | - Seyed Fazel Nabavi
- Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Olga Gortzi
- Department of Food Technology, Technological Educational Institution of Thessaly, Terma N. Temponera Str., Greece
| | - Morteza Izadi
- Health Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Seyed Mohammad Nabavi
- Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
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58
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Phase behavior, microstructural transition, antimicrobial and antioxidant activities of a water-dilutable thymol microemulsion. Colloids Surf B Biointerfaces 2015; 136:859-66. [DOI: 10.1016/j.colsurfb.2015.10.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 09/15/2015] [Accepted: 10/20/2015] [Indexed: 11/23/2022]
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59
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Bhargava K, Conti DS, da Rocha SRP, Zhang Y. Application of an oregano oil nanoemulsion to the control of foodborne bacteria on fresh lettuce. Food Microbiol 2015; 47:69-73. [PMID: 25583339 DOI: 10.1016/j.fm.2014.11.007] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/11/2014] [Accepted: 11/18/2014] [Indexed: 11/25/2022]
Abstract
Although antimicrobial activities of plant essential oils are well documented, challenges remain as to their application in fresh produce due to the hydrophobic nature of essential oils. Oregano oil nanoemulsions were formulated with a food-grade emulsifier and evaluated for their efficacy in inactivating the growth of foodborne bacteria on fresh lettuce. Lettuce was artificially inoculated with Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli O157:H7, followed by a one-minute dipping in oregano oil nanoemulsions (0.05% or 0.1%). Samples were stored at 4 °C and enumerated for bacteria at fixed intervals (0 h, 3 h, 24 h, and 72 h). Compared to control, 0.05% nanoemulsion showed an up to 3.44, 2.31, and 3.05 log CFU/g reductions in L. monocytogenes, S. Typhimurium, and E. coli O157:H7, respectively. Up to 3.57, 3.26, and 3.35 log CFU/g reductions were observed on the same bacteria by the 0.1% treatment. Scanning Electron Microscopy (SEM) demonstrated disrupted bacterial membranes due to the oregano oil treatment. The data suggest that applying oregano oil nanoemulsions to fresh produce may be an effective antimicrobial control strategy.
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Affiliation(s)
- Kanika Bhargava
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI, USA; Department of Human Environmental Sciences, University of Central Oklahoma, Edmond, OK, USA
| | - Denise S Conti
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, MI, USA
| | - Sandro R P da Rocha
- Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, MI, USA
| | - Yifan Zhang
- Department of Nutrition and Food Science, Wayne State University, Detroit, MI, USA.
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60
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Nanocapsular dispersion of cinnamaldehyde for enhanced inhibitory activity against aflatoxin production by Aspergillus flavus. Molecules 2015; 20:6022-32. [PMID: 25853318 PMCID: PMC6272766 DOI: 10.3390/molecules20046022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 01/21/2023] Open
Abstract
Cinnamaldehyde (CA) is marginally soluble in water, making it challenging to evenly disperse it in foods, and resulting in lowered anti-A. flavus efficacy. In the present study, nano-dispersed CA (nano-CA) was prepared to increase its aqueous solubility. Free and nano-dispersed CA were compared in terms of their inhibitory activity against fungal growth and aflatoxin production of A. flavus both in Sabouraud Dextrose (SD) culture and in peanut butter. Our results indicated that free CA inhibited the mycelia growth and aflatoxin production of A. flavus with a minimal inhibitory concentration (MIC) value of 1.0 mM, but promoted the aflatoxin production at some concentrations lower than the MIC. Nano-CA had a lower MIC value of 0.8 mM against A. flavus, and also showed improved activity against aflatoxin production without the promotion at lower dose. The solidity of peanut butter had an adverse impact on the antifungal activity of free CA, whereas nano-dispersed CA showed more than 2-fold improved activity against the growth of A. flavus. Free CA still promoted AFB1 production at the concentration of 0.25 mM, whereas nano-CA showed more efficient inhibition of AFB1 production in the butter.
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61
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Chaftar N, Girardot M, Labanowski J, Ghrairi T, Hani K, Frère J, Imbert C. Comparative evaluation of the antimicrobial activity of 19 essential oils. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 901:1-15. [DOI: 10.1007/5584_2015_5011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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62
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Physical and antimicrobial properties of spray-dried zein–casein nanocapsules with co-encapsulated eugenol and thymol. J FOOD ENG 2015. [DOI: 10.1016/j.jfoodeng.2014.07.021] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Chen H, Davidson PM, Zhong Q. Antimicrobial properties of nisin after glycation with lactose, maltodextrin and dextran and the thyme oil emulsions prepared thereof. Int J Food Microbiol 2014; 191:75-81. [PMID: 25240139 DOI: 10.1016/j.ijfoodmicro.2014.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 08/27/2014] [Accepted: 09/06/2014] [Indexed: 11/17/2022]
Abstract
To clarify the reported conflicting antimicrobial activities of nisin after glycation, nisin was glycated with lactose, maltodextrin, and dextran at 70 °C and 50% relative humidity for 1-24 h. Nisin before and after glycation was studied for the first time to prepare thyme oil emulsions. The activity of glycated nisin and the thyme oil emulsions was tested in both tryptic soy broth (TSB) and 2% reduced fat milk. Results showed that nisin glycated with a smaller saccharide for a longer duration had a higher degree of glycation and the reduced number of positive charges lowered its antibacterial activity. The emulsified thyme oil had an additive effect with either glycated or native nisin against Listeria monocytogenes Scott A and Bacillus subtilis in TSB and 2% reduced fat milk. However, emulsions were less effective against L. monocytogenes Scott A in milk than same units of native nisin and same concentration of free thyme oil, likely due to the reduced availability of thymol and carvacrol, the main components of thyme oil. These results showed that glycation of nisin cannot broaden its antimicrobial activity and nisin is not a good compound to prepare emulsions of essential oils.
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Affiliation(s)
- Huaiqiong Chen
- Department of Food Science and Technology, University of Tennessee, Knoxville, United States
| | - P Michael Davidson
- Department of Food Science and Technology, University of Tennessee, Knoxville, United States
| | - Qixin Zhong
- Department of Food Science and Technology, University of Tennessee, Knoxville, United States.
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65
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Wu JE, Lin J, Zhong Q. Physical and antimicrobial characteristics of thyme oil emulsified with soluble soybean polysaccharide. Food Hydrocoll 2014. [DOI: 10.1016/j.foodhyd.2013.12.029] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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66
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Xue J, Zhong Q. Blending lecithin and gelatin improves the formation of thymol nanodispersions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:2956-2962. [PMID: 24627984 DOI: 10.1021/jf405828s] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Delivery systems of lipophilic antimicrobials such as thymol prepared with generally recognized-as-safe ingredients are needed to enhance the microbiological safety of low-acid (pH > 4.6) foods. Nanodispersions with particle diameters below 100 nm are particularly demanded because of the low turbidity and physical stability. In this study, thymol dispersions were prepared by gelatin and soy lecithin on an individual basis or in combination. Dispersions prepared with the lecithin-gelatin blend were translucent and stable at pH 5.0-8.0, contrasting with turbid and unstable dispersions when the emulsifiers were used individually. The synergistic surface activity of gelatin and lecithin was due to complex formation that effectively prevented particle size change due to coalescence and Ostwald ripening. Electrostatic interactions were observed to be the colloidal force responsible for preventing particle aggregation. The studied generally recognized-as-safe nanodispersions have great potential to deliver lipophilic antimicrobials such as thymol in low-acid foods to enhance food safety.
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Affiliation(s)
- Jia Xue
- Department of Food Science and Technology, University of Tennessee , Knoxville, Tennessee 37996, United States
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67
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Pan K, Chen H, Davidson PM, Zhong Q. Thymol nanoencapsulated by sodium caseinate: physical and antilisterial properties. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:1649-1657. [PMID: 24484459 DOI: 10.1021/jf4055402] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this work, thymol was encapsulated in sodium caseinate using high shear homogenization. The transparent dispersion at neutral pH was stable for 30 days at room temperature as determined by dynamic light scattering and atomic force microscopy, which agreed with high ζ potential of nanoparticles. The slightly decreased particle dimension during storage indicates the absence of Ostwald ripening. When molecular binding was studied by fluorescence spectroscopy, thymol was observed to bind with tyrosine and possibly other amino acid residues away from tryptophan of caseins. At pH 4.6 (isoelectric point of caseins), the stabilization of thymol nanoparticles against aggregation was enabled by soluble soybean polysaccharide, resulting from the combined electrostatic and steric repulsions. The encapsulated thymol showed the significantly improved antilisterial activity in milk with different fat levels when compared to thymol crystals, resulting from the quicker mixing and increased solubility in the milk serum. The transparent thymol nanodispersions have promising applications to improve microbiological safety and quality of foods.
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Affiliation(s)
- Kang Pan
- Department of Food Science and Technology, The University of Tennessee , 2510 River Drive, Knoxville, Tennessee 37996-4539, United States
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68
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Chen H, Davidson PM, Zhong Q. Impacts of sample preparation methods on solubility and antilisterial characteristics of essential oil components in milk. Appl Environ Microbiol 2014; 80:907-16. [PMID: 24271170 PMCID: PMC3911218 DOI: 10.1128/aem.03010-13] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 11/14/2013] [Indexed: 11/20/2022] Open
Abstract
Essential oil components (EOCs) have limited water solubility and are used at much higher concentrations in complex food matrices than in growth media to inhibit pathogens. However, the correlation between solubility and activity has not been studied. The objective of this work was to characterize the solubility of EOCs in solvents and milk and correlate solubility with antilisterial activity. The solubilities of four EOCs, thymol, carvacrol, eugenol, and trans-cinnamaldehyde, in water was significantly increased in the presence of 5% (vol/vol) ethanol. In milk, the solubility of EOCs was lower than in water, with lower solubility in higher-fat milk. EOCs applied to milk as stock solutions (in 95% aqueous ethanol) enabled quicker dissolution and higher solubility in milk serum than other methods of mixing, such as end to end, and greater reductions of Listeria monocytogenes Scott A after 0 and 24 h. When the EOC concentration detected in milk serum was above the minimum bactericidal concentration, complete inhibition of L. monocytogenes in tryptic soy broth resulted. Therefore, the antilisterial properties in milk could be correlated with the solubility by comparison to the minimum inhibitory or bactericidal concentrations of EOCs. While the EOCs applied using ethanol generally had solubility and activity characteristics superior to those of other mixing methods, ethanol is not used to a great extent in nonfermented foods. Therefore, mixing methods without an organic solvent may be more readily adaptable to enhancing the distribution of EOCs in complex food systems.
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Affiliation(s)
- Huaiqiong Chen
- Department of Food Science and Technology, University of Tennessee, Knoxville, Tennessee, USA
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69
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Xue J, Davidson PM, Zhong Q. Thymol nanoemulsified by whey protein-maltodextrin conjugates: the enhanced emulsifying capacity and antilisterial properties in milk by propylene glycol. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:12720-6. [PMID: 24328082 DOI: 10.1021/jf4043437] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The objective of this research was to enhance the capability of whey protein isolate-maltodextrin conjugates in nanoemulsifying thymol using propylene glycol to improve antilisterial properties in milk. Thymol was predissolved in PG and emulsified in 7% conjugate solution. Transparent dispersions with mean diameters of <30 nm were observed up to 1.5%w/v thymol. In skim and 2% reduced fat milk, Listeria monocytogenes Scott A was reduced from ∼5 log CFU/mL to below the detection limit in 6 h by 0.1% w/v and 0.45% w/v nanoemulsified thymol, respectively, contrasting with gradual reductions to 1.15 and 2.26 log CFU/mL after 48 h by same levels of free thymol. In full fat milk, L. monocytogenes was gradually reduced to be undetectable after 48 h by 0.6% w/v nanoemulsified thymol, contrasting with the insignificant reduction by free thymol. The improved antilisterial activities of nanoemulsified thymol resulted from the increased solubility in milk and synergistic activity with propylene glycol.
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Affiliation(s)
- Jia Xue
- Department of Food Science and Technology, University of Tennessee , 2510 River Drive, Knoxville, Tennessee 37996, United States
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Shah B, Davidson PM, Zhong Q. Antimicrobial activity of nanodispersed thymol in tryptic soy broth. J Food Prot 2013; 76:440-7. [PMID: 23462081 DOI: 10.4315/0362-028x.jfp-12-354] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Food safety is a continuing challenge for the food industry due to sporadic illness outbreaks caused by foodborne pathogens. Plant essential oils have been studied extensively as natural antimicrobials to control foodborne pathogens. However, their hydrophobic nature makes application in foods difficult because of their low water solubility, adverse impact on sensory quality, and binding with food components, which can interfere with antimicrobial efficacy. The objective of this study was to characterize antimicrobial activities of transparent nanodispersions of thymol encapsulated in whey protein isolate-maltodextrin conjugates, with comparison to free thymol. Tests were conducted for Escherichia coli O157:H7 strains ATCC 43889 and 43894, Salmonella Typhimurium strain 2576, Listeria monocytogenes strains Scott A and 101, and Staphylococcus aureus strains 27708 and SA113 in tryptic soy broth at various pHs and temperatures. Results indicate that the MIC for nanodispersed and free thymol against all strains of both gram-negative and gram-positive pathogens tested was 500 ppm at pH 6.8 and at the optimal growth temperature, with the exception of E. coli O157:H7 and L. monocytogenes strain Scott A, which were inhibited by 300 ppm of free thymol. Nanodispersed thymol was further tested at 500 ppm for inhibition of E. coli O157:H7 and L. monocytogenes at 35, 32, 25, and 4°C in tryptic soy broth adjusted to pH 5.5 and 3.5. At pH 5.5, L. monocytogenes was completely inhibited after 3 h, and E. coli O157:H7 showed a reduction of 1.0 to 3.0 log CFU/ml after 48 h. At pH 3.5, L. monocytogenes controls did not grow, but E. coli O157:H7 survived. At both pH 5.5 and 3.5, no significant effect of temperature on antimicrobial activity was observed at 500 mg/ml nanodispersed thymol. The present study demonstrated that transparent nanodispersions of thymol have promising antimicrobial activity against a broad spectrum of foodborne pathogens.
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Affiliation(s)
- Bhavini Shah
- Department of Food Science and Technology, University of Tennessee, 2605 River Drive, Knoxville, Tennessee 37996-4591, USA
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