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Ge Y, Yu X, Zhao X, Liu C, Li T, Mu S, Zhang L, Chen Z, Zhang Z, Song Z, Zhao H, Yao S, Zhang B. Fermentation characteristics and postacidification of yogurt by Streptococcus thermophilus CICC 6038 and Lactobacillus delbrueckii ssp. bulgaricus CICC 6047 at optimal inoculum ratio. J Dairy Sci 2024; 107:123-140. [PMID: 37641256 DOI: 10.3168/jds.2023-23817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023]
Abstract
This study aimed to investigate the symbiosis between Streptococcus thermophilus CICC 6038 and Lactobacillus delbrueckii ssp. bulgaricus CICC 6047. In addition, the effect of their different inoculum ratios was determined, and comparison experiments of fermentation characteristics and storage stability of milk fermented by their monocultures and cocultures at optimal inoculum ratio were performed. We found the time to obtain pH 4.6 and ΔpH during storage varied among 6 inoculum ratios (1:1, 2:1, 10:1, 19:1, 50:1, 100:1). By the statistical model to evaluate the optimal ratio, the ratio of 19:1 was selected, which exhibited high acidification rate and low postacidification with pH values remaining between 4.2 and 4.4 after a 50-d storage. Among the 3 groups included in our analyses (i.e., the monocultures of S. thermophilus CICC 6038 [St] and Lb. bulgaricus CICC 6047 [Lb] and their cocultures [St+Lb] at 19:1), the coculture group showed higher acidification activity, improved rheological properties, richer typical volatile compounds, more desirable sensor quality after the fermentation process than the other 2 groups. However, the continuous accumulation of acetic acid during storage showed that acetic acid was more highly correlated with postacidification than d-lactic acid for the Lb group and St+Lb group. Our study emphasized the importance of selecting an appropriate bacterial consortium at the optimal inoculum ratio to achieve favorable fermentation performance and enhanced postacidification stability during storage.
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Affiliation(s)
- Yuanyuan Ge
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China; China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Xuejian Yu
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Xiaoxin Zhao
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Chong Liu
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Ting Li
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Shuaicheng Mu
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Lu Zhang
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Zhuoran Chen
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Zhe Zhang
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Zhiquan Song
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China
| | - Hongfei Zhao
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Su Yao
- China National Research Institute of Food and Fermentation Industries Co. Ltd., China Center of Industrial Culture Collection, Beijing 100015, China.
| | - Bolin Zhang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China.
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Wang A, Zhong Q. Drying of probiotics to enhance the viability during preparation, storage, food application, and digestion: A review. Compr Rev Food Sci Food Saf 2024; 23:e13287. [PMID: 38284583 DOI: 10.1111/1541-4337.13287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 11/18/2023] [Accepted: 12/11/2023] [Indexed: 01/30/2024]
Abstract
Functional food products containing viable probiotics have become increasingly popular and demand for probiotic ingredients that maintain viability and stability during processing, storage, and gastrointestinal digestions. This has resulted in heightened research and development of powdered probiotic ingredients. The aim of this review is to overview the development of dried probiotics from upstream identification to downstream applications in food. Free probiotic bacteria are susceptible to various environmental stresses during food processing, storage, and after ingestion, necessitating additional materials and processes to preserve their activity for delivery to the colon. Various classic and emerging thermal and nonthermal drying technologies are discussed for their efficiency in preparing dehydrated probiotics, and strategies for enhancing probiotic survival after dehydration are highlighted. Both the formulation and drying technology can influence the microbiological and physical properties of powdered probiotics that are to be characterized comprehensively with various techniques. Furthermore, quality control during probiotic manufacturing and strategies of incorporating powdered probiotics into liquid and solid food products are discussed. As emerging technologies, structure-design principles to encapsulate probiotics in engineered structures and protective materials with improved survivability are highlighted. Overall, this review provides insights into formulations and drying technologies required to supplement viable and stable probiotics into functional foods, ensuring the retention of their health benefits upon consumption.
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Affiliation(s)
- Anyi Wang
- Department of Food Science, University of Tennessee, Knoxville, Tennessee, USA
- International Flavors and Fragrances, Palo Alto, California, USA
| | - Qixin Zhong
- Department of Food Science, University of Tennessee, Knoxville, Tennessee, USA
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Khan A, Nadeem M, Al-Asmari F, Imran M, Ambreen S, Rahim MA, Oranab S, Esatbeyoglu T, Bartkiene E, Rocha JM. Effect of Lactiplantibacillus plantarum on the Conversion of Linoleic Acid of Vegetable Oil to Conjugated Linoleic Acid, Lipolysis, and Sensory Properties of Cheddar Cheese. Microorganisms 2023; 11:2613. [PMID: 37894271 PMCID: PMC10609100 DOI: 10.3390/microorganisms11102613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023] Open
Abstract
Conjugated linoleic acid (CLA) is perceived to protect the body from metabolic diseases. This study was conducted to determine the effect of Lactiplantibacillus plantarum (Lp. plantarum) on CLA production and sensory characteristics of cheddar cheese. Lp. plantarum can convert linoleic acid (LA) to CLA. To increase CLA in cheddar cheese and monitor the conversion of LA to CLA by Lp. plantarum, the LA content of cheese milk (3.4% fat) was increased by partially replacing fat with safflower oil (85% LA of oil) at 0, 3, 6, and 9% concentrations (T1, T2, T3, and T4). Furthermore, Lp. plantarum 108 colony-forming units (CFU)/mL (8 log CFU mL-1) was added in all treatments along with traditional cheddar cheese culture (Lactococcus lactis ssp. lactis and L. lactis ssp. cremoris). After 30 days of ripening, Lp. plantarum in T1, T2, T3, and T4 was 6.75, 6.72, 6.65, and 6.55 log CFU g-1. After 60 days of ripening, Lp. plantarum in T1, T2, T3, and T4 was 6.35, 6.27, 6.19, and 6.32 log CFU g-1. After 60 days of ripening, Lp. plantarum in T1, T2, T3, and T4 was 6.41, 6.25, 6.69, and 6.65 log CFU g-1. GC-MS analysis showed that concentrations of CLA in the 90 days' control, T1, T2, T3, and T4 were 1.18, 2.73, 4.44, 6.24, and 9.57 mg/100 g, respectively. HPLC analysis revealed that treatments containing Lp. plantarum and LA presented higher concentrations of organic acids than the control sample. The addition of safflower oil at all concentrations did not affect cheese composition, free fatty acids (FFA), and the peroxide value (POV) of cheddar cheese. Color flavor and texture scores of experimental cheeses were not different from the control cheese. It was concluded that Lp. plantarum and safflower oil can be used to increase CLA production in cheddar cheese.
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Affiliation(s)
- Awais Khan
- Department of Dairy Technology, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan; (A.K.); (M.N.)
| | - Muhammad Nadeem
- Department of Dairy Technology, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan; (A.K.); (M.N.)
| | - Fahad Al-Asmari
- Department of Food and Nutrition Sciences, College of Agricultural and Food Sciences, King Faisal University, Al-Ahsa 31982, Saudi Arabia;
| | - Muhammad Imran
- Department of Food Science, Faculty of Life Sciences, Government College University, Faisalabad 38000, Pakistan;
| | - Saadia Ambreen
- University Institute of Food Science and Technology, The University of Lahore, Lahore 54590, Pakistan;
| | - Muhammad Abdul Rahim
- Department of Food Science, Faculty of Life Sciences, Government College University, Faisalabad 38000, Pakistan;
- Department of Food Science and Nutrition, Faculty of Medicine and Allied Health Sciences, Times Institute, Multan 60700, Pakistan
| | - Sadaf Oranab
- Department of Biochemistry, Faculty of Life Sciences, Government College University, Faisalabad 38000, Pakistan;
| | - Tuba Esatbeyoglu
- Department of Food Development and Food Quality, Institute of Food Science and Human Nutrition, Gottfried Wilhelm Leibniz University Hannover, Am Kleinen Felde 30, 30167 Hannover, Germany;
| | - Elena Bartkiene
- Department of Food Safety and Quality, Veterinary Academy, Lithuanian University of Health Sciences, Tilzes Str. 18, LT-47181 Kaunas, Lithuania;
- Institute of Animal Rearing Technologies, Faculty of Animal Sciences, Lithuanian University of Health Sciences, Tilzes Str. 18, LT-47181 Kaunas, Lithuania
| | - João Miguel Rocha
- Universidade Católica Portuguesa, CBQF—Centro de Biotecnologia e Química Fina—Laboratório Associado, Escola Superior de Biotecnologia, Rua Diogo Botelho 1327, 4169-005 Porto, Portugal
- LEPABE—Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal
- ALiCE—Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal
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Mousavi M, Gharekhani M, Alirezalu K, Roufegarinejad L, Azadmard‐Damirchi S. Production and characterization of nondairy gluten-free fermented beverage based on buckwheat and lentil. Food Sci Nutr 2023; 11:2197-2210. [PMID: 37181300 PMCID: PMC10171538 DOI: 10.1002/fsn3.3095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 09/20/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022] Open
Abstract
The present study aimed to optimize the formulation of buckwheat/lentil gluten-free beverages fermented with Lactobacillus plantarum and Bifidobacterium bifidum. Physicochemical parameters of 14 different beverages, such as pH, acidity, total solids, ash, total phenol content, antioxidant activity, and sensory test, were assessed after 24 h of fermentation. The results showed that the numbers of viable cells of lactobacilli and bifidobacteria on the first day of the experiment were 9.9 and 9.6 log (CFU ml-1), respectively, which were over 9 log (CFU ml-1). During 24 h from the fermentation, the number of viable cells for all beverages decreased, which reached an average probiotic count of 8.81 log (CFU ml-1) that was statistically significantly different from the probiotic count before fermentation (p < .05). Cell viability was evaluated and shelf life was estimated during 15-day refrigerated storage. At the end of the storage (15th day), the beverages contained an average of 8.4 log (CFU ml-1) of live lactobacilli cells and 7.8 log (CFU ml-1) of viable bifidobacterial cells. The optimized levels of independent factors for sprouted buckwheat and lentil flours were 51.96% and 48.04%, respectively. The optimized probiotic beverage was contained 0.25 (% lactic acid) acidity, 5.7 pH, 7.9% total solids, 0.4% ash, 41.02% DPPH, 26.96 (mg GAE/ml) phenol compounds, and 8.65 log (CFU ml-1) probiotic count. The optimized beverage had distinct organoleptic properties on day 15 of refrigerated storage. This study showed that Bifidobacterium bifidum can be used for the development of potentially probiotic beverage with sprouted buckwheat and lentil.
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Affiliation(s)
- Mir‐Hossein Mousavi
- Department of Food Science and TechnologyTabriz Branch, Islamic Azad UniversityTabrizIran
| | - Mehdi Gharekhani
- Department of Food Science and TechnologyTabriz Branch, Islamic Azad UniversityTabrizIran
| | - Kazem Alirezalu
- Department of Food Science and Technology, Ahar Faculty of Agriculture and Natural RecoursesUniversity of TabrizTabrizIran
| | - Leila Roufegarinejad
- Department of Food Science and TechnologyTabriz Branch, Islamic Azad UniversityTabrizIran
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Molecular Detection and Identification of Plant-Associated Lactiplantibacillus plantarum. Int J Mol Sci 2023; 24:ijms24054853. [PMID: 36902287 PMCID: PMC10003612 DOI: 10.3390/ijms24054853] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Lactiplantibacillus plantarum is a lactic acid bacterium often isolated from a wide variety of niches. Its ubiquity can be explained by a large, flexible genome that helps it adapt to different habitats. The consequence of this is great strain diversity, which may make their identification difficult. Accordingly, this review provides an overview of molecular techniques, both culture-dependent, and culture-independent, currently used to detect and identify L. plantarum. Some of the techniques described can also be applied to the analysis of other lactic acid bacteria.
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Microbiological, morpho-textural, and volatile characterization of Portuguese Queijo de Nisa PDO cheese. Food Res Int 2022; 162:112011. [DOI: 10.1016/j.foodres.2022.112011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 11/17/2022]
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Bulut M, Çelebi Sezer Y, Ceylan MM, Alwazeer D, Koyuncu M. Hydrogen-rich water can reduce the formation of biogenic amines in butter. Food Chem 2022; 384:132613. [DOI: 10.1016/j.foodchem.2022.132613] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/28/2022] [Accepted: 02/28/2022] [Indexed: 12/24/2022]
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Guo Q, Li S, Tang J, Chang S, Qiang L, Du G, Yue T, Yuan Y. Microencapsulation of Lactobacillus plantarum by spray drying: Protective effects during simulated food processing, gastrointestinal conditions, and in kefir. Int J Biol Macromol 2022; 194:539-545. [PMID: 34808148 DOI: 10.1016/j.ijbiomac.2021.11.096] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/08/2021] [Accepted: 11/14/2021] [Indexed: 01/07/2023]
Abstract
Probiotics are incorporated into food products because of numerous favorable effects on human health. The viability of probiotics is often affected by unfavorable interference during processing. The encapsulation can provide protection to probiotics during mechanical processing, storage, and gastrointestinal digestion. This study aimed to evaluate the protective effect of whey protein isolate (WPI) and dextran (DX) conjugates for Lactobacillus plantarum. The WPI-DX conjugate was prepared by Maillard-based glycation and confirmed by gel electrophoresis. Extending the heating time from 1 to 5 h decreased the content of tryptophan residues and increased the amide I and amide II bands. The enhanced protective ability of Maillard reaction products (MRPs) for L. plantarum was observed under conditions of stress (pH, heat, and salt) and in vitro digestion. In situ viability tests showed that encapsulation improved the survival of bacteria in kefir during 15 days of storage at 4 °C. Overall, our results provide valuable information for the development of functional probiotic food products.
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Affiliation(s)
- Qi Guo
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China
| | - Shidong Li
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China
| | - Jiaxin Tang
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China
| | - Shuaidan Chang
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China
| | - Liyue Qiang
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China
| | - Gengan Du
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China
| | - Tianli Yue
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China; College of Food Science and Techonology, Northwest University, Xi'an, 710069, China
| | - Yahong Yuan
- College of Food Science and Engineering, Northwest A & F University, Yangling 712100, China; Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of Agriculture, Yangling, 712100, China.
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Jouki M, Khazaei N, Rezaei F, Taghavian-Saeid R. Production of synbiotic freeze-dried yoghurt powder using microencapsulation and cryopreservation of L. plantarum in alginate-skim milk microcapsules. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105133] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Wu Y, Li S, Tao Y, Li D, Han Y, Show PL, Wen G, Zhou J. Fermentation of blueberry and blackberry juices using Lactobacillus plantarum, Streptococcus thermophilus and Bifidobacterium bifidum: Growth of probiotics, metabolism of phenolics, antioxidant capacity in vitro and sensory evaluation. Food Chem 2021; 348:129083. [PMID: 33517000 DOI: 10.1016/j.foodchem.2021.129083] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/04/2021] [Accepted: 01/07/2021] [Indexed: 11/18/2022]
Abstract
In this study, three potential probiotic strains were selected to ferment blueberry and blackberry juices. The viable cell counts of selected strains were increased by 0.4-0.7 log CFU/mL in berry juices environments after 48-h fermentation. Meanwhile, the contents of cyanindin-3-glucoside and peonidin-3-glucoside decreased over 30%. Heatmap presented an upgrade trend of syringic acid, ferulic acid, gallic acid and lactic acid during fermentation. However, the contents of p-coumaric acid, protocatechuic acid, chlorogenic acid, critic acid and malic acid showed downgrade trend. The metabolism of phenolics probably contributed to the enhancement of the ABTS radical scavenging activity (40%-60%) in fermented berry juices. Moreover, the three strains presented different capacities on changing the quality of berry juices according to the PCA and LDA analysis. The contents of individual organic acids had positive correlations with sensory quality, especially for sourness. Overall, probiotic fermentation could improve the sensory quality of berry juices.
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Affiliation(s)
- Yue Wu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Sujin Li
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Yang Tao
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
| | - Dandan Li
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Yongbin Han
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
| | - Pau Loke Show
- Department of Chemical and Environmental Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, 43500 Semenyih, Selangor, Malaysia
| | - Guangzhong Wen
- Majiang Postgraduate Working Station, Majiang, Guizhou 557600, China
| | - Jianzhong Zhou
- Institute of Agro-product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
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Effect of manganese sulfate and vitamin B12 on the properties of physicochemical, textural, sensory and bacterial growth of set yogurt. JOURNAL OF FOOD MEASUREMENT AND CHARACTERIZATION 2020. [DOI: 10.1007/s11694-020-00720-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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12
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Nero LA, de Freitas CF, Flores Carvalho LMV, Constantino C. 3M Petrifilm Lactic Acid Bacteria Count Plate Is a Reliable Tool for Enumerating Lactic Acid Bacteria in Bacon. J Food Prot 2020; 83:1757-1763. [PMID: 32421789 DOI: 10.4315/jfp-20-155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/15/2020] [Indexed: 12/25/2022]
Abstract
ABSTRACT This study aimed to evaluate the behavior of Petrifilm Lactic Acid Bacteria Count Plates (PLAB) as an alternative methodology to enumerate lactic acid bacteria (LAB) in bacon. Bacon samples (n = 40) were obtained from retail sale, 10-fold diluted with buffered peptone water (BPW, 0.2% [w/v]) and Letheen broth, and subjected to LAB enumeration according to four protocols: (i) de Man Rogosa Sharpe (MRS) agar, pH 5.7, 30°C; (ii) MRS, pH 5.7, 30°C, anaerobiosis; (iii) all-purpose Tween agar (APT), 25°C; and (iv) PLAB, 30°C. Colonies were enumerated at 24, 48, and 72 h, and the results expressed as log CFU per gram for comparison by analysis of variance and regression (P < 0.05). Furthermore, colonies were randomly selected and characterized as LAB (Gram staining and catalase). Mean LAB counts from MRS and PLAB did not present significant differences independently of incubation time or diluent (P > 0.05), whereas counts in APT with BPW after 24 h were significantly lower (P < 0.05). PLAB counts with BPW (24, 48, and 72 h) presented significant correlation with MRS (r ranging from 0.87 to 0.89; in anaerobiosis, r ranging from 0.94 to 0.95) and APT (r ranging from 0.84 to 0.86). With Letheen broth, PLAB (24, 48, and 72 h) presented significant correlation with MRS (r ranging from 0.92 to 0.94; in anaerobiosis, r ranging from 0.93 to 0.96) and APT (r ranging from 0.77 to 0.79). In total, 1,032 colonies (97%) from 1,063 colonies were characterized as LAB. Thus, PLAB can be considered as an alternative tool for enumerating LAB in bacon, with reliable results even after 24 h of incubation. HIGHLIGHTS
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Affiliation(s)
- LuÍs Augusto Nero
- Laboratório de Inspeção de Produtos de Origem Animal, Universidade Federal de Viçosa, Departamento de Veterinária, Campus Viçosa, Centro, 36570-900 Viçosa, Minas Gerais, Brazil (ORCID: https://orcid.org/0000-0002-4954-5824 [L.A.N.])
| | - Caio Fialho de Freitas
- Laboratório de Inspeção de Produtos de Origem Animal, Universidade Federal de Viçosa, Departamento de Veterinária, Campus Viçosa, Centro, 36570-900 Viçosa, Minas Gerais, Brazil (ORCID: https://orcid.org/0000-0002-4954-5824 [L.A.N.])
| | - Lara Maria Vieira Flores Carvalho
- Laboratório de Inspeção de Produtos de Origem Animal, Universidade Federal de Viçosa, Departamento de Veterinária, Campus Viçosa, Centro, 36570-900 Viçosa, Minas Gerais, Brazil (ORCID: https://orcid.org/0000-0002-4954-5824 [L.A.N.])
| | - Cristina Constantino
- 3M Food Safety, 3M do Brasil, Via Anhanguera, s/n - Nova Veneza, 13181-900 Sumaré, São Paulo, Brazil
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Fricke C, Harms H, Maskow T. Rapid Calorimetric Detection of Bacterial Contamination: Influence of the Cultivation Technique. Front Microbiol 2019; 10:2530. [PMID: 31736935 PMCID: PMC6838224 DOI: 10.3389/fmicb.2019.02530] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/21/2019] [Indexed: 11/13/2022] Open
Abstract
Modern isothermal microcalorimeters (IMC) are able to detect the metabolic heat of bacteria with an accuracy sufficient to recognize even the smallest traces of bacterial contamination of water, food, and medical samples. The modern IMC techniques are often superior to conventional detection methods in terms of the detection time, reliability, labor, and technical effort. What is missing is a systematic analysis of the influence of the cultivation conditions on calorimetric detection. For the acceptance of IMC techniques, it is advantageous if already standardized cultivation techniques can be combined with calorimetry. Here we performed such a systematic analysis using Lactobacillus plantarum as a model bacterium. Independent of the cultivation techniques, IMC detections were much faster for high bacterial concentrations (>102 CFU⋅mL-1) than visual detections. At low bacterial concentrations (<102 CFU⋅mL-1), detection times were approximately the same. Our data demonstrate that all kinds of traditional cultivation techniques like growth on agar (GOA) or in agar (GIA), in liquid media (GL) or on agar after enrichment via membrane filtration (GF) can be combined with IMC. The order of the detection times was GF < GIA ≈ GL ≈ GOA. The observed linear relationship between the calorimetric detection times and the initial bacterial concentrations can be used to quantify the bacterial contamination. Further investigations regarding the correlation between the filling level (in mm) of the calorimetric vessel and the specific maximum heat flow (in μW⋅g-1) illustrated two completely different results for liquid and solid media. Due to the better availability of substrates and the homogeneous distribution of bacteria growing in a liquid medium, the volume-related maximum heat flow was independent on the filling level of the calorimetric vessels. However, in a solid medium, the volume-related maximum heat flow approached a threshold and achieved a maximum at low filling levels. This fundamentally different behavior can be explained by the spatial limitation of the growth of bacterial colonies and the reduced substrate supply due to diffusion.
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Affiliation(s)
| | | | - Thomas Maskow
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
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