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Gélébart P, Riaublanc A, Famelart MH, Jonchère C, Beaumal V, Anton M, Garnier C. Protein aggregates modulate the texture of emulsified and acidified acid milk gels. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Liu H, Grosvenor AJ, Li X, Wang XL, Ma Y, Clerens S, Dyer JM, Day L. Changes in Milk Protein Interactions and Associated Molecular Modification Resulting from Thermal Treatments and Storage. J Food Sci 2019; 84:1737-1745. [PMID: 31225661 DOI: 10.1111/1750-3841.14663] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 04/29/2019] [Accepted: 04/29/2019] [Indexed: 11/30/2022]
Abstract
We investigated protein modifications that occur during short- and long-term storage of raw, pasteurized, and ultra-high-temperature processed (UHT) milks using RE-HPLC and redox proteomics. The RE-HPLC results show that casein dissociation and whey protein/κ-casein association occurred in both pasteurized and UHT milk. The extent of protein interactions was more pronounced in UHT milk after storage. The redox proteomics analyses show that primary structural level protein modifications were not correlated to processing type on the of day processing but did occur and increase during storage. Methionine oxidation was the most significant type of oxidative modification in all samples, particularly in the caseins. Methionine oxidation increased in the UHT-treated milk samples with longer storage times, especially in the micelle-phase proteins, likely due to the increasing exposure of these proteins as they migrated to the serum phase. Glycated and lactosylated early-stage Maillard reaction products were also found after heat treatment, particularly in UHT-treated milk, with the levels of these products maintained and generally increased with increasing storage time. PRACTICAL APPLICATION: Understanding changes in protein modification during heat processing and storage of liquid milk products may help develop a model to predict the quality and shelf-life stability of heat treated milk products.
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Affiliation(s)
- Haiyan Liu
- School of Chemical Engineering and Technology, Harbin Inst. of Technology, Harbin, Heilongjiang, 150090, China.,New Hope Dairy Ltd., Chengdu, Sichuan, 610063, China
| | - Anita J Grosvenor
- Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln, Canterbury, New Zealand
| | - Xing Li
- School of Chemical Engineering and Technology, Harbin Inst. of Technology, Harbin, Heilongjiang, 150090, China.,Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln, Canterbury, New Zealand
| | - Xin-Lu Wang
- New Hope Dairy Ltd., Chengdu, Sichuan, 610063, China
| | - Ying Ma
- School of Chemical Engineering and Technology, Harbin Inst. of Technology, Harbin, Heilongjiang, 150090, China
| | - Stefan Clerens
- Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln, Canterbury, New Zealand.,Biomolecular Interaction Centre, Univ. of Canterbury, Christchurch, New Zealand
| | - Jolon M Dyer
- Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln, Canterbury, New Zealand.,Biomolecular Interaction Centre, Univ. of Canterbury, Christchurch, New Zealand.,Riddet Inst., based at Massey Univ., Palmerston North, New Zealand.,Wine, Food & Molecular Biosciences, Lincoln Univ., Lincoln, Canterbury, New Zealand
| | - Li Day
- School of Chemical Engineering and Technology, Harbin Inst. of Technology, Harbin, Heilongjiang, 150090, China.,AgResearch Ltd, Grasslands Research Centre, Tennent Drive, Palmerston North, 4442, New Zealand
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Jiao C, Pang J, Shen L, Lu W, Zhang P, Liu Y, Li J, Jia X, Wang Y. A “weak acid and weak base” type fluorescent probe for sensing pH: mechanism and application in living cells. RSC Adv 2019; 9:20982-20988. [PMID: 35515522 PMCID: PMC9066030 DOI: 10.1039/c9ra03203g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 06/30/2019] [Indexed: 12/14/2022] Open
Abstract
A simple pH fluorescent probe, N-(6-morpholino-1, 3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl) isonicotinamide (NDI), based on naphthalimide as the fluorophore and isonicotinic acid hydrazide as the reaction site was synthesized and characterized. It is useful for monitoring acidic and alkaline pH. The results of pH titration indicated that NDI exhibits obvious emission enhancement with a pKa of 4.50 and linear response to small pH fluctuations within the acidic range of 3.00–6.50. Interestingly, NDI also displayed strong pH-dependent characteristics with pKa 9.34 and linearly responded to an alkaline range of 8.30–10.50. The sensing response mechanism was confirmed by 1H NMR and ESI-MS spectroscopy. The mechanism of the optical responses of NDI toward pH was also determined by density functional theory (DFT) calculations. In addition, NDI displayed a highly selective and sensitive response to hydrogen ions and hydroxyl ions. The probe was successfully applied to image acidic and alkaline pH value fluctuations in HeLa cells and has lysosomal targeting ability. When the probe was in the protonation process, the fluorescence intensity gradually decreased, whereas when the probe was in the deprotonation process, the fluorescence intensity gradually increased.![]()
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Affiliation(s)
- Chunpeng Jiao
- School of Medicine and Life Sciences
- University of Jinan-Shandong Academy of Medical Sciences
- Jinan 250200
- China
- Institute of Materia Medica
| | - Jingxiang Pang
- Shandong Medicinal Biotechnology Center
- Shandong Academy of Medical Sciences
- Jinan
- China
| | - Li Shen
- College of Science
- China University of Petroleum (East China)
- Qingdao
- China
- College of Chemical Engineering and Environmental Chemistry
| | - Wenjuan Lu
- School of Medicine and Life Sciences
- University of Jinan-Shandong Academy of Medical Sciences
- Jinan 250200
- China
- Institute of Materia Medica
| | - Pingping Zhang
- School of Medicine and Life Sciences
- University of Jinan-Shandong Academy of Medical Sciences
- Jinan 250200
- China
- Institute of Materia Medica
| | - Yuanyuan Liu
- School of Medicine and Life Sciences
- University of Jinan-Shandong Academy of Medical Sciences
- Jinan 250200
- China
- Institute of Materia Medica
| | - Jing Li
- School of Medicine and Life Sciences
- University of Jinan-Shandong Academy of Medical Sciences
- Jinan 250200
- China
- Institute of Materia Medica
| | - Xianhui Jia
- School of Medicine and Life Sciences
- University of Jinan-Shandong Academy of Medical Sciences
- Jinan 250200
- China
- Institute of Materia Medica
| | - Yanfeng Wang
- School of Medicine and Life Sciences
- University of Jinan-Shandong Academy of Medical Sciences
- Jinan 250200
- China
- Institute of Materia Medica
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Yang M, Zhang G, Yang J, Sun D, Wen P, Zhang W. Effect of pH on dissociation of casein micelles in yak skim milk. J Dairy Sci 2018; 101:2998-3007. [DOI: 10.3168/jds.2017-13653] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 11/26/2017] [Indexed: 11/19/2022]
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9
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Abstract
In this study, the relationship between the dissociation of κ-casein from casein micelles due to heat-induced denaturation and the strength of acid milk gel was investigated. The κ-casein-dissociated micelles were fractionated by gel filtration chromatography and two-dimensional polyacrylamide gel electrophoresis, and their zeta potential and surface hydrophobicity were measured. The negative charge of the κ-casein-dissociated micelles was lower than that of native micelles, and micellar surface hydrophobicity was higher. For confirmation, the isoelectric point of the casein micelles was measured. The κ-casein-dissociated micelles were found to cohere at an earlier stage of acidification than the native micelles. These results demonstrated that the heat-induced increase in the strength of acid milk gel was partly due to the decrease in micellar surface charge and partly to the increase in surface hydrophobicity caused by the dissociation of κ-casein.
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