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Zhang H, Goff HD, Liu C, Luo S, Hu X. Preparation of liquid yogurt in the presence of pectin and its formation mechanism. Food Chem 2024; 452:139473. [PMID: 38723564 DOI: 10.1016/j.foodchem.2024.139473] [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: 03/06/2024] [Revised: 04/20/2024] [Accepted: 04/22/2024] [Indexed: 06/01/2024]
Abstract
We had previously observed that adding pectin into milk before fermentation inhibited gelation of yogurt but did not affect the pH. Thus, this work aimed to prepare such liquid yogurt and clarify its formation mechanism. It was found that liquid yogurt was obtained in the presence of 0.10%-0.20% pectin. However, at lower or higher pectin concentrations, yogurt was gelled. Confocal laser scanning microscopy analysis demonstrated that 0.10%-0.20% pectin induced milk protein aggregating into separated particles rather than a continuous network, which explained why liquid yogurt was formed. Moreover, adding 0.10%-0.20% pectin into the casein micelle suspension induced aggregation of casein micelles at pH 6.8. After pH decreased to 4.3, casein micelles showed more aggregation but they were still separated particles, which was the same in the corresponding yogurt samples. These results suggested that pectin changed the aggregation mode of casein micelles and induced formation of liquid yogurt.
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Affiliation(s)
- Hongkai Zhang
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - H Douglas Goff
- Department of Food Science, University of Guelph, Guelph, Ontario N1G2W1, Canada
| | - Chengmei Liu
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Shunjing Luo
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Xiuting Hu
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China.
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2
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Sözeri Atik D, Öztürk Hİ, Akın N. Perspectives on the yogurt rheology. Int J Biol Macromol 2024; 263:130428. [PMID: 38403217 DOI: 10.1016/j.ijbiomac.2024.130428] [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: 11/26/2023] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
The oral processing of yogurt is a dynamic process involving a series of deformation processes. Rheological knowledge is essential to understand the structure and flow properties of yogurt in the mouth and to explore its relationship with sensory perception. Yogurt is rheologically characterized as a non-Newtonian viscoelastic material. The rheological properties of yogurt are affected by many factors, from production to consumption. Therefore, rheological measurements are widely used to predict and control the final quality and structure of yogurts. Recent studies focus on the elucidation of the effects of cultures and processes used in production, as well as the design of different formulations to improve the rheological properties of yogurts. Moreover, the science of tribology, which dominates the surface properties of interacting substances in relative motion to evaluate the structural sensation in the later stages of eating in addition to the rheological properties that give the feeling of structure in the early stages of eating, has also become the focus of recent studies. For a detailed comprehension of the rheological properties of yogurt, this review deals with the factors affecting the rheology of yogurt, analytical methods used to determine rheological properties, microstructural and rheological characterization of yogurt, and tribological evaluations.
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Affiliation(s)
- Didem Sözeri Atik
- Tekirdağ Namık Kemal University, Department of Food Engineering, Tekirdağ, Turkey; University of Wisconsin-Madison, Department of Food Science, Madison, WI, USA.
| | - Hale İnci Öztürk
- Konya Food and Agriculture University, Department of Food Engineering, Konya, Turkey
| | - Nihat Akın
- Selçuk University, Department of Food Engineering, Konya, Turkey
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3
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Shi H, Ding C, Yuan J. Effect and Mechanism of Soluble Starch on Bovine Serum Albumin Cold-Set Gel Induced by Microbial Transglutaminase: A Significantly Improved Carrier for Active Substances. Foods 2023; 12:4313. [PMID: 38231786 DOI: 10.3390/foods12234313] [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: 10/24/2023] [Revised: 11/17/2023] [Accepted: 11/25/2023] [Indexed: 01/19/2024] Open
Abstract
Soluble starch (SS) could significantly accelerate the process of bovine serum albumin (BSA) cold-set gelation by glucono-δ-lactone (GDL) and microbial transglutaminase (MTGase) coupling inducers, and enhance the mechanical properties. Hardness, WHC, loss modulus (G″) and storage modulus (G') of the gel increased significantly, along with the addition of SS, and gelation time was also shortened from 41 min (SS free) to 9 min (containing 4.0% SS); the microstructure also became more and more dense. The results from FTIR, fluorescence quenching and circular dichroism (CD) suggested that SS could bind to BSA to form their composites, and the hydrogen bond was probably the dominant force. Moreover, the ability of SS to bind the original free water in BSA gel was relatively strong, thereby indirectly increasing the concentration of BSA and improving the texture properties of the gel. The acceleration of gelling could also be attributed to the fact that SS reduced the negative charge of BSA aggregates and further promoted the rapid formation of the gel. The embedding efficiency (EE) of quercetin in BSA-SS cold-set gel increased from 68.3% (SS free) to 87.45% (containing 4.0% SS), and a controlled-released effect was detected by simulated gastrointestinal digestion tests. The work could put forward new insights into protein gelation accelerated by polysaccharide, and provide a candidate for the structural design of new products in the food and pharmaceutical fields.
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Affiliation(s)
- Haoting Shi
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), College of Bioengineering and Food, Hubei University of Technology, Wuhan 430068, China
| | - Changsheng Ding
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), College of Bioengineering and Food, Hubei University of Technology, Wuhan 430068, China
| | - Jianglan Yuan
- Cooperative Innovation Center of Industrial Fermentation (Ministry of Education & Hubei Province), College of Bioengineering and Food, Hubei University of Technology, Wuhan 430068, China
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4
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Li D, Lai M, Wang P, Ma H, Li H, Wang R, Wu X. Effects of Different Prebiotics on the Gel Properties of Milk Protein and the Structural Features of Yogurt. Gels 2023; 9:863. [PMID: 37998953 PMCID: PMC10670424 DOI: 10.3390/gels9110863] [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: 09/10/2023] [Revised: 10/21/2023] [Accepted: 10/25/2023] [Indexed: 11/25/2023] Open
Abstract
The impact of prebiotics on the structural characteristics of yogurt is an important aspect of evaluating its functional properties. This study aimed to evaluate and compare the effects of several commonly used prebiotics, including fructooligosaccharide (FOS), galactooligosaccharide (GOS), inulin (INU), polydextrose (PDX), and xylooligosaccharide (XOS), on the gel properties of milk protein and the structural features, with respect to the texture and rheology, of stirred yogurt during and after fermentation. The results revealed that the supplementation of INU, PDX, and XOS was involved in the construction of protein networks during fermentation, promoting a viscous and more elastic gel structure, due to the enhanced protein-water interactions. This resulted in a significant increase (p < 0.05) in structural stability (higher critical strain (γc) and greater thixotropy), firmness, cohesiveness, and rheology (G' and G″) and a significant decrease (p < 0.05) in the loss of yogurt during centrifugation. Conversely, the supplementation of GOS and FOS did not appear to be involved in the construction of the protein network and barely affected the rheological properties of the gel during fermentation. However, a significant increase (p < 0.05) in viscosity and firmness, and a slight decrease (p > 0.05) in loss during centrifugation were still observed in the yogurt. These findings could be useful for a comprehensive assessment of the application potential of these prebiotics in yogurt, when combined with their respective prebiotic properties.
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Affiliation(s)
- Dongdong Li
- Mengniu Hi-Tech Dairy Product Beijing Co., Ltd., Beijing 101100, China;
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Nutrition and Health, China Agricultural University, Beijing 100190, China;
| | - Mengxuan Lai
- Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Hohhot 011500, China; (M.L.); (H.M.); (H.L.)
| | - Pengjie Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Nutrition and Health, China Agricultural University, Beijing 100190, China;
| | - Hairan Ma
- Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Hohhot 011500, China; (M.L.); (H.M.); (H.L.)
| | - Hongliang Li
- Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Hohhot 011500, China; (M.L.); (H.M.); (H.L.)
| | - Ran Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Nutrition and Health, China Agricultural University, Beijing 100190, China;
| | - Xiuying Wu
- Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Hohhot 011500, China; (M.L.); (H.M.); (H.L.)
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Gao F, Li D, Li H, Chen H, Mao X, Wang P. Influence of Post-Heating Treatment on the Sensory and Textural Properties of Stirred Fermented Milk. Foods 2023; 12:3042. [PMID: 37628041 PMCID: PMC10453288 DOI: 10.3390/foods12163042] [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: 07/17/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023] Open
Abstract
The purpose of this study was to investigate the post-heating induced changes in the textural and sensory characteristics of stirred fermented milk. The textural and rheological properties of post-heating fermented milk (55-85 °C, 25 s) with respect to viscoelastic behaviors, viscosity, textural parameters, etc., were monitored, and the friction behaviors and sensory attributes were assessed. Treatments below 65 °C/25 s increased the textural properties of fermented milk such as gel strength, firmness, and viscosity, due to the moderate aggregation and increased linkages of microgels. In this case, despite the size and amount their aggregates increased (~15-~21 μm), they exhibited similar frictional behaviors and sensory attributes. However, treatments above 65 °C/25 s degraded textural properties due to excessive aggregation (~46-~63 μm), accompanied by unacceptable grainy attributes, which could be characterized by their good correlations with tribological coefficients and particle size parameters. These findings could provide an understanding of the quality formation of post-heating fermented milk and a perspective to improve the textural defects of ambient fermented milk products.
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Affiliation(s)
- Fei Gao
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China;
| | - Dongdong Li
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Nutrition and Health, China Agricultural University, Beijing 100190, China; (D.L.); (H.C.)
- Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Hohhot 011500, China;
| | - Hongliang Li
- Inner Mongolia Mengniu Dairy (Group) Co., Ltd., Hohhot 011500, China;
| | - Han Chen
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Nutrition and Health, China Agricultural University, Beijing 100190, China; (D.L.); (H.C.)
| | - Xueying Mao
- College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China;
| | - Pengjie Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Department of Nutrition and Health, China Agricultural University, Beijing 100190, China; (D.L.); (H.C.)
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Zhang H, Bian X, Luo S, Liu C, Hu X. Effect of sodium alginate on the yogurt stability was dependent on the thickening effect and interaction between casein micelles and sodium alginate. Int J Biol Macromol 2023; 235:123887. [PMID: 36870663 DOI: 10.1016/j.ijbiomac.2023.123887] [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: 12/02/2022] [Revised: 02/24/2023] [Accepted: 02/26/2023] [Indexed: 03/06/2023]
Abstract
The effect of sodium alginate (SA) on the yogurt stability and the related mechanisms were investigated. It was found that low-concentration SA (≤0.2 %) increased the yogurt stability, while high-concentration SA (≥0.3 %) decreased the yogurt stability. Sodium alginate increased the viscosity and viscoelasticity of yogurt and this effect was positively correlated with its concentration, suggesting that SA worked as the thickening agent in yogurt. However, addition of ≥0.3 % SA damaged the yogurt gel. These results suggested that interaction between milk protein and SA might play an important role in the yogurt stability besides the thickening effect. Addition of ≤0.2 % SA did not change the particle size of casein micelles. However, addition of ≥0.3 % SA induced aggregation of casein micelles and increased the size. And the aggregated casein micelles precipitated after 3 h storage. Isothermal titration calorimetry analysis showed that casein micelles and SA were thermodynamically incompatible. These results suggested that the interaction between casein micelles and SA induced aggregation and precipitation of casein micelles, which was critical in the destabilization of yogurt. In conclusion, the effect of SA on the yogurt stability was dependent on the thickening effect and the interaction between casein micelles and SA.
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Affiliation(s)
- Hongkai Zhang
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China
| | - Xiaofang Bian
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China
| | - Shunjing Luo
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China
| | - Chengmei Liu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China
| | - Xiuting Hu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China.
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7
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Effect of the Heat Exchanger Type on Stirred Yogurt Properties Formulated at Different Total Solids and Fat Contents. DAIRY 2023. [DOI: 10.3390/dairy4010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In this work stirred yogurts were produced using a technical scale pilot in which the cooling step was processed using either a tubular (THX; low shear) or a plate (PHX, high shear) heat exchanger. The aim was to determine how total solids (TS, adjusted using lactose) and fat contents (FC) impact stirred yogurt properties during storage, depending on the heat exchanger used. Using raw milk, cream, skim milk powder, and lactose, four yogurts were formulated at 16.5% TS and 4.2% proteins, with different FC (0.0, 1.3, 2.6, and 3.9%); one more control yogurt was formulated at 14% TS, 4.2% proteins, and 0.0% FC. Analyses of yogurts (firmness, viscosity, induced syneresis) were realized at days 1, 3, 7, 21, and 34 after production. The addition of lactose between the non-fat yogurt at 14 or 16.5% TS had little to no effect on stirred yogurt properties. Increasing FC reduced syneresis while increasing firmness and viscosity. The use of PHX reduced the syneresis compared to THX; however, it also tended to reduce the firmness of the yogurts with 3.9% FC.
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8
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Zhao XL, Bao YH, Guo Y, Luo JY, Jiang SL, Yang X. Effect of phenolic compounds and hydroxyl content on the physicochemical properties of pine nut oil Pickering emulsions. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2022; 102:5814-5825. [PMID: 35426140 DOI: 10.1002/jsfa.11931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 03/10/2022] [Accepted: 04/15/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND For decades, pine nut oil Pickering emulsions have been stabilized using a covalent composite of two phenolic chemicals (tannic acid, TA; and gallic acid, GA) and whey protein isolate (WPI) following alkali treatment. Based on covalent composite particles being excellent sources of high-quality stabilizers, this research explored the influence of phenolic addition and hydroxyl content on stability, rheological parameters and characterization of Pickering emulsions. RESULTS Tannic acid was more effective in reducing the average particle size of the emulsion, which decreased from 479.4 ± 2.1 nm without addition to between 187.6 ± 5.9 and 368.2 ± 16.8 nm (P < 0.05). The potential values of all the emulsions were between -30 and -50 mV (except for the gallic acid addition of 2.5 g kg-1 ). When the phenolic addition was 7.5 g kg-1 , emulsions demonstrated the best emulsification ability. Pickering emulsion stabilized by WPI-TA and WPI-GA particles were successfully generated, according to confocal laser scanning microscopy. Rheological results showed that the increase of phenolic addition contributed to larger elastic modulus (G'), viscosity modulus (G″) and viscosity of emulsions, which was beneficial to the stability of emulsions. CONCLUSION Both phenolic compounds significantly improved the physicochemical stability of the emulsions (P < 0.05) and their oxidative stability. Covalently crosslinking phenolic compounds to proteins is a better method to prepare stable emulsions. It is more prominent that TA shows a more significant improvement in emulsion stability due to the number of hydroxyl groups it can provide. This research might serve as a theoretical foundation for enhancing the quality of pine nut oil-related products. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Xin-Lei Zhao
- College of Forestry, Northeast Forestry University, Harbin, PR China
| | - Yi-Hong Bao
- College of Forestry, Northeast Forestry University, Harbin, PR China
- College of Forestry, Heilongjiang Key Laboratory of Forest Food Resources Utilization, Harbin, PR China
| | - Yang Guo
- College of Forestry, Northeast Forestry University, Harbin, PR China
| | - Jia-Yuan Luo
- College of Forestry, Northeast Forestry University, Harbin, PR China
| | - Shi-Long Jiang
- Heilongjiang Feihe Dairy Company Limited, Beijing, PR China
| | - Xue Yang
- College of Forestry, Northeast Forestry University, Harbin, PR China
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9
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Heat-induced changes in milk fat and milk fat globules and its derived effects on acid dairy gelation – A review. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2021.105213] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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10
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Effect of chest physiotherapy on cystic fibrosis sputum nanostructure: an experimental and theoretical approach. Drug Deliv Transl Res 2022; 12:1943-1958. [PMID: 35286625 PMCID: PMC9242959 DOI: 10.1007/s13346-022-01131-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2022] [Indexed: 11/26/2022]
Abstract
Cystic fibrosis (CF) is a disease characterized by the production of viscous mucoid secretions in multiple organs, particularly the airways. The pathological increase of proteins, mucin and biological polymers determines their arrangement into a three-dimensional polymeric network, affecting the whole mucus and impairing the muco-ciliary clearance which promotes inflammation and bacterial infection. Thus, to improve the efficacy of the drugs usually applied in CF therapy (e.g., mucolytics, anti-inflammatory and antibiotics), an in-depth understanding of the mucus nanostructure is of utmost importance. Drug diffusivity inside a gel-like system depends on the ratio between the diffusing drug molecule radius and the mesh size of the network. Based on our previous findings, we propose the combined use of rheology and low field NMR to study the mesh size distribution of the sputum from CF patients. Specifically, we herein explore the effects of chest physiotherapy on CF sputum characteristic as evaluated by rheology, low field NMR and the drug penetration through the mucus via mathematical simulation. These data show that chest physiotherapy has beneficial effects on patients, as it favourably modifies sputum and enhances drug penetration through the respiratory mucus.
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11
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Can ultrasound treatment replace conventional high temperature short time pasteurization of milk? A critical review. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2022.105375] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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12
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Glover Z, Gregersen SB, Wiking L, Hammershøj M, Simonsen AC. Microstructural changes in acid milk gels due to temperature‐controlled high‐intensity ultrasound treatment: Quantification by analysis of super‐resolution microscopy images. INT J DAIRY TECHNOL 2021. [DOI: 10.1111/1471-0307.12838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Zachary Glover
- Department of Physics, Chemistry and Pharmacy University of Southern Denmark Campusvej 55 Odense M 5230 Denmark
| | | | - Lars Wiking
- Department of Food Science Aarhus University Agro Food Park 48 Aarhus N 8200 Denmark
| | - Mariannne Hammershøj
- Department of Food Science Aarhus University Agro Food Park 48 Aarhus N 8200 Denmark
| | - Adam Cohen Simonsen
- Department of Physics, Chemistry and Pharmacy University of Southern Denmark Campusvej 55 Odense M 5230 Denmark
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Gilbert A, Turgeon SL. Studying stirred yogurt microstructure and its correlation to physical properties: A review. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2021.106970] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Gilbert A, Rioux LE, St-Gelais D, Turgeon SL. Smoothing temperature and ratio of casein to whey protein: Two tools to improve nonfat stirred yogurt properties. J Dairy Sci 2021; 104:10485-10499. [PMID: 34275633 DOI: 10.3168/jds.2020-20040] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 06/07/2021] [Indexed: 11/19/2022]
Abstract
Consumers are not always ready to compromise on the loss of texture and increased syneresis that nonfat stirred yogurts display compared with yogurts that contain fat. In this study, we investigated milk protein composition and smoothing temperature as a means to control nonfat yogurt microstructure, textural properties, and syneresis. Yogurts were prepared with different ratios of casein to whey protein (R1.5, R2.8, and R3.9). Yogurts were pumped through a smoothing pilot system comprising a plate heat exchanger set at 15, 20, or 25°C and then stored at 4°C until analysis (d 1, 9, and 23). Yogurt particle size and firmness were measured. Yogurt syneresis and water mobility were determined, respectively, by centrifugation and time domain low-frequency proton nuclear magnetic resonance (1H-LF-NMR). Increasing the smoothing temperature increased gel firmness and microgel (dense protein aggregates) sizes independently of the whey protein content. Also, yogurt microgel sizes changed with storage time, but the evolution pattern depended on protein ratio. Yogurt R1.5 showed the largest particles, and their sizes increased with storage, whereas R2.8 and R3.9 had smaller microgels, and R3.9 did not show any increase in microgel size during storage. Micrographs showed a heterogeneous gel with the empty area occupied by serum for R1.5, whereas R2.8 and R3.9 showed fewer serum zones and a more disrupted gel embedding microgels. Induced syneresis reduced with greater whey protein content and time of storage. This is in agreement with 1H-LF-NMR showing less bulk water mobility with increasing whey protein content during storage. However, 1H-LF-RMN revealed higher values of spontaneous serum separation during storage for R1.5 and R3.9 yogurts, whereas these were lower and stable for R2.8 yogurt. Microgels play an important structural role in yogurt textural attributes, and their characteristics are modulated by whey protein content and smoothing temperature. Optimization of these parameters may help improve nonfat stirred dairy gel.
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Affiliation(s)
- A Gilbert
- Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; STELA Dairy Research Centre and Institute of Nutrition and Functional Foods, Université Laval, Quebec City, QC, Canada, G1V 0A6
| | - L-E Rioux
- Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; STELA Dairy Research Centre and Institute of Nutrition and Functional Foods, Université Laval, Quebec City, QC, Canada, G1V 0A6
| | - D St-Gelais
- Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada, J2S 8E3
| | - S L Turgeon
- Department of Food Sciences, Université Laval, Quebec City, QC, Canada, G1V 0A6; STELA Dairy Research Centre and Institute of Nutrition and Functional Foods, Université Laval, Quebec City, QC, Canada, G1V 0A6.
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