Progress 06/01/22 to 05/31/23
Outputs
Target Audience:The primary audience of this work will be the product developers working to create clean-label products with specific attributes, but R&D scientists will also benefit from the results, opening doors for new and creative applications and products. Changes/Problems:This project was delayed significantly by the pandemic. However, we are on-track to complete the project objectives with the no-cost extension. What opportunities for training and professional development has the project provided?To date, the project has been primarily conducted by a PhD student, with the involvement of a post-doctoral researcher on Objective 2. Several undergraduate researchers have been trained on this project including one in polyphenol extraction and analysis and several others on ice cream analyses. How have the results been disseminated to communities of interest?-Poster presented at Frozen Dessert Center Technical Symposium, Madison WI -Several presentations on berry polyphenols for health. What do you plan to do during the next reporting period to accomplish the goals?For Obj 2, we will finalize the second study by publishing a scientific paper. We will complete the study to assess polyphenol extracts in a frozen dessert model system, replacing both hydrocolloids and emulsifiers in a clean label application. For Obj 3, we will complete the experimental design, analyze the results and publish in an appropriate journal.
Impacts
What was accomplished under these goals?
Objective 1: Identify the chemical nature of PPs that affect structure development in cream and model systems. Polyphenols are known to be complex with proteins and impact emulsion properties. With dairy products containing milk fat and/or proteins, many researchers have observed unique results when adding polyphenols to these systems, such as a decreased melting rate in fortified ice cream. However, very few have investigated the mechanisms behind the increase in viscosity, fat destabilization index, and fat clusters observed after polyphenol addition. Preliminary testing and commercial products have led to the hypothesis that protein-mediated fat aggregation and partial coalescence are the main drivers of fat clustering and cream gelation. The objective of this study was to understand the effects of a polyphenol, tannic acid (TA), on dairy cream. TA was added to cream at 0.75%, 1.5% and 3% (wt/wt) concentrations. An increase in complex viscosity was seen as TA% increased. The effect of pH on protein aggregation was minimal since the pH values of the resulting TA-cream samples were generally above the isoelectric point of milk proteins. Microscope images and particle size distributions confirmed the presence of fat globule clusters in these samples, creating a network at 3% TA. Using sodium dodecyl sulfate (SDS) and ethylenediaminetetraacetic acid (EDTA) to disperse both fat and protein, average particle size and microscope images suggested that milk protein-TA interactions helped create the clusters. No evidence of partial coalescence was observed. These findings can help optimize the complex effect of polyphenols in the dairy matrix to create higher quality products. Objective 2: Based on results from Obj. 1, identify target extracts that contain PP that give desired effects. Building upon the findings of Objective 1, polyphenol-rich ingredients with potential desired effects, including cranberry juice, strawberry juice, peanut extract, green tea extract, aronia berry extract, red bean extract, and grape seed extract (GSE), were chosen. A gravimetric microscale screening method was developed to investigate the impact of the addition of different extracts on the structure of the cream. Compared to other extracts, stronger interaction with the cream was observed in GSE that contains more proanthocyanidin (PAC) with higher mean degree of polymerization (mDP). The isolation of PAC fractions with varying mDP ranges was carried out using Sephadex LH-20 chromatograph. These PAC isolates underwent further analysis by high-resolution mass spectrometry (HRMS) to characterize PACs in GSE, determine mDP by thiolysis, and establish an HILIC profile. Based on HRMS data, GSE contained >100 types of PACs ranging from monomer up to DP16. The utilization of isolated PAC fractions with different mDP ranges to interact with proteins in the cream revealed DP-dependent PAC-protein interactions, with higher-DP PACs exhibiting a greater capacity for precipitation and protein binding than low-DP PACs due to multiple hydrophobic interactions. Viscosity and particle size of PAC-cream mixture were measured, revealing a progressively DP-dependent increase in aggregated fat globules and cream viscosity. These findings enhance our understanding of PACs' structural intricacies and highlight their functional role of PAC-rich natural ingredients in creation of structured cream systems. Objective 3: Evaluate logical target PPs and/or extracts from Objectives 1 and 2 for further study in frozen dessert systems. To evaluate tannic acid (TA) in frozen desserts, formulations were made with 12% fat and 3% protein with increasing levels of TA up to 2.5% to investigate the melting profile and stability of ice to recrystallization during storage. Additional formulations were made with increased fat and increased protein at 2.5% TA addition to evaluate the dependency on these important parameters. Since it proved impossible to quantify particle size with light scattering, a rheological method of measuring structure was used. This method involves measuring shear stress as shear rate is increased and then decreased. As structure is broken in the increasing ramp, the area between the curves (hysteresis) provides a measure of structure. As expected, melting rate at 2.5% TA was significantly lower than at any other addition level. However, an interesting phenomenon occurred where melt rate actually increased at 1 and 1.5% addition. Further work will be needed to evaluate the mechanisms of this effect. Work continues on correlating structure measures from hysteresis to melt-down rates as well as quantifying ice recrystallization during storage. The higher protein formulation was not affected by TA addition whereas the higher fat formulation showed a significant decrease in melt rate, indicating that fat content appears to be the most important factor in these "no-collapse" products. This is an interesting finding given that the PP precipitate the protein. The next steps will be to evaluate commercial extracts and powders on melting of ice cream. We have obtained several commercial extracts, juices and powders as well as produced an in-house preparation of strawberry polyphenol extracts for this study. The experimental design will begin shortly. We also have formulations where PP will replace either emulsifiers and/or stabilizers.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2023
Citation:
Wicks CJ, Bolling BW, Hartel RW. Effects of tannic acid on proteins and fat in cream. Food Production, Processing and Nutrition. 2023;5:51
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Progress 06/01/21 to 05/31/22
Outputs
Target Audience:The primary audience of this work will be the product developers working to create clean-label products with specific attributes, but R&D scientists will also benefit from the results, opening doors for new and creative applications and products. Changes/Problems:This project was hit severely by the covid pandemic, especially being able to engage a post-doctoral researcher. We finally have that person with us and are beginning to make better progress. What opportunities for training and professional development has the project provided?To date, the primary researcher has been a PhD student. A post-doctoral researcher was recently hired to help with this work. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?We will continue working with various extracts to evaluate their effects on cream and ultimately work to understand how these polyphenols influence the melting properties of ice cream.
Impacts
What was accomplished under these goals?
Objective 1: Identify the chemical nature of PPs that affect structure development in cream and model systems. Polyphenols are known to complex with proteins and impact emulsion properties. With dairy products containing milk fat and/or proteins, many researchers have observed unique results when adding polyphenols to these systems, such as a decreased melting rate in fortified ice cream. However, very few have investigated the mechanisms behind the increase in viscosity, fat destabilization index, and fat clusters observed after polyphenol addition. Preliminary testing and commercial products have led to the hypothesis that protein-mediated fat aggregation and partial coalescence are the main drivers of fat clustering and cream gelation. The objective of this study was to understand the effects of a polyphenol, tannic acid (TA), on dairy cream. TA was added to cream at 0.75%, 1.5% and 3% (wt/wt) concentrations. An increase in complex viscosity was seen as TA% increased. The effect of pH on protein aggregation was minimal since the pH values of the resulting TA-cream samples were generally above the isoelectric point of milk proteins. Microscope images and particle size distributions confirmed the presence of fat globule clusters in these samples, creating a network at 3% TA. Using sodium dodecyl sulfate (SDS) and ethylenediaminetetraacetic acid (EDTA) to disperse both fat and protein, average particle size and microscope images suggested that milk protein-TA interactions helped create the clusters. No evidence of partial coalescence was observed. These findings can help optimize the complex effect of polyphenols in the dairy matrix to create higher quality products. Objective 2: Based on results from Obj 1, identify target extracts that contain PP that give desired effects (includes pulse sources per RFP). Due to difficulties hiring a post-doctoral researcher during covid, this aspect of the work is just beginning. We are selecting various extracts for analysis and will be evaluating their effects on cream. Objective 3: Evaluate logical target PPs and/or extracts from Objectives 1 and 2 for further study in frozen dessert systems. Not started yet.
Publications
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Progress 06/01/20 to 05/31/21
Outputs
Target Audience:The primary audience of this work will be the product developers working to create clean-label products with specific attributes, but R&D scientists will also benefit from the results, opening doors for new and creative applications and products. Changes/Problems:This project has been severely disrupted by the pandemic. In addition to the delays caused by lab shutdowns and slowdowns that have impeded grad student progress, we have had difficulties hiring the post-doc to start Objective 2. We will definitely be requesting at least one no-cost extension to be able to complete the work as intended. What opportunities for training and professional development has the project provided?One MS student has been trained on this project. How have the results been disseminated to communities of interest?Preliminary results were presented as a poster at the Frozen Dessert Center Technical Symposium in October 2020 (virtual). What do you plan to do during the next reporting period to accomplish the goals?Objective 1: • Finalize first study using gallic acid in cream. • Continue to investigate the nature of polyphenols that cause these effects by investigating different ingredients. • Continue efforts to elucidate mechanisms of action of polyphenols on proteins and fats in cream. Objective 2: • Initiate study on use of extracts for developing structures in ice cream products. Objective 3: • Future work.
Impacts
What was accomplished under these goals?
Objective 1: The focus of the first set of experiments has been to compare the effects of polyphenols, specifically gallic acid, on proteins in cream versus their effect on fats, leading to partial coalescence. This study has been just about completed with the preliminary conclusion that polyphenols do indeed affect both proteins and fats to create structures in cream that could potentially influence physical attributes (e.g., melting) of ice cream products produced with them. Gallic acid, when added to cream, caused rapid protein aggregation leading to precipitates or even to gelation depending on the amount added. However, by careful analysis of the coagulated structure, it is apparent that there are also clusters of fat globules reminiscent of partial coalescence of the fat globules. How exactly the gallic acid influences fat globules is still uncertain. Objective 2: No progress as yet due to limitations in engaging a post-doctoral researcher.
Publications
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