PHYSICO-CHEMICAL PROPERTIES OF DAIRY MACROMOLECULES IN FOOD SYSTEMS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1004745
• Project Start Date: Nov 10, 2014
• Project End Date: Sep 30, 2019
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108

Performing Department
Food Science & Nutrition

Non Technical Summary
In food systems large macromolecules contribute to the overall quality and acceptability of the food. Included in this group are dairy macromolecules. These dairy-derived molecules primarily proteins and triglycerides, interact with various molecules found in food systems, e.g. carbohydrates, proteins, stabilizers, and emulsifiers. Unfortunately, how these interactions affect various physico chemical properties of the food systems is not well understood. Some of the properties of concern are rheological characteristics, emulsifying ability, and extent of protein denaturation and interactions, and carbohydrate-protein interactions. An understanding of these complex interactions is critical in that the distinctive characteristics of many foods are influenced by these interactions. Among these characteristics are the texture or mouth feel of ice cream, the emulsifying properties of various milk protein fractions, as well as their water holding behavior.A better understanding of such macromolecule effects in foods would help insure the production of desirable food products. This understanding would allow for better prediction of overall product quality, e.g. the effects different amounts of denaturation will have on altering the gelling properties of milk proteins, or the effect of various carbohydrates on the smoothness of ice cream. Additionally, basic knowledge of the interaction of macromolecules would be obtained and aid the understanding of their behavior in aqueous systems other than just foods.The overall benefit will be higher quality food products. Characteristics such as the smoothness of products like ice cream and thickness of salad dressing will be better controlled. The stability of oil and water emulsions will be enhanced by information gained from this project.

Animal Health Component

60%

Research Effort Categories

Basic

20%

Applied

60%

Developmental

20%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
502	3450	2000	100%

Knowledge Area
502 - New and Improved Food Products;

Subject Of Investigation
3450 - Milk;

Field Of Science
2000 - Chemistry;

Keywords

macro molecules

milk proteins

physical properties

casein

beta glucan

Goals / Objectives
Number 1Hypothesis: Addition of citrates and phosphates to concentarted milk products will produce products with modified physical properties.Objectives:Deterime the extent of casein micelle disintergration in various concentrated milk products (concentrated skim and whole milks as well as at various concentartions of protein in milk protein concentrates) with additon of various amounts and types of citrates and phosphates.Determine the gelling, emulsifying and foaming characteristics of theses modified milk products.Determine the impact drying has the characteristics of these modified milk products.Determine the impact these modified product will have in food products that contain the non modified counter part of these products.Number 2Hypothesis:Barley β Glucan will interact with casein to produce unique gelling properties in fluid milk.Objectives:Determine the chemical nature of the interaction between barley β glucan and milk. 2. Determine the impact of casein amount, β glucan amount, and homogenization pressure on the gelling time of a β glucan-milk system. 3. Determine the impact of casein amount, β glucan amount, and homogenization pressure on the gel strength of a β glucan-milk system.

Project Methods
For Hypothesis and Objectives 1:Raw whole milk will be separated into cream and skim or used as received. Following pasteurization the milks (skim and whole) will be processed in two general ways. The first will be to use reverse osmosis to concentrate the milks to various levels (in the 1 to 4 fold range). The second general means of processing will be to concentrate and fractionate the milks by means of ultra filtration. The target concentrations will in the range of initial protein concentration up to a fivefold concentration. Products will then are either used in the liquid form or spray dried.General Evaluation of the Products Proximate analysis of the products will be carried out using standard techniques currently used in the dairy industry. The protein profile (both casein and whey proteins) of the samples will be determined by Urea PAGE gel electrophoresis and other techniques. Quantification of the individual proteins will be done using HPLC.Emulsion Stability StudiesEmulsion stability will be conducted by first producing emulsions by combining various oils, e.g., butter, corn, soy and canola, in 5% v/v oil in water system and adding solutions of the various concentrated milk products to give protein concentrations of 0.1 to 1.0 %. The samples will then be homogenized using a single stage homogenizer (Manton Gaulin).The samples will be evaluated over time using two techniques as follows:The first will be a modified homogenization index protocol. Samples of the emulsion will be placed in graduated cylinders. Daily for a one-week period samples will be evaluated for the amount of lipid in the top 10% and the bottom 90% of the cylinder. The determination will be done by the Mojonnier ether extraction method. Based on these data it will be possible to calculate the rate of separation of the various samples. These data will be statistically analyzed to determine if there are any differences present among the samples and how these differences might relate to whey source.The second technique to be used will monitor turbidity difference over time. A sample of the emulsion immediately after preparation will be placed in a spectrophotometer and the rate of clearing in the sample will be monitored.Also, confocal laser light microscopy coupled with image analysis will be used to determine the particle size distribution of the droplets in the emulsion. This data will then be used to calculate the total interfacial area per unit mass of emulsion as well as volume to surface ratio.Foaming PropertiesProtein stabilized foam will be made by sparging air through a protein solution. For this purpose, a jacketed graduated glass column, open at the top and blocked at the bottom by a sintered glass disk will be used. With this device foam volume and rate of foam decay will be determined for various protein concentrations.Gelation and Rheological StudiesProtein solutions (8-10% by weight) will be heated, at temperatures of 85-100C, in glass tubes (of fixed diameter and wall thickness) plugged on either side by silicone rubber stoppers. After cooling gels will be cut to the required height and gel properties will be studied using an Instron. This instrument measures force versus displacement (under either extension or compression).Gel and rheological properties will also be studied using a Controlled Stress Dynamic Rheometer. The sample will be subjected to rotational strain between parallel plates or between a cone and plate. This instrument measures viscosity versus rate of shear, creep, stress relaxation, and oscillation, bulk modulus and storage modulus, etc.The above experiments with the Dynamic Rheometer will be repeated, but with the addition of chymosin to the sample. This approach was previously used by Kameswaran (1994).For Hypothesis and Objectives 2:Experimental DesignUnderstanding the interaction of barley β-glucan (BBG) with other food components and gaining knowledge about how processing affects functionality can lead to greater use of BBG in food systems. A central composite rotatable design (Neter et al 1996) has been chosen as a tool for gaining such knowledge and understanding. Three factors have been chosen which leads to a total of 20 treatments (α = 1.682) for the design. The three variables include BBG concentration (1% - 2%), NDM concentration (1% - 9%) and homogenization temperature (5ºC - 40ºC). The dependant variable is gel time (Tg).Analysis of data will be performed using SAS® software and the PROC RSREG procedure (SAS® Institute, Cary, NC).Sample PreparationGlucagel™ (81% β-glucan, 52,000 kD) is the barley β-glucan source for this experiment and was obtained from PolyCell Technologies, Crookston, MN. (Later experiments will utilize different β-glucan sources.) Low heat nonfat dry milk (NDM) was obtained from Dairy America, Fresno, CA. Glucagel™ and NDM are weighed out according to the factor levels for each treatment and dry blended together. This blend is then added slowly to deionized water with stirring until dispersed. Small agglomerates would form occasionally but are kept to a minimum by controlling the addition of the dry blend to the water (from preliminary trial). Stirring is held to a minimum to avoid excessive formation of foam. The mixture is heated on a double boiler with stirring to 70ºC and transferred to an ice water bath after 15 seconds for cooling. The mixture is cooled in an ice water bath to the shear temperature prescribed for the treatment and transferred to a homogenizer (Microfluidics™ HC-8000/3A, Newton, MA). The homogenizer serves as the shear apparatus and the mixture is sheared at 620,000 s-1 (2000 psi through a Microfuidics™ E230Z chamber). A sample is collected from the homogenizer and returned to the ice water bath for further cooling to 5ºC.Gel MeasurementOnce sheared and cooled, the sample is transferred immediately to an AR 1000 rheometer (TA Instruments, New Castle, DE) with 60mm acrylic flat plate geometry. The geometry is equipped with a solvent trap that was filled with water. Approx. 1.5 ml of sample is loaded onto the plate and the geometry is lowered to within 750 µm (gap) of the plate. The plate temperature is set at 5ºC. The solvent trap cover is placed over the geometry for the duration of the test to slow the rate of evaporation or condensation. Each sample is pre-sheared prior to the start of the time sweep. The time sweep is conducted at a frequency of 0.1000 Hz and controlled oscillatory stress of 0.05 Pa. The stress and frequency setting's for the time sweep were established from stress sweeps conducted previously and is in the linear viscoelastic region (LVR) of the treatments in the design. G' and G'' are measured during the time sweep and the time recorded from the start of the sweep to when TAN δ = 1.0. Once Tg is established, gel formation will be allowed to continue until TAN δ = 0.07. This is the gel strength provided by Steffe (1996) as being typical of a gel in a dilute system. A stress sweep will be conducted after time sweep data has been collected to confirm the LVR for that treatment.

Progress 11/10/14 to 09/30/19

Outputs
Target Audience:Target audiences are food industry professionals and others interested in food safety and food ingredient functionality. As well as students in various graduate and undergraduate classes. Changes/Problems:Lack of funding is a problem so focus has been to educate Plan B MS students who have their own funding. This however leads to work outside of the exact initial intent of the project, but has led to 2 students graduated and 3 currently being advised. What opportunities for training and professional development has the project provided?As mentioned above the material from the Plan B paper on Allergens has served as the basis for lectures on allergens and their control to over 300 students per academic year. The course is FSCN 1011, The Science of Food and Cooking. Some material is also use in short course lectures given as part of the Applied Dairy Chemistry course at the University of Wisconsin-Madison each year. How have the results been disseminated to communities of interest?See above as the material is used ibn educational programs. What do you plan to do during the next reporting period to accomplish the goals?This is the final report for this project (18-100).

Impacts
What was accomplished under these goals? No major accomplishments were achieved for these specifc objectives. However as mentioned above two Plan B paper was developed.

Publications

• Type: Other Status: Accepted Year Published: 2015 Citation: Was Plan B paper which was part of the requirements for the degree of MS in Food Science. Topic of paper was the impact of food service establishments on outbreaks of food borne illness
• Type: Other Status: Accepted Year Published: 2017 Citation: Was Plan B paper which was part of the requirements for the degree of MS in Food Science. Topic of the paper was the approach the various countries and regions of the world take with respect to allergen labelling and control.

Progress 10/01/17 to 09/30/18

Outputs
Target Audience: Main audience for the allergens project are individuals in the purchasing of processed food product from around the world. By knowing what is and isn't labeled, these individuals will know what question to ask and what addition analyzes to have conducted so the products conform to labeling regulations in their country. The new work will help in the understanding of what is being done at various parts of the food supply chain. With this extra knowledge individuals will be able to ask the right questions and require additional tests to help ensure safe food ultimately reached the consumer. Changes/Problems: Due to a lack of funding, the work was conducted by a student on her own funding. The new effort in analyzing the governance framework for food regulations will also be conducted by a student on her own funding. What opportunities for training and professional development has the project provided? The material generated has served as the basis of a section of a graduate course on food allergens. It is hoped that with the publication of the paper a wider audience of food professionals will gain a greater knowledge concerning allergen labeling and the wide array of approaches or non-approaches in various countries. Material from this paper was also used for lectures in an undergraduate course related to the science of food and cooking (approximately 300 plus students across all majors). How have the results been disseminated to communities of interest? As mentioned above the material has been used in two academic classes and also been part of an industrial short course. One of the University's Extension Food Safety people has used elements of this work with various companies to help them enhance their allergen control programs. What do you plan to do during the next reporting period to accomplish the goals? There are two main goals in the next year. The first is to complete the publication project on allergen labelling and control in various countries and regions of the world. The second is to get a good start on the comparative analyze the food safety governance framework and regulations of the major food trading partners of the United States.

Impacts
What was accomplished under these goals? As in the previous year there were no major accomplishments toward the specific goals and objectives of the project. Work continued on the modification of the Plan B MS paper to format it for more wide spread dissemination of the information gathered. The hope being better decisions can be made by food professionals for labelling and control of allergens in the food supply and thus improve food safety. A major new initiative has been started to comparatively analyze the food safety governance framework and regulations of the major food trading partners of the United States. With this information an effort will be undertaken to evaluate the effectiveness of these food safety regulations and ensure product safety through the entire food supply chain, i.e. farm to fork.

Publications

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The traget of this work is individuals who have an interest as well as responsiblities for the control of food allergens and how the public in general is made aware of through labeling the possiblity of allergens being in the food product. Changes/Problems:Main issue is the lack of funding to hire help with the project. The student mentioned above was self funded and I am curerently looking for another perosn to carry on this work and other aspects of the project. What opportunities for training and professional development has the project provided?In addition to the graduation of a student working in the area of food allergens this work was used in variuos other venues. The paper served as a major resource in a graduate course on current issues in food science. The students oin the class were given a segment of the food industry and made a presentation to the whole class. From this the students were made much more aware of the issues related to food allergens and the various approaches used across the world related to control of allergens. Material from this paper was also used for lectures in an undergraduate course realted to the scinec of food and cooking (approximately 280 students). How have the results been disseminated to communities of interest?As mentioned above the material has been used in two academic classes and also been part of an industrial short course. One of the University's Extension Food Safety people has used elements of this work with various companies to help them enhance their allergen control programs. What do you plan to do during the next reporting period to accomplish the goals?The goal for the next reporting period is to combine this paper with some real world senerios and publish this information as an aid to various components of the food industry.

Impacts
What was accomplished under these goals? During the past year there were no major accomplishments specific to these goals. There was however, a substantial investment in time related to literature work on food allergens. This resulted in the Plan B MS paper with over 200 reference and the graduation of a student who works for food service company supplying food to airlines. Her responsiblity is confirming what if an allergens maybe present in foods being served on airline flights. This work is going to be used as the basis of a publication on food safety. Overall, the paper covered the topics of allergic reactions, approaches to control of allergens in foods. Also, an extensive review of the means or lack of means used in the various parts of world as related to allergen control.

Publications

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:The groups reached this reporting period included health professional with an interest in the proper sanitary design for food preparation areas. Also, individuals interested in the control of allergenic material thought out the food chain can gain information form the extensive review of international laws regarding allergen control. Changes/Problems:Lack of funding has greatly reduced the ability to do much constructive work on this project's main goals. Thus, related work has been the main items that can be undertaken. What opportunities for training and professional development has the project provided?One plan B MS student was graduated during the past year. Also, short course presentations were made concerning the material that is the focus of this project. How have the results been disseminated to communities of interest?A departmental seminar was presented that focused on the Plan B paper material that was part of this project. What do you plan to do during the next reporting period to accomplish the goals?Completion of the allergen work related to this project should be done.

Impacts
What was accomplished under these goals? One MS graduate student was completed and another almost done. Some of the information generated over the years by this project is being used in classes and short courses serving the dairy industry in particular.

Publications

Progress 11/10/14 to 09/30/15

Outputs
Target Audience:Target audience is food industry professionals as well as other concerned about food safety. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Project has helped to provide training for individuals who can work within the food industry. This fact was demostrated in the completion of one Plan B MS in the area preventing the spread of the Norwalk virus in food service establishments. 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?Continue the efforts on the allergenic effects of specific food macro molecules and how to minimize potential contamination of foods with these types of molecules.

Impacts
What was accomplished under these goals? Number 1 Nothing to report this year as work is on going Number 2 No physical lab work was done toward these objectives this year. Some planning is being done to do experiments on depletion flocculation by beta glucans in fluid milk systems in the coming year.

Publications