Source: AUBURN UNIVERSITY submitted to
STABILITY OF TAGATOSE, A PREBIOTIC CARBOHYDRATE, IN MODEL SOLUTIONS AND BEVERAGES
 
PROJECT DIRECTOR: Bell, L. N.
 
PERFORMING ORGANIZATION
NUTRITION & FOOD SCIENCE
AUBURN UNIVERSITY
AUBURN,AL 36849
 
NON TECHNICAL SUMMARY: Tagatose is a novel carbohydrate which offers the benefit to consumers of improving intestinal health and lowering the amount of digestible sugars in the diet. However, the susceptibility of tagatose for breaking down during processing and storage has not been studied. The purpose of this study is to learn about the factors that affect tagatose retention in beverage-type products.
 
OBJECTIVES: Food products are containing more bioactive substances to provide unique health benefits to the consumer. These bioactive substances are in addition to the traditionally recognized nutrients (e.g., vitamins and minerals) and are referred to as nutraceuticals. One relatively new bioactive substance that may be added to foods is tagatose. This minimally absorbed sugar is fermented by colonic microorganisms into short chain fatty acids. Tagatose changes the intestinal environment, allowing for the growth of more favorable microflora and improved intestinal health; it is thus classified as a prebiotic. In addition, tagatose does not cause a rise in blood glucose levels and contributes few calories to the diet making it a possible sugar replacer. For the consumer to gain a benefit from tagatose, it must not be lost during processing or storage. However, stability studies on tagatose have not been reported in the literature. The objective of this project is to collect and analyze data on the thermal and storage stability of tagatose in model solutions of varying composition. Tagatose storage stability will also be evaluated in juice and milk.
 
APPROACH: To achieve the objectives set forth in this project, several kinetic experiments will be conducted. Sixteen buffer solutions will be prepared containing tagatose. The compositional variables will include buffer type and concentration, pH, and presence of an amino acid. Storage stability at 20-40 degrees Celsius will be determined over 9-12 months by placing samples into constant temperature incubators and removing samples for analysis at regular time intervals. Similary, thermal stability will be studied at 55-75 degrees Celsius by placing samples into a controlled-temperature water bath. Tagatose loss over time will be analyzed and quantitated using high performance liquid chromatography. Reactivity of tagatose with amino acids may cause discoloration due to the non-enzymatic browning reaction and will also be measured. Data will be analyzed using appropriate kinetic modeling suitable for shelf life determinations.
 
CRIS NUMBER: 0206887 SUBFILE: CRIS
PROJECT NUMBER: ALA013-021 SPONSOR AGENCY: CSREES
PROJECT TYPE: NRI COMPETITIVE GRANT PROJECT STATUS: EXTENDED MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Sep 15, 2006 TERMINATION DATE: Sep 14, 2009

GRANT PROGRAM: FOOD CHARACTERIZATION/PROCESS/PRODUCT
GRANT PROGRAM AREA: Value Added Products

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
502501020002.125%
503501020002.175%

CLASSIFICATION HEADINGS
KA502 - New and Improved Food Products
KA503 - Quality Maintenance in Storing and Marketing Food Products
S5010 - Food
F2000 - Chemistry
G2.1 - Expand Domestic Market Opportunities


RESEARCH EFFORT CATEGORIES
BASIC 85%
APPLIED 15%
DEVELOPMENTAL (N/A)%

KEYWORDS: tagatose; prebiotic; reaction kinetics; stability; beverages; nutraceutical; storage stability; thermal stability

PROGRESS: Sep 15, 2007 TO Sep 14, 2008
OUTPUTS: This project involves studying how formulation and storage conditions affect the stability of tagatose in beverage-like products. If tagatose undergoes degradation, its beneficial health effects (i.e., prebiotic effect) would be lost. The experiments conducted to evaluate tagatose stability as affected by pH, buffer type and concentration, added amino acids, and temperature are one of the major outputs of this project. Forty-eight experimental solutions were prepared, stored at 20-40 degrees Celsius, and analyzed for over 200 days to determine the amount of tagatose remaining. Over the past year, these experiments were repeated at higher temperatures (i.e., 60-80 degrees Celsius). During the course of these experiments, a new graduate student was mentored with respect to experimental methodologies, including sample preparation, data acquisition, and data analysis. Thus, this project has helped develop her research skills in the laboratory. One abstract published in the Institute of Food Technologists' (IFT) Book of Abstracts and one poster presentation at the IFT Annual Meeting are other outputs from the past year. PARTICIPANTS: The project director aided in the preparation of the experimental solutions, trained the graduate student, analyzed some samples, and is monitoring the data as it is being collected. One graduate student also aided in the preparation of the experimental solutions, performed sample analysis, and collected data. This new student (different from the previous year) worked on the 60-80 degree Celsius experiments. TARGET AUDIENCES: Our audiences include members of the scientific community and food product development scientists interested exploring ways of incorporating tagatose into the food system. Dissemination to these audiences started during the summer of 2008 by presenting a poster at the annual meeting of the Institute of Food Technologists (Dobbs CM, Bell, LN. 2008. Storage stability of tagatose, a prebiotic monosaccharide, in solutions. #007-06. Presented at the Annual Meeeting of the Institute of Food Technologists, New Orleans, LA, June 28-July 1) as well as by the presentation's accompanying abstract. PROJECT MODIFICATIONS: No major changes have been required; thus the scope of this project remains the same as stated in the grant application. The main issue remaining to be resolved is that during our method development, fructose and tagatose appear to elute from the HPLC at the same time, which means we may not be able to analyze tagatose in apple juice as initially planned. Changes to the mobile phase helped only slightly, and enzymatic strategies for the removal of fructose did not work. We are considering replacing the apple juice with a commercially-available diet lemonade, which would still be acidic but without the fructose. The third phase of this project, tagatose in real beverages, should start before the end of the year.

IMPACT: 2007-09-15 TO 2008-09-14 Two of the three sets of data have been collected: experimental solutions at 20-40 degrees Celsius and experimental solutions at 60-80 degrees Celsius. Tagatose does degrade at varying rates in solution, depending upon composition and storage conditions. Phosphate buffer causes a greater loss of tagatose than citrate buffer. More tagatose is lost as buffer concentration increases. The degradation is faster at pH 7 than pH 3. In all these cases, the basic experimental solutions contain only tagatose and the buffer salts dissolved in water; yet, tagatose is being lost, and the solution is also darkening. At 20-40 degrees Celsius, the addition of the amino acid glycine to the buffer solutions did not enhance the loss of tagatose, which is an unexpected result. In some solutions, glycine appeared to reduce the rate of tagatose loss. However, the glycine-containing solutions did display a darker brown discoloration. As expected, the temperature had a significant effect on tagatose stability. In evaluating the kinetic data, short term processing at elevated temperatures should not pose a problem with respect to tagatose stability. Shelf-stable products having a pH around 7 will lose some tagatose over time. Because phosphate buffer catalyzes the degradation of tagatose, lowering the buffer salt concentration in beverage products will allow for the shelf life to be optimized. This knowledge with respect to tagatose's behavior in solution has not been reported previously.

PUBLICATION INFORMATION: 2007-09-15 TO 2008-09-14
Dobbs C, Bell L. 2008. Storage stability of tagatose, a prebiotic monosaccharide, in solutions. 2008 IFT Annual Meeting Book of Abstracts. IFT: Chicago, IL. p. 17.

PROJECT CONTACT INFORMATION
NAME: Bell, L. N.
PHONE: 334-844-3272
FAX: 334-844-3268