Case Study

Gas Chromatography Technology for Solving Aroma and Odor Issues

By Pam Ahlberg

Problem: A supplier of meats to the fast food industry encountered aroma problems with relatively large batches of product as shipped to clients. This off-aroma was most pronounced when the meat was prepared in a particular manner and in a particular environment. Left unresolved, the issue threatened several million dollars of annual revenue.

Solution: Using multidimensional gas chromatography techniques, Microanalytics Instrumentation Corp. was able to identify the source of this off-aroma. In a relatively short period of time the company located and identified a significant odor contributor in the off-odor material that correlated with the taste and odor panel results. Based on the chemical identification of this odor contributor the supplier was able to determine that it was introduced into the meat as a metabolic byproduct of a particular organic feed supplement, which was fed at somewhat higher levels at some supplier's production facilities. The problem was resolved, and a good business relationship with their client continued.

Fragrance and odor characteristics are critically important to many commercial products and applications. Ironically, it is usually the case that the most critical aroma component is quantitatively a very minor component that is difficult to isolate and measure using conventional gas chromatographic techniques.

Microanalytics Instrumentation Corp., (MAI) a wholly owned subsidiary of MOCON Company, has developed specific chromatographic techniques for identifying just this kind of off-odor. The latest weapon in their arsenal is their recently introduced AromaTrax system, a multidimensional GC-based system that features integrated FID/PID/Olfactory/MS detectors.

AromaTrax System

Utilizing AromaTrax and multidimensional GC techniques, it is possible to:

  1. take a very complex aroma mixture,

2. separate that mixture into smaller volatile groups,

3. and quickly locate and identify critical aroma or odor components.

Don Wright, Technical Director of Microanalytics' MDGC lab, has a unique success record locating, tracking and identifying client's off-odor, aroma and flavor issues.

The AromaTrax system consists of the following:

• H-P Model 6890 Gas Chromatograph (1 injector, FID and PID).
• H-P Chemstation Data Collection Software
• Microanalytics Model 8880 Multidimensional System with 2 columns
• Industrial PC System
• H-P LaserJet 5P laser printer
• Microanalytics MultiTrax Multidimensional Software
• Microanalytics AromaTrax Aroma Characterization Software
• Olfactory Detector ("Sniff port")
• On-site training and installation.

Gas Chromatograph
Hewlett Packard Model 6890 gas chromatograph is configured as a dual-column, dual detector, Dean switch based multidimensional system. Other columns and detectors may be included based on customer's requirements.

Multidimensional Controller
MAI's Model 8880 multidimensional controller system utilizes a remote microcontroller mounted with the GC chassis, with a remote link to the PC. All multidimensional events and programs are configured with the MultiTrax software running on the PC. The control system also includes dual pressure regulators, heartcut and cryotrap valves, midpoint and open split interfaces, and complete installation into the GC.

Data Collection System
All data collection and reporting utilizes the HP Chemstation software. The data display and reporting functions are fully compatible with the AromaTrax software.

Control Computer System
To maximize longevity, an industrial quality PC-based computer system is used for all control and monitoring operations. All electronics components are isolated from the laboratory atmosphere by a combination of cooling fans and filters.

AromaTrax Software System
AromaTrax is a software/hardware system for an IBM-PC or compatible running under Windows 95 Workstation. AromaTrax was designed to work in conjunction with a gas chromatograph equipped with one or more detectors and an attached "Sniff Port". During a chromatographic analysis, the user monitors the "sniff port" for aroma notes. When an odor is detected, the user may select one of the customized odor buttons on the AromaTrax screen. This defines the start of an aroma event. An aroma intensity may then be selected, closing the event. Up to 256 aroma events may be selected during a run of up to 60 minutes.

AromaTrax Features

• Complete user-defined methodology for each analysis.
• Monitors signals from up to 2 external detectors with a resolution of up to 0.01 millivolts. The signal from the primary detector is saved and displayed during report generation.
• 48 user-definable buttons with customizable labels and colors.
• Up to 256 aroma events per analysis.
• Full review and report capabilities.
• User defined aroma lists in standard ASCII format.
• Fully touch-screen compatible for mouse-free operation.

MultiTrax Software System
MultiTrax is a software/hardware system for an IBM-PC or compatible running under Windows 95 Workstation. MultiTrax was designed to work in conjunction with a gas chromatograph equipped with multidimensional control system. The MultiTrax software allows the user complete control of all valve and other external events from PC. Multiple programmed sequences give the user autosampler and multiple run capabilities.

The AromaTrax system has been utilized to solve a wide variety of aroma and odor application challenges. These have ranged from food and packaging to environmental and beverage. Using their special techniques and methodologies, the MAI team can identify subtle odor components that very often are not visible on a normal GC Chromatogram, or which are overlooked by conventional laboratories.

In addition to the AromaTrax system, MAI provides a comprehensive range of technical support services for the GC and related fields -- from custom instrument and integrated systems construction to contract analytical services.

MOCON, which acquired Microanalytics in early 1998, is a leading provider of systems and services designed to assess materials and processes. The company develops, manufactures and markets high technology instrumentation designed to test packages and packaging materials, films and pharmaceutical products.

For more information contact MOCON, 7500 Boone Ave. N, Minneapolis, MN 55428. Tel: 612-493-6370; Fax: 612-493-6358.