Real-Time Monitoring of Milk Powder Browning and Oxidation Products, Using SIFT-MS

Importance of the Topic

Spray drying of milk solids is widely used in dairy processing but may lead to uncontrolled exothermic reactions and even explosive combustion. Current safety measures rely on carbon monoxide monitoring, which often signals too late and may suffer interferences. Real-time detection of volatile markers specific to browning and oxidation offers a proactive approach to predict hazardous conditions and enhance both safety and quality control.

Objectives and Study Overview

This study aimed to develop and demonstrate a Selected Ion Flow Tube Mass Spectrometry method for continuous, real-time monitoring of reaction products generated during heating of milk powder. The focus was on identifying volatile organic compounds linked to Maillard browning and lipid oxidation under conditions relevant to spray drying.

Methodology and Instrumentation

• Samples: 0.1 g of New Zealand skim and whole milk powders.
• Instrumentation: Syft Technologies Voice200 SIFT-MS using NO+, H3O+, and O2+ reagent ions; resistively heated stainless steel tube furnace; K-type thermocouple for temperature measurement.
• Experimental setup: Powder held in a glass-wool-plugged stainless steel tube inside a furnace ramped from ambient to ≈180 °C; laboratory air drawn at ~250 sccm past the sample; 30 sccm of headspace gas introduced into the SIFT-MS.

Main Results and Discussion

• Full NO+ mass scans recorded every few seconds revealed evolving patterns of known browning products as temperature rose from 80 to 150 °C.
• Selected Ion Monitoring detected volatile fatty acids, heterocyclic Maillard reaction products, and other VOCs with a total cycle time under seven seconds.
• Both skim and whole milk powders exhibited similar VOC profiles, with quantitative differences in specific analytes reflecting compositional variations.
• Continuous, real-time VOC data correlate directly with thermal reaction progress, offering early indicators of smoldering.

Benefits and Practical Applications

• Enables earlier warning of smoldering and potential combustion than CO detection, improving process safety in spray dryers.
• Offers direct monitoring of flavor-forming Maillard products for quality control in dairy and baking industries.
• Delivers quantitative results without extensive calibration, thanks to well-characterized ion chemistry in SIFT-MS.

Future Trends and Applications

Integration of real-time VOC monitoring into automated process control systems could enable predictive maintenance and dynamic adjustment of drying parameters. Extension of this approach to other powdered and thermal processes may broaden its impact. Advanced data analytics and machine learning could enhance predictive models for safety and quality assurance.

Conclusion

SIFT-MS provides a sensitive, rapid, and specific method to track volatile markers of browning and oxidation in milk powder. This approach holds promise for early hazard detection in spray drying and for improved quality monitoring in food processing.

Reference

• C G Bloore, D O’Callaghan 2009 Hazards in Drying in Dairy Powders and Concentrated Products A Tamime Ed Wiley-Blackwell
• G K Huijs, R E M Verdurmen, G van Houwelingen, B Blommestein 2007 CO Detection of Smouldering Powder in Spray Dryers NIZO publication
• C G Freeman, M J McEwan 2002 Rapid analysis of trace gases in complex mixtures using SIFT-MS Australian Journal of Chemistry 55 491-494
• D Smith, P Spanel 2005 Selected ion flow tube mass spectrometry for on-line trace gas analysis Mass Spectrometry Reviews 24 661-700
• A Ferretti, V P Flanagan 1971 Volatile Constituents of Whey Powder Subjected to Accelerated Browning Journal of Dairy Science 54 1764-1768
• J A Turner, R S T Linforth, A J Taylor 2002 Real-Time Monitoring of Thermal Flavor Generation in Skim Milk Powder Using Atmospheric Pressure Chemical Ionization Mass Spectrometry Journal of Agricultural and Food Chemistry 50 5400-5405
• L V Chong, X D Chen, A R Mackereth 2006 Experimental Results Contributed to Early Detection of Smouldering Milk Powder as an Integrated Part of Maintaining Spray Drying Plant Safety Drying Technology 24 783-789