Chemical and physical stability of spray-dried and glass encapsulated spray-dried flavors stored below their glass transition temperatures

Gao, Yang

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Description

Title

Chemical and physical stability of spray-dried and glass encapsulated spray-dried flavors stored below their glass transition temperatures

Author(s)

Gao, Yang

Issue Date

2011-05-25T14:37:23Z

Director of Research (if dissertation) or Advisor (if thesis)

• Schmidt, Shelly J.
• Cadwallader, Keith R.

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• benzaldehyde
• extrusion
• evaporated cane juice
• glass encapsulation
• glass transition temperature
• isomalt
• oxidation
• physical aging
• spray dried flavor stability

Abstract

Product shelf life is among the top concerns of the flavor industry. The purpose of this study was to investigate multiple encapsulation technology (MET) for the extension of the limited shelf life of readily volatilized and/or oxidized spray-dry flavors. MET is the use of a quenched melted glass-forming crystalline material as an extra layer of encapsulation for spray-dried (SD) flavors to further enhance stability and extend shelf life. The objectives of this research were to: 1) compare and contrast the chemical and physical stability of SD and two MET flavors, 2) compare the chemical and physical stability at all storage temperatures (Ts) and times, 3) determine possible mechanisms of flavor loss, such as volatile permeation and/or oxidative degradation, and 4) provide recommendations for shelf-life extension of MET flavors. One benzaldehyde SD flavor and two MET materials, isomalt (ISO) and evaporated cane juice (ECJ), were used as model systems. Samples were packaged in individual aluminum pouches and sealed in the presence of air to allow for possible oxidation of benzaldehyde during storage. Finished products were then stored below their glass transition temperatures (Tg) at 7°C, 25°C and 45°C, and analyzed at zero time and at monthly intervals for 6 months. Physical stability parameters, measured using Differential Scanning Calorimetry (DSC), were Tg, crystalline content, melting temperature, and physical aging. In addition, Scanning Electron Microscope (SEM) was used for micro-level observation of physical structure. Chemical stability was based on the total percent change in benzaldehyde determined by Stable Isotope Dilution Assay-Gas Chromatography-Mass Spectrometry (SIDA-GC-MS). Benzoic acid, as the major oxidative degradation product of benzaldehyde, was also measured. Regression modeling of data was conducted using Statistical Analysis System (SAS). As predicted, both MET flavors had significantly higher flavor stability (p<0.0001) than the SD flavor at all storage temperatures, as indicated by less loss of benzaldehyde. The ECJ MET, with an average Tg of at least 10°C greater than the ISO MET Tg, exhibited better overall flavor stability at all storage temperatures (p<0.0001). Over storage time, the ECJ MET exhibited much less physical aging and re-crystallization than ISO MET. This research suggests that ECJ MET, with a large ΔT (Tg-Ts), provides the highest flavor stability. Benzoic acid formation was higher in SD than in MET. Overall, the amount of benzoic acid formed was much less compared to benzaldehyde loss, indicating the main mechanism for flavor loss might be volatilization of benzaldehyde.

Graduation Semester

2011-05

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Copyright 2011 Yang Gao. All rights reserved.

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