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Aroma and Flavor Solvent
CHAPTER
27
Aroma and Flavor Solvent: Impact on the Matrix Nicole Yanga, Joanne Horta, Robert S.T. Linfortha, Andrew J. Taylorb, Keith Brownc, Stuart Walshc and Ian D. Fiska a
Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, UK b Mars Petcare, Freeby Lane, Waltham on the Wolds, Melton Mowbray, Leicestershire, UK c Aromco Ltd, Bell Farm Industrial Park, Nuthampstead, Hertfordshire, UK
27.1 INTRODUCTION Commercial liquid flavorings are created by mixing aroma compounds with a carrier solvent. The carrier solvent can affect the stability of aroma compounds in different ways: it may interact chemically or physically with aroma compounds, or change the physical properties of the food. For example, propylene glycol (PG), the most commonly used flavor carrier, can form acetals and ketals readily with carbonyl flavor compounds, such as vanillin [1]. Triacetin (TA), which is preferentially used in chewing gum, contributes to the desired gum texture by acting as a plasticizer, whereas PG hardens the gum [2].
27.2 MATERIALS AND METHODS The impact of carrier solvent on the color and microstructure of a model biscuit system was evaluated. PG and TA were applied into the biscuit dough and compared directly with biscuits containing no solvent (blank system). Forty replicates of each system were produced within one tray, spatially located in a random design to minimize oven effects (Figure 27.1, where A = blank biscuits, B = PG biscuits, and C = TA biscuits). The impact of flavor carrier solvent on biscuit microstructure was analyzed by X-ray CT scanning. Shortcake biscuits (Figure 27.2) were produced with 0.2% carrier solvent. The biscuits were baked in a standard commercial oven, allowed to cool, then stored at 20°C for 2 weeks to replicate consumer usage V. Ferreira and R. Lopez (Eds): Flavour Science. DOI: http://dx.doi.org/10.1016/B978-0-12-398549-1.00027-1
© 2014 2013 Elsevier Inc. All rights reserved.
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Figure 27.1 Biscuit distribution in tray during baking.
Figure 27.2 Illustration of biscuit shape.
Aroma and Flavor Solvent: Impact on the Matrix
149
Figure 27.3 X-ray CT scan mount.
TA
PG
5 mm
5 mm
55
0.12
Solvent PG TA
0.11
50
0.10 45
0.09 0.08
40 B1
B2
B3
B4
B1
B2
B3
B4
Figure 27.4 Impact of carrier solvent on biscuit structure (X-ray CT scan), porosity (%), and pore size (mm), illustrated in graphs left to right.
patterns, and analyzed by X-ray CT scanning in a 450 mount as shown in Figure 27.3. Biscuits were separated into four (B1–B4, Figure 27.4) threedimensional spatial regions for computational analysis, and the pore structure was analyzed by Image-J software.
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Nicole Yang et al.
Figure 27.5 Average color distribution across baking tray.
27.3 RESULTS Across the oven tray there was a distribution of adsorbed heat which resulted in inhomogeneous baking kinetics (Figure 27.5). When peripheral samples were excluded and the remaining samples evaluated, a significant impact of flavor solvent on color and texture was identified (ANOVA, Tukeys, P < 0.05). TA samples were more brittle, and less yellow and less red in color. Moreover, the biscuit aroma compounds generated from Maillard chemistry were present in significantly higher amounts in the TA biscuits. The microstructure of the biscuit demonstrated a significant impact of flavor carrier solvent on the pore size; biscuits containing PG as the flavor solvent had greater porosity (a large void volume) within the structure, and, of the pores present, generally the diameter was smaller.
27.4 DISCUSSION AND CONCLUSION Choice of carrier solvent (propylene glycol vs triacetin) in shortcake biscuits had a significant impact on the microstructure of the biscuit; biscuits formed with PG were less brittle, more yellow, more red, and had greater porosity and smaller-diameter internal pores.
ACKNOWLEDGEMENTS The authors would like to thank KTP, C. Sturrock, and the Sensory Science Centre for support.
REFERENCES [1] J.S. Elmore, A.T. Dodson, D.S. Mottram, Reactions of propylene glycol with the constituents of food flavourings. Weurman Flavour Symposium, 2011. [2] R.V. Potieni, D.G. Peterson, Influence of flavor solvent on flavor release and perception in sugar-free chewing gum, J. Agric. Food Chem. 56 (2008) 3254–3259.
27
Aroma and Flavor Solvent: Impact on the Matrix Nicole Yanga, Joanne Horta, Robert S.T. Linfortha, Andrew J. Taylorb, Keith Brownc, Stuart Walshc and Ian D. Fiska a
Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire, UK b Mars Petcare, Freeby Lane, Waltham on the Wolds, Melton Mowbray, Leicestershire, UK c Aromco Ltd, Bell Farm Industrial Park, Nuthampstead, Hertfordshire, UK
27.1 INTRODUCTION Commercial liquid flavorings are created by mixing aroma compounds with a carrier solvent. The carrier solvent can affect the stability of aroma compounds in different ways: it may interact chemically or physically with aroma compounds, or change the physical properties of the food. For example, propylene glycol (PG), the most commonly used flavor carrier, can form acetals and ketals readily with carbonyl flavor compounds, such as vanillin [1]. Triacetin (TA), which is preferentially used in chewing gum, contributes to the desired gum texture by acting as a plasticizer, whereas PG hardens the gum [2].
27.2 MATERIALS AND METHODS The impact of carrier solvent on the color and microstructure of a model biscuit system was evaluated. PG and TA were applied into the biscuit dough and compared directly with biscuits containing no solvent (blank system). Forty replicates of each system were produced within one tray, spatially located in a random design to minimize oven effects (Figure 27.1, where A = blank biscuits, B = PG biscuits, and C = TA biscuits). The impact of flavor carrier solvent on biscuit microstructure was analyzed by X-ray CT scanning. Shortcake biscuits (Figure 27.2) were produced with 0.2% carrier solvent. The biscuits were baked in a standard commercial oven, allowed to cool, then stored at 20°C for 2 weeks to replicate consumer usage V. Ferreira and R. Lopez (Eds): Flavour Science. DOI: http://dx.doi.org/10.1016/B978-0-12-398549-1.00027-1
© 2014 2013 Elsevier Inc. All rights reserved.
147
148
Nicole Yang et al.
Figure 27.1 Biscuit distribution in tray during baking.
Figure 27.2 Illustration of biscuit shape.
Aroma and Flavor Solvent: Impact on the Matrix
149
Figure 27.3 X-ray CT scan mount.
TA
PG
5 mm
5 mm
55
0.12
Solvent PG TA
0.11
50
0.10 45
0.09 0.08
40 B1
B2
B3
B4
B1
B2
B3
B4
Figure 27.4 Impact of carrier solvent on biscuit structure (X-ray CT scan), porosity (%), and pore size (mm), illustrated in graphs left to right.
patterns, and analyzed by X-ray CT scanning in a 450 mount as shown in Figure 27.3. Biscuits were separated into four (B1–B4, Figure 27.4) threedimensional spatial regions for computational analysis, and the pore structure was analyzed by Image-J software.
150
Nicole Yang et al.
Figure 27.5 Average color distribution across baking tray.
27.3 RESULTS Across the oven tray there was a distribution of adsorbed heat which resulted in inhomogeneous baking kinetics (Figure 27.5). When peripheral samples were excluded and the remaining samples evaluated, a significant impact of flavor solvent on color and texture was identified (ANOVA, Tukeys, P < 0.05). TA samples were more brittle, and less yellow and less red in color. Moreover, the biscuit aroma compounds generated from Maillard chemistry were present in significantly higher amounts in the TA biscuits. The microstructure of the biscuit demonstrated a significant impact of flavor carrier solvent on the pore size; biscuits containing PG as the flavor solvent had greater porosity (a large void volume) within the structure, and, of the pores present, generally the diameter was smaller.
27.4 DISCUSSION AND CONCLUSION Choice of carrier solvent (propylene glycol vs triacetin) in shortcake biscuits had a significant impact on the microstructure of the biscuit; biscuits formed with PG were less brittle, more yellow, more red, and had greater porosity and smaller-diameter internal pores.
ACKNOWLEDGEMENTS The authors would like to thank KTP, C. Sturrock, and the Sensory Science Centre for support.
REFERENCES [1] J.S. Elmore, A.T. Dodson, D.S. Mottram, Reactions of propylene glycol with the constituents of food flavourings. Weurman Flavour Symposium, 2011. [2] R.V. Potieni, D.G. Peterson, Influence of flavor solvent on flavor release and perception in sugar-free chewing gum, J. Agric. Food Chem. 56 (2008) 3254–3259.