Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate

Michael Crafack; Hanna Keul; Carl Emil Aae Eskildsen; Mikael Agerlin Petersen; Sofie Saerens; Andreas Blennow; Mathias Skovmand-Larsen; Jan H. Swiegers; Gert B. Petersen; Hanne Heimdal; Dennis Sandris Nielsen

doi:10.1016/j.foodres.2014.04.032

Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate

Michael Crafack, Hanna Keul, Carl Emil Aae Eskildsen, Mikael Agerlin Petersen, Sofie Saerens, Andreas Blennow, Mathias Skovmand-Larsen, Jan H. Swiegers, Gert B. Petersen, Hanne Heimdal, Dennis Sandris Nielsen^*

^*Corresponding author for this work

61 Citations (Scopus)

Abstract

The sensory quality of chocolate is widely determined by the qualitative and quantitative composition of volatile compounds resulting from microbial metabolism during fermentation, and Maillard reactions taking place during drying, roasting and conching. The influence of applying mixed starter cultures on the formation of flavour precursors, composition of volatile aroma compounds and sensory profile was investigated in cocoa inoculated with cultures encompassing a highly aromatic strain of Pichia kluyveri or a pectinolytic strain of Kluyveromyces marxianus, and compared to commercially fermented heap and tray cocoa. Although only minor differences in the concentration of free amino acids and reducing sugars was measured, identification and quantification by dynamic headspace gas chromatography-mass spectrometry (HS/GC-MS) revealed pronounced differences in the composition of volatiles in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri inoculated chocolate was characterized by a significantly higher concentration of phenylacetaldehyde and the K. marxianus inoculated chocolate by significantly higher amounts of benzyl alcohol, phenethyl alcohol, benzyl acetate and phenethyl acetate compared to a spontaneously fermented control. Sensory profiling described the heap and tray fermented chocolates as sweet with cocoa and caramel flavours, whilst the inoculated chocolates were characterized as fruity, acid and bitter with berry, yoghurt and balsamic flavours. The choice of fermentation technique had the greatest overall impact on the volatile aroma and sensory profile, but whilst the application of starter cultures did affect the volatile aroma profile, differences were too small to significantly change consumer perception of the chocolates as compared to a spontaneously fermented control.

Original language	English
Journal	Food Research International
Volume	63
Issue number	Part C
Pages (from-to)	306–316
Number of pages	11
ISSN	0963-9969
DOIs	https://doi.org/10.1016/j.foodres.2014.04.032
Publication status	Published - Sept 2014

Keywords

Cocoa fermentation technique
Kluyveromyces marxianus
Pichia kluyveri
Sensory profiling
Starter culture
Volatile aroma compounds

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10.1016/j.foodres.2014.04.032

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Crafack, M., Keul, H., Eskildsen, C. E. A., Petersen, M. A., Saerens, S., Blennow, A., Skovmand-Larsen, M., Swiegers, J. H., Petersen, G. B., Heimdal, H., & Nielsen, D. S. (2014). Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate. Food Research International, 63(Part C), 306–316. https://doi.org/10.1016/j.foodres.2014.04.032

Crafack, M, Keul, H, Eskildsen, CEA, Petersen, MA, Saerens, S, Blennow, A, Skovmand-Larsen, M, Swiegers, JH, Petersen, GB, Heimdal, H & Nielsen, DS 2014, 'Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate', Food Research International, vol. 63, no. Part C, pp. 306–316. https://doi.org/10.1016/j.foodres.2014.04.032

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title = "Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate",

abstract = "The sensory quality of chocolate is widely determined by the qualitative and quantitative composition of volatile compounds resulting from microbial metabolism during fermentation, and Maillard reactions taking place during drying, roasting and conching. The influence of applying mixed starter cultures on the formation of flavour precursors, composition of volatile aroma compounds and sensory profile was investigated in cocoa inoculated with cultures encompassing a highly aromatic strain of Pichia kluyveri or a pectinolytic strain of Kluyveromyces marxianus, and compared to commercially fermented heap and tray cocoa. Although only minor differences in the concentration of free amino acids and reducing sugars was measured, identification and quantification by dynamic headspace gas chromatography-mass spectrometry (HS/GC-MS) revealed pronounced differences in the composition of volatiles in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri inoculated chocolate was characterized by a significantly higher concentration of phenylacetaldehyde and the K. marxianus inoculated chocolate by significantly higher amounts of benzyl alcohol, phenethyl alcohol, benzyl acetate and phenethyl acetate compared to a spontaneously fermented control. Sensory profiling described the heap and tray fermented chocolates as sweet with cocoa and caramel flavours, whilst the inoculated chocolates were characterized as fruity, acid and bitter with berry, yoghurt and balsamic flavours. The choice of fermentation technique had the greatest overall impact on the volatile aroma and sensory profile, but whilst the application of starter cultures did affect the volatile aroma profile, differences were too small to significantly change consumer perception of the chocolates as compared to a spontaneously fermented control.",

keywords = "Cocoa fermentation technique, Kluyveromyces marxianus, Pichia kluyveri, Sensory profiling, Starter culture, Volatile aroma compounds",

author = "Michael Crafack and Hanna Keul and Eskildsen, {Carl Emil Aae} and Petersen, {Mikael Agerlin} and Sofie Saerens and Andreas Blennow and Mathias Skovmand-Larsen and Swiegers, {Jan H.} and Petersen, {Gert B.} and Hanne Heimdal and Nielsen, {Dennis Sandris}",

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T1 - Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate

AU - Crafack, Michael

AU - Keul, Hanna

AU - Eskildsen, Carl Emil Aae

AU - Petersen, Mikael Agerlin

AU - Saerens, Sofie

AU - Blennow, Andreas

AU - Skovmand-Larsen, Mathias

AU - Swiegers, Jan H.

AU - Petersen, Gert B.

AU - Heimdal, Hanne

AU - Nielsen, Dennis Sandris

N1 - 2nd Conference on Coffee Cocoa and Tea Science (CoCoTea2013)

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Y1 - 2014/9

N2 - The sensory quality of chocolate is widely determined by the qualitative and quantitative composition of volatile compounds resulting from microbial metabolism during fermentation, and Maillard reactions taking place during drying, roasting and conching. The influence of applying mixed starter cultures on the formation of flavour precursors, composition of volatile aroma compounds and sensory profile was investigated in cocoa inoculated with cultures encompassing a highly aromatic strain of Pichia kluyveri or a pectinolytic strain of Kluyveromyces marxianus, and compared to commercially fermented heap and tray cocoa. Although only minor differences in the concentration of free amino acids and reducing sugars was measured, identification and quantification by dynamic headspace gas chromatography-mass spectrometry (HS/GC-MS) revealed pronounced differences in the composition of volatiles in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri inoculated chocolate was characterized by a significantly higher concentration of phenylacetaldehyde and the K. marxianus inoculated chocolate by significantly higher amounts of benzyl alcohol, phenethyl alcohol, benzyl acetate and phenethyl acetate compared to a spontaneously fermented control. Sensory profiling described the heap and tray fermented chocolates as sweet with cocoa and caramel flavours, whilst the inoculated chocolates were characterized as fruity, acid and bitter with berry, yoghurt and balsamic flavours. The choice of fermentation technique had the greatest overall impact on the volatile aroma and sensory profile, but whilst the application of starter cultures did affect the volatile aroma profile, differences were too small to significantly change consumer perception of the chocolates as compared to a spontaneously fermented control.

AB - The sensory quality of chocolate is widely determined by the qualitative and quantitative composition of volatile compounds resulting from microbial metabolism during fermentation, and Maillard reactions taking place during drying, roasting and conching. The influence of applying mixed starter cultures on the formation of flavour precursors, composition of volatile aroma compounds and sensory profile was investigated in cocoa inoculated with cultures encompassing a highly aromatic strain of Pichia kluyveri or a pectinolytic strain of Kluyveromyces marxianus, and compared to commercially fermented heap and tray cocoa. Although only minor differences in the concentration of free amino acids and reducing sugars was measured, identification and quantification by dynamic headspace gas chromatography-mass spectrometry (HS/GC-MS) revealed pronounced differences in the composition of volatiles in roasted cocoa liquors and finished chocolates. 19 of the 56 volatile compounds identified in the chocolates were found in significantly higher amounts in the tray fermented sample, whilst significantly higher amounts of 2-methoxyphenol was measured in the two inoculated chocolates. The P. kluyveri inoculated chocolate was characterized by a significantly higher concentration of phenylacetaldehyde and the K. marxianus inoculated chocolate by significantly higher amounts of benzyl alcohol, phenethyl alcohol, benzyl acetate and phenethyl acetate compared to a spontaneously fermented control. Sensory profiling described the heap and tray fermented chocolates as sweet with cocoa and caramel flavours, whilst the inoculated chocolates were characterized as fruity, acid and bitter with berry, yoghurt and balsamic flavours. The choice of fermentation technique had the greatest overall impact on the volatile aroma and sensory profile, but whilst the application of starter cultures did affect the volatile aroma profile, differences were too small to significantly change consumer perception of the chocolates as compared to a spontaneously fermented control.

KW - Cocoa fermentation technique

KW - Kluyveromyces marxianus

KW - Pichia kluyveri

KW - Sensory profiling

KW - Starter culture

KW - Volatile aroma compounds

U2 - 10.1016/j.foodres.2014.04.032

DO - 10.1016/j.foodres.2014.04.032

M3 - Journal article

SN - 0963-9969

VL - 63

SP - 306

EP - 316

JO - Food Research International

JF - Food Research International

IS - Part C

ER -

Impact of starter cultures and fermentation techniques on the volatile aroma and sensory profile of chocolate

Abstract

Keywords

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