HAZELNUT QUALITY INFLUENCES SHELF LIFE OF CHOCOLATE WITH WHOLE NUTS

HAZELNUT QUALITY INFLUENCES SHELF LIFE OF CHOCOLATE WITH WHOLE NUTS ProSweets 2017 Isabell Rothkopf File photo Fraunhofer

Fraunhofer Institute for Process Engineering and Packaging IVV

Overview Whole nuts in chocolate Fat bloom and influencing factors Methods and results Nut quality Storage tests, fat migration and fat bloom Summary and Outlook File photo Fraunhofer

Fat bloom on whole hazelnut chocolates Nut oil migration may cause fat bloom File photos Fraunhofer

Influencing factors from nut and chocolate

Methods for assessment of nut qualities Basic nut quality: Fat content via Caviezel and GC Water content Color after grinding the roasted nuts Surface oil / mobile oil: Surface oil by washing of with solvent Free / mobile oil in a migration test of whole and chopped hazelnuts in cocoa butter Storage test: fat migration and fat bloom Fat migration via NMR or DSC Fat bloom storage test at 18/20/23 C, measurement via DigiEye

Results: Basic quality; Harvest 2013 Nut Fat content (GC) / % Water content / % Akcakoca 62,8 5,14 Ordu 63,9 5,24 Experiment name L* a* b* Water content [g/100g] A 50-142 53,6 10,0 30,0 1,5 A 30-142 60,5 7,2 25,9 1,5 A 9,5-200 58,6 8,3 28,1 1,5 A 7-200 65,6 4,1 22,1 2,0 A predrying-50-142 51,3 10,0 29,8 1,0 A predrying-10-200 48,0 11,3 31,1 1,0 O 50-142 56,1 9,1 28,7 1,4 O 30-142 59,8 7,1 26,9 1,6 O 9,5-200 60,6 6,9 26,7 1,3 O 7-200 65,6 3,5 20,8 2,3

Results: Basic Nut quality - Color Roasting for 50 min @ 142 C results in similar color as 7 min @ 200 C Ordu shows less browning at same roasting conditions than Akcakoca

Centrifugation of the cocoa butter and quantification of nut oil (NMR, DSC, HPLC) Centrifugation of the cocoa butter and quantification of nut oil (NMR, DSC, HPLC) Results: mobile oil chopping Nut Cocoa butter:nuts 50:50 Storage at 45 C (whole) or 30 C (chopped)

Hazelnut oil content [g/100g] Results: mobile oil chopped or whole nuts 45 40 35 30 25 20 15 10 5 0 1 2 3 4 Storage time [weeks] O (30-142) whole O (9.5-200) whole O (30-142) chopped O (9.5-200) chopped

Hazelnut oil content [g/100g] Results: mobile oil roasting degree Whole Akcakoca hazel nuts after four weeks storage 12 10 8 6 4 2 0

hazelnut oil content [%] hazelnut oil content [%] Results: mobile oil Akcakoca and Ordu Oil migration from whole hazelnuts into cocoa butter at different storage temperatures. Increase of hazelnut oil and reaching of a saturation. Oil migration after roasting: O (142 C / 50min) > A (142 C / 30min) Ordu (142 C / 50min) Akcakoca (142 C / 30min) 20 20 18 18 whole nuts Akcakoca 40 C 16 14 16 14 whole nuts Akcakoca 30 C 12 12 10 10 8 8 6 4 whole nuts Ordu 40 C 6 4 2 whole nuts Ordu 30 C 2 0 0 20 40 60 80 storage time [d] 0 0 20 40 60 80 storage time [d]

Methods for assessment of nut qualities Basic nut quality: Fat content via Caviezel and GC Water content Color after grinding the roasted nuts Surface oil / mobile oil: Surface oil by washing of with solvent Free / mobile oil in a migration test of whole and chopped hazelnuts in cocoa butter. Storage test: fat migration and fat bloom Fat migration via NMR or DSC Fat bloom storage test at 18/20/23 C, measurement via DigiEye

Results: Storage test and fat bloom development Dark chocolate: Tempering of the nuts at 27 C Tempering of the chocolate Mixing of nuts and chocolate for 2 min Filling into molds with one nut per chocolate piece Crystallization at 18 C for 1 h Demolding Further stabilization at 18 C for 24h Storage at 18 C/20 C/23 C

Whiteness index [%] Results: Storage test and fat bloom development Fat bloom development on dark chocolate with whole hazelnuts (example: Ordu high temperature roasting) at different storage temperatures. 32 30 28 18 C 20 C 23 C O7-200 26 24 23 C 0d 22 0 2 4 6 8 10 12 Storage time [weeks] WI = 100 100 L 2 + a 2 + b ² 23 C 12d

WI after 78 days storage [-] Results: Storage test and fat bloom development 30 29 28 27 26

Summary Basic nut quality: Breed and provenience (Akcakoca and Ordu) have an impact Roasting at high temperature for short time results in higher water content Surface oil / mobile oil: Hazelnut oil from chopped nuts migrates to fast Higher roasting degree leads to more hazelnut oil migration Akcakoca shows less oil migration than Ordu Storage test: Storage at 23 C leads to fast fat bloom formation and is suitable for accelerated storage tests Ordu shows less dependency on roasting degree than Akcakoca

Outlook Methods Fat content measured via Caviezel and GC leads to different results and destroys the samples nondestructive evaluation e.g. NMR has to be used additionally Surface oil is difficult to measure, but the used oil mobility test is promising Migration in stored bars: DSC sample collection NMR ratio of chocolate and nut Impact factors Breed, provenience, size, climate conditions Higher water content may stabilize the nut structure and reduce oil mobility Impact of mechanical treatment of the nuts and chocolate, comparable to nut skin removal, mixing and transportation during manufacturing is unclear Age of the nuts: time between the harvest periods

Acknowledgment Scientific & experimental work: Wolfgang Danzl Rainer Perren Gottfried Ziegleder Thorsten Tybussek Cristina Heredia Aguirre Judith Stigler Financial support: Providing material: Chocoladefabriken Lindt & Sprüngli GmbH Alfred Ritter GmbH & Co. KG Contact: Isabell Rothkopf Food Process Development phone: +49(0)8161/491-635 email: isabell.rothkopf@ivv.fraunhofer.de