Migration fat bloom in composed chocolate products: a phenomenological approach

Transcription

1 Migration fat bloom in composed chocolate products: a phenomenological approach Frédéric Depypere Martien Segers, Benny Lewille, Nathalie De Clercq, Koen Dewettinck Universiteit Gent Crystallisation and physical properties of fats: from molecules to market Gent, June 2008

2 Outline Introduction Chocolate bloom Migration fat bloom Research: marbled filled chocolate Conclusions Future

3 Outline Introduction Chocolate bloom Migration fat bloom Research: marbled filled chocolate Conclusions Future

4 Introduction European chocolate manufacture industry 2,000 companies over 200,000 employees over 3 billion Euros export value Producing exclusive niche-oriented composed chocolates technologically more complicated than plain chocolate bars (filling characteristics) bloom on pralines is a major issue (quality problem n 1) leading to shelf life reduction, export hampering, consumer rejection

5 Introduction Flemish technological Advisory Centre for the Chocolate, Biscuits and Confectionary Industries (VLAZ) Ghent University Lab Food Technology and Engineering (FTE) Royal Belgian Federation of the Chocolate, Praline, Biscuits and Confectionary Industries Choprabisco vzw 2003, in 2007 approved by I.W.T.-Vlaanderen for funding till 2011 Since summer of 2005 increased consultancy related to chocolate bloom problems pralines, chocolate bars with hazelnuts, chocolate covered biscuits

6 Outline Introduction Chocolate bloom Migration fat bloom Research: marbled filled chocolate Conclusions Future

7 Chocolate bloom Grey-whitish haze formed on chocolate surface light dispersion on small fat or sugar crystals Sugar bloom caused by condensation (colder warmer) solubilization and recrystallization of chocolate surface Fat bloom pure chocolate: cocoa butter crystal polymorphism (βv βvi) composed chocolate products: migration of liquid foreign lipids (e.g. from the filling, nut, biscuit) into the chocolate

8 Chocolate bloom Cryo-SEM image of the moulded surface of fresh chocolate compared to the same chocolate covered with fat bloom and sugar bloom. All images at same magnification [Courtesy: B. James, University Auckland]

9 Chocolate bloom Cryo-SEM image of fat crystals on chocolate surface. This image is of high cocoa solid pure plain dark chocolate and shows the initial stages of fat bloom. Note the striations on the fat blades suggesting extrusion from the surface. [Courtesy: B. James, University Auckland]

10 Outline Introduction Chocolate bloom Migration fat bloom Research: marbled filled chocolate Conclusions Future

11 Migration fat bloom

12 Migration fat bloom Less research compared to plain chocolate bloom in contrast with current higher industrial relevance! Most data lacks transferability to practice model systems, e.g., cocoa butter instead of chocolate non-realistic production / storage conditions: stabilized (crystallized) chocolate in contact with other phase thick layers of phases physically placed next to / onto each other conditions of tempering / cooling unclear or different from practice accelerated ageing / cycling + too short follow-up time Little research on real products / conditions

13 Research at VLAZ, FTE-UGent Research on commercial products Real manufacturing conditions Real storage conditions room temperature / cooling / freezing no cycling or induced accelerated fat bloom development

14 Outline Introduction Chocolate bloom Migration fat bloom Research: marbled filled chocolate Conclusions Future

15 Marbled filled chocolate Chocolate shell marbled: white chocolate milk chocolate ~ 1-2 mm thickness, variable Filling hazelnut filling milk fat, cocoa butter, hazelnuts, sugar Chocolate irregular shape one location: pure milk chocolate at the surface sample

16 Marbled filled chocolate Triacylglycerol profile of filling versus chocolate FILLING LOO 7.1 % OOO 50.2% POO 5.0% Migration CHOCOLATE LOO 0.0% OOO 0.0% POO 0.5% HPLC-ELSD analysis of TAG (5-10 replicates!) Chocolate enriched with LOO, OOO, POO Decrease of % POP, POS and SOS in chocolate

17 Marbled filled chocolate chocolate TAG as a function of 18 C 9 8 LOO OOO POO TAG (%) ! Migration! Markers: OOO LOO Storage time at 18 C (months)

18 Marbled filled chocolate

19 Marbled filled chocolate Experimental set-up 18 C: bloom development (reference) -20 C followed by thawing believed to retard bloom development logistically / economically expensive operation thawing: avoid condensation stepwise thawing is 4 C an good (sufficient) alternative to freezing?

20 Marbled filled chocolate Experimental set-up 18 C 4 C + 18 C Day 0: production -20 C + 18 C Storage 0-8 months

21 Marbled filled chocolate Results Extent of triglyceride migration Data after 4 months: LOO (%) 4 18 C: 0.47 ± 0.08 (a) C C: 0.06 ± 0.06 (b) 2 4 C C: 0.20 ± 0.13 (b) OOO (%) 4 18 C: 3.52 ± 0.74 (a) C C: 0.52 ± 0.35 (b) 2 4 C C: 1.54 ± 0.93 (b)

22 Marbled filled chocolate Results Extent of triglyceride migration Data after 6 months (similar for LOO): OOO (%) 6 18 C: 4.83 ± 1.89 (a) C C: 2.17 ± 0.84 (b,c) C C: 1.39 ± 0.33 (b) 2 4 C C: 3.30 ± 0.35 (a,c) 4 4 C C: 3.13 ± 2.60 (a,b,c)

23 Marbled filled chocolate Results Extent of triglyceride migration Data after 8 months (similar for LOO): OOO (%) 8 18 C: 6.38 ± 2.44 (a) C C: 4.15 ± 1.74 (b) C C: 2.53 ± 1.03 (c) C C: 2.05 ± 1.61 (c)

24 Marbled filled chocolate Results Extent of triglyceride migration Data after 8 months (similar for LOO): OOO (%) 8 18 C: 6.38 ± 2.44 (a) 2 4 C C: 4.71 ± 1.83 (a,b) 4 4 C C: 3.57 ± 0.78 (b) 6 4 C C: 3.93 ± 0.48 (b)

25 Marbled filled chocolate Results Extent of triglyceride migration Pretreatment at 4 C -20 C? Data after 8 months: (same for LOO) OOO (%) C C: 4.15 ± C C: 4.71 ± C C: 2.53 ± C C: 3.57 ± C C: 2.05 ± C C: 3.93 ± 0.48 p > 0.05 p = 0.05 p < 0.05

26 Marbled filled chocolate Results Effect of pretreatment? Data after 2 18 C : (same for LOO) OOO (%) No pretreatment: 1.98 ± 1.03 (a) C: 0.52 ± 0.35 (b) C: 1.39 ± 0.33 (a) C: 2.05 ± 1.61 (a) 2 4 C: 1.54 ± 0.93 (a) 4 4 C: 3.13 ± 2.60 (a,b,c) 6 4 C: 3.93 ± 0.48 (c)

27 Marbled filled chocolate Results Effect of pretreatment? Data after 4 18 C : (same for LOO) OOO (%) No pretreatment: 3.52 ± 0.74 (a) C: 2.17 ± 0.84 (a) C: 2.53 ± 1.03 (a) 2 4 C: 3.30 ± 0,35 (a) 4 4 C: 3.57 ± 0.78 (a)

28 Marbled filled chocolate Results Visual fat bloom inspection after 6 months 6 trained company employees fresh sample = 100 samples are scored relative to the fresh sample Results score %OOO 6 18 C: ± C C: ± C C: ± C C: ± C C: ± 0.33 No correlation?

29 Marbled filled chocolate Results Taste evaluation after 6 months 6 trained company employees fresh sample = 100 samples are scored relative to the fresh sample Results 6 18 C: score = C C: score = C C: score = C C: score = C C: score = 100 No difference

30 Marbled filled chocolate Results Taste evaluation after 10 months 30 students and staff coworkers Triangle test: different sample? 15/30 correct α = 0,05 to reject H 0 (π correct 1/3) Results C vs C C: 10/30 correct H C vs. 4 C C: 13/30 correct H C C vs. 4 4 C C : 14/30 correct H 0

31 Marbled filled chocolate Results Taste evaluation after 10 months 30 students and staff coworkers Triangle test: different sample? 15/30 correct α = 0,05 to reject H 0 (π correct 1/3) Results Overall no difference in taste ~ storage conditions observed (α = 0,05) Good tasters: lower temperature storage leads to More pronounced hazelnut flavour More perceived sweetness More fresh overall taste

32 Outline Introduction Chocolate bloom Migration fat bloom Research: marbled filled chocolate Conclusions Future

33 Conclusions Storage temperature storage at 4 C and -20 C retard TAG migration storage at -20 C is more effective towards TAG migration Pretreatment storage at -20 C less TAG migration during later storage at RT less or not the case with 4 C: (nearly) equal TAG migration during later storage at RT

34 Conclusions Possible explanation(s) lower temperature slower diffusion less liquid fat in matrix less capillary transport immobilization of LOO and OOO at T < T m (β polymorph: OOO = 5 C, LOO ~ -1 C ) effect crystallization > effect of T on diffusion BUT: towards bloom development 4 C may be sufficient!!

35 Outline Introduction Chocolate bloom Migration fat bloom Research: marbled filled chocolate Conclusions Future

36 Future? Need for a common project with major stakeholders Cooperation between industries and knowledge centers in Europe EU 7th Framework: SME Association project ProPraline Caobisco SME associations (Belgium, Sweden, Czech Republic) Research institutes (Belgium, Sweden, Switzerland, UK, Hungary) SMEs (Belgium, Sweden, Hungary) Large companies (Buhler, AAK) Lifts off at end of summer 2008

37 Future? UGent Cacaolab for in-house production of chocolates (4 kg) Exakt 80S 3-roll mill Bühler Elk olino conche Herbst HR-S3 tempering unit Chocolate World cooling cabinets

38 Acknowledgements B. James, Univ. Auckland Colleagues of FTE Industrial partner Thank you for your attention Questions? Universiteit Gent