Buttermilk solids as health ingredients?

Transcription

1 Buttermilk solids as health ingredients? Les solides du babeurre comme ingrédients santé? Yves Pouliot, Valérie Conway & Sylvie F. Gauthier Centre STELA, Institut des Nutraceutiques et des Aliments Fonctionnels (INAF) Université Laval Repousser les fontières de la science laitière / Beyond frontiers of dairy science Colloque STELA Québec, Qc Mai 2009

2 Why giving attention to buttermilk? It has the composition of skim milk BUT Poor stability & taste Difficult to use as cheese milk Low volumes to process (compared to whey )

3 Why giving attention to buttermilk? Potentially exploitable molecules: Phospholipids Ceramids Bioactive membrane proteins & enzymes (Dewettinck et al., 2008; Spitsberg, 2005) BUT Composition, activity & effects of processing not well characterized

4 The milk fat globule membrane (MFGM) 60-70% of milk s phospholipids MFGM Cream is a emulsion (O/W) stabilized by the MFGM (Robenek & Severs, 2008) (Evers et al., 2008)

5 The milk fat globule membrane (MFGM) (Morin et al., 2007)

6 The milk fat globule membrane (MFGM)

7 The milk fat globule membrane (MFGM) Effects of heat treatment (Gassi, Famelart & Lopez, 2008)

8 Producing buttermilk Cream Buttermilk FMGG Butter MC (Morin et al.,2006)

9 Buttermilk s composition Composition Relative concentration (%) Buttermilk Skim milk Solids Proteins Lactose Lipids Phospholipids Cholesterol N.D. Ash (Morin, 2006; Walstra et al., 2006; MacGibbon & Taylor, 2006)

10 Buttermilk s microstructure (Morin et al., 2007)

11 Buttermilk s properties Many studies* have attributed some health benefits to MFGM components *(Astaire et al., 2003; Noh & Koo, 2003; Noh & Koo, 2004; Spitsberg, 2005; Rombaut & Dewettinck, 2006; Singh, 2006; Dewettinck et al., 2008) Minor lipids from MFGM would have positive effects on cardiovascular health, e.g. some cholesterol-lowering (Noh & Koo, 2004; Spitsberg, 2005)

12 Adding value to buttermilk Since many components of MFGM have been associated with health effects, why not try to separate them from buttermilk?

13 Adding value to buttermilk A number of membrane-based approaches have been unsuccessful until now mainly because MFGM fragments and casein micelles are heterogeneous mixtures having similar size Casein micelles can be removed by coagulation, washing the cream or by dissociating them using Na-citrate but still difficult to separate (Corredig et al., 2003; Morin, 2006; Rombaut et al., 2006; Britten et al., 2008) Losses in MFGM are encountered

14 Research problem The health potential of a number of MFGM components studied in purified form has been evidenced, but how about their effect in the complex buttermilk composition? Can any cholesterol-lowering effect be measured in buttermilk? How would gastrointestinal digestion impact on this property?

15 Hypotheses Buttermilk contains enough cholesterollowering minor compounds, mainly from MFGM, to elicit an in vitro response The biological activity of buttermilk components is maintained upon gastrointestinal digestion

16 Mechanism of cholesterol absorption Transport to intestinal microvilli 1. Solubilization Dissociation 2. Transport from micelles and diffusion 3. Concentration Cholesterol Absorption by the enterocytes (Ros, 2000)

17 Cholesterol lowering-activity? The in vitro micellar solubility of cholesterol (Nagoaka et al., 2002; Ikeda et al., 1992) Principle: The suppression of micellar solubility of cholesterol induces the inhibition of cholesterol absorption in the intestine

18 Objectives 1) To prepare raw and pasteurized buttermilks and to generate differentiated fractions (MFGM) my means of microfiltration (MF) 2) To characterize the cholesterol-lowering activity of buttermilks and their MF-fractions 3) To characterize the impact of in vitro gastrointestinal digestion of buttermilks and their MF-fractions

19 Methodology Membrane processing of buttermilk According to Morin et al (2006) Freshly prepared buttermilk (not rehydrated) Ideally from raw buttermilk Membrane pore size 0.5 m MF temperature 50 o C

20 Methodology

21 Methodology Buttermilk & MF-fractions 1. Effect of pasteurization 2. Effect of fractionation n = 4 (different batches)

22 % of solids Results: Composition of fractions 10 Ash content (means ± SEM) Significant interaction (P < 0.05) Raw Pasteurized 2 0 Buttermilk Permeate Retentate

23 % of solids Results: Composition of fractions Lipid content (means ± SEM) Significant interaction (P < 0.05) Raw Pasteurized Buttermilk Permeate Retentate

24 % of solids Results: Composition of fractions 75 Protein content (means ± SEM) * Raw Pasteurized 15 0 Buttermilk Permeate Retentate

25 Results: Composition of fractions PROTEIN PROFILE (MW) STD MUC1 XO CD36 BTN PAS 6/7 MFGM proteins Raw retentate Pasteurized retentate α-cn β-cn κ-cn β-lg α-la SDS-PAGE (12.5%) for raw and pasteurized fractions 1 : Raw retentate 2 : Pasteurized buttermilk 3 : Raw buttermilk 4 : Pasteurized retentate 5 : Raw permeate 6 : Pasteurized permeate

26 Results: Composition of fractions SUMMARY Significant changes upon MF-fractionation : Protein concentration in retentates Ash concentration in permeates Interactions between T x F in lipid and ash content Following pasteurization : Better lipid retention in retentates Increase of β-lg in the retentates

27 Results: Composition of fractions SUMMARY MF-separation and pasteurization induced important compositional changes... Therefore... Significant differences in micellar solubility of cholesterol should be expected!!

28 Micellar solubility (%) Results: Micellar solubility of cholesterol 100 Micellar solubility of cholesterol (%) in presence of 200 mg of raw and pasteurized buttermilk fractions (Means and SEM (n = 4 ), P < 0.05) Raw Pasteurized 20 No significant difference 0 Buttermilk Retentate Permeate

29 Methodology: In vitro enzymatic hydrolysis Solution of 5 % (w/w) in a gastric salts mixture Peptic hydrolysis (37 C, 2 h and ph at 2.5) Tryptic hydrolysis (37 C, 3 h and ph at 8.0) 5 h-process

30 Micellar solubility (%) Results: Micellar solubility of cholesterol Micellar solubility of cholesterol (%) in presence of 200 mg of raw and pasteurized buttermilk hydrolysates. (Means SEM (n = 3), P < 0.05) Raw Pasteurized 20 0 Control (t = 0 h) Pepic (t = 2 h) Total (t = 5 h)

31 Micellar solubility (%) Results: Micellar solubility of cholesterol Micellar solubility of cholesterol (%) in presence of 200 mg of raw and pasteurized buttermilk hydrolysates (Means SEM (n = 3), P < 0.05) (Significant interaction P < 0.05) Raw Pasteurized Time (h)

32 Results: Micellar solubility of cholesterol SUMMARY No significant effect of MF-fractionation : Buttermilk showed the greatest capacity to the micellar solubility of cholesterol compared to MF-Fractions Negative impact of pumping and shear stress? (McPherson & Kitchen, 1983) Following pasteurization : Negative impact on the capacity to micellar solubility of cholesterol Protein absorption at the MFGM surface? (Corredig & Dalgleish, 1998; Ye et al., 2004) The enzymatic hydrolysis process renversed the negative impact of pasteurization

33 Conclusions Buttermilk showed a cholesterol-lowering capacity in vitro The exact nature of cholesterol-lowering molecules is still unknown Gastrointestinal digestion may improve the cholesterol-lowering potential of buttermilk

34 Conclusions Buttermilk as health ingredient? Why not!!! BUT In vivo experiments need to be done

35 Acknowledgements Collaborators, Michel Britten, Rafael Jiménez-Flores, Benoît Lamarche Past post-doc & Graduate students, Pierre Morin, Jessika Bédard-St-Amant, Sophie Izmiroglu Research Professionnals & technicians Johanne Marin, Diane Gagnon, Alain Gaudreau, Bernard Béliveau, Pascal Cliche, Mélanie Gagnon, Gaétan Desnoyers

36 Acknowledgements Funding Dairy Farmers of Canada Novalait Inc. FQRNT Canadian Dairy Commission NSERC

37 Questions? Thanks to you!!!

38 Results: Composition of fractions Fraction % of solids Ash Protein Lipid Raw Buttermilk Permeate Retentate Pasteurized Buttermilk Permeate Retentate SEM Means ± standard error (n=4), P < 0.05

39 Micellar solubility of cholesterol in vitro Preparation of a micellar solution of cholesterol Ultracentrifugation (1 h 30 à x g) Cholesterol Taurocholic acid Oleic acid Phosphatidylcholine Saponification and hexane extraction Colorimetric method (absorbance at 550 nm) (Nagoaka et al., 2002; Ikeda et al., 1992)