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How does the preparation of rye porridge affect molecular weight distribution of extractable dietary fibers?

Rakha A, Aman P, Andersson R - Int J Mol Sci (2011)

Bottom Line: However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight.The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes.The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Science, Swedish University of Agricultural Sciences, Box, 7051, S-75007 Uppsala, Sweden; E-Mails: Per.Aman@slu.se (P.A.); Roger.Andersson@slu.se (R.A.).

ABSTRACT
Extractable dietary fiber (DF) plays an important role in nutrition. This study on porridge making with whole grain rye investigated the effect of rest time of flour slurries at room temperature before cooking and amount of flour and salt in the recipe on the content of DF components and molecular weight distribution of extractable fructan, mixed linkage (1→3)(1→4)-β-d-glucan (β-glucan) and arabinoxylan (AX) in the porridge. The content of total DF was increased (from about 20% to 23% of dry matter) during porridge making due to formation of insoluble resistant starch. A small but significant increase in the extractability of β-glucan (P = 0.016) and AX (P = 0.002) due to rest time was also noted. The molecular weight of extractable fructan and AX remained stable during porridge making. However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight. The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes. The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan. These results show that whole grain rye porridge made without a rest time before cooking contains extractable DF components maintaining high molecular weights. High molecular weight is most likely of nutritional importance.

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Related in: MedlinePlus

Chromatograms showing distribution of fructan in whole grain rye flour and porridge rested for 60 min before cooking. Dotted line (-------) shows chromatogram after fructanase treatment.
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f3-ijms-12-03381: Chromatograms showing distribution of fructan in whole grain rye flour and porridge rested for 60 min before cooking. Dotted line (-------) shows chromatogram after fructanase treatment.

Mentions: In the main experiment, the effects of salt, amount of flour and rest time of flour slurry before cooking on the relative DP distribution of fructan were non-significant (Figure 2). However, the rye flour had slightly more long-chain fructan compared with all porridges tested. The chromatograms for flour and porridge rested for 60 min were very similar (Figure 3). This indicates great stability of fructan during rye porridge making, and thus endogenous fructan hydrolases (FEHs), if present, appear to have very low activity. The DP distribution is only based on relative area and is thus likely to overestimate short oligomers, but this fact does not affect the conclusion that the fructan were stable. The complexity of linkages in cereal fructan and the specificity of FEHs might be the reason for the stability of fructan to endogenous enzymes in rye [24,25]. Another reason for the stability of fructan during resting in this study could be the sub-optimal temperature and pH (20 °C and 6.2, respectively), since the optimum temperature and pH for FEH activity have been shown to be around 40 °C and 4.5–5.5, respectively [26,27]. This stability of rye fructan to endogenous enzymes has also been observed during bread making, where breads made without yeast contain nearly as much fructan as the original rye grain [2,28]. This is an important consideration for modern processing of rye products, where the aim is to avoid losses of physiological functions associated with DF components.


How does the preparation of rye porridge affect molecular weight distribution of extractable dietary fibers?

Rakha A, Aman P, Andersson R - Int J Mol Sci (2011)

Chromatograms showing distribution of fructan in whole grain rye flour and porridge rested for 60 min before cooking. Dotted line (-------) shows chromatogram after fructanase treatment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3116197&req=5

f3-ijms-12-03381: Chromatograms showing distribution of fructan in whole grain rye flour and porridge rested for 60 min before cooking. Dotted line (-------) shows chromatogram after fructanase treatment.
Mentions: In the main experiment, the effects of salt, amount of flour and rest time of flour slurry before cooking on the relative DP distribution of fructan were non-significant (Figure 2). However, the rye flour had slightly more long-chain fructan compared with all porridges tested. The chromatograms for flour and porridge rested for 60 min were very similar (Figure 3). This indicates great stability of fructan during rye porridge making, and thus endogenous fructan hydrolases (FEHs), if present, appear to have very low activity. The DP distribution is only based on relative area and is thus likely to overestimate short oligomers, but this fact does not affect the conclusion that the fructan were stable. The complexity of linkages in cereal fructan and the specificity of FEHs might be the reason for the stability of fructan to endogenous enzymes in rye [24,25]. Another reason for the stability of fructan during resting in this study could be the sub-optimal temperature and pH (20 °C and 6.2, respectively), since the optimum temperature and pH for FEH activity have been shown to be around 40 °C and 4.5–5.5, respectively [26,27]. This stability of rye fructan to endogenous enzymes has also been observed during bread making, where breads made without yeast contain nearly as much fructan as the original rye grain [2,28]. This is an important consideration for modern processing of rye products, where the aim is to avoid losses of physiological functions associated with DF components.

Bottom Line: However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight.The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes.The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Science, Swedish University of Agricultural Sciences, Box, 7051, S-75007 Uppsala, Sweden; E-Mails: Per.Aman@slu.se (P.A.); Roger.Andersson@slu.se (R.A.).

ABSTRACT
Extractable dietary fiber (DF) plays an important role in nutrition. This study on porridge making with whole grain rye investigated the effect of rest time of flour slurries at room temperature before cooking and amount of flour and salt in the recipe on the content of DF components and molecular weight distribution of extractable fructan, mixed linkage (1→3)(1→4)-β-d-glucan (β-glucan) and arabinoxylan (AX) in the porridge. The content of total DF was increased (from about 20% to 23% of dry matter) during porridge making due to formation of insoluble resistant starch. A small but significant increase in the extractability of β-glucan (P = 0.016) and AX (P = 0.002) due to rest time was also noted. The molecular weight of extractable fructan and AX remained stable during porridge making. However, incubation of the rye flour slurries at increased temperature resulted in a significant decrease in extractable AX molecular weight. The molecular weight of extractable β-glucan decreased greatly during a rest time before cooking, most likely by the action of endogenous enzymes. The amount of salt and flour used in the recipe had small but significant effects on the molecular weight of β-glucan. These results show that whole grain rye porridge made without a rest time before cooking contains extractable DF components maintaining high molecular weights. High molecular weight is most likely of nutritional importance.

Show MeSH
Related in: MedlinePlus