Relationship of grain fructan content to degree of polymerisation in different barleys.
Nemeth, C., Andersson, A. A. M., Andersson, R., Mangelsen, E., Sun, C. & Åman, P. (2014). Food and Nutrition Sciences, 5, 581-589.
Fructans are important in the survival of plants and also valuable for humans as potentially health promoting food ingredients. In this study fructan content and composition were determined in grains of 20 barley breeding lines and cultivars with a wide variation in chemical composition, morphology and country of origin, grown at one site in Chile. There was significant genotypic variation in grain fructan content ranging from 0.9% to 4.2% of grain dry weight. Fructan degree of polymerisation (DP) was analysed using high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Changes in the distribution of different chain lengths and the pattern of structures of fructan were detected with increasing amount of fructan in the different barleys. A positive correlation was found between fructan content and the relative amount of long chain fructan (DP > 9) (r = 0.54, p = 0.021). Our results provide a basis for selecting promising barley lines and cultivars for further research on fructan in barley breeding with the aim to produce healthy food products.
How does the preparation of rye porridge affect molecular weight distribution of extractable dietary fibers?
Rakha, A., Åman, P. & Andersson, R. (2011). International journal of molecular sciences, 12(5), 3381-3393.
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.
Effect of fructans‐based fat replacer on chemical composition, starch digestibility and sensory acceptability of corn snacks.
Capriles, V. D., Soares, R. A. M., Pinto E Silva, M. E. M. & Arêas, J. A. G. (2009). International Journal of Food Science & Technology, 44(10), 1895-1901.
To develop a convenience healthy food snack the partially hydrogenated vegetable fat, used as the flavour fixative agent, was replaced by a non-fat-flavouring solution enriched with inulin and oligofructose. The effects of this replacement on chemical composition, in vitro rate of starch digestion and sensory acceptability were assessed. The new snack presented low-fat levels (0.1%) and around a sevenfold increase in dietary fibre (15.3% of dietary fibre, being 13.3% of fructans) when compared with the traditional ones. The enrichment with fructans reduced the predicted Glycaemic Index by 25%, thus indicating that this dietary fibre contributes effectively towards delaying the in vitro glycaemic response. Fructans-enriched snack presented overall acceptability score (6.6 ± 1.7) similar to the traditional one, flavoured with fatty fixative agent (7.4 ± 1.4). The healthy low-fat fibre-enriched snack produced presented the high sensory acceptability typical for this food product type.
Measurement of the distribution of non‐structural carbohydrate composition in onion populations by a high‐throughput microplate enzymatic assay.
Revanna, R., Turnbull, M. H., Shaw, M. L., Wright, K. M., Butler, R. C., Jameson, P. E. & McCallum, J. A. (2013). Journal of the Science of Food and Agriculture, 93(10), 2470-2477.
Background: Non-structural carbohydrate (NSC; glucose, fructose, sucrose and fructan) composition of onions (Allium cepa L.) varies widely and is a key determinant of market usage. To analyse the physiology and genetics of onion carbohydrate metabolism and to enable selective breeding, an inexpensive, reliable and practicable sugar assay is required to phenotype large numbers of samples. Results: A rapid, reliable and cost-effective microplate-based assay was developed for NSC analysis in onions and used to characterise variation in tissue hexose, sucrose and fructan content in open-pollinated breeding populations and in mapping populations developed from a wide onion cross. Sucrose measured in microplates employing maltase as a hydrolytic enzyme was in agreement with HPLC-PAD results. The method revealed significant variation in bulb fructan content within open-pollinated ‘Pukekohe Longkeeper’ breeding populations over a threefold range. Very wide segregation from 80 to 600 g kg−1 in fructan content was observed in bulbs of F2 genetic mapping populations from the wide onion cross ‘Nasik Red × CUDH2150’. Conclusion: The microplate enzymatic assay is a reliable and practicable method for onion sugar analysis for genetics, breeding and food technology. Open-pollinated onion populations may harbour extensive within-population variability in carbohydrate content, which may be quantified and exploited using this method. The phenotypic data obtained from genetic mapping populations show that the method is well suited to detailed genetic and physiological analysis.
Effects of prebiotic inulin-type fructans on structure, quality, sensory acceptance and glycemic response of gluten-free breads.
Capriles, V. D. & Arêas, J. A. G. (2013). Food & Function, 4(1), 104-110.
The effect of adding increasing levels of prebiotic inulin-type fructans (ITFs) (0, 4, 8, 10 and 12%) on the sensory and nutritional quality of gluten-free bread (GFB) was assessed. ITFs can provide structure and gas retention during baking, thus improving GFB quality by yielding better specific volume, softer crumb, improved crust and crumb browning with enhanced sensory acceptance. During baking, approximately one-third of the ITFs was lost. The addition of 12% ITFs to the basic formulation is required in order to obtain GFB enriched with 8% ITFs (4 g of fructans per 50 g bread serving size), levels that can provide health benefits. 12% ITFs-addition level decreased GFB glycemic index (from 71 to 48) and glycemic load (from 12 to 8). Prebiotic ITFs are a promising improver for GFB that can provide nutritional (11% dietary fiber content, low glycemic response) and functional benefits to patients with celiac disease, since ITFs are prebiotic ingredients that can also increase calcium absorption.
Characterisation of dietary fibre components in rye products.
Rakha, A., Åman, P. & Andersson, R. (2010). Food Chemistry, 119(3), 859-867.
In this study, dietary fibre (DF) was characterised in rye products from a local supermarket. Soft breads generally had lower DF contents (8–18%) than had crisp breads (13–20%) due to high inclusion of wheat flour. For some products, the labelled DF values contained fructan, but others did not. However, for most products, the DF values analysed exceeded those declared. Arabinoxylan (AX) and fructan were generally the main DF components in the products, followed by cellulose and resistant starch, β-glucan, Klason lignin and arabinogalactan. In the soft breads, cellulose and resistant starch concentrations were relatively high, due to significant formation of resistant starch. During bread manufacturing, the molecular weight of β-glucan was highly degraded, while that of AX was more resistant. Extruded products had the highest β-glucan extractability and the extracted β-glucan retained its molecular weight most, which may be of nutritional significance. In rye milling fractions, about 50% of the fructan content analysed had a degree of polymerisation below 10, i.e. it comprised oligosaccharides. The crisp breads produced without yeast had the highest DF and fructan contents and the highest proportion of low-molecular weight fructan. These results indicate that, during bread-making, the low-molecular weight fraction of fructan was most available for degradation by yeast or by endogenous enzymes present in the ingredients.
Nutrition claims for functional guava mousses produced with milk fat substitution by inulin and/or whey protein concentrate based on heterogeneous food legislations.
Komatsu, T. R., Buriti, F. C. A., da Silva, R. C., Lobo, A. R., Colli, C., Gioielli, L. A. & Saad, S. M. I. (2013). LWT-Food Science and Technology, 50(2), 755-765.
Functional guava mousses were prepared with inulin (I) and whey protein concentrate (WPC), in different combinations, with the purpose of partially or totally substituting their milk fat (MF) content, using a simplex-centroid design. In order to verify the adequacy of mousses to comply the standards for the nutrient content and nutrient comparative claims, their composition and energy values were compared with the food legislation adopted currently in Brazil, the European Union (E.U.), and the United States (U.S.), besides the new proposal for the Brazilian standards. Most of the formulations, especially I, WPC, I + WPC, and MF + I + WPC, and except for MF + WPC, were able to fulfil the requisites for receiving the “low” (nutrient content) and “reduced” (comparative) claims for total and saturated fat. Also, products with inulin could achieve the requisites for the “high” claim for dietary fibre. Nonetheless, important differences between the legislations for achieving some claims were noted, especially when the serving portion was used as standard instead of 100 g. This would require some attention by regulatory authorities, once the possibility of manufacturers to reduce or to increase the products’ serving portions up to achieve a claim, misunderstanding the consumer, may exist.