Camilla Melegari

In Vitro Bioaccessibility of Phenolics and Vitamins from Durum Wheat Aleurone Fractions

Durum wheat aleurone, thanks to its nutrient-rich composition, might be of potential use as a functional ingredient in cereal-based foods provided nutrients can be made available for absorption. We evaluated the in vitro bioaccessibility of thiamine, niacin, and phenolic acids in different aleurone fractions obtained with an industrial processing aimed to obtain material of different composition and particle size. Results indicate that the main phenolic compounds and vitamins investigated have a higher bioaccessibility when present in the inner part of the aleurone layer compared to the outer part of aleurone or the unfractionated bran. Moreover, an ultramicronization treatment employed to reduce particle size does not further improve the bioaccessibility of these compounds. We conclude that aleurone fractions from durum wheat bran could represent a nutritionally relevant ingredient, bringing together a high fiber content and an excellent bioaccessibility of vitamins and phytochemicals generally associated with nutritional benefits.

The effect of breakfasts varying in glycemic index and glycemic load on dietary induced thermogenesis and respiratory quotient

BACKGROUND AND AIM Glycemic index (GI) and Glycemic Load (GL) are parameters of carbohydrate bioavailability able to influence risk of chronic diseases. GL can be lowered either by reducing carbohydrate intake or by reducing the GI of the carbohydrate moiety of a mixed meal. These two approaches might have a different impact on Dietary-Induced Thermogenesis (DIT) and preferential substrate oxidation in the postprandial period, which are variables known to be involved in the regulation of body weight and body composition. This dietary, crossover intervention trial was designed to evaluate the effect on DIT and Respiratory Quotient (RQ) of three isocaloric breakfasts different in GI and/or GL (high GI and high GL [HGI-HGL] vs. low GI and low GL [LGI-LGL]; vs. high GI and low GL [HGI-LGL]) followed by a standard meal. METHODS AND RESULTS RQ and DIT were measured in 16 lean young males by indirect calorimetry for 8h. DIT resulted significantly higher after the LGI-LGL compared to the HGI-HGL breakfast (p<0.05). Postprandial changes in RQ differed among all breakfasts (p<0.001). RQ increased from baseline after the two breakfasts with highest carbohydrate content and significantly more after the HGI-HGL than after the LGI-LGL (p<0.02), whereas it decreased after the HGI-LGL breakfast, which contained a higher amount of fat. CONCLUSIONS Reducing the GL of a meal by reducing GI seems an effective strategy to increase energy expenditure while maintaining a good rate of lipid oxidation. This might be related to different profiles of postprandial hormones affecting substrate oxidation.

In Vitro Bioaccessibility of Phenolic Acids from a Commercial Aleurone-Enriched Bread Compared to a Whole Grain Bread

Wheat aleurone, due to its potentially higher bioaccessibility and bioavailability of micronutrients and phenolic acids, could represent a useful ingredient in the production of commonly consumed cereal-based food. The aim of the present study was to investigate the in vitro bioaccessibility of phenolic acids both from an aleurone-enriched bread and from a whole grain bread. The two bread samples were firstly characterized for the phenolic acid content. An in vitro digestion was then performed in order to evaluate the release of phenolic acids. The results obtained suggest that the bioaccessibility of the phenolic acids in the aleurone-enriched bread is higher than in the whole grain bread. These in vitro results suggest the potential use of aleurone in the production of foods, and this may represent an attractive possibility to vehicle nutritionally interesting components to consumers.

Wheat aleurone polyphenols increase plasma eicosapentaenoic acid in rats

Methods These studies were designed to assess whether wheat polyphenols (mainly ferulic acid [FA]) increased the very-long-chain omega-3 fatty acids (VLC n-3) [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] in rats. Wheat aleurone (WA) was used as a dietary source of wheat polyphenols. Two experiments were performed; in the first one, the rats were fed WA or control pellets (CP) in presence of linseed oil (LO) to provide alpha-linolenic acid (ALA), the precursor of VLC n-3. In the second one, the rats were fed WA or CP in presence of control oil (CO) without ALA. The concentrations of phenolic acid metabolites in urine were also investigated. Results The urinary concentration of conjugated FA increased with WA ingestion (p<0.05). Plasma EPA increased by 25% (p<0.05) with WA in the CO group but not in the LO group. In contrast, there was no effect of WA on plasma DHA and omega-6 fatty acids (n-6). Finally, both n-3 and n-6 in the liver remained unchanged by the WA. Conclusion These results suggest that WA consumption has a significant effect on EPA in plasma without affecting n-6. Subsequent studies are required to examine whether these effects may explain partly the health benefits associated with whole wheat consumption.

Wheat aleurone fractions and plasma n−3 fatty acids in rats

Abstract The main aim of this study was to compare the effects of two wheat aleurone (WA) fractions on circulating n−3 fatty acids in rats. We demonstrated that only the fraction able to induce the highest urinary excretion of polyphenol metabolites (>1µmol) resulted in a significant increase in plasma level of Eicosapentanoic acid (+22%, p < 0.05). While other constituents of whole wheat can be involved in this response, our data suggest that cereals containing high levels of phenolic compounds can increase blood n−3 without affecting n−6 fatty acids. Further studies are required to confirm this hypothesis and explore the underlying biological mechanisms.