Maria Cristina Casiraghi

Post-Prandial Responses to Cereal Products Enriched with Barley β-Glucan

Background: High amounts of soluble β-glucan in barley products may exert beneficial effects on glucose tolerance and blood lipids. Objective: To investigate the acute postprandial response on plasma glucose, insulin and lipids after consumption of two experimental products made from barley flour enriched with β-glucan in comparison with similar products made from whole-wheat flour. Methods: A group of 10 healthy volunteers (5 males, age 25.4 ± 0.5 y, BMI 22.6 ± 0.7 Kg/m2) received at breakfast, in random order and in different days, portions (40g of available carbohydrate) of different cereal products or white bread consumed together with a load of 90000 UI retinol. Products were crackers and cookies made either from barley or whole-wheat flour in a 2 × 2 design, where the two factors were the cereal source of dietary fiber (DF), and the food processing. Barley products supplied 12 g DF, 50% soluble, with 3.5 g of β-glucan per portion. Whole-wheat products supplied about 14 g of dietary fiber, mainly in the insoluble form, with negligible amount of β-glucan. Fasting and post-prandial glucose and insulin were evaluated for 180 min after the meals; retinyl-palmitate (RP) and triacylglycerol (TAG) were evaluated hourly over 8 hours. Glycemic (GI) and Insulinemic (II) indexes of products were also assessed, using white bread as reference. Results: Glucose curves were significantly different between types of food processing (p < 0.01) but not between cereal sources of DF (p = 0.07). On the contrary, the effect of fiber but not of processing was evident when glucose response was expressed as Glycemic Index (effect of DF p < 0.01, effect of processing p = 0.69). Individual GI values were 78, 81, 49 and 34 for whole-wheat crackers (WWCr), whole-wheat cookies (WWc), barley crackers (BCr) and barley cookies (Bc) respectively. Insulin curves were significantly different both between type of processing and fiber source (p < 0.001 for both effects). Again, insulin indices were different between fiber but not between processing (p < 0.5 and p = 0.174 respectively). RP and TAG daily profiles were not significantly different between the factors studied. Conclusions: Products prepared from barley flour enriched with β-glucan exhibit favourable responses on glucose metabolism, and particularly on insulinemic responses. In general, cookies responded better to the addition of barley fiber than crackers. Our results highlight the complexity of the effect that barley fiber may exert when added to different food products in reducing postprandial metabolic responses.

Process conditions affect starch structure and its interactions with proteins in rice pasta

Structural changes of starch and proteins in rice pasta were investigated as a function of raw-materials and pasta-making conditions, and their impact on cooking behaviour and glycaemic index was assessed. Rice pasta was prepared from untreated or parboiled rice flour by conventional extrusion or by extrusion-cooking. Starch structure was studied by assessing starch accessibility to specific enzymes (α-amylase and pullulanase), and by evaluating the molecular properties of fragments from enzymatic action. Protein solubility in presence/absence of chaotropes and accessibility of protein cysteine thiols allowed to evaluate the intensity and nature of inter-protein interactions. Parboiling stiffens the protein network in rice flour and makes starch more accessible to hydrolysis. Pasta-making induced further changes in the starch structure, that were most evident in pasta made from untreated rice and were mainly related to the amylopectin fraction. Thus, the interplay among structural modifications on starch and/or proteins affects the features of products.

L-Arginine enriched biscuits improve endothelial function and glucose metabolism: A pilot study in healthy subjects and a cross-over study in subjects with impaired glucose tolerance and metabolic syndrome

OBJECTIVE The aim of this study was to evaluate the effects of a new L-arginine-enriched biscuit on endothelial function, insulin sensitivity/secretion and body composition. MATERIALS/METHODS The project was composed of two studies. The first study was an acute pilot postprandial study in 7 healthy subjects that evaluated bio-availability and vascular effects of L-arginine-enriched biscuits that contained 6.6 gL-arginine, 21.9 g carbohydrates, 3.6 g protein, 7.5 g fat and 4.3 g dietary fiber compared with placebo biscuits and 6.6 g powdered L-arginine. Subjects underwent the tests in random order, in at least 14-day intervals. The second study was a double-blind crossover study in 15 obese subjects with IGT and MS. These subjects consumed 6.6 g of L-arginine-enriched biscuits or placebo biscuits in a 1600 kcal diet. Each study period lasted 2 weeks with a 2-week washout in between. Endothelial function, glucose tolerance, insulin sensitivity and insulin secretion were evaluated at the end of each intervention period. RESULTS In the first study, the groups that received the L-arginine-enriched biscuits and the powdered L-arginine had similarly increased L-arginine, NOx and cGMP levels and post-ischemic blood flow (PI-BF). In both cases, these levels were significantly higher than those in the placebo biscuit recipient group. In the second study, the L-arginine-enriched biscuit recipient group displayed increased L-arginine, NOx, cGMP, PI-BF, and Matsuda index levels, whereas their circulating glucose, proinsulin/insulin ratio and fat mass were decreased compared with the placebo biscuit recipient group. CONCLUSIONS L-Arginine-enriched biscuits with low sugar and protein content enhance endothelial function and improve glucose metabolism, insulin sensitivity and insulin secretion in subjects with IGT and MS.

Lack of effect of high temperature drying on digestibility of starch in spaghetti

The aim of this work was to study the influence of three different drying temperatures on starch digestibility in spaghetti. Completeness of starch digestion and glycaemic response to three types of spaghetti dried at 50, 80 and 90 ·C were evaluated using the breath H2 and the glycaemic index techniques in six healthy volunteers. Samples of spaghetti were analysed for starch susceptibility to α-amylolysis in vitro. No differences were found either in glycaemic response or degree of carbohydrate malabsorption among samples. In vitro results revealed a small but significant decrease in starch digestibility for the higher drying temperature. We conclude that even though heat treatment induced modification in starch digestibility, possibly by affecting starch availability to α-amylase, these differences did not seem to influence significantly the physiological processes of digestion in vivo.

Effects of a synbiotic milk product on human intestinal ecosystem

Aims:  To investigate the effect of prolonged consumption of a synbiotic milk (Synbiotic) containing Lactobacillus acidophilus (strain 74‐2, 107 CFU ml−1), Bifidobacterium lactis (strain 420, 107 CFU ml−1) and 2% inulin on colonic ecosystem in healthy humans.

Quality and nutritional properties of pasta products enriched with immature wheat grain

In this study, nutritional and sensory properties of pasta enriched with 30% immature wheat grain (IWG), a natural source of fructo-oligosaccharides (FOS), are evaluated. Colour and cooking quality, nutritional value and glycaemic index (GI) of pasta were assessed in comparison with commercially enriched inulin and 100% wholewheat pastas. IWG integration induced deep changes in colour, without negatively affecting the cooking quality of pasta, and promoted nutritional quality by increasing the fibre content; IWG pasta presented a remarkable leaching of FOS in cooking water, thus providing only 1 g of FOS per serving. IWG pastas showed a GI of 67 (dried) and 79 (fresh), not significantly different from commercial pasta products. IWG can be considered an interesting ingredient to obtain functional products ‘naturally enriched’ in FOS and fibre. Results about FOS leaching suggest that, in dealing with functional effects, the actual prebiotic content should be carefully considered on food ‘as eaten’.

Microbiota in anorexia nervosa: The triangle between bacterial species, metabolites and psychological tests

Anorexia nervosa (AN) is a psychiatric disease with devastating physical consequences, with a pathophysiological mechanism still to be elucidated. Metagenomic studies on anorexia nervosa have revealed profound gut microbiome perturbations as a possible environmental factor involved in the disease. In this study we performed a comprehensive analysis integrating data on gut microbiota with clinical, anthropometric and psychological traits to gain new insight in the pathophysiology of AN. Fifteen AN women were compared with fifteen age-, sex- and ethnicity-matched healthy controls. AN diet was characterized by a significant lower energy intake, but macronutrient analysis highlighted a restriction only in fats and carbohydrates consumption. Next generation sequencing showed that AN intestinal microbiota was significantly affected at every taxonomic level, showing a significant increase of Enterobacteriaceae, and of the archeon Methanobrevibacter smithii compared with healthy controls. On the contrary, the genera Roseburia, Ruminococcus and Clostridium, were depleted, in line with the observed reduction in AN of total short chain fatty acids, butyrate, and propionate. Butyrate concentrations inversely correlated with anxiety levels, whereas propionate directly correlated with insulin levels and with the relative abundance of Roseburia inulinivorans, a known propionate producer. BMI represented the best predictive value for gut dysbiosis and metabolic alterations, showing a negative correlation with Bacteroides uniformis (microbiota), with alanine aminotransferase (liver function), and with psychopathological scores (obsession-compulsion, anxiety, and depression), and a positive correlation with white blood cells count. In conclusion, our findings corroborate the hypothesis that the gut dysbiosis could take part in the AN neurobiology, in particular in sustaining the persistence of alterations that eventually result in relapses after renourishment and psychological therapy, but causality still needs to be proven.

Study of the Chemical Changes and Evolution of Microbiota During Sourdoughlike Fermentation of Wheat Bran

ABSTRACT Several studies have emphasized the possibility of enhancing nutritional properties of cereal by-products through biotechnological processes. Bran fermentation positively affects the bioavailability of several functional compounds. Moreover, bran fermentation could increase water-extractable arabinoxylans (WEAX), compounds with positive effects on glucose metabolism and prebiotic properties. This study was aimed at increasing the amount of bran bioactive compounds through a sourdoughlike fermentation process. Wheat bran fermentations were conducted through continuous propagation by back-slopping of fermented bran (10% inoculum) until a stable microbiota was established, reaching high counts of lactic acid bacteria and yeasts (109 and 107 CFU/g, respectively). At each refreshment step, bacterial strains were isolated, clustered, molecularly analyzed by randomly amplified polymorphic DNA, and identified at the species level by 16S rRNA gene sequencing. Leuconostoc mesenteroides, Lactobacillus brevi...

Rett Syndrome: A Focus on Gut Microbiota

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder affecting 1 in 10,000 live female births. Changes in microbiota composition, as observed in other neurological disorders such as autism spectrum disorders, may account for several symptoms typically associated with RTT. We studied the relationship between disease phenotypes and microbiome by analyzing diet, gut microbiota, and short-chain fatty acid (SCFA) production. We enrolled eight RTT patients and 10 age- and sex-matched healthy women, all without dietary restrictions. The microbiota was characterized by 16S rRNA gene sequencing, and SCFAs concentration was determined by gas chromatographic analysis. The RTT microbiota showed a lower α diversity, an enrichment in Bacteroidaceae, Clostridium spp., and Sutterella spp., and a slight depletion in Ruminococcaceae. Fecal SCFA concentrations were similar, but RTT samples showed slightly higher concentrations of butyrate and propionate, and significant higher levels in branched-chain fatty acids. Daily caloric intake was similar in the two groups, but macronutrient analysis showed a higher protein content in RTT diets. Microbial function prediction suggested in RTT subjects an increased number of microbial genes encoding for propionate and butyrate, and amino acid metabolism. A full understanding of these critical features could offer new, specific strategies for managing RTT-associated symptoms, such as dietary intervention or pre/probiotic supplementation.

In Vitro Starch Digestibility of Commercial Gluten‐Free Pasta: The Role of Ingredients and Origin

Gluten replacement in gluten-free (GF) products presents major challenges for the food industry in terms of sensorial, technological and nutritional characteristics. The absence of gluten reportedly affects starch digestibility, thus increasing the postprandial glycaemic response. However, the role of ingredients and processing conditions has been addressed only seldom. We investigated the in vitro starch digestibility of 9 commercial GF products (5 Italian pasta and 4 Oriental noodles) differing in formulation and processing conditions. Content of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) were assessed and combined with information on starch pasting properties and on the overall protein organization. Oriental noodles presented higher relative levels of RS and RDS than Western-style pasta, that often had SDS levels compatible with low rates of starch digestion. As regard formulation, presence of multiple ingredients seems to likely increase the RDS level, as did the different protein organization in the various samples.