Publications by authors named "Mauro Marengo"

22 Publications

  • Page 1 of 1

Cefoxitin treatment of MRSA leads to a shift in the IL-12/IL-23 production pattern in dendritic cells by a mechanism involving changes in the MAPK signaling.

Mol Immunol 2021 Mar 3;134:1-12. Epub 2021 Mar 3.

Department of Veterinary and Animal Sciences, University of Copenhagen, Copenhagen, Denmark. Electronic address:

Methicillin resistant Staphylococcus aureus (MRSA) constitute a serious health care problem worldwide. This study addresses the effect of β-lactam treatment on the ability of clinically relevant MRSA strains to induce IL-12 and IL-23. MRSA strains induced a dose-dependent IL-12 response in murine bone-marrow-derived dendritic cells that was dependent on endocytosis and acidic degradation. Facilitated induction of IL-12 (but not of IL-23) called for activation of the MAP kinase JNK, and was suppressed by p38. Compromised peptidoglycan structure in cefoxitin-treated bacteria - as denoted by increased sensitivity to mutanolysin -caused a shift from IL-12 towards IL-23. Moreover, cefoxitin treatment of MRSA led to a p38 MAPK-dependent early up-regulation of Dual Specificity Phosphatase (DUSP)-1. Compared to common MRSA, characteristics associated with a persister phenotype increased intracellular survival and upon cefoxitin treatment, the peptidoglycan was not equally compromised and the cytokine induction still required phagosomal acidification. Together, these data demonstrate that β-lactam treatment changes the MRSA-induced IL-12/IL-23 pattern determined by the activation of JNK and p38. We suggest that accelerated endosomal degradation of the peptidoglycan in cefoxitin-treated MRSA leads to an early expression of DUSP-1 and accordingly, a reduction in the IL-12/IL-23 ratio in dendritic cells. This may influence the clearance of S. aureus.
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http://dx.doi.org/10.1016/j.molimm.2021.02.025DOI Listing
March 2021

Effect of Sprouting on Proteins and Starch in Quinoa (Chenopodium quinoa Willd.).

Plant Foods Hum Nutr 2020 Dec 17;75(4):635-641. Epub 2020 Oct 17.

Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, via G. Celoria 2, 20133, Milan, Italy.

This study aims at understanding the relation among sprouting time (from 12 up to 72 h), changes in protein and starch components, and flour functionality in quinoa. Changes related to the activity of sprouting-related proteases were observed after 48 h of sprouting in all protein fractions. Progressive proteolysis resulted in relevant modification in the organization of quinoa storage proteins, with a concomitant increase in the availability of physiologically relevant metals such as copper and zinc. Changes in the protein profile upon sprouting resulted in improved foam stability, but in impaired foaming capacity. The increased levels of amylolytic enzymes upon sprouting also made starch less prompt to gelatinize upon heating. Consequently, starch re-association in a more ordered structure upon cooling was less effective, resulting in low setback viscosity. The nature and the intensity of these modifications suggest various possibilities as for using flour from sprouted quinoa as an ingredient in the formulation of baked products.
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http://dx.doi.org/10.1007/s11130-020-00864-6DOI Listing
December 2020

Probiotic Administration Increases Amino Acid Absorption from Plant Protein: a Placebo-Controlled, Randomized, Double-Blind, Multicenter, Crossover Study.

Probiotics Antimicrob Proteins 2020 12;12(4):1330-1339

Human Performance Laboratory, School of Exercise & Sport Science, University of Mary Hardin-Baylor, Belton, TX, USA.

The fate of dietary protein in the gut is determined by microbial and host digestion and utilization. Fermentation of proteins generates bioactive molecules that have wide-ranging health effects on the host. The type of protein can affect amino acid absorption, with animal proteins generally being more efficiently absorbed compared with plant proteins. In contrast to animal proteins, most plant proteins, such as pea protein, are incomplete proteins. Pea protein is low in methionine and contains lower amounts of branched-chain amino acids (BCAAs), which play a crucial role in muscle health. We hypothesized that probiotic supplementation results in favorable changes in the gut microbiota, aiding the absorption of amino acids from plant proteins by the host. Fifteen physically active men (24.2 ± 5.0 years; 85.3 ± 12.9 kg; 178.0 ± 7.6 cm; 16.7 ± 5.8% body fat) co-ingested 20 g of pea protein with either AminoAlta™, a multi-strain probiotic (5 billion CFU L. paracasei LP-DG® (CNCM I-1572) plus 5 billion CFU L. paracasei LPC-S01 (DSM 26760), SOFAR S.p.A., Italy) or a placebo for 2 weeks in a randomized, double-blind, crossover design, separated by a 4-week washout period. Blood samples were taken at baseline and at 30-, 60-, 120-, and 180-min post-ingestion and analyzed for amino acid content. Probiotic administration significantly increased methionine, histidine, valine, leucine, isoleucine, tyrosine, total BCAA, and total EAA maximum concentrations (Cmax) and AUC without significantly changing the time to reach maximum concentrations. Probiotic supplementation can be an important nutritional strategy to improve post-prandial changes in blood amino acids and to overcome compositional shortcomings of plant proteins. ClinicalTrials.gov Identifier: ISRCTN38903788.
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http://dx.doi.org/10.1007/s12602-020-09656-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7641926PMC
December 2020

Bio-Functional and Structural Properties of Pasta Enriched with a Debranning Fraction from Purple Wheat.

Foods 2020 Feb 8;9(2). Epub 2020 Feb 8.

Department of Food, Environmental, and Nutritional Sciences (DeFENS), Università degli Studi di Milano, Via G. Celoria 2, 20133 Milan, Italy.

A colored and fiber-rich fraction from the debranning of purple wheat was incorporated at 25% into semolina- and flour-based pasta produced on a pilot-plant scale, with the aim of increasing anthocyanin and total phenolic content with respect to pasta obtained from whole pigmented grains. The debranning fraction impaired the formation of disulfide-stabilized protein networks in semolina-based systems. Recovery of phenolics was impaired by the pasta making process, and cooking decreased the phenolic content in both enriched samples. Cooking-related losses in anthocyanins and total phenolics were similar, but anthocyanins in the cooked semolina-based pasta were around 20% of what was expected from the formulation. HPLC (High Performance Liquid Chromatography) profiling of phenolics was carried out on extracts from either type of enriched pasta both before and after cooking and indicate possible preferential retention of specific compounds in each type of enriched pasta. Extracts from cooked samples of either enriched pasta were tested as inhibitors of enzymes involved in glucose metabolism and uptake, as well as for their capacity of suppressing the response to inflammatory stimuli. Results of both biological tests indicate that the phenolics in extracts from both cooked pasta samples had inhibitory capacities higher than extracts of the original debranning fraction at identical concentrations of total bioactives.
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http://dx.doi.org/10.3390/foods9020163DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7073741PMC
February 2020

Inhibition of Pancreatic α-amylase by Resveratrol Derivatives: Biological Activity and Molecular Modelling Evidence for Cooperativity between Viniferin Enantiomers.

Molecules 2019 Sep 5;24(18). Epub 2019 Sep 5.

Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Via Celoria 2, 20133 Milano, Italy.

To improve the current understanding of the role of stilbenoids in the management of diabetes, the inhibition of the pancreatic α-amylase by resveratrol derivatives was investigated. To approach in a systematic way, the mechanistic and structural aspects of the interaction, potential bioactive agents were prepared as single molecules, that were used for the biological evaluation of the determinants of inhibitory binding. Some dimeric stilbenoids-in particular, viniferin isomers- were found to be better than the reference drug acarbose in inhibiting the pancreatic α-amylase. Racemic mixtures of viniferins were more effective inhibitors than the respective isolated pure enantiomers at an equivalent total concentration, and displayed cooperative effects not observed with the individual enantiomers. The molecular docking analysis provided a thermodynamics-based rationale for the measured inhibitory ability and for the observed synergistic effects. Indeed, the binding of additional ligands on the surface of the alpha-amylase was found to decrease the dissociation constant of inhibitors bound to the active site of the enzyme, thus providing a mechanistic rationale for the observed inhibitory synergies.
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http://dx.doi.org/10.3390/molecules24183225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6766848PMC
September 2019

Effects of starch addition on the activity and specificity of food-grade lipases.

Biotechnol Appl Biochem 2019 Jul 30;66(4):607-616. Epub 2019 May 30.

Section of Chemical and Biomolecular Sciences, Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, Milan, Italy.

Lipases are surface-active enzymes, acting on their substrates at the polar/nonpolar interface in emulsions. This study was aimed to test whether their activity, specificity, and the rates of formation/degradation of the various hydrolysis intermediates (i.e., mono- and diglycerides of interest as surface-active agents) could be modulated by adhesion of the triglyceride substrates as a thin layer on the surface of solids. These hypotheses were tested by using an array of food-grade lipases used in bakery, testing various types of starch as the "solid" phase. Starch-dependent increase in the hydrolysis rate was tested by pH-stat techniques on pure triglycerides and on food-grade oils in diluted emulsions. Starch-related improvements in the rate of fatty acids release were most evident at temperatures above 40 °C, and when using maize starch instead of wheat starch. Starch-dependent changes in the nature of the hydrolysis products were tested by chromatographic profiling of ethyl ether extracts from aqueous slurries containing up to 33% fat and 33% starch. Accumulation of mono- and diglycerides as hydrolysis intermediates was found to be modulated by the type of oil being used, by the reaction conditions, as well as by the enzyme nature and amount.
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http://dx.doi.org/10.1002/bab.1761DOI Listing
July 2019

Greetings from foodland: Teaching biochemistry to BS students in food-related courses in Italy.

Biochem Mol Biol Educ 2019 07 15;47(4):394-403. Epub 2019 Apr 15.

Department of Food, Environmental, and Nutritional Sciences (DeFENS), University of Milan, Milan, Italy.

Biochemistry has always been a mandatory topic within BS courses aimed at food science students at the University of Milan, namely: Food Science & Technology and Catering Sciences. Addressing biochemistry topics in this peculiar setting requires: (i) specific focus on topics that are seldom considered in courses offered in bio-medical curricula; (ii) close integration with other area disciplines, such as food biotechnology; (iii) ad hoc design of laboratory classes; and (iv) an array of elective courses covering specific aspects of biochemistry. In this context, for example, protein chemistry is presented by using food proteins of known structure and discussed in terms of structural features in the raw materials and of structural and chemical modifications occurring upon processing. Along the same lines, metabolic pathways and their regulation are presented starting from widespread metabolism-related issues and to issues related to food safety (including food allergies and intolerances). A similar "hands on" approach is used for laboratory classes, that cover about one third of total credits and are aimed at providing fundamental-type information by analyzing practical situations in the food chain. In spite of their inherent complexity and volume, biochemistry courses score very well with the students in mandatory anonymous surveys. Our approach to biochemistry courses seems to help the students in "visualizing" the practical implications of concepts acquired in other courses within their curricula. The students' appreciation is confirmed by the sizeable attendance to elective and specialized biochemical-themed courses. © 2019 International Union of Biochemistry and Molecular Biology, 47(4):394-403, 2019.
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http://dx.doi.org/10.1002/bmb.21245DOI Listing
July 2019

Topological features of the intermolecular contacts in gluten-forming proteins: Exploring a novel methodological approach based on gold nanoparticles.

Food Res Int 2019 05 8;119:492-498. Epub 2019 Jan 8.

Section of Chemistry and Biomolecular Sciences, DeFENS, University of Milan, Italy.

This work introduces a novel methodological approach to study both the geometry of complex protein networks and the nature of the interacting proteins. This approach is based on the high reactivity of Au ions on the surface of gold nanoparticles (AuNPs) towards thiols, that allows fast formation of a covalent bond between accessible protein thiols and AuNPs. In the case of the durum wheat semolina used in the exploratory studies reported here, the nature of proteins covalently bound to AuNPs is expected to be affected by both the compactness of the protein network and by the AuNPs size. Simple centrifugation procedures allowed recovery of the protein-loaded AuNPs that remained soluble, and the protein(s) covalently bound on the surface of soluble AuNP were identified by MS analysis of their proteolytic fragments. Gluten-forming proteins were found to be bound to soluble AuNPs only when detergents or chaotropes were added to the semolina/AuNPs suspension at room temperature. AuNPs-bound proteins also included gluten-forming proteins with no reported free thiols, suggesting that they are piggybacked on other thiol-containing gluten-forming proteins via disulfide bonds already present in the otherwise untreated semolina. The potential of this approach is discussed in terms of the possibility of developing a methodology suitable for further clarification of the geometrical features of protein networks, of the nature of the involved proteins, and of the type of interaction they establish, as well as any modifications of these features upon processing.
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http://dx.doi.org/10.1016/j.foodres.2019.01.013DOI Listing
May 2019

Surface Layer of MIMLh5 Promotes Endocytosis by Dendritic Cells.

Appl Environ Microbiol 2019 05 18;85(9). Epub 2019 Apr 18.

Department of Veterinary and Animal Sciences, University of Copenhagen, Copenhagen, Denmark

Surface layers (S-layers) are proteinaceous arrays covering the cell walls of numerous bacteria. Their suggested properties, such as interactions with the host immune system, have been only poorly described. Here, we aimed to elucidate the role of the S-layer from the probiotic bacterial strain MIMLh5 in the stimulation of murine bone-marrow-derived dendritic cells (DCs). MIMLh5 induced greater production of interferon beta (IFN-β), interleukin 10 (IL-10), and IL-12p70, compared to S-layer-depleted MIMLh5 (naked MIMLh5 [n-MIMLh5]), whereas the isolated S-layer was a poor immunostimulator. No differences in the production of tumor necrosis factor alpha (TNF-α) or IL-1β were found. Inhibition of the mitogen-activated protein kinases JNK1/2, p38, and ERK1/2 modified IL-12p70 production similarly in MIMLh5 and n-MIMLh5, suggesting the induction of the same signaling pathways by the two bacterial preparations. Treatment of DCs with cytochalasin D to inhibit endocytosis before the addition of fluorescently labeled MIMLh5 cells led to a dramatic reduction in the proportion of fluorescence-positive DCs and decreased IL-12 production. Endocytosis and IL-12 production were only marginally affected by cytochalasin D pretreatment when fluorescently labeled n-MIMLh5 was used. Treatment of DCs with fluorescently labeled S-layer-coated polystyrene beads (Sl-beads) resulted in much greater uptake of beads, compared to noncoated beads. Prestimulation of DCs with cytochalasin D reduced the uptake of Sl-beads more than plain beads. These findings indicate that the S-layer plays a role in the endocytosis of MIMLh5 by DCs. In conclusion, this study provides evidence that the S-layer of MIMLh5 is involved in endocytosis of the bacterium, which is important for strong Th1-inducing cytokine production. Beneficial microbes may positively affect host physiology at various levels, e.g., by participating in immune system maturation and modulation, boosting defenses and dampening reactions, thus affecting the whole homeostasis. As a consequence, the use of probiotics is increasingly regarded as suitable for more extended applications for health maintenance, not only microbiota balancing. This implies a deep knowledge of the mechanisms and molecules involved in host-microbe interactions, for the final purpose of fine tuning the choice of a probiotic strain for a specific outcome. With this aim, studies targeted to the description of strain-related immunomodulatory effects and the identification of bacterial molecules responsible for specific responses are indispensable. This study provides new insights in the characterization of the food-origin probiotic bacterium MIMLh5 and its S-layer protein as a driver for the cross-talk with DCs.
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http://dx.doi.org/10.1128/AEM.00138-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6495763PMC
May 2019

The Bio-Functional Properties of Pigmented Cereals may Involve Synergies among Different Bioactive Species.

Plant Foods Hum Nutr 2019 Mar;74(1):128-134

Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Giovanni Celoria 2, 20133, Milan, Italy.

This study was aimed at characterizing the anthocyanins and phenolics profile in different varieties of pigmented corn and wheat and in some of their milling fractions. Acid/ethanol extracts were used to assess total anthocyanins, overall antioxidant activity, the overall polyphenol profile, and for evaluating the inhibition of pancreatic α-amylase and of intestinal α-glucosidase. Both enzymes were inhibited in a dose-dependent manner by all extracts, but individual extracts had specific effects on each enzyme. Anti-inflammatory response was evaluated by using acid-free extracts and Caco-2 cells transiently transfected with a luciferase reporter gene responding to cytokine stimulation. The immune response of interleukin-stimulated cells decreased significantly in a dose-dependent manner in the presence of 20-50 μM/l anthocyanins from all grains extracts, again with a different efficiency. The inhibitory ability and the anti-inflammatory capability of these extracts are in most cases higher than in similar extracts from other sources, suggesting that activities in each extract may imply specific synergies between anthocyanins and other phenolics.
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http://dx.doi.org/10.1007/s11130-019-0715-4DOI Listing
March 2019

Enriching gluten-free rice pasta with soybean and sweet potato flours.

J Food Sci Technol 2018 Jul 30;55(7):2641-2648. Epub 2018 Apr 30.

1Department of Food, Environmental and Nutritional Sciences, University of Milan, Via G. Celoria 2, 20133 Milan, Italy.

The development of innovative rice products is a way to exploiting and adding value to low-grade African rice varieties. To this purpose, rice-based pasta was enriched with flours from soybean and orange-fleshed sweet potato, that are common ingredients in the African tradition. Four different formulations based on pre-gelatinized rice flour and liquid egg albumen, and containing soybean and/or sweet potato (up to 20%) were prepared and characterized via a multidisciplinary approach. Soybean and sweet potato enrichment leads to a decrease in the pasta consistency and in significant changes in the color of the resulting samples, likely due to Maillard-type reactions. E-sensing approaches indicated that the sensory profile of the various pasta products strongly depends on the type of enrichment. Data collected after cooking suggest that both soybean and sweet potato have a role in defining the firmness and water absorption, as well as the optimum cooking time. Structural characterization of proteins in the uncooked products indicates the presence of protein aggregates stabilized by hydrophobic interactions and disulfide bonds in all samples, although structural properties of the aggregates related to specific compositional traits.
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http://dx.doi.org/10.1007/s13197-018-3185-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6033823PMC
July 2018

Structural consequences of the interaction of puroindolines with gluten proteins.

Food Chem 2018 Jul 31;253:255-261. Epub 2018 Jan 31.

Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, via G. Celoria 2, 20133 Milan, Italy.

The effect of puroindolines (PINs) on structural characteristics of wheat proteins was investigated in Triticum turgidum ssp. durum (cv. Svevo) and Triticum aestivum (cv. Alpowa) and in their respective derivatives in which PIN genes were expressed (Soft Svevo) or the distal end of the short arm of chromosome 5D was deleted and PINs were not expressed (Hard Alpowa). The presence of PINs decreased the amount of cold-SDS extractable proteins and the accessibility of protein thiols to specific reagents, but resulted in facilitated solvation of gluten proteins, as detected by tryptophan fluorescence measurements carried out on minimally mixed flour/water mixtures. We propose that PINs and gluten proteins are interacting in the grain or flour prior to mixing. Hydrophobic interactions between PINs and some of the gluten proteins modify the pattern of interactions among gluten proteins, thus providing an additional mechanistic rationale for the effects of PINs on kernel hardness.
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http://dx.doi.org/10.1016/j.foodchem.2018.01.146DOI Listing
July 2018

Understanding the influence of buckwheat bran on wheat dough baking performance: Mechanistic insights from molecular and material science approaches.

Food Res Int 2017 12 20;102:728-737. Epub 2017 Sep 20.

TNO, Food & Nutrition, Utrechtseweg 48, 3704, HE, Zeist, The Netherlands. Electronic address:

A molecular and material science approach is used to describe the influence of coarse and fine buckwheat bran on wheat dough properties and bread textural quality. Focus is given on (i) gluten solvation and structural arrangements in presence of bran as studied by front-face fluorescence; (ii) thermo-mechanical behavior of dough during heating studied by dynamic mechanical thermal analysis and (iii) texture of bread crumb analyzed in terms of a cellular solid. The thermo-mechanical behavior of dough was found to be largely related to starch phase transitions during heating. The use of thermodynamic approaches to biopolymer melting revealed that key transitions such as the onset of starch gelatinization were function of the interplay of water and bran volume fractions in the dough. Front-face fluorescence studies in wheat dough revealed that gluten solvation and structural arrangements were delayed by increasing bran addition level and reduction in particle size, as indicated by the drastic decrease in the protein surface hydrophobicity index. Variations in gluten structure could be strongly related to dough baking performance, i.e. specific volume. With regards to texture, the approach revealed that crumb texture was controlled by variations in density, moisture and bran volume fractions. Overall, this study elucidates a number of physical mechanisms describing the influence of buckwheat bran addition to dough and bread quality. These mechanisms strongly pointed at the influence of bran on water partitioning among the main polymeric components. In the future, these mechanisms should be investigated with bran material of varying source, composition and structure.
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http://dx.doi.org/10.1016/j.foodres.2017.09.052DOI Listing
December 2017

Physicochemical properties of sorghum flour are selectively modified by combined germination-fermentation.

J Food Sci Technol 2017 Sep 22;54(10):3307-3313. Epub 2017 Aug 22.

Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, via G. Celoria 2, 20133 Milan, Italy.

The combined effects of grain germination and of subsequent fermentation on the physicochemical properties of sorghum flour were investigated by studying the structural changes occurring in the starch and protein fractions and by assessing their effects on physical properties of the resulting materials most relevant to end use. The sequential treatments were more effective than either individual treatment in the modification of starch-related properties, whereas modification of the protein components only occurs in the fermentation step, almost regardless of a previous germination step. The resulting profile of physicochemical traits offers several hints as for the suitability of flour from treated sorghum as an ingredient for various types of gluten-free food products, and provides a basis for expanding the use of processed sorghum in applications other than traditional African foods.
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http://dx.doi.org/10.1007/s13197-017-2781-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5602995PMC
September 2017

Macromolecular Traits in the African Rice Oryza glaberrima and in Glaberrima/Sativa Crosses, and Their Relevance to Processing.

J Food Sci 2017 Oct 29;82(10):2298-2305. Epub 2017 Aug 29.

Dipto. di Scienze per gli Alimenti, la Nutrizione e l'Ambiente (DeFENS), Univ.à degli Studi di Milano, Italy.

Molecular properties of proteins and starch were investigated in 2 accessions of Oryza glaberrima and Oryza sativa, and in one NERICA cross between the 2 species, to assess traits that could be relevant to transformation into specific foods. Protein nature and organization in O. glaberrima were different from those in O. sativa and in NERICA. Despite the similar cysteine content in all samples, thiol accessibility in O. glaberrima proteins was higher than in NERICA or in O. sativa. Inter-protein disulphide bonds were important for the formation of protein aggregates in O. glaberrima, whereas non-covalent protein-protein interactions were relevant in NERICA and O. sativa. DSC and NMR studies indicated only minor differences in the structure of starch in these species, as also made evident by their microstructural features. Nevertheless, starch gelatinization in O. glaberrima was very different from what was observed in O. sativa and NERICA. The content of soluble species in gelatinized starch from the various species in the presence/absence of treatments with specific enzymes indicated that release of small starch breakdown products was lowest in O. glaberrima, in particular from the amylopectin component. These findings may explain the low glycemic index of O. glaberrima, and provide a rationale for extending the use of O. glaberrima in the production of specific rice-based products, thus improving the economic value and the market appeal of African crops.

Practical Application: The structural features of proteins and starch in O. glaberrima are very different from those in O. sativa and in the NERICA cross. These results appear useful as for extending the use of O. glaberrima cultivars in the design and production of specific rice-based products (for example, pasta), that might, in turn, improve the economic value and the market appeal of locally sourced raw materials, by introducing added-value products on the African market.
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http://dx.doi.org/10.1111/1750-3841.13853DOI Listing
October 2017

Stabilization of beta-lactoglobulin by polyols and sugars against temperature-induced denaturation involves diverse and specific structural regions of the protein.

Food Chem 2017 Nov 21;234:155-162. Epub 2017 Apr 21.

Section of Chemical and Biomolecular Sciences, DeFENS, Università degli Studi di Milano, Milano, Italy.

Temperature sensitivity of bovine milk beta-lactoglobulin (BLG) was assessed in the presence/absence of non-reducing sugars (sucrose and trehalose) and polyols (glycerol and sorbitol). None of them affected the structural features of the protein at room temperature, where the only observed effect was an increased affinity towards hydrophobic probes in the presence of all co-solutes but glycerol. Although most of the observed effects in temperature-ramp experiments are due to entropic effects (fitting within the "preferential exclusion" theory of protein stabilization), this study indicates that each co-solute exhibit different efficacy at stabilizing specific regions of BLG, suggesting that each of them acts in a specific way on the solvent/protein system. The relevance of these observations with respect to systems of practical relevance is discussed, given the widespread use of heat-polymerizing proteins - such as BLG - in many food formulations that very often include significant amounts of sugars and/or polyols.
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http://dx.doi.org/10.1016/j.foodchem.2017.04.132DOI Listing
November 2017

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

J Food Sci 2017 Apr 8;82(4):1012-1019. Epub 2017 Mar 8.

Dept. of Food, Environmental, and Nutritional Sciences (DeFENS), Univ. degli Studi di Milano, Via G. Celoria 2, 20133, Milan, Italy.

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.
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http://dx.doi.org/10.1111/1750-3841.13673DOI Listing
April 2017

Soybean-Enriched Snacks Based on African Rice.

Foods 2016 May 20;5(2). Epub 2016 May 20.

Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, Milan 20133, Italy.

Snacks were produced by extruding blends of partially-defatted soybean flour with flours from milled or parboiled African-grown rice. The interplay between composition and processing in producing snacks with a satisfactory sensory profile was addressed by e-sensing, and by molecular and rheological approaches. Soybean proteins play a main role in defining the properties of the protein network in the products. At the same content in soybean flour, use of parboiled rice flour increases the snack's hardness. Electronic nose and electronic tongue discriminated samples containing a higher amount of soybean flour from those with a lower soybean flour content.
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http://dx.doi.org/10.3390/foods5020038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5302339PMC
May 2016

Structural changes in emulsion-bound bovine beta-lactoglobulin affect its proteolysis and immunoreactivity.

Biochim Biophys Acta 2016 Jul 13;1864(7):805-13. Epub 2016 Apr 13.

Section of Chemical and Biomolecular Sciences, DeFENS, University of Milan, Via G. Celoria 2, 20133 Milano, Italy.

Adsorption on the surface of sub-micrometric oil droplets resulted in significant changes in the tertiary structure of bovine beta-lactoglobulin (BLG), a whey protein broadly used as a food ingredient and a major food allergen. The adsorbed protein had increased sensitivity to trypsin, and increased immunoreactivity towards specific monoclonal antibodies. In spite of the extensive tryptic breakdown of emulsion-bound BLG, some sequence stretches in BLG became trypsin-insensitive upon absorption of the protein on the fat droplets. As a consequence - at contrast with free BLG - proteolysis of emulsion-bound BLG did not decrease the immunoreactivity of the protein, and some of the large peptides generated by trypsinolysis of emulsion-bound BLG were still recognizable by specific monoclonal antibodies. Structural changes occurring in emulsion-bound BLG and their consequences are discussed in comparison with those occurring when the tertiary structure of BLG is modified by lipophilic salts, by urea, or upon interaction with solid hydrophobic surfaces. Such a comparison highlights the relevance of situation-specific structural modifications, that in turn may affect physiologically relevant features of the protein.
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http://dx.doi.org/10.1016/j.bbapap.2016.04.007DOI Listing
July 2016

Analysis of Pseudomonas aeruginosa cell envelope proteome by capture of surface-exposed proteins on activated magnetic nanoparticles.

PLoS One 2012 30;7(11):e51062. Epub 2012 Nov 30.

Department of Life Sciences, Università degli Studi di Milano, Milan, Italy.

We report on specific magneto-capturing followed by Multidimensional Protein Identification Technology (MudPIT) for the analysis of surface-exposed proteins of intact cells of the bacterial opportunistic pathogen Pseudomonas aeruginosa. The magneto-separation of cell envelope fragments from the soluble cytoplasmic fraction allowed the MudPIT identification of the captured and neighboring proteins. Remarkably, we identified 63 proteins captured directly by nanoparticles and 67 proteins embedded in the cell envelope fragments. For a high number of proteins, our analysis strongly indicates either surface exposure or localization in an envelope district. The localization of most identified proteins was only predicted or totally unknown. This novel approach greatly improves the sensitivity and specificity of the previous methods, such as surface shaving with proteases that was also tested on P. aeruginosa. The magneto-capture procedure is simple, safe, and rapid, and appears to be well-suited for envelope studies in highly pathogenic bacteria.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0051062PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3511353PMC
May 2013

Structure-quality relationship in commercial pasta: a molecular glimpse.

Food Chem 2012 Nov 10;135(2):348-55. Epub 2012 May 10.

Dipartimento di Scienze Molecolari Agroalimentari, Università di Milano, Via Celoria 2, I-20133 Milano, Italy.

Presence and stability of a protein network was evaluated by fluorescence spectroscopy, by protein solubility studies, and by assessing the accessibility of protein thiols in samples of commercial Italian semolina pasta made in industrial plants using different processes. The pasting properties of starch in each sample were evaluated by means of a viscoamylograph. Magnetic resonance imaging (MRI) was used to evaluate water distribution and water mobility in dry pasta, and at various cooking times. The molecular information derived from these studies was related to sensory indices, indicating that protein reticulation was dependent on the process conditions, which affected water penetration, distribution, and mobility during cooking. Products with a crosswise gradient of water mobility once cooked had the best sensory scores at optimal cooking time, whereas products with a less compact protein network performed better when slightly overcooked.
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http://dx.doi.org/10.1016/j.foodchem.2012.05.026DOI Listing
November 2012

Recognition and uptake of free and nanoparticle-bound betalactoglobulin--a food allergen--by human monocytes.

Mol Nutr Food Res 2011 Nov 23;55(11):1708-16. Epub 2011 Sep 23.

Dipartimento di Scienze Molecolari Agroalimentari, University of Milan, Milan, Italy.

Scope: To improve our understanding of the interaction of food allergens with cells of the immune system, the endocytosis by human monocytes of bovine β-lactoglobulin (BLG) and ovomucoid (OM)--two major food allergens--and human serum albumin (HSA) was studied.

Methods And Results: BLG was covalently conjugated to dextran-coated magnetic nanoparticles (MNPs) without affecting its structure and immunoreactivity. BLG-conjugated MNPs were taken up by human monocytes much more efficiently than non-conjugated MNPs, allowing easy magnetic separation of cells that had adsorbed the allergen. BLG, OM, and HSA were conjugated to MNPs also labeled with a fluorescent probe. The uptake of these materials by human monocytes was monitored through flow cytometry, and compared with fluorescent MNPs and the free fluorescently labeled proteins, confirming higher uptake of the BLG-conjugated MNPs versus non-conjugated MNPs. OM but not HSA conjugation to particles enhanced uptake of the MNPs. Confocal microscopy provided direct evidence of the actual internalization of BLG-MNP conjugates into the cytoplasm.

Conclusions: These results contribute to the current understanding of the interaction between food allergens and antigen-presenting cells, and demonstrate that the BLG is readily endocytosed by monocytes both as the single protein and as a conjugate.
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http://dx.doi.org/10.1002/mnfr.201100386DOI Listing
November 2011