Effect of Microwave Radiation Pretreatment of Rice Flour on Gluten-Free Breadmaking and Molecular Size of β-Glucans in the Fortified Breads

Producción CientíficaCereal β-glucan concentrates can be used in gluten-free breads to improve dough handling properties and quality of final products as well as to enhance their nutritional value; however, the presence of endogenous β-glucanases in rice flour, in combination with prolonged mixing, fermentation and proofing time, can cause a substantial reduction in β-glucan molecular weight, affecting detrimentally their efficacy for bioactivity. In this study, microwave (MIWA) heating was applied to the rice flours before breadmaking at different flour water contents (13-25%) and treatment times (0- 4min) to reduce β-glucanase activity. Gluten-free breads made from the MIWA treated rice flours were fortified with oat β-glucan concentrate to enhance their nutritional profile. The molecular weight of added β-glucan in the final products increased with increasing both flour water content and time of MIWA treatment, reflecting the magnitude of residual β-glucanase activity in the flour. Pretreatment with MIWA radiation for 4 min of the rice flour tempered at 25% moisture resulted in negligible residual β-glucanase activity and preserved to a great extent the molecular weight of β-glucans in the enriched breads. End-product quality was not affected by flour MIWA pretreatment, and even a slightly higher loaf specific volume was noted for breads made from the MIWA -treated flours (4min MIWA at 25% moisture content) compared to that of untreated flour. These findings can contribute to the improvement of nutritional value of rice-based gluten-free breads for celiac consumers as well as of any β-glucan containing yeast-leavened bakery product without altering its sensorial attributes. Additional studies are still required for further evaluation of the effect of more intense microwave treatment on rice flour and its application on breadmaking

Effect of b-glucan molecular weight on rice flour dough rheology, quality parameters of breads and in vitro starch digestibility

Producción CientíficaThe study aimed at investigating the effects of molecular weight(peak molecular weight, Mp, 83, 192 and 650 kDa) and level (1.3, 2.6 and 3.9 g/100 g flour basis) of enriched in β-glucan (BG) concentrates (from oat and barley) added into rice flour gluten-free (GF) doughs on their viscoelastic and pasting properties, as well as the quality parameters of bread and the in vitro starch digestibility. A purification process of a commercial BG concentrate, followed by an acid hydrolysis step were employed to reduce the content of interfering excipients (e.g. maltodextrins) and obtain preparations with a range of molecular weights. BG-enriched GF breads of improved quality, that can fulfil the EFSA claims (ingest of 3 g of BG per day with a daily bread intake of ∼200 g of bread), were obtained, exhibiting slower starch digestibility (in vitro assay) dependent on the molecular weight and concentration of BG. With the higher Mp BG used, showing the largest impact on dough rheology characteristics and having a greater potential for health benefits, higher specific volume and lower bread crumb hardness were noted among the GF breads. The medium and lowest Mp BG also had an influence on dough rheological behavior and bread quality attributes. The rapidly available glucose of the bread decreased from 81g/100 g to 72g/100 g as result of the 3.9g/100 g addition of the highest Mp BG in the GF formulations

Impact of acidification and protein fortification on thermal properties of rice, potato and tapioca starches and rheological behaviour of their gels

Producción CientíficaThe impact of acidification and non-gluten protein fortification (egg-albumin and soy-protein isolate) on thermal transitions of rice, potato and tapioca starches as well as the viscoelastic properties of their gels prepared at two casting temperatures, 90ºC and 120ºC, was investigated. The thermal and rheological behaviour of starches depended on their botanical origin and were significantly influenced by the presence and type of protein added as well as by the pH of the aqueous dispersion. Acidification to pH 4.5 increased the gelatinization temperature of rice starch in the presence of albumin or soy proteins, while reduced it in the case of tapioca starch, regardless of the presence of proteins. Acidification of rice starch dispersions decreased significantly the apparent gelatinization enthalpy; this effect was even greater in the presence of proteins. The addition of proteins brought about a structuring effect on tapioca gels leading to higher viscoelastic moduli and lower tan δ values. In general, acidification led to weaker gel structures, with more pronounced effect for potato starch, most likely related to its higher phosphate content (charge screening). Much weaker gels were obtained at 120ºC compared to those processed at lower temperatures; however, protein incorporation reinforced gel structure, an effect that was not observed in gels formed at 90º, as also revealed by microstructure analysis using confocal scanning laser microscopy. In conclusion, protein addition and pH adjustments of aqueous starch dispersions can provide an effective means to modulate the functional and textural properties of gel-like starch-based gluten-free formulations.Ministerio de Economía, Industria y Competitividad - FEDER (Projects AGL2012-35088 and AGL2015-63849-C2-2-R)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA072P17

Inactivation of Endogenous Rice Flour β-Glucanase by Microwave Radiation and Impact on Physico-chemical Properties of the Treated Flour

Producción CientíficaThe apparent reduction of β-glucan (BG) molecular weight in rice based gluten-free (GF) breads fortified with cereal BG concentrates reveals the presence of β-glucanase activity in rice flour. Inactivation of endogenous β-glucanase in rice flour thus seems to be necessary step when developing GF breads enriched with BG of high molecular-weight. The aim of this work was to study the thermal inactivation of endogenous β-glucanase in rice flour by means of microwave (MW) processing; rice flours preconditioned at four different moisture levels (13%, 16%, 19%, 25%) were treated by MW radiation at 900 W and five MW treatment times (ranging from 40s to 8 min, applied stepwise at 20s intervals). The effects of microwaves on starch crystallinity, pasting and thermal properties of MW-treated rice flours were also explored. The β-glucanase activity in rice flours was assessed by the rate of decrease in specific viscosity of a dilute solution of a purified β-glucan preparation, upon addition of flour extracts. MW proved to be a useful alternative for thermal inactivation of endogenous β-glucanase in rice flours when applied to moistened samples. The inactivation process followed a first order kinetic response and the apparent rate constant of thermal inactivation increased exponentially with the moisture content of the flour, M, according to the equation 0.0146·exp (0.212·M) (R2 = 0.97). The MW time required for complete β-glucanase inactivation was only 4 min when the initial flour moisture increased to 25%. Following MW treatment, the starch crystallinity was unaffected (p>0.05) and the side effects of the treatment on flour pasting and thermal properties were rather negligible.Ministerio de Economía, Industria y Competitividad - FEDER (Projects AGL2012-35088 and AGL2015-63849-C2-2-R

Mashes to Mashes, Crust to Crust. Presenting a novel microstructural marker for malting in the archaeological record

The detection of direct archaeological remains of alcoholic beverages and their production is still a challenge to archaeological science, as most of the markers known up to now are either not durable or diagnostic enough to be used as secure proof. The current study addresses this question by experimental work reproducing the malting processes and subsequent charring of the resulting products under laboratory conditions in order to simulate their preservation (by charring) in archaeological contexts and to explore the preservation of microstructural alterations of the cereal grains. The experimentally germinated and charred grains showed clearly degraded (thinned) aleurone cell walls. The histological alterations of the cereal grains were observed and quantified using reflected light and scanning electron microscopy and supported using morphometric and statistical analyses. In order to verify the experimental observations of histological alterations, amorphous charred objects (ACO) containing cereal remains originating from five archaeological sites dating to the 4th millennium BCE were considered: two sites were archaeologically recognisable brewing installations from Predynastic Egypt, while the three broadly contemporary central European lakeshore settlements lack specific contexts for their cereal-based food remains. The aleurone cell wall thinning known from food technological research and observed in our own experimental material was indeed also recorded in the archaeological finds. The Egyptian materials derive from beer production with certainty, supported by ample contextual and artefactual data. The Neolithic lakeshore settlement finds currently represent the oldest traces of malting in central Europe, while a bowl-shaped bread-like object from Hornstaad– Ho¨ rnle possibly even points towards early beer production in central Europe. One major further implication of our study is that the cell wall breakdown in the grain’s aleurone layer can be used as a general marker for malting processes with relevance to a wide range of charred archaeological finds of cereal products

Mashes to Mashes, Crust to Crust. Presenting a novel microstructural marker for malting in the archaeological record

The detection of direct archaeological remains of alcoholic beverages and their production is still a challenge to archaeological science, as most of the markers known up to now are either not durable or diagnostic enough to be used as secure proof. The current study addresses this question by experimental work reproducing the malting processes and subsequent charring of the resulting products under laboratory conditions in order to simulate their preservation (by charring) in archaeological contexts and to explore the preservation of microstructural alterations of the cereal grains. The experimentally germinated and charred grains showed clearly degraded (thinned) aleurone cell walls. The histological alterations of the cereal grains were observed and quantified using reflected light and scanning electron microscopy and supported using morphometric and statistical analyses. In order to verify the experimental observations of histological alterations, amorphous charred objects (ACO) containing cereal remains originating from five archaeological sites dating to the 4th millennium BCE were considered: two sites were archaeologically recognisable brewing installations from Predynastic Egypt, while the three broadly contemporary central European lakeshore settlements lack specific contexts for their cereal-based food remains. The aleurone cell wall thinning known from food technological research and observed in our own experimental material was indeed also recorded in the archaeological finds. The Egyptian materials derive from beer production with certainty, supported by ample contextual and artefactual data. The Neolithic lakeshore settlement finds currently represent the oldest traces of malting in central Europe, while a bowl-shaped bread-like object from Hornstaad–Hornle possibly even points towards early beer production in central Europe. One major further implication of our study is that the cell wall breakdown in the grain's aleurone layer can be used as a general marker for malting processes with relevance to a wide range of charred archaeological finds of cereal products

Drug Survival of Interleukin (IL)‑17 and IL‑23 Inhibitors for the Treatment of Psoriasis: A Retrospective Multi‑country, Multicentric Cohort Study

Background: Drug survival, defined as the length of time from initiation to discontinuation of a given therapy, allows comparisons between drugs, helps to predict patient's likelihood of remaining on a specific treatment, and achieving the best decision for each patient in daily clinical practice. Objective: The aim of this study was to provide data on drug survival of secukinumab, ixekizumab, brodalumab, guselkumab, tildrakizumab, and risankizumab in a large international cohort, and to identify clinical predictors that might have an impact on the drug survival of these drugs. Methods: This was a retrospective, multicentric, multi-country study that provides data of adult patients with moderate to severe psoriasis who started treatment with an interleukin (IL)-17 or IL-23 inhibitor between 1 February 2015 and 31 October 2021. Data were collected from 19 distinct hospital and non-hospital-based dermatology centers from Canada, Czech Republic, Italy, Greece, Portugal, Spain, and Switzerland. Kaplan-Meier estimator and proportional hazard Cox regression models were used for drug survival analysis. Results: A total of 4866 treatment courses (4178 patients)-overall time of exposure of 9500 patient-years-were included in this study, with 3164 corresponding to an IL-17 inhibitor (secukinumab, ixekizumab, brodalumab) and 1702 corresponding to an IL-23 inhibitor (guselkumab, risankizumab, tildrakizumab). IL-23 inhibitors had the highest drug survival rates during the entire study period. After 24 months of treatment, the cumulative probabilities of drug survival were 0.92 (95% confidence interval [CI] 0.89-0.95) for risankizumab, 0.90 (95% CI 0.88-0.92) for guselkumab, 0.80 (95% CI 0.76-0.84) for brodalumab, 0.79 (95% CI 0.76-0.82) for ixekizumab, and 0.75 (95% CI 0.73-0.77) for secukinumab. At 36 months, only guselkumab [0.88 (95% CI 0.85-0.91)], ixekizumab [0.73 (95% CI 0.70-0.76)], and secukinumab [0.67 (95% CI 0.65-0.70)] had more than 40 patients at risk of drug discontinuation. Only two drugs had more than 40 patients at risk of drug discontinuation at 48 months, with ixekizumab demonstrating to have a higher cumulative probability of drug survival [0.71 (95% CI 0.68-0.75)] when compared with secukinumab [0.63 (95% CI 0.60-0.66)]. Secondary failure was the main cause for drug discontinuation. According to the final multivariable model, patients receiving risankizumab, guselkumab, and ixekizumab were significantly less likely to discontinue treatment than those receiving secukinumab. Previous exposure to biologic agents, absent family history of psoriasis, higher baseline body mass index (BMI), and higher baseline Psoriasis Area and Severity Index (PASI) were identified as predictors of drug discontinuation. Conclusion: The cumulative probability of drug survival of both IL-17 and IL-23 inhibitors was higher than 75% at 24 months, with risankizumab and guselkumab demonstrating to have overall cumulative probabilities ≥ 90%. Biological agent chosen, prior exposure to biologic agents, higher baseline BMI and PASI values, and absence of family history of psoriasis were identified as predictors for drug discontinuation. Risankizumab, guselkumab, and ixekizumab were less likely to be discontinued than secukinumab

Structure - function relations of polyssacharides in high and low moisture systems

Structure - function relations of polysaccharides in high and low solvent systems were explored in this study. Pullulan solutions and (1>3), (1>4)-β-D-glucan solutions and hydrogels, as well as amorphous systems of pullulan, chitosan and starch-chitosan and pullulan-chitosan blends plasticized with small amounts of water and/or sorbitol were the study systems. The microbial polysaccharide pullulan was fractionated by a solvent-gradient technique into different molecular mass fractions and characterized by 13C-NMR spectroscopy and high-performance size exclusion chromatography (HPSEC) combined with a multiangle laser light scattering (MALLS) and a refractive index detector (RI). The isolation and purification of β-glucans from three different cereal genera (oat, barley and wheat) was carried out under mild conditions and involved successive enzyme digestions with a thermostable microbial a-amylase, pancreatin, and a microbial xylanase. The molecular size of β-glucans was determined by a HPSEC- RI system and all samples analyzed by NMR spectroscopy (1H, and 13C, and 1H-1H and 1H-13C 2D-NMR) and high-performance anion exchange chromatograph (HPAEC) of the cellulosic oligomers released by the action of lichenase have shown the typical fine structure of mixed-linkage linear (1>3), (1>4)-β-D-glucan. The lichenase digestion of β-glucans from different origins revealed differences in the amounts of 3-O-β-cellobiosyl-D-glucose (DP3) and 3-O-β-cellotriosyl-D-glucose (DP4) in the polymeric chain. Moreover, the total amount of cellulosic oligosaccharides with degrees of polymerization DP?5 was similar (3.6-9.7%) for the cereal β-glucans, whereas it differed significantly from that of lichenan (22,5%). The molar ratios of tri- to tetrasaccharides (DP3/DP4) were found to follow the order of lichenan (24.5) > wheat (3.7) > barley (2.8-3.0) > oat (2.0-2.3). For pullulan samples with weight average molecular weight (Mw) ranging between 100 and 560 x 103, the values of limiting viscosity ([η]), critical concentration (c*) and coil overlap parameter (c*[η]) were within the range 0.38-0.70 dl/g, 1.4-3.1 g/dl and 1.0-1.2, respectively. For β-glucan samples with molecular weight (Mw of the peak fraction of the main eluting peak) ranging between 35 to 250 x 103, the values of limiting viscosity ([η]), second critical concentration (c**) and coil overlap parameter (c**[η]) were within 0.67-3.83 dl/g, 0.70-2.10 g/dl and 1.4-3.2, respectively.Οι σχέσεις της μοριακής δομής και των φυσικοχημικών ιδιοτήτων πολυσακχαριτών μελετήθηκαν τόσο σε συστήματα υψηλής συγκέντρωσης διαλύτη (διαλύματα και υδροπηκτές πουλλουλάνης και (1>3),(1>4)-β-D-γλυκανών) όσο και σε άμορφες καταστάσεις πλαστικοποιημένες με μικρές συγκεντρώσεις νερού και σορβιτόλης (πουλλουλάνη, χιτοσάνη και μίγματα αμύλου-χιτοσάνης και πουλλουλάνης-χιτοσάνης). Η κλασμάτωση του μικροβιακού πολυσακχαρίτη πουλλουλάνη σε κλάσματα διαφορετικού μοριακού μεγέθους έγινε με βαθμίδωση της συγκέντρωσης του διαλύτη και ο χαρακτηρισμός της μοριακής δομής με 13C-NMR φασματοσκοπία και χρωματογραφία αποκλεισμού μεγέθους υψηλής απόδοσης (HPSEC) συνδεμένης με δύο ανιχνευτές, σκεδασμού του φωτός υπό πολλαπλές γωνίες (MALLS) και δείκτη διάθλασης (RI). Η απομόνωση και ο καθαρισμός των β-γλυκανών από τρεις διαφορετικές πηγές δημητριακών καρπών έγινε με ήπιες συνθήκες και περιλάμβανε διαδοχικά υδρολυτικά στάδια με καθαρά ένζυμα, όπως α-αμυλάση (θερμοάντοχη, μικροβιακής προέλευσης), παγκρεατίνη, ξυλανάση (μικροβιακής προέλευσης). Το μοριακό μέγεθος των β-γλυκανών προσδιορίστηκε με HPSEC-RI σύστημα, ενώ η ανάλυση όλων των δειγμάτων των β-γλυκανών με NMR φασματοσκοπία (1Η, 13C και δύο διαστάσεων 1Η-1Η και 1Η-13C φάσματα) και των κυτταρινικών ολιγοσακχαριτών, που απελευθερώνονται από τη δράση της λιχενάσης, με χρωματογραφία ανιοανταλλαγής υψηλής απόδοσης (HPAEC) έδειξε την τυπική πρωτοταγή δομή των γραμμικών (1>3), (1>4)-β-D-γλυκανών. Μεταξύ των ενζυμικών υδρολυμάτων των β-γλυκανών από διαφορετικές πηγές υπήρξαν διαφορές στις μοριακές συγκεντρώσεις του τρισακχαρίτη 3-Ο-β-κελλοβιόζη-D-γλυκόζη (DP3) και του τετρασακχαρίτη 3-Ο-β-κελλοτριόζη-D-γλυκόζη (DP4) στην αλυσίδα του πολυμερούς. Επίσης το συνολικό ποσό των κυτταρινικών ολιγοσακχαριτών με βαθμό πολυμερισμού DP?5 ήταν παρόμοιο (3,6-9,7%) για τις β-γλυκάνες που απομονώθηκαν από δημητριακά (βρώμη, κριθάρι, σιτάρι), αλλά διέφερε σημαντικά στο δείγμα της λιχενάνης (22,5%). Η μοριακή αναλογία DP3/DP4 ακολούθησε τη σειρά λιχενάνη (24,5) > σιτάρι (3,7) > κριθάρι (2,8-3,0) > βρώμη (2,0-2,3). Για τα δείγματα πουλλουλάνης με μέση μοριακή μάζα (Mw) μεταξύ 100 και 560 x 103, οι τιμές του οριακού ιξώδους ([η]), της κρίσιμης συγκέντρωσης (c*) και της παραμέτρου αλληλοεπικάλυψης των αλυσίδων (c*[η]) κυμάνθηκαν μεταξύ 0,38-0,70 dl/g, 1,4-3,1 g/dl και 1,0-1,2, αντίστοιχα. Για τα δείγματα των β-γλυκανών με φαινομενικό μοριακό βάρος (Mw της κορυφής των HPSEC χρωματογραφημάτων) μεταξύ 35 και 250 x 103 οι αντίστοιχες τιμές του [η], της δεύτερης κρίσιμης συγκέντρωσης (c**) και της παραμέτρου αλληλοεπικάλυψης των αλυσίδων (c**[η]) βρέθηκαν μεταξύ των 0,67-3,83 dl/g, 0,7-2,1 g/dl και 1,4-3,2

Molecular weight effects on solution rheology of pullulan and mechanical properties of its films

The effects of molecular weight on solution rheology of pullulan, and on thermomechanichal properties of sorbitol and/or water-plasticized pullulan specimens, prepared by either hot pressing or casting of aqueous solutions, were studied. Pullulan samples differing in molecular weight were characterized by 13C NMR spectroscopy and size exclusion chromatography combined with a multiangle laser light scattering and a refractive index detector. For samples with weight average molecular weight (Mw) ranging between 100 and 560×103, the values of limiting viscosity ([η]), critical concentration (c*) and coil overlap parameter (c*[η]) were within the range 0.38–0.70 dl/g, 1.4–3.1 g/dl and 1.0–1.2 dl/g, respectively. The thermomechanical properties of five molecular weight grades of pullulan, either alone or with sorbitol (plasticized at a 10% d.b. level) were examined by dynamic mechanical thermal analysis (DMTA). A large drop in storage modulus E′ (101.5–103 Pa) and a peak in tan δ in the DMTA traces accompanied the glass–rubber transition (Tg) or the α-relaxation (Tα) of pullulan; the magnitude of the drop in E′ and the tan δ peak height increased with increasing water content. The plasticizing action of water and sorbitol was evident in the DMTA curves, and the Tg vs. moisture content data were fitted to the Gordon–Taylor empirical model. Within the range of molecular weights tested there was no effect of polymer molecular weight on Tg. A β-relaxation detected by DMTA was shifted to lower temperature with increasing moisture content and to higher temperature with addition of sorbitol. Apparent activation energies for α-relaxation (Eαα) and β-relaxation (Eαβ) processes, estimated from multifrequency measurements, were within 171–640 and 118–256 kJ/mol, respectively; the values for Eαα and ‘fragility’ parameter decreased with increasing moisture content. Analysis of viscoelasticity data using the time–temperature superposition principle with the Williams–Landel–Ferry equation was successful over the range Tg to Tg+40 °C, provided that the coefficients C1 and C2 are optimized and not allowed to assume their ‘universal’ values. Large deformation mechanical tests demonstrated large decreases in tensile (Young's) modulus (E) and strength (σmax), and an increase in percentage elongation with increasing water content and/or addition of sorbitol in pullulan films. Relationships between the tensile parameters (E and σmax) and water content showed an increase in stiffness of the films from 3 to 7% moisture, and a strong softening effect at higher water contents. The tensile tests revealed some relationships between mechanical properties under uniaxial load and the molecular characteristics of pullulan, e.g. E, σmax, and elongation values increased with increasing molecular weight

Comparative Evaluation of the Nutritional, Antinutritional, Functional, and Bioactivity Attributes of Rice Bran Stabilized by Different Heat Treatments

The objective of this study was to evaluate the effects of different stabilization treatments—namely, dry-heating, infrared-radiation, and microwave-heating—on the nutritional, antinutritional, functional, and bioactivity attributes of rice bran (RB). Among the heating treatments, infrared-radiation exerted the strongest inactivation, resulting in 34.7% residual lipase activity. All the stabilization methods were found to be effective in the reduction of antinutrients, including phytates, oxalate, saponins, and trypsin inhibitors. No adverse effect of stabilization was noted on chemical composition and fatty acid profile of RB. Instead, stabilization by all heat treatments caused a significant decrease of vitamin E and total phenolics content in RB; the same trend was observed for the antioxidant activity as evaluated by the DPPH test. The antioxidant activity, as evaluated by ABTS and FRAP tests, and water absorption capacity were improved by the stabilization of RB, whereas the oil absorption capacity and emulsifying properties decreased. Microwave-heating enhanced the foaming properties, whereas infrared-radiation improved the water solubility index and swelling power of RB. Consequently, treatment of RB with infrared-radiation has a potential for industrialization to inactivate the lipase and improve some functional properties of this material for uses as a nutraceutical ingredient in food and cosmetic products