New application of a traditional method: colorimetric sensor array for reducing sugars based on the in-situ formation of core-shell gold nanorod-coated silver nanoparticles by the traditional Tollens reaction.

An effective and robust colorimetric sensor array for simultaneous detection and discrimination of five reducing sugars (i.e., glyceraldehyde (Gly), fructose (Fru), glucose (Glu), maltose (Mal), and ribose (Rib)) has been proposed. In the sensor array, two negatively charged polydielectrics (sodium polystyrenesulfonate (NaPSS) and sodium polymethacrylate (NaPMAA)), which served as the sensing elements, were individually absorbed on the surface of the cetyltrimethylammonium bromide (CTAB)-coated gold nanorods (AuNR) with positive charges through electrostatic action, forming the designed sensor units (NaPSS-AuNR and NaPMAA-AuNR). In the presence of Tollens reagent (Ag(NH3)2OH), Ag+ was absorbed on the surface of negatively charged NaPSS-AuNR and NaPMAA-AuNRs. When confronted with differential reducing sugars, different reducing sugars exhibited differential levels of deoxidizing abilities toward Ag+, thus Ag+ was reduced to diverse amounts of silver nanoparticles (AgNPs) in situ to form core-shell AuNR@AgNP by the traditional Tollens reaction method, leading to distinct colorimetric response patterns (value of AS/AL (the ratio of absorbance at 360 nm to that at 760 nm in Ag+-NaPMAA-AuNR, and the ratio of absorbance at 360 nm to that at 740 nm in Ag+-NaPSS-AuNR)). These response patterns are characteristic for each reducing sugar, and can be quantitatively distinguished by linear discriminant analysis (LDA) at concentrations as low as 10 nM with relative standard deviation (RSD) of 4.11% (n = 3). The practicability of this sensor array has been validated by recognition of reducing sugars in serum and urine samples. A colorimetric sensor array for reducing sugar discrimination based on the reduction of Ag+ and in situ formation of AuNR@AgNP.

A highly stable raw starch digesting α-amylase from Nile tilapia (Oreochromis niloticus) viscera.

A raw starch digesting α-amylase from Nile tilapia (Oreochromis niloticus) intestine was identified. The α-amylase, AMY-T, had an estimated molecular weight of 60 kDa and purified to near homogeneity. AMY-T showed an apparent KM 4.78 mg/mL and Vmax 0.44 mg/mL/min) towards soluble starch. It was highly stable for 24 h in the pH range 3.0-10.0, and to solvents like methanol, isopropanol, butanol, dimethylformamide, DMSO and ethyl-ether. AMY-T was able to digest different carbohydrates, mainly showing endo-activity. Importantly, AMY-T was catalytically efficient and adsorbing towards raw potato starch at temperature documented for other raw starch digesting α-amylases. Thin layer and anion exchange chromatography characterization showed that the end products of raw starch hydrolysis were glucose, maltose and maltodextrins, with degree of polymerisation ranging 1-8. Scanning electron microscopy analysis of the AMY-T treated starch granules documented both granular exo- and endo-attack by AMY-T. These catalytic capabilities suggest high potential for AMY-T for industrial use.

A rapid liquid chromatography-electrospray ionization-ion mobility spectrometry method for monitoring nine representative metabolites in the seedlings of cucumber and wheat.

A fast and convenient high-performance liquid chromatography-electrospray ionization-ion mobility spectrometry method was developed to determine nine representative metabolites in the seedlings of cucumber and wheat. The analytical conditions were obtained by optimizing the parameters of high-performance liquid chromatography and ion mobility spectrometry. Briefly, acetonitrile-0.1% formic acid solution was selected as the mobile phase for gradient elution at a flow velocity of 0.4 mL/min. Under negative electrospray ionization mode, spray voltage of ion mobility spectrometry was 4.5 kV, and drift tube temperature was set at 90°C. The metabolites from seedling leaves were extracted using 80% acetonitrile as the solvent at 4°C for 12 h. Results showed that under soilless culture conditions, the contents of maltose, citric acid, and p-hydroxybenzoic acid in the seedlings of cucumber and wheat were reduced by low concentration of itaconic acid, succinic acid, and citric acid. Importantly, this analytical approach demonstrated high sensitivity, good linear response, and high selectivity. The lowest limit of detection was 0.004 µg for p-hydroxybenzoic acid. Overall, this high-performance liquid chromatography-electrospray ionization-ion mobility spectrometry method is sensitive and efficient for rapid separation and identification of plant metabolites.

Improvement of gluten-free steamed bread quality by partial substitution of rice flour with powder of Apios americana tuber.

This study investigated the effect of powder made from tubers of the legume Apios americana (Apios) as a rice flour substitute in the making of gluten-free steamed bread. The carbohydrates of Apios powder were mainly starch and sucrose, and included legume-specific raffinose and stachyose. Apios powder contained almost no α-amylase but had a high level of ß-amylase activity. Substitution of rice flour with Apios powder delayed the hardening of bread on storage and helped to maintain cohesiveness. Apios powder-substituted bread had higher maltose content than unsubstituted control bread due to ß-amylase activity in the Apios powder. Bread substituted with 10% Apios powder had a significantly higher degree of gelatinization than the control even after storage, most likely due to lower amounts of recrystallized amylose as determined by differential scanning calorimetry. These results demonstrate Apios powder as promising a new food ingredient for improving the quality of gluten-free rice bread.

A temperature-mediated two-step saccharification process enhances maltose yield from high-concentration maltodextrin solutions.

BACKGROUND: Designing a high-concentration (50%, w/w) maltodextrin saccharification process is a green method to increase the productivity of maltose syrup. RESULTS: In this study, a temperature-mediated two-step process using ß-amylase and pullulanase was investigated as a strategy to improve the efficiency of saccharification. During the saccharification process, both pullulanase addition time and temperature adjustment greatly impacted the final maltose yield. These results indicated that an appropriate ß-amylolysis in the first stage (the first 8 h) was required to facilitate saccharification process, with the maltose yield of 8.46% greater than that of the single step saccharification. Molecular structure analysis further demonstrated that a relatively low temperature (50 °C), as compared with a normal temperature (60 °C), in the first stage resulted in a greater number of chains polymerized by at least seven glucose units and a less heterogeneity system within the residual substrate. The molecular structure of the residual substrate might be beneficial for the subsequent cooperation between ß-amylase and pullulanase in the following 40 h (second stage). CONCLUSION: Over a 48 h saccharification, the temperature-mediated two-step process dramatically increased the conversion rate of maltodextrin and yielded significantly more maltose and less byproduct, as compared with a constant-temperature process. The two-step saccharification process therefore offered an efficient and green strategy for maltose syrup production in industry. © 2020 Society of Chemical Industry.

Maltitol: Analytical Determination Methods, Applications in the Food Industry, Metabolism and Health Impacts.

Bulk sweetener maltitol belongs to the polyols family and there have been several dietary applications in the past few years, during which the food industry has used it in many food products: bakery and dairy products, chocolate, sweets. This review paper addresses and discusses in detail the most relevant aspects concerning the analytical methods employed to determine maltitol's food safety and industry applications, its metabolism and its impacts on human health. According to our main research outcome, we can assume that maltitol at lower doses poses little risk to humans and is a good alternative to using sucrose. However, it causes diarrhoea and foetus complications at high doses. Regarding its determination, high-performance liquid chromatography proved the primary method in various food matrices. The future role of maltitol in the food industry is likely to become more relevant as processors seek alternative sweeteners in product formulation without compromising health.

Short communication: Characterization of an atypical maltose-negative Staphylococcus aureus through the use of phenotypic and molecular techniques.

The most clinically relevant staphylococci in veterinary medicine are those that are coagulase-positive, namely Staphylococcus aureus. During microbiological udder health monitoring (2009-2018), a new S. aureus strain (coagulase-positive and maltose-negative) was discovered as an emerging udder pathogen during routine examinations of South African dairy herds. This study challenged the conventional microbiological diagnosis of staphylococci by comparing its results to those of the MALDI-TOF mass spectrometry and 16S rRNA sequencing. Both of these tests confirmed that the maltose-negative staphylococcus (MNS), identified as Staphylococcus pseudintermedius by conventional microbiology, was S. aureus ST2992. Multi locus sequence typing was performed on 3 of the MNS isolates and indicated that these isolates were of single origin. These strains tested positive for both MALA and MALR genes (control: S. aureus ATCC 25923). Although the α-glucosidase gene was present, it was not expressed phenotypically. The latter may be attributed to the abnormal stop codon identified in the MALA gene sequence of S. aureus ST2992 (GenBank accession number, MN531305). The newly identified MNS has a field behavior different to that of maltose-positive S. aureus, and more similar to the low virulence of non-aureus staphylococci.

Fast and Robust Quantification of Detergent Micellization Thermodynamics from Isothermal Titration Calorimetry.

Detergents are widely used in modern in vitro biochemistry and biophysics, in particular to aid the characterization of integral membrane proteins. An important characteristic of these chemicals in aqueous solutions is the concentration above which their molecular monomers self-associate to form micelles, termed the critical micellar concentration (CMC). Micelles are supramolecular assemblies arranged with the hydrophobic portions oriented inward and the hydrophilic head groups positioned outward to interact with the aqueous solvent. Knowledge of the CMC is not only of practical relevance but also of theoretical interest because it provides thermodynamic insights. Isothermal titration calorimetry (ITC) is a powerful method to determine CMCs, as it furnishes additional information on the enthalpy and entropy of micellization. Here we describe our extension of previous methods to determine CMCs and other thermodynamic parameters from ITC demicellization curves. The new algorithm, incorporated into the stand-alone software package D/STAIN, analyzes ITC demicellization curves by taking advantage of state-of-the-art thermogram-integration techniques and automatically providing rigorous confidence intervals on the refined parameters. As a demonstration of the software's capabilities, we undertook ITC experiments to determine the respective CMCs of n-octyl ß-d-glucopyranoside (OG), n-dodecyl ß-d-maltopyranoside (DDM), and lauryldimethylamine N-oxide (LDAO). Motivated by the fact that in vitro membrane protein studies often require additives such as precipitants (e.g., polyethylene glycol (PEG)), we also carried out ITC demicellization studies in the presence of PEG3350, finding in all cases that PEG had significant effects on the thermodynamics of detergent micellization.

Quantitative analysis of wheat maltose by combined terahertz spectroscopy and imaging based on Boosting ensemble learning.

To improve the prediction accuracy of existing data modeling that is based on either spectral data or image data alone, we herein propose a method for the quantitative analysis of wheat maltose contents based on the fusion of terahertz spectroscopy and terahertz imaging, which allows features and balance fusion information to be extracted from the data, and fusion modeling of the feature information to be conducted. Moreover, a Boosting-based, novel multivariate data fusion method and a Boosting iteration termination index based on the structural risk minimization theory are proposed to achieve automatic optimization of the basic model parameters of least squares support vector machines (LS-SVMs). The best results were obtained with data fusion combining spectroscopy and image feature data, with classification performances better than those obtained on single analytical sources, thereby indicating that the multivariate data fusion method proposed is an effective method for the quantitative detection of maltose content in wheat. Furthermore, four unknown maltose concentration wheat samples are analyzed quantitatively using proposed model.

The use of of inulin, maltitol and lecithin as fat replacers and plasticizers in a model reduced-fat mozzarella cheese-like product.

BACKGROUND: Mono-, di- and oligosaccharides, polyhydric alcohols and lipids are three main types of plasticizers used to process food materials. In the present study, inulin, maltitol and lecithin were selected as representative oligosaccharide, polyhydric alcohol and lipid fat replacers, respectively. Their effects on the physicochemical properties of reduced-fat mozzarella cheese were evaluated. RESULTS: Lecithin reduced the hardness and increased the degree of free oil released. Inulin and lecithin decreased the hydrophobic interaction of reduced-fat cheese. Maltitol improved the elasticity of the reduced-fat cheese and increased the hydrophobic interaction within the casein matrix. Maltitol-added cheese had a lower glass transition temperature (Tg ) than the other cheeses. Maltitol significantly improved the stretchability of the reduced-fat cheese. CONCLUSION: The results obtained in the present study suggest that maltitol is an effective fat replacer in reduced-fat mozzarella cheese and might enhance the cheese's functional properties. The Tg of cheese was related to the water and fat content, fat replacer addition and cross-linking degree of casein. The relationship between Tg and the physicochemical properties of cheese will be studied in further research. © 2019 Society of Chemical Industry.

Self-Assembly Behaviors of a Penta-Phenylene Maltoside and Its Application for Membrane Protein Study.

We prepared an amphiphile with a penta-phenylene lipophilic group and a branched trimaltoside head group. This new agent, designated penta-phenylene maltoside (PPM), showed a marked tendency to self-assembly into micelles via strong aromatic-aromatic interactions in aqueous media, as evidenced by 1 H NMR spectroscopy and fluorescence studies. When utilized for membrane protein studies, this new agent was superior to DDM, a gold standard conventional detergent, in stabilizing multiple proteins long term. The ability of this agent to form aromatic-aromatic interactions is likely responsible for enhanced protein stabilization when associated with a target membrane protein.

Salivary α-Amylase Activity and Starch-Related Sweet Taste Perception in Humans.

Starch-related sweet taste perception plays an important role as a part of the dietary nutrient sensing mechanisms in the oral cavity. However, the release of sugars from starchy foods eliciting sweetness has been less studied in humans than in laboratory rodents. Thus, 28 respondents were recruited and evaluated for their starch-related sweet taste perception, salivary alpha-amylase (sAA) activity, oral release of reducing sugars, and salivary leptin. The results demonstrated that a 2-min oral mastication of starchy chewing gum produced an oral concentration of maltose above the sweet taste threshold and revealed that the total amount of maltose equivalent reducing sugars produced was positively correlated with the sAA activity. In addition, respondents who consistently identified the starch-related sweet taste in two sessions (test and retest) generated a higher maltose equivalent reducing sugar concentration compared to respondents who could not detect starch-related sweet taste at all (51.52 ± 2.85 and 29.96 ± 15.58 mM, respectively). In our study, salivary leptin levels were not correlated with starch-related sweet taste perception. The data contribute to the overall understanding of oral nutrient sensing and potentially to the control of food intake in humans. The results provide insight on how starchy foods without added glucose can elicit variable sweet taste perception in humans after mastication as a result of the maltose generated. The data contribute to the overall understanding of oral sensing of simple and complex carbohydrates in humans.

[Method of Quantitative Analysis by HPLC and Confirmation by LC-MS/MS of Erythritol, Maltitol, Lactitol and Trehalose in Foods].

A quantitative determination method of erythritol, maltitol, lactitol and trehalose in foods by HPLC, and confirmation method by LC-MS/MS were developed. HPLC analysis was performed on a separation column packed with amino group-binding polymer with acetonitrile-water (80 : 20) as the mobile phase. The column was operated at room temperature, and the three sugar alcohols and trehalose were quantified. LC-MS/MS confirmation was performed on an amino group-bound column with acetonitrile-ammonium acetate solution as the mobile phase, with detection in the SRM mode. At low sample dilution ratios, the analysis may be affected by matrix derived from the sample, but this can be suppressed by 1,000-fold or greater dilution. Recoveries of the three sugar alcohols and trehalose spiked into food samples, such as tea, jelly, tablets (ramune candy), and chocolate, exceeded 90% (CV≦6.1%) in HPLC and 94% (CV≦4.8%) in LC-MS/MS.

Development of Quantitative Analysis Techniques for Saccharification Reactions Using Raman Spectroscopy.

A technique for the analysis of saccharification reactions by a specific enzyme was developed on the basis of Raman spectroscopy using multivariate analysis. It is a microvolume, quantitative, and in situ technique, which can be used for studying saccharification processes in plant tissues. Prediction models for quantitative analysis of maltose, glucose, and starch were built with partial least squares regression (PLSR) analysis to monitor the saccharification process caused by α-amylase. We examined the reliability of the prediction models built using seven test samples. The spectral regions used to build the models were optimized for each sugar and were selected in such a manner that they did not overlap with strong protein and lipid bands that generally exist in plant tissues. The models were validated by monitoring the composition of reduced sugars and starch in a reactor and by comparing the results with those obtained by a conventional method. The results of Raman analysis and the conventional method showed good agreement for the reaction with α-amylase; however, it is not perfect for reactions with a different enzyme, especially ß-amylase. The results suggest that the present Raman technique is reliable and useful for sugar analysis. However, the prediction model built for a specific enzyme is valid only for that enzyme.

Use of Fourier transform infrared spectroscopy to monitor sugars in the beer mashing process.

Mashing is an enzymatic procedure for the extraction of sugars from malt. It has strong temperature dependence, so monitoring the sugar production is very important for optimization of the brewing process. In this work, Fourier transform infrared spectroscopy (FTIR) was used to monitor three different mashing programs. These all presented high concentrations of maltose and dextrin, enabling their differentiation according to the FTIR absorption bands at 991 and 1022 cm-1, characteristic of maltose and dextrin, respectively. The absorption intensities of these bands were used to monitor the concentrations of the compounds during mashing, and the values were compared to HPLC data. Multivariate analysis of variance was applied to the FTIR absorption intensities in order to separate groups corresponding to the temperature steps of each mashing program. The results demonstrated that infrared absorption offers an alternative to the HPLC method for monitoring the mashing process.

Xylitol, mannitol and maltitol as potential sucrose replacers in burger buns.

Burger buns are a source of added sugar, containing 7-12%, in order to ensure their unique texture and taste. Hence, suitable sugar substitutes for burger buns are urgently needed. This study aimed to elucidate the effect of three different polyols on dough and product quality of burger buns. Xylitol, mannitol and maltitol were incorporated individually in a burger bun system, by replacing added sucrose by 30%, 50% and 100%. Wheat starch was used to compare the impact of polyols with another non-sweet bulking agent. The effects on dough properties as well as on the burger buns themselves were investigated. Compared to sugar-rich doughs, polyols lowered the fermentation quality, resulting in lower dough development (-37 to -81%) and poorer gaseous release (-62 to -87%). Furthermore, a delay in gluten network development (+50 to +161%) and a decrease in extensibility (-14 to -18%) with increasing concentrations were detected. Interestingly, maltitol and xylitol did not affect the pasting properties, whereas mannitol increased pasting temperature (+15 °C). Moreover, polyols did not influence the viscoelastic properties of the dough. The incorporation of sugar alcohols led to a significant decrease in specific volume (-30 to -48%), and to a harder crumb texture (+135 to +678%). Moreover, the L*-value increased with increasing amount of polyols, resulting in a very pale crust colour. In conclusion, a reduction of 50% added sucrose by polyols was applicable, whereas mannitol was the most suitable sugar replacer amongst the polyols tested.

Relationships among Dietary Intakes and Persistent Gastrointestinal Symptoms in Patients Receiving Enzyme Treatment for Genetic Sucrase-Isomaltase Deficiency.

BACKGROUND: Sucrose-isomaltase deficiency (SID) remains underdiagnosed. Absent or reduced enzyme activity promotes diarrhea, abdominal bloating, and flatulence from undigested and malabsorbed disaccharides. Frequency and severity of gastrointestinal symptoms may be associated with the type of carbohydrates consumed. OBJECTIVE: To characterize the dietary intakes of patients treated with sacrosidase (Sucraid; QOL Medical) for SID and determine relationships between type of carbohydrates, sacrosidase dose, and gastrointestinal symptoms. DESIGN: A prospective 30-day observational study. PARTICIPANTS/SETTING: Forty-nine patients treated with sacrosidase for ≥3 months were recruited from the enzyme manufacturer's nationwide clinical database between November 2014 and August 2015. MAIN OUTCOME MEASURES: Dietary energy and nutrient intakes reported during 24-hour diet recall interviews, frequency and severity of gastrointestinal (GI) symptoms, and sacrosidase dose. STATISTICAL ANALYSES PERFORMED: Relationships between nutrient intakes, sacrosidase dose, and GI symptoms were evaluated using Spearman ρ correlation coefficients. RESULTS: Sacrosidase dose averaged 5.2±3.1 mL/day. Participants reported 1.3±0.9 bowel movements daily. Having less frequent GI symptoms was associated with higher sacrosidase intake. Energy intakes averaged 1,562.5±411.5 kcal/day in children, 1,964.7±823.6 kcal/day in adolescents, and 1,952.6±546.5 kcal/day in adults. Macronutrient composition averaged 44% carbohydrate, 39% fat, and 17% protein. Average carbohydrate composition was 35% starch, 8% fiber, and 59% sugars. Sucrose and fructose intakes were not associated with GI symptoms. Lactose intake was associated with diarrhea. Maltose intake was associated with nausea, distension, and reflux. CONCLUSIONS: Intakes were lower in carbohydrates and higher in fat compared with the Acceptable Macronutrient Distribution Ranges. Sucrose and fructose intakes were not associated with GI symptoms. Higher maltose and lactose intakes were associated with GI symptom frequency and severity. These findings provide evidence to guide nutrition counseling for patients treated for SID.

Effects of maltose and lysine treatment on coffee aroma by flash gas chromatography electronic nose and gas chromatography-mass spectrometry.

BACKGROUND: Arabica coffee is a sub-tropical agricultural product in China. Coffee undergoes a series of thermal reactions to form abundant volatile profiles after roasting, so it loses a lot of reducing sugars and amino acids. Adding carbonyl compounds with amino acids before roasting could ensure the nutrition and flavour of coffee. The technology is versatile for the development of coffee roasting process. This investigation evaluates the effects of combining maltose and lysine (Lys) to modify coffee aroma and the possibly related mechanisms. Arabica coffee was pretreated with a series of solvent ratios of maltose and Lys with an identical concentration (0.25 mol L-1 ) before microwave heating. RESULTS: It was found that the combination of maltose and Lys significantly (P ≤ 0.05) influenced quality indices of coffee (pH and browning degree). Ninety-six aromatic volatiles have been isolated and identified. Twelve volatile profiles revealed the relationship between fragrance difference and compound content in coffee. Moreover, coffee aroma was modified by a large number of volatiles with different chemical classes and character. CONCLUSION: Thus, our results suggest that the combination of reagents changed overall aroma quality through a series of complex thermal reactions, especially the ratio of Lys/maltose over 2:1. © 2017 Society of Chemical Industry.

Efficient Expression of Maltohexaose-Forming α-Amylase from Bacillus stearothermophilus in Brevibacillus choshinensis SP3 and Its Use in Maltose Production.

The maltohexaose-forming, Ca2+-independent α-amylase gene from Bacillus stearothermophilus (AmyMH) was efficiently expressed in Brevibacillus choshinensis SP3. To improve the production of AmyMH in B. choshinensis SP3, the temperature and initial pH of culture medium were optimized. In addition, single-factor and response surface methodologies were pursued to optimize culture medium. Addition of proline to the culture medium significantly improved the production of recombinant α-amylase in B. choshinensis SP3. This improvement may result from improved cellular integrity of recombinant B. choshinensis SP3 in existence of proline. Culture medium optimization resulted in an 8-fold improvement in α-amylase yield, which reached 1.72 × 104 U·mL-1. The recombinant α-amylase was applied to the production of maltose on a laboratory scale. A maltose content of 90.72%, which could be classified as an extremely high maltose syrup, could be achieved using 15% (m/v) corn starch as the substrate. This study demonstrated that the B. choshinensis SP3 expression system was able to produce substantial quantities of recombinant α-amylase that has potential application in the starch industry.