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关键词： FAU(Y)   ion exchange   cesium   alkylation   aniline   methanol  

摘要： This study investigates the effects of the degree of ion exchange of sodium cations for cesium cations in FAU(Y) on its physicochemical properties. Using aqueous and solid-state ion exchange, a number of NaY samples with an exchange degree of sodium cations for cesium cations varying from 29 to 89% were prepared. The samples were examined by SEM, X-ray fluorescence, low-temperature nitrogen adsorption, XRD, NH3-TPD, IR spectroscopy of adsorbed chloroform, and Al-27 MAS NMR. It was demonstrated that samples with exchange degrees up to 87% can be synthesized with their crystalline structure intact. The test of the catalytic properties of the synthesized samples in aniline alkylation with methanol showed a growth in the selectivity for N-alkylated products as the number and strength of basic sites were progressively increased. Impregnating the Cs-containing zeolites with CsOH was found to significantly enhance the operating stability of the samples and the yield of N-alkylated products, compared to CsNaY. The CsOH-modified catalysts with a Na+/Cs+ exchange degree of 54-77% proved to be the most active and stable in aniline alkylation with methanol: they provided aniline conversion of 81-88% and selectivity for N-alkylation products as high as 99.6-99.7 mol %.

关键词： Collagen film   Collagen fiber   Glutaraldehyde   Cross-linking   pH   Physicochemical properties  

摘要： Collagen films cross-linked with glutaraldehyde (GTA) at different pH values were prepared to explore the in-fluence of pH on their physicochemical properties. The films were characterized using FTIR spectroscopy, XRD analysis, SDS-PAGE, shrinkage temperature, fluorescence analysis and SEM. The results indicated that cross-linking degree and reaction position were different at different pH values. The optimal cross-linking degree in collagen films was obtained under neutral and alkaline conditions. The main reaction under acidic conditions was intramolecular cross-linking and this gradually shifted to intermolecular cross-linking with an increase in pH. Cross-linked films had improved mechanical properties and thermal stability as well as higher b* values compared to films without cross-linking. These improvements correlated with the degree and position of cross-linking reactions. Controlling the reaction pH can be used to modulate the physicochemical properties of the collagen films to match specific application requirements.

关键词： Germination  

摘要： The effect of soaking, germination, and roasting on some physicochemical properties of defatted Moringa seeds flour was studied using a 2(3) complete factorial design. Soaking was operated for 24 hr in water (1/10, w/v) with changing of water every 4 hr. Germination consisted of soaking seeds previously for 6 hr in water and sprouting for 8 days. Roasting was done at 140 degrees C/50 min. A total of eight treatments were then applied to the seeds which were then dehulled, finely ground, and defatted, and the resulting flours were submitted to physicochemical analysis. The results showed that particle size of defatted flour was bimodal (13 and 300 mu m). The whiteness index varied from 66.9 for the soaked-germinated-unroasted (***) sample to 79.8 for the nonsoaked-germinated-unroasted (***) sample. The moringa flours (treated or untreated) were concentrated in proteins (57.21-70.45 g/100 g DW). While the protein and crude fiber (3.11-5.20 g/100 g DW) contents significantly increased with the treatment, the carbohydrate (14.56-24.67 g/100 g DW) and total dietary fibers (22.99-38.28 g/100 g DW) diminished. The antinutrients/toxicants as saponins, oxalates, phytates, and trypsin inhibitors were significantly (p < .05) reduced with treatment. While most of the antinutrients were at low level in the flour, the glucosinolates were at remarkably higher levels which may induce toxicity if consumed. Glucosinolates ranged 5.84-7.95 g/100 g DW and were not reduced above the tolerance limit (0.79 g/100 g DW). In overall, the treatments induced important improvement of the nutritional quality of the flour with combined treatment being more efficient. Novelty impact statement The combined treatments (***., ***.R, NS.G.R, and S.G.R) were more efficient compared to single treatments (***, ***, and ***.R) with raw (untreated) sample (***) as a reference. The most efficient combined treatment was S.G.R. followed by ***, NS.G.R., and ***.R because they pro

关键词： Ascorbic acid  

摘要： Sweet corn kernels are easily perishable because of their high amount of moisture content. Microwave blanching was applied at the power level of 180-900 W for 30-70 s to inactivate the enzymes of sweet corn kernels. The increase in microwave power level and processing time reduced the length from 11.13 to 10.78 mm, width from 9.54 to 9.24 mm, thickness from 4.01 to 3.71 mm, true density from 1052.07 to 1012.03 kg/m(3), porosity from 37.43 to 24.54%, moisture content from 70.00% to 68.93% on a wet basis, total soluble solid from 22.3 to 18.7 degrees Brix, total sugar from 8.80% to 6.67%, ascorbic acid from 8.04 to 5.92 mg/100 g, and peroxidase activity up to 1.37% in sweet corn kernels, but it increased the bulk density from 658.23 to 763.6 kg/m(3) and total color difference up to 14.55. Novelty impact statement The microwave blanching was found adequate for processing sweet corn kernels at the power level of 720 W for a short duration of 40 s to achieve a 90% reduction in peroxidase activity. The ascorbic acid, total sugar, overall acceptability after the microwave blanching were 6.86 mg/100 g, 7.87%, and 8.21, respectively, indicating 85, 89, and 94% retention of fresh samples properties. The total plate count was 9.1 log cfu/g in fresh kernels, which was also reduced to 1.8 log cfu/g in kernels blanched at the power level of 720 W for 40 s duration.

关键词： Fermentation   functional properties   legumes   microstructural properties   nutritional properties   Rhizopus oligosporus  

摘要： The present study investigated the effect of fermentation by Rhizopus oligosporus on the nutritional, functional, colour and microstructural properties of some commonly consumed legumes, that is, chickpea (kabuli and desi), pigeon pea and soybean. Results revealed a substantial (P < 0.05) increment in the protein (5-14%) and ash (5-15%) contents as well as those of essential (13-21%) and non-essential (3-15%) amino acids with fermentation. Fatty acid composition showed the varied concentrations of polyunsaturated, monounsaturated and saturated fatty acids in fermented legumes. Further, fermentation significantly (P < 0.05) modified the functional and colour properties of legumes. The alteration in the structural conformation of legumes upon fermentation was observed with scanning electron microscopy which confirmed the enzymatic action on the proteins, fibres and lipid bodies. The results concluded that fermentation of these legumes could be a potential approach in developing the novel functional foods to address the concerns of food and nutrition securities.

关键词： Hydrogels  

摘要： The impact of three arabinoxylan (AX) cultivars (262, 44, 229) on the physicochemical, rheological, and microstructural characteristics of AX hydrogels was explored. The gelation of AX262 was faster and the viscoelastic modulus was higher. During the gelation process, the consumption of ferulic acids was 96%, 87%, and 69% for AX262, AX44, and AX229, respectively, indicating a higher oxidative cross-linking degree of AX262. The decline of adsorption intensity for AX262 hydrogel at 1,644 and 3,423 cm(-1) was more pronounced, which might be related to a denser gel network as a result of higher oxidation degree of FA. Meanwhile, AX262 hydrogel was more capable of binding water molecules and exhibited better thermal stability. The difference in the gelation properties of varied AX cultivars lied in the molecular structure. AX262 had a higher ferulic acid content (0.23 mu g/mg) and larger molecular weight with 1.17 x 10(6) Da, contributing to an enhanced oxidative cross-linking capacity. Novelty impact statement Wheat bran arabinoxylans extracted from strong gluten wheat cultivars with higher contents of FA were suitable to fabricate hydrogel system, due to their better oxidative cross-linking capacity. The prepared AX hydrogel had uniform honeycomb structure with enhanced thermal stability and mechanical properties, which could be potentially used as delivery system for bioactive compounds.

关键词： Starch  

摘要： This work produced pyrodextrins from breadfruit (Artocarpus altilis) starch and evaluated the effect of HCl and CH3COOH as catalysts of pyrodextrinization on physicochemical and structural properties of pyrodextrins. Pyroconversion was performed by spraying the acid solution on starch (1.82 g acid/kg starch) and heated to 140 degrees C for 180 min. The pyrodextrins were analyzed for chemical composition, dextrose equivalent (DE), color parameters, solubility, intrinsic viscosity, infrared spectrum, and granule morphology. The pyroconversion decreased (p < .05) the ash content and the intrinsic viscosity of native starch. The HCl-pyrodextrin was slightly yellow, very water soluble with 8.8% DE. The CH3COOH-pyrodextrin was white, 8.8% soluble with 1.2% DE. The pyrodextrinization reduced alpha(1,4) bonds of glucans without drastically changing the granule's morphology. The use of acetic acid was considered a milder treatment, however, it caused an increase in the total and soluble dietary fiber contents, supporting its use to produce pyrodextrins for food applications. Novelty impact statement This article provides the first report of pyrodextrinization of breadfruit (Artocarpus altilis) starch. The HCl as catalyst caused greater changes in starch properties than acetic acid. The acetic acid caused a 10% increase in the total and soluble dietary fiber contents of pyrodextrin.

关键词： Physicochemical properties  

摘要： The different drying methods significantly affected the physicochemical properties of okra powder including its color value (L* a* b*). The okra powder from freeze-drying method exhibited the highest viscosity value (7,961.00 +/- 34.83 cP). It also exhibited the highest TPC (1,871.61 +/- 28.68 mg GAE/100 g dried sample), TFC (168.07 +/- 13.10 mg CE/100 g dried sample), and high antioxidant activities as measured by the DPPH, FRAP, and ABTS assay (89.72 +/- 0.72, 1,853.60 +/- 61.54, and 646.93 +/- 54.48 mg TE/100 g dried sample, respectively). However, the okra powder from the microwave vacuum drying using powder at 1,800 W provided the highest methoxyl content (6.88 +/- 0.66%) and the hot air drying (50 degrees C) provided okra powder with the highest total chlorophyll content (1,232.48 +/- 3.79 mu g/g DW). These results of different drying processes on okra fruit can be applied as a food ingredient to deliver the desirable properties for food product. Novelty impact statement Six drying methods are compared for drying of okra fruit (Abelmoschus esculentus L.). It is revealed that freeze-drying is the good quality of okra powder in term of phenolic content, flavonoid content, and antioxidant activities. Furthermore, the freeze-drying also provides the lowest methoxyl content which can be applied to create the low calorie confectionery product except it is the most expensive method. Howsoever, the highest total chlorophyll content can be expected from hot air drying which employed much shorter drying time and lower power consumption.

关键词： corn starch   films   Tremella fuciformis polysaccharide  

摘要： Composite films are prepared using corn starch and Tremella fuciformis polysaccharide (TFP) at different ratios (4:0, 3:1, 2:2, 1:3, 0:4, corn starch:TFP). The morphology, thermal properties, water resistance properties, opacity, and mechanical properties are investigated to evaluate the performance of composite films. The film surface becomes smooth with the increase in TFP proportion. The retrogradation enthalpy of corn starch is decreased from 2.60 to 1.10 J g(-1) starch by the presence of TFP. The moisture content of films does not change with TFP ratio. The water vapor transmission and solubility increase significantly with the increasing TFP ratio. Moreover, the solubility of the pure TFP film is 100%. The transparency and surface hydrophobicity of films are improved with the increase in TFP ratio. The increase in TFP ratio decreases the tensile strength and glass transition temperature of films, while the elongation at break increases from 33.12% to 141.96%. In conclusion, composite films obtained from corn starch and TFP have the potential to be used as food packaging films. However, the ratio of corn starch and TFP should be more than 2:2 to ensure thermal stability of the composite film.

关键词： Small-granule starch   Starch granule-associated proteins   Gelatinization   Pasting viscosity   Rheological properties  

摘要： The properties of four small-granule (oat, quinoa, amaranth and rice) starches before and after removal of starch granule-associated proteins (SGAPs), particularly surface-proteins and channel-proteins, were investigated and compared with two large-granule (waxy and normal maize) starches. The hypothesis, which was confirmed by results, was that the small-granule starches would be more susceptible to water and heat than the large-granule starches after removal of SGAPs on surfaces and in channels using protease. Surface-proteins of some granules in oat and rice starch presented as a film and channel-proteins were observed in oat, quinoa and rice starches. Compared to large-granule starches, removing SGAPs led to a greater reduction in gelatinization temperature for small granule starches. Meanwhile the reduced extent of rigidity of swollen small-granules during shearing was greater after removing SGAPs, corresponding to the reduced peak, breakdown and final viscosities. Furthermore, the removal of SGAPs for small-granule starch pastes weakened pseudoplasticity and shear-thinning behaviour. Removing SGAPs contributed to amylose leaching, accelerated the recrystallization and rearrangement of starch molecules, and facilitated retrogradation, thereby leading to a stronger gel network.