教学课程资源库 更多>>

关键词： β   -glucan concentrate   Molecular weight   Viscosity   Rheological properties   Thermal behavior  

摘要： The present study was aimed at assessing the influence of acid hydrolysis on the physicochemical and rheological properties of beta-glucan concentrate. Barley beta-glucan concentrate was subjected to acid hydrolysis for 30 and 60 min. The molecular weight and viscosity were observed to be a function of hydrolysis time and decreased in a duration-based approach. Significant reduction in water binding capacity and swelling power was observed after acid hydrolysis. Acid hydrolysis dramatically altered the flow properties and a Newtonian behavior was observed for HBG(60). The oscillatory measurements revealed enhanced visco-elasticity for HBG(30) solutions in comparison to its native counterpart and were greatly reliant on molecular weight and concentration. DSC measurements showed reduced thermal stability of acid hydrolysates in comparison to native beta-glucan concentrate. Overall, this study provides useful information on the hydration, thermal and rheological behavior of beta-glucan concentrates and could be helpful in optimizing the concentration of beta-glucan concentrates in food formulations.

关键词： Chickpea protein   Enzymatic hydrolysis   Bioactive peptide   Antioxidant activity   Alcalase   Papain  

摘要： Alcalase is a protease which prepared from the Bacillus licheniformis bacteria, whereas papain is a cysteine protease which prepared from plant sources papaya fruit latex, and both are utilized in enzymatic hydrolysis. However, each enzyme showed different effect during the hydrolysis process. In this present research, the effects of two commercial proteases, alcalase and papain, on the preparation and characterisation of physiochemical properties and antioxidant activity of chickpea (Cicer arietinum L.) protein hydrolysate (CPH) were studied. Different parameters were used during hydrolysis using alcalase (pH 10, temperature 45 degrees C) and papain (pH 6.7, temperature 65 degrees C). CPH hydrolysed by enzyme alcalase (CPHA) showed higher yields (32.5%) and degree of hydrolysis (DH) (8.62%) than CPH hydrolysed by enzyme papain (CPHP), which had lower yields (13.92%) and DH (7.99%). In addition, CPHA led to a lower molecular weight (10 kDa) than CPHP (14.3 kDa). However, in terms of chemical composition and solubility, no significant differences existed between CPHA and CPHP. Moreover, CPHA showed significantly higher foaming capacity, foaming stability, emulsifying stability, anti-oxidant activity on DPPH radical scavenging activity as compared to CPHP. CPHA also showed significantly lower emulsifying capacity than CPHP. These findings indicate that the type of protease used to hydrolyse CPH has a significant impact on the physicochemical properties and antioxidant activity of the produced CPH.

关键词： Superheated steam   Wheat starch   Physicochemical property   Structural property   Digestibility  

摘要： This paper explored the impact of superheated steam (SS) treatment on the physicochemical, crystalline characteristics and in vitro digestibility of wheat starch. Upon SS treatment, treated samples showed lower swelling power, solubility, and viscosities, but had higher gelatinization temperature, which might be due to the partial gelatinization of starch granules. This agreed with micromorphology characterization, indicating the degradation of Maltese cross. In addition, SS treatment decreased the long-range crystalline and short-range order of starch, compared to native starch sample. This change of physicochemical and structural properties was responsible for the decrease of starch hydrolysis rate. Meanwhile, SS treatment obviously increased the slowly digestible starch (SDS) and resistant starch (RS) content from 10.6% to 7.9% (native starch) to 17.2% and 13.6% (150 ?C, 1 min), respectively. This knowledge indicates that superheat steam technology possibly is a promising strategy in starch modification.

关键词： Chalcogenide glass ceramics   Chemical bond approach   Physico-chemical properties   Band-gap engineering   Glass-transition temperature  

摘要： The physico-chemical properties of (GeS2-Sb2S3)100-x(CsCl)x (0 < x < 40 mol%) chalcogenide glass ceramics were theoretically studied. The band gap (Eg) of the studied glassy system was estimated and was found to increase by adding the CsCl content. Furthermore, the positions of the valence band and conduction band edges was determined. The results reveal that the molar volume (Vm) of the studied samples increased while the density (rho) and the number of atoms per unit volume (N) decreased with increasing the CsCl content. The overall coordination number (CN), constraints number (Ns) and overall mean bond energy ( E ) were computed using the chemical bond approach and were found to decrease. In contrast, the number of lone-pair electrons (LP) and cohesive energy (CE) increased. Finally, the glass-transition temperature (Tg) was also estimated based on the overall mean bond energy, and was found to decrease with increasing the CsCl content.

关键词： Chewability   Color index   Fast-food   Goaty aroma   Ruminants  

摘要： This study evaluated the optimum inclusion of a feed oil additive chemically extracted from cashew nuts in lamb diets on the physicochemical and sensory attributes of burgers produced from their meat. Forty lambs (26 +/- 2.4 kg of initial BW and 5 months of age) were used in a block randomized design with ten experimental units per treatment. Lambs were fed a total mixed ration containing cashew nut shell liquid (tCNSL) at levels of 0, 7.5, 15 and 22.5 g/kg g/kg of dietary dry matter. Lambs were slaughtered, and the meat was processed for burger production. The addition of tCNSL to the diets promoted a quadratic increase in DMI (P = 0.034), ADG (P = 0.016) and slaughter BW (P = 0.002). However, the addition of tCNSL to the lamb diet did not change (P 0.001) with lower formations of peroxides and metomyoglobins in lamb meat burger when dietary levels 15 and 22.5 g/kg of tCNSL were added in diets. The pH of the lamb meat burgers increased linearly (P = 0.0196), due to the inclusion of tCNSL in the lamb diets. The L* color index reduced linearly (P = 0.0179) while b* and C* color increased linearly (P <= 0.05) with the addition of tCNSL in the diet. The inclusion of tCNSL did not change (P 0.05) in the sensory attributes of the lamb meat burgers. All variables scored between 7 and 8, being considered by the tasters as moderately liked and very liked, obtaining a good overall acceptance. However, the preference (P = 0.042) ranking of the panellists was for burgers from the meat of lambs fed with tCNSL, regardless of the level of inclusion, compared to treatment without tCNSL. It is recommended to include up to 15 g tCNSL/kg DM as antioxidant in the lamb's diet because it improves growth performance, color index and physical quality, and reduces the elasticity, chewability, lipid peroxidation and metmyoglobins, and increasing the preference of lamb meat burgers.

关键词： A-type starch granules   B-type starch granules   in vitro digestibility   structural properties  

摘要： In this study, the compositions, structural properties, and digestive characteristics of green wheat starch (GWS) and its isolated A- and B-type starch granules are analyzed and compared with their mature wheat starch (MWS) counterparts. The proportion of small granules in GWS is higher than that in MWS, as revealed by the particle size distribution curves. The scanning electron microscopy of GWS shows agglomeration of more granules in the presence of B-type starch. The predicted glycemic index (pGI) ranged from 76.20 to 86.35 for different types of starch, and the lowest and highest pGIs are obtained from B-type granule in GWS and B-type granule in MWS, respectively. According to the analysis of differential scanning calorimetry, GWS and its A- and B-starch granules demonstrates higher gelatinization temperatures (T-o,T- T-p, and T-c) and enthalpy than those of their MWS counterparts. The X-ray diffraction pattern reveals the A-type pattern of crystalline starch for all the starch samples, where the crystallinity index of GWS is higher than that of MWS, which is consistent with the higher relative content of double helices determined by nuclear magnetic resonance.

关键词： Famotidine   Crystal structure   Physicochemical properties   Solubility   DFT calculation  

摘要： The coordination ability of the antisecretor agent Famotidine (FMT) was explored using Ni(II) as central ion. [NiFMTH-2] and [Ni(FMT)(2)]Cl(2)were obtained by the solvent evaporation method from the corresponding starting solutions at pH 8 and 4, respectively;the crystal structure was elucidated by single crystal X-ray diffraction in both cases.[NiFMTH-2] resulted in a distorted square-planar geometry, where FMT acts as a tetradentate dianionic ligand through nitrogen atoms belonging to the guanidine group, the thiazolic ring and the side chain, and a sulfur atom from the thioether moiety. [Ni(FMT)(2)]Cl(2)exhibits an octahedral environment composed by two FMT molecules that coordinate by nitrogen atoms deriving from guanidine and thiazole ring moieties, and the thioether sulfur atom. The physicochemical characterization was completed by means of FTIR and UV-Vis spectroscopies, and thermal analysis. Solubility measurements were performed and the results could be satisfactorily correlated with the solvation Gibbs free energy (Delta G(solv)) values in aqueous solution obtained using the SDM model by DFT calculations. Graphic Abstract Ni(II) and famotidine form an octahedral complex at pH 4 where famotidine acts as a tridentate neutral ligand. In basic medium, it behaves as a tetradentate dianion, resulting in a quasi-planar complex. Spectroscopic and thermal data are consistent with single crystal X-ray diffraction structural elucidation. The relative stabilities were assessed by theoretical studies. [GRAPHICS] .

关键词： Fourier transform infrared spectroscopy  

摘要： Abstract: A study is performed of the mechanism behind the effect high-voltage nanosecond electromagnetic pulses and dielectric barrier discharges have on surfaces of ilmenite in air at atmospheric pressure. Fourier-transform infrared spectroscopy, scanning electron microscopy, electron microprobe analysis, microhardness testing, contact angles of surface wetting, and streaming potentials are used to examine the morphology of ilmenite, its physicochemical properties (microhardness, contact angle, and electrokinetic potential), and the structural state of ilmenite surfaces. Advantages are shown of using brief energy treatments (ttreat = 10–30 s) to modify the chemical structure of surfaces of ilmenite and its physicochemical properties in order to improve the efficiency of processing complex titanium ores. © 2021, Allerton Press, Inc.

关键词： Cost effectiveness  

摘要： The objective of this study was to investigate the stability of saramunete sausages submitted to different post-packaging procedures [heat treatment-HT (80 degrees C/10 min);ultrasound-US (37 kHz/10 min);the combination of heat treatment and ultrasound-HT+US (80 degrees C & 37 kHz/10 min);and control-C (no treatment)]. The combination HT+US at day 1 provided lower water activity (0.974 +/- 0.002), pH (6.79 +/- 0.03), and non-protein nitrogen (NPN-440.14 +/- 4.86 mg/100 g) compared to the other treatments. During storage at 6.0 +/- 1.0 degrees C, HT+US provided better stability with lower rates of lipid oxidation, a shorter time for NPN stabilization, and a longer time for the accumulation of TVB-N. On the 22nd storage day, counts of similar to 4 log CFU psychrotrophic microorganisms were found and kept up to end of storage. Therefore, shelf life of up to 22 days is recommended for vacuum-packed saramunete sausage submitted to HT+US during refrigerated storage. Practical applications Fish consumption in Brazil is low compared to the recommended by the Food and Agriculture Organization. To increase consumption, it is necessary to use species of commercial interest, such as saramunete, to produce high added value products such as sausages (easier to prepare at home and longer shelf life). The use of combined processing steps employing emerging conservation techniques such as ultrasound may warrant the quality and increase the stability of saramunete sausages. It was observed that the use of ultrasound combined with heat treatment, after vacuum packing, warranted quality and increased the shelf life of the sausages. Ultrasound is a cost-effective and easy-to-apply technique that can be implemented at pilot and industrial scales.

关键词： Linoleic acid  

摘要： Supercritical CO2 extraction was selected to extract oil from pressed sesame seed cake. The effect of extraction parameters on the quantity and quality of extracted oil, namely temperature (40-60celcius), pressure (175-225 bar) and time (1-5 hr), was studied. By using response surface methodology with the Box-Behnken design, the optimal extraction condition was achieved at 50celcius, 220 bar, and 5 hr and provided 29.80% db of the oil yield. The extracted oil contained sesamin (225.79 mg/100 g cake), sesamolin (75.57 mg/100 g cake), tocopherols (7.03 mg/100 g cake) and Folin-Ciocalteu reducing capacity (29.11 mg GAE/100 g cake). Main fatty acids observed in the extracted oil were linoleic acid (36.18%-45.38%) and oleic acid (31.84%-39.40%). The experimental results indicated that supercritical CO2 extraction could be a viable technique to extract the residual oil from pressed sesame seed cake. Practical applications It is obvious that supercritical CO2 extraction technique could be used to recover a residual oil efficiently from pressed sesame seed cake. The extracted oil was obtained at the optimum extraction temperature of 50celcius, extraction pressure of 220 bar and extraction time of 5 hr. The extracted oil samples had high scavenging activity containing bioactive compounds including tocopherols, sesamin, and sesamolin. The fatty acid compositions of extracted oil from pressed sesame seed cake by supercritical CO2 extraction were linoleic acid and oleic acid. It was implied that the unsaturated fatty acid of the sesame oil was more than the saturated fatty acid. On the basis of this result, the extracted oil from pressed sesame seed cake can be considered as potential source of linoleic acid and oleic acid and alternative source of edible vegetable oil.