查看更多>>摘要：A new chitosan/zein-cinnamaldehyde (CHI/zein-CMA) nano composite film was developed, which possessed remarkable features favorable for mango preservation, including retardation of yellowing, respiration rate, weight and vitamin C loss and malondialdehyde (MDA) accumulation during storage of mango at 25 degrees C. The formula of chitosan/zein nano composite film was optimized through single factor experiments and orthogonal experiment with fuzzy comprehensive assessment. The results showed that the optimal formula is chitosan 35.0 g/L, zein 3.0 g/L, nano-cellulose 25.0 g/L, acetic acid 0.26 mol/L. Besides, cinnamaldehyde was incorporated into CHI/zein composite film and 3.0 g/L was chosen as the favorable concentration. The crack-free film surface observed under scanning electron microscopy (SEM) suggested that the incorporation of CMA contributed to a more flexible and dense film structure, and the significant increase in beta-sheets (from 17.06% to 27.00%) accompanied with the decrease in a-helix (from 55.5% to 44.41%) further confirmed the strong cross-linking of CMA with CHI/zein matrix. The results showed that the accumulation of H2O2 to desired level and storage adjusting of antioxidant enzymes activity (SOD) might be related to the excellent storage quality of mango coated with CHI/zein-CMA, suggesting that stress response was beneficial to the preservation of mango.
查看更多>>摘要：The study focused on the effect of different concentrations of sodium chloride (0%, 0.5%, 1%, 3%, 5%, and 10%; NaCl) on the physicochemical and structural properties, including texture properties, protein polymerization, rheological properties and morphology formation, of extruded wheat gluten. The hardness, chewiness, and resilience of the extrudates were increased by NaCl. The highest value of the degree of texturization was obtained at 3%, but decreased at 5% and 10%. The extrudates exhibited lower bulk density and darker colour when NaCl was added. The sodium dodecyl sulfate (SDS)-soluble protein polymers exhibited a similar trend and the lowest value was obtained at 3% addition, which indicated the highest degree of aggregation. The addition of NaCl (0.5%-3%) showed positive effect on the oxidation of sulfhydryl groups to disulfide bonds. The content of beta-sheets showed an increase tendency at 0.5%-3% NaCl addition. The addition of NaCl increased the storage and loss modulus in wheat gluten dough while decreasing that of the extrudates. Microstructure analysis by light microscopy and SEM confirmed that the fibrous structure was enhanced with increasing levels of NaCl, and the 3% treatment showed the best, but that collapsed at 5% and 10% NaCl concentrations.
查看更多>>摘要：Western consumers prefer tea products with little or no green flavor. Accordingly, edible basidiomycetes have been addressed as an innovative tool to naturally aromatize tea infusion to mask or reduce green flavor. After submerged fermentation of green tea infusion with basidiomycetes, multiple pleasant odor impressions were perceived which significantly differed from the characteristic green and floral odor of the substrate. Among twenty-nine screened fungi, enokitake (Flammulina velutipes) was regarded as an ideal species to potentially drive a sensorial tea drink because of its appealing nutty and chocolate-like flavor and a rapid fermentation process (16 h). To better understand flavor formation during fermentation as perceived by sensory evaluation, the flavor profile was decoded by direct immersion - stir bar sorptive extraction - gas chromatography - mass spectrometry - olfactometry. During the fermentation, a series of key odorants of the non-fermented tea infusion imparting green and floral were decreased, while compounds responsible for the nutty and chocolate-like aroma increased. Enokitake biosynthesized the sensory-relevant compound 2-ethyl-3,5-dimethylpyrazine, which has not been reported in basidiomycetes yet. We assume that vitamin B1 and sodium acetate are potential precursors in enokitake. In parallel, the accumulation of various alkylpyrazines (2,5-dimethylpyrazine, 2,3,5-trimethylpyrazine, and 2-ethyl-3,6-dimethylpyrazine) has been observed as well.
查看更多>>摘要：The crystalline structure and the physicochemical properties of highland barley under two different dry heat parboiling processing including low temperatures for a long time (LTLT) and high temperatures for a short time (HTST) and the relationship between them were studied. As measured by the techniques such as Fourier transform infrared spectroscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, differential scanning calorimetry, X-ray diffraction pattern, and the crystalline structure was shown that highland barley was rearranged and resulted beta-sheet was the main influence on protein helical structure during dry heat parboiling processing. The aggregation of protein was degraded in LTLT processing. After dry heat parboiling processing, the crystal structure exhibited A, B, and V-style polymorphs, the peak temperatures of gelatinization were increased (from 64.18 degrees C to 71.58 degrees C), the enthalpy was decreased (from 5.99 J/g to 2.79 J/g), and the degree of gelatinization was up to 53.42%. LTLT dry heat parboiling was severe processing to highland barely.
查看更多>>摘要：Reduction in the total thawing time for pork loin subjected to two-stage air thawing was investigated. The pork loins were frozen at -60 and -18 degrees C and stored for up to 6 months at the freezing temperature. Samples were thawed using constant-temperature air thawing (-1.5, 2, and 25 degrees C) and two-stage air thawing methods. In the two-stage air thawing method, the samples were thawed at 25 degrees C in the initial stage. When the core temperature of the sample reached -5 degrees C, the samples were transferred to -1.5 degrees C (25/-1.5 method) or 2 degrees C (25/2 method). The physicochemical properties of the thawed pork loins, including thawing loss, cooking loss, water holding capacity (WHC), volatile basic nitrogen (VBN), and thiobarbituric acid reactive substances (TBARS) were analyzed. Thawing at 25 degrees C was the most rapid thawing method, and the total thawing time were reduced effectively using two-stage air thawing. Generally, samples thawed by two-stage air thawing (25/-1.5, and 25/2 methods) exhibit better moisture related properties. The effects of the thawing methods on VBN content were minimal; only trace levels of TBARS were detected in the samples. Therefore, two-stage air thawing is expected to reduce the total thawing time and prevent meat quality deterioration caused by the freezing and thawing processes.
查看更多>>摘要：Natural pigment carotenoids specifically beta-carotene present in carrots is very sensitive to heat and light. The present work studied the co-crystallization as a process to increase the stability of the carotenoids extracted from carrots. Carotenoids encapsulated co-crystals were evaluated for their encapsulation efficiency, antioxidant activity, thermal behavior, physicochemical, and structural properties. Co-crystallization of the carotenoids with sucrose showed an encapsulation efficiency of 77.58% and an antioxidant activity of 68% towards DPPH free radicals. DSC thermogram confirmed the thermal stability of carotenoids encapsulated co-crystals by indicating the endothermic peaks at 190 degrees C. XRD pattern and FTIR spectra revealed that the crystal nature of sucrose and functional groups remained the same even after co-crystallization. SEM results revealed the irregular cavities in well-defined cubic crystals of sucrose which suggested the better entrapment of carotenoids into sucrose. Hence, co-crystallization significantly improved the overall stability of the carotenoids, and these co-crystals can be used as a natural colorant, sweetener, and antioxidant.
查看更多>>摘要：The efficient utilization of rice bran is severely impeded because of the rapid rancidity caused by rice bran lipase, so the investigation of rice bran lipase characteristic and catalytic mechanism was urgently required. The extracted crude proteins from rice bran were purified to obtain two lipases with 16.31 times of purification fold and 10.64% of purification yield. The molecular masses of these two homologous lipases were 34929.00 Da and 34072.00 Da, respectively. Rice bran lipase showed highest catalytic activity at 40.00 degrees C, pH 7.50 and held good stability below 50.00 degrees C and at pH 7.00-7.50. Most metal ions (except Na+ and Co+) and organic solvents had significant inhibition effect (P < 0.05) on the purified lipase activity. Surfactants like Tween 80, Triton 100 and sodium dodecyl sulfonate (SDS) decreased the lipase activities significantly (P < 0.05) to 70.88%, 80.08% and 73.74% respectively and cetyltrimethyl ammonium bromide (CTAB) increased the catalytic activity significantly (P < 0.05) to 109.00%. The Ser-His-Asp residues were speculated to be the catalytic center of purified lipases by using the inhibitors (Phenylmethanesulfonyl fluoride (PMSF), diethylpyrocarbonate (DEPC) and Pepstatin) which aimed at specific amino acids and then verified by molecular docking. Therefore, blocking or destroying the Ser-His-Asp catalytic triad might be new choices to restrain the rancidity of rice bran.
查看更多>>摘要：This study aimed to obtain and characterize dehydrated chickpea snacks by sequential hydration, cooking, and drying processes. Hydration was performed at 4, 25, and 60 degrees C until reaching the maximum water uptake by the grains. Then, they were boiled until 80% of the grains reached firmness minor than 15 N. Cooked chickpeas were peeled and dried by three methods, air-drying (AD), freeze-drying (FD), and microwave multi-flash drying (MWMFD). The grains moisture was reduced from 1.681 +/- 0.076 g/g to less than 0.050 +/- 0.003 g/g and a w below 0.270. The constant drying rate was observed for all the three drying processes, followed by a falling drying rate period. MWMFD required a much shorter processing time (0.4 h) when compared to AD (10 h) and FD (15 h). The microstructure, and texture of the product were determined. Freeze-dried chickpeas were 1.2 and 2 times more porous than the MWMFD and AD samples, respectively. Micrographs showed small and uniform pores in FD samples, while MWMFD and AD samples had irregular porous matrix. MWMFD and AD samples exhibit jagged strain-force curves, characteristic of crispy foods. Therefore, MWMFD is a suitable process to obtain crispy chickpeas in short time.
查看更多>>摘要：We evaluated gamma-aminobutyric acid (GABA) production by Lactobacillus brevis RK03 immobilized fermentation using three types of porous ceramic materials, All Clean (AC), Ocean Free (OF), and Power Material (PM). Almost same surface areas of the three porous ceramic materials were used to perform batch cultures with a modified GM broth and 500 mM monosodium glutamate (MSG). PM produced the highest GABA production after 96 h with an MSG conversion rate of 96.5% at pH 4.5 and 10% bacterial inoculum growing in a 500 mL flask. We then developed a semi-continuous GABA fermentation system by culturing 10% cells in the 500 mL flask comprising AC, OF, and PM carriers with similar surface areas and 500 mM MSG, for 288 h and five cycles at 30 degrees C. PM produced the highest GABA yield with a 86% conversion rate after five cycles. Semi-continuous fermentation was performed in a 10 L fermenter; MSG conversion rates still reached 97.3% or more following 25 consecutive fermentations, resulting in a maximum GABA yield, which was high for five cycles. Therefore, PM was the best carrier for continuous fermentation of GABA after 25 cycles and 1200 h. PM can be applied to industrial mass production of GABA.
NSTL
Elsevier