首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 15 毫秒
1.
Juices from two varieties of cactus pear, a green (Opuntia ficus-indica) and a red (Opuntia streptacantha), were obtained and concentrated by evaporation. Both fruit varieties and their juices at different concentrations were characterized. Green cactus pears had significantly higher amount of pulp than red cactus pears; the peel of O. ficus-indica represented only 38 versus 52 % of the fruit for the O. streptacantha. Both varieties had no significant differences on moisture, density, pH, and titratable acidity, in contrary to soluble solids. Juice was concentrated under vacuum conditions to reach a final concentration of 42, 53–55, and 58–60 °Brix, respectively, and stored under refrigeration (10 °C) during 4 weeks. Physicochemical properties of the pears and juices were determined as fresh items (time zero) and every week for the concentrate juices through storage; similarly, flow parameters were measured at 10 and 25 °C. Concentrate density (1160–1283 kg/m3) was mainly affected by final soluble solids, while pH and acidity were affected differently depending on the variety. Concentrated juices at 42 °Brix were considered with Newtonian behavior with a viscosity of 2–22 mPa s, while those at higher concentrations were of pseudoplastic nature (n < 1.0 and K > 69 mPa sn). Power Law model fitted better the flow behavior than Herschel-Bulkley model of concentrates of both varieties. Temperature, solid concentration, and/or storage time affected the consistency coefficient (K) and flow index (n) depending on the cactus pear variety. Overall, those concentrated juices from O. streptacantha were more stable and exhibited lower apparent viscosity.  相似文献   

2.
Cactus pear cladodes processing has potential value for mainstream industries and is equally important for marginal rural communities in arid regions. This work is focused on physico-chemical and rheological properties of Opuntia ficus-indica (OFI) peeled cladodes extracted by conventional method “CE” and using microwave-assisted extraction “MAE.” MAE gave the highest yield extraction (8.13 %, w/w) within the lowest extraction time (500 W/7 min) and provided more protein (×1.03) and carbohydrates (×1.51) than CE. The monosaccharides detected by gas chromatography were arabinose, galactose, rhamnose, xylose, and galacturonic acid. The dialyzed mucilage solution characterized by SEC/MALS/VD/DRI (size-exclusion chromatography coupled with online multi-angle light scattering, viscometer detectors, and differential refractive index) revealed fractions with molecular weight (M w ) ranging from 15.3–15.7?×?106 g mol?1 for the CE extracts and about 16.7–17.5?×?106 g mol?1 for the MAE extracts. Dynamic oscillatory testing has been used to study the rheological properties of mucilage solution within the concentration of 0.50–3.00 % (w/v) at 25 °C. The rheological profiles of CE and MAE showed similar behavior. At low frequency and low mucilage concentration (<2.00 %), the viscous component (G") predominated over the elastic component (G'), while for higher frequencies, the behavior is reversed (G'?>?G"). If safely controlled, alternative energies like microwaves could extract soluble polymers with comparable properties to commercial ones, conventionally extracted.  相似文献   

3.
The lipid peroxidation inhibitory effects of cactus pear fruit (Opuntia ficus-indica) extracts (CPFE) on fish oil, fish oil-in-water emulsion and linoleic acid were studied using conjugated diene hydroperoxides (CDH), weight gaining, peroxide value (PV), and thiobabituric acid reactive substances (TBARS) assays. A modified DPPH assay was used in the characterization of CPFE antioxidants for their thermal stability. CPFE successfully controlled lipid peroxidation at different stages of the pathway in a dose-dependent manner. Inhibition of the lipid peroxidation in oils and emulsion was successfully improved by increasing the level of CPFE from 0.01 to 0.1%. CPFE controlled conjugated diene formation from lipid radicals, demonstrating lower conjugated diene hydroperoxide values than its control counterpart. Moreover, it controlled the addition of oxygen to conjugated dienes to form lipid peroxyl radicals, resulting in lower weight gain. It also recorded a lower PV than its control counterpart, indicating its inhibitory effect on peroxyl radical formation. Such multiple and integrated effects controlled the overall lipid peroxidation, resulting in lower TBARS values than the control. Characterization of the CPFE antioxidants proved that those antioxidants are heat-resistant, although the color of the CPFE pigments disappeared rapidly.  相似文献   

4.
Prickly pear (Opuntia ficus-indica) is a longdomesticated crop plant of arid and semiarid parts of the world. The efficacy of extracts of prickly pear root for managing diabetes and diabetes complications was evaluated using a variety of in vitro bioassays. The ethyl acetate-soluble fraction was most effective in the prevention of diabetes and its complications via the inhibition of rat lens aldose reductase activity, the formation of advanced glycation end products, and α-glucosidase activity. MS and NMR were used to identify the bioactive compound from the ethyl acetate-soluble fraction as 3,5,7,4′-tetrahydroxyflavanone (aromadendrin).  相似文献   

5.
Psidium guajava L. has gained a special attention as health plant due to the presence of phenolic compounds. Box-Behnken design (BBD) has been applied for the extraction of target compounds from guava leaves via sonotrode ultrasound-assisted extraction (UAE). Different extraction times (5, 30, and 55 min), ratios of ethanol/water (50, 75, and 100% (v/v)), and ultrasound (US) power (80, 240, and 400 W) were tested to find their effect on the sum of phenolic compound (SPC), flavonols and flavan-3-ols via HPLC-ESI-QqQ-MS, and antioxidant activity (DPPH and TEAC assays). The best process conditions were as follows: 40 min, 60% ethanol/water (v/v), and 200 W. Established method has been used to extract phenolic compounds in two guava leaves varieties (pyrifera and pomifera). Pyrifera var. showed greater values of the SPC via HPLC-ESI-QqQ-MS (49.7 mg/g leaf dry weight (d.w.)), flavonols (12.51 mg/g d.w.), flavan-3-ols (7.20 mg/g d.w.), individual phenolic compounds, and antioxidant activity (8970 ± 5 and 465 ± 6 μmol Trolox/g leaf d.w, respectively) than pomifera var. Conventional extraction showed lower amounts of phenolic compounds (7.81 ± 0.03 and 4.64 ± 0.01 mg/g leaf d.w. for flavonols and flavan-3ols, respectively) in comparison to the ultrasound-assisted ones.  相似文献   

6.
This study aimed to evaluate the in vitro antioxidant and enzyme inhibitory activities of ethyl acetate, methanol, and water extracts of Bituminaria bituminosa. In phosphomolybdenum assay, the methanol extract showed the highest activity (166.78 μmol TEs/g dry plant). The water extract exhibited the highest scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH?) and 2,2-azino-bis (3-ethylbenzothiazloine-6-sulphonic acid) (ABTS?+). In addition, it exhibited the highest activity in cupric ion reducing (CUPRAC) and ferric reducing antioxidant power (FRAP) assays (41.26 and 46.82 μmol TEs/g dry plant). The extracts did not show cholinesterase and tyrosinase inhibitory activity. However, α-glucosidase inhibition assay resulted in the superiority of water extract (1233.86 μmol ACEs/g dry plant). In the case of α-amylase inhibitory assay, the ethyl acetate extract showed the highest activity (53.65 μmol ACEs/g dry plant). The water extract exhibited the highest phenolic content (31.70 μmol GAEs/g dry plant). In contrast, the methanol extract was found rich in flavonoid compounds (5.29 μmol REs/g dry plant). The water extract contained considerable amounts of rosmarinic acid, luteolin, quercetin, and rutin. Therefore, it can be used as a source of new and alternative antioxidant and enzyme inhibitory agents.  相似文献   

7.
Fruits have been the focus of several studies aimed at finding new antioxidant sources for protection against the damage caused by reactive species. In this study, the antioxidant activity and the presence of phenolic compounds in all parts (peel, pulp, and seeds) of Eugenia involucrata DC. fruits were evaluated. DPPH·, ABTS·+, and ORAC methods were used to determine the antioxidant activity, and an UHPLC-MS/MS method was developed for determining the phenolic compounds (gallic, chlorogenic, ferulic, p-coumaric and ellagic acids, quercetin, and myricetin). In the determination of both antioxidant activity and phenolic composition, the efficiency of solvents with different polarities—methanol/H2O (80:20, v/v), ethanol/H2O (80:20, v/v), methanol/acidified water with phosphoric acid pH 3.00 (80:20, v/v), and ethyl acetate—for the extraction of the phenolic compounds, was also evaluated. All parts of E. involucrata fruits showed antioxidant activity, in the range of 36.68 ± 1.44 to 873.87 ± 18.24 μmol TE g?1, being the highest values found in the seeds and peel when more polar extraction solvents were used. Six, five, and three phenolic compounds were identified and quantified in the pulp, peel, and seeds, respectively, with the highest abundance as p-coumaric acid (14 ± 2 mg kg?1) in the pulp, quercetin (47 ± 5 mg kg?1) in the peel, and gallic acid (74 ± 4 mg kg?1) in the seeds, also when more polar solvents were used. Although antioxidant activity methods suggested that the peel and seeds have more antioxidant potential, a wider variety of compounds were determined in the pulp.  相似文献   

8.
Microwave-assisted extraction was applied to Juglans regia L. fresh male flowers and unripe walnut seeds to evaluate the total phenolic contents of the extracts as well as the percentage of water-soluble polyphenols. The research was planned using the Design of Experiments technique to investigate the role on the extraction efficiency of different parameters, such as temperature, time and number of microwave heating cycles, together with their possible interactions. Optimization was achieved by applying a Response Surface Methodology comprising a three-factor, two-level, full-factorial Face-Centred Central Composite Design. The two input variables with a significant effect on the recovery of phenols from fresh male flowers were the extraction temperature and the number of microwave cycles. In the case of unripe walnut seeds, a linear two-factor interaction model was selected, with significant interactions occurring between temperature and time, and time and number of microwave cycles. The best experimental conditions were as follows: 100 °C, 6 min, three microwave heating cycles and 22.7 ± 0.2 mg gallic acid equivalent (GAE)/g (total phenolic content, PC); energy consumption calculations suggested slightly different conditions: 60 °C, 30 min, three microwave heating cycles and 20.7 ± 0.3 mg GAE/g (TPC).  相似文献   

9.
The impact of added ascorbic, isoascorbic, and citric acid on heat stability of cactus pear betalains was investigated at pH 4 and 6, respectively. To assess the influence of cactus pear juice matrix compounds such as sugars, organic acids, amino acids, and pectic substances on pigment stability, juice and purified pigment preparations derived therefrom were assayed separately. Immediately after heating at 85 °C for 1 h and a 24 h cool storage period, betalain retention, betanin and proline-betaxanthin isomerisation as well as overall colour changes were determined. Pigment stability and colour characteristics depended on type and concentration of the respective additive as well as on pH conditions. Interestingly, the stabilising effects of the additives under investigation were less pronounced in matrix-free pigment preparations compared to juice samples. Maximum pigment retention amounting to 79% was obtained when 0.1% citric acid was added to the juice at pH 6. For the first time, formation of 2-decarboxy-betanin upon thermal treatment of yellow-orange cactus pear juice being more distinct at pH 4 as compared to pH 6 is reported.  相似文献   

10.
Ionic liquid-based ultrasonic-assisted extraction (IL-UAE) was successfully developed to extract the known phenolics gallic acid, chlorogenic acid, rutin, psoralen, and bergapten present in the leaves, pulps, and peels of Ficus carica L. In this work, the proposed method was evaluated in comparison with regular ultrasonic-assisted extraction in which methanol was the extractant and exhibited higher efficiency. Moreover, ionic liquids with different cations were investigated and 1-butyl-3-methylimidazole hexafluorophosphate solution was selected as the optimal extractant at concentration of 1.0 mol L?1. The corresponding extraction parameters including extraction solvent, the concentration of [BMIM][PF6], solid–liquid ratio (g mL?1), ultrasonic extraction time, and extraction temperature were optimized. The phenolics were then determined by high-performance liquid chromatography (HPLC). Under the optimized conditions, the content of gallic acid, chlorogenic acid, rutin, psoralen, and bergapten in leaves, pulps, and peels of F. carica L. was 12.67–37.16, 14.75–90.07, 107.91–222.37, 2.59–67.83, and 1.99–20.21 μg/0.1 g, respectively. This study suggests that IL-UAE is a rapid, simple, and green preparation technique.  相似文献   

11.
Two cheese varieties with different surface features (Gouda and Manchego) were tested for pulsed light decontamination of Listeria sp. on ready-to-eat presentations. Sensory quality and volatile profile were also studied. Cheese slices were flashed with fluences comprised between 0.9 and 8.4 J/cm2. The treatment was less effective in Manchego than in Gouda, in which 3 log cfu/cm2 were obtained with 0.9 J/cm2. No sensory changes were observed due to the application of this dose. In Manchego slices, the maximum inactivation obtained was lower than 1 log cfu/cm2 even at the highest fluence used. In both cheeses, differences in odour and flavour were reported immediately after treatment for fluences ≥4.2 J/cm2, due to the development of sulfur notes. Volatile analysis showed an increase of sulfur compounds which could explain these observations. The concentration of sulfur volatiles and the corresponding sensory notes disappeared during cold storage. In view of these results, pulsed light could be considered a useful strategy to decontaminate smooth-surface ready-to-eat cheeses.  相似文献   

12.
Characterization of Syrian (Kaissy cultivar) olive fruits and evaluation of physic-chemical properties of oils were carried out during 3 years of production. The mean values of data for both measured and calculated variables of fruits were: grain length (21.89 mm), grain width (17.92 mm), length/width (1.22), weight of grain (3.79 g), weight of pulp (flesh) (3.19 g), weight of pit (0.60 g), pulp/pit ratio (5.35), crude oil (17.13%), water content (moisture) (51.34%). The 3 year average values of chemical properties of Syrian Kaissy cultivar olive oils (SKOO) including acid value, peroxide vale, Thiobarbituric acid value, iodine value(IV), saponification value, and phenolic content were 0.58%, 4.33 mEq O2 kg??1, 0.028 mg MDA kg??1 oil, 90.77 g I2, 100 g??1, 194.91 mg KOH g??1, and 218.08 g gallic acid kg??1, respectively. Pefractive index (RI), and viscosity were 1.4666 nD at 25?°C and 139.56 mPa.s, respectively. However, the 2 years average values of Hunter’s color parameters of SKOO were; the lightness (L*= 66.91), redness (a* = 18.80), yellowness (b* = 29.08) and the color differences (?E?=?65.49). FA analysis of the SKOO used showed a high content of monounsaturated fatty acids (oleic acid 70.82% and palmitic acid 1.01%) and low polyunsaturated fatty acids (Linoleic acid 10.72% and Linolenic 0.82%) and saturated fatty acids (Palmitic 14.10% and stearic 2.57%). Results for 3 years production of Syrian Kaissy cultivar olive fruit and oil are discussed in detail.  相似文献   

13.
Washing and sanitation of fresh produce are critical for detachment and inactivation of pathogenic and spoilage microorganisms. The overall goal of this study was to evaluate the influence of processing conditions such as washing time, shear stress, and a food grade surfactant on the detachment of Escherichia coli O157:H7 from lettuce leaf surfaces during a simulated washing process. A benchtop scale rotating disk washing device was designed to simulate the processing conditions used in commercial washing systems. Numerical simulations were carried out to calculate the flow profile and shear stress near the leaf surface. Removal of E. coli O157:H7 as a function of processing conditions in the rotating disk washing device was evaluated by enumeration of bacterial population using plate counting and changes in bioluminescence intensity and further confirmed by bioluminescence imaging. The results showed that shear stress was necessary to remove attached bacteria from inoculated leaf samples and simple incubation of inoculated leaves with wash water was not effective. Furthermore, detachment of bacteria from inoculated leaf samples increased with increasing shear stress and incubation time. Shear stress values in the range of 0 – 300 mPa were adequate to induce removal of approximately 1.5 log CFU/cm2 of bacteria from inoculated samples. The addition of a surfactant increased the removal of bacteria from inoculated leaf samples by 0.5 log CFU/cm2. Overall, these results may guide the design of new produce wash systems as well as current industrial practice related to flow conditions and use of surfactants during washing of fresh produce.  相似文献   

14.
The present investigation aimed to evaluate the effects of ultrasound, high pressure, and manosonication on phenolic profile in correlation to antioxidant properties of aged mulberry wines (AMWs). The results indicated a positive effect of non-thermal processes on total phenol content of the AMW conversely to total anthocyanin content, which was negatively affected by pressurization and manosonication. With regard to total flavonoid content, sonication was found to exert a positive effect. A similar trend was also observed for each of the 18 phenolic compounds quantified. The outcome suggests that these phenolic compounds have potent antioxidant properties. From correlation analysis, phenolic acids were noted to be responsible for 1,1-diphenyl-2-picrylhydrazyl, N,N-dimethyl-p-phenylenediamine, and hydrogen peroxide capacities, while total antioxidant, ferric reducing antioxidant power, reducing power, cupric ion, metal chelating, lipid peroxidation, superoxide anion, 2,2′-azino-bis(3-ethylbenzothiazolin-6-sulfonic acid), nitric oxide, and hydroxyl radical capacities were attributed to flavonols and anthocyanins.  相似文献   

15.
Storage life of strawberry fruit is limited due to its high softening rate and susceptibility to fungal attack. Thus, it is of interest to develop and improve preservation techniques to reduce postharvest losses. The aim of this study was to evaluate the effect of ozonized water washing (maximum concentration of 3.5 mg L?1; 5–15 min) on fungal spoilage, water loss, mechanical properties, and structure of strawberries (cv. Albion) harvested in different years and stored at 5 °C. The effect of ozone treatment on decontamination and weight loss was dose-dependent. Ozonization for 5 min significantly reduced fungal incidence (~?22–25% lesser than control) and weight loss of strawberries throughout storage. High doses (10 or 15 min) did not reduce significantly fungal growth in relation to control, although weight loss in fruit treated for 15 min was higher than control. In both harvest years studied, cold storage provoked a diminution in deformability modulus and an increase in deformation but a significant effect of treatment was not observed. These changes were correlated with alteration of cell walls and turgor loss. Otherwise, cuticular membrane of strawberries treated for 5 min was observed thicker and more electron dense than in fruit ozonized for 15 min or control. It could partially explain the lower moisture loss observed in 5-min treated fruit. Results showed that ozonized water washing for 5 min can be an alternative strategy for extending postharvest strawberry shelf-life by decreasing fungal decay and water loss along cold storage, without affecting mechanical parameters.  相似文献   

16.
The pre-fermentation techniques applied during the production of white wine, such as skin maceration or grape pressing, can directly affect the quality of the final product. There is a constant search for methods that can enhance the sensorial characteristics, such as varietal aromas, and phenolic composition of white wines. The aim of this study was to investigate the effect of different pressing conditions on the phenolic composition, antioxidant activity and glutathione content of white musts and wines produced in southern Brazil and to evaluate these characteristics during bottle ageing. By applying different pressures, three fractions of musts were obtained: free-run must, light pressed must and heavy pressed must. The musts and their corresponding wines were analysed by spectrophotometric and chromatographic assays. Pressing positively affected the chemical composition of the musts and wines, and the wines produced with pressed fractions of the musts presented higher polyphenol content and radical scavenging power. The main phenolic compounds affected by the pressing conditions were caftaric acid, catechin and epicatechin. During bottle ageing, an increase in certain individual phenolic compounds could be observed by liquid chromatography. Samples produced with heavy pressed musts presented a higher browning index. Furthermore, the application of pressure to the grape musts during winemaking increased the contents of total glutathione by factors of up to 22 and 15 for light pressed and heavy pressed musts, respectively. After 8 months of bottle ageing, the glutathione content decreased in all samples.  相似文献   

17.
The aim of this study was to compare the effectiveness of microwave-vacuum pretreatment conducted at 100, 500 and 800 W on the drying kinetics of whole cranberries (Vaccinium macrocarpon) during hybrid osmotic and microwave-vacuum drying. Additionally, the effect of microwave-vacuum pretreatment and subsequent osmo-microwave-vacuum drying on selected quality indicators of dried cranberries, including phenolic content, antioxidant activity and color, was studied, and the quality of samples was compared with freeze dried, microwave-vacuum dried and osmo-microwave-vacuum dried samples. Irrespective of microwave power, the initial pretreatment accelerated mass transfer during osmotic dehydration of cranberries, and the Weibull model well fitted the experimental data. Final microwave-vacuum drying of cranberries was a two-stage process involving a relatively long phase with a constant drying rate, followed by a short period with a decreasing drying rate. Microwave-vacuum and osmo-microwave-vacuum drying resulted in similar retention of polyphenols and similar antioxidant activity, both of which were relatively higher than in freeze-dried cranberries. However, microwave-vacuum pretreatment at low microwave power (100 W) before dehydration also resulted in high retention of phenolic compounds, high antioxidant activity and attractive color, which were consistent with the high content of total anthocyanins and flavonoids. Microwave-vacuum, osmo-microwave-vacuum and osmo-microwave-vacuum drying combined with microwave-vacuum pretreatment at low microwave power (100 W) were the most suitable methods for the production of high-quality dried whole cranberries.  相似文献   

18.
In this study, the effective variables involved in ultrasound-assisted extraction (UAE) of fenugreek (Trigonella foenum graecum) seeds polysaccharides (FSPs) were optimized through Box–Behnken response surface design. The maximum yield of FSPs was 33.49% under the modified optimum conditions of an ultrasound power of 120 W, an irradiation time of 22 min and a liquid-to-solid ratio (L/S) of 30:1 mL g?1. The predicted yield was in a very good agreement with the experimental yield of 33.41%. This value was higher than the FSPs yield obtained using conventional extraction (CE) method for 180 min at the same extraction temperature and L/S ratio. The primary chemical and structural characteristics were investigated by UV, FT-IR, and GC-MS. FSPs found to be a heteropolysaccharide consisted of galactose (38.18%), glucose (3.71%), mannose (46.13%), rhamnose (1.02%), and arabinose (0.83%). Furthermore, the FSPs exhibited considerable scavenging activity against 1,1-Diphenyl-2-Picrylhydrazyl free radicals and ferric reducing antioxidant power and reducing power, in a concentration-dependent mode in vitro. Our results suggested that UAE technique gave a higher yield of FSPs with a shorter extraction time than the CE and FSPs can also be used as promising resources of natural agent for functional foods and medicinal industries.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号