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1.
The aim of this study was to evaluate near-infrared reflectance spectroscopy (NIR), and multivariate calibration potential as a rapid method to determinate anthocyanin content in intact fruit (açaí and palmitero-juçara). Several multivariate calibration techniques, including partial least squares (PLS), interval partial least squares, genetic algorithm, successive projections algorithm, and net analyte signal were compared and validated by establishing figures of merit. Suitable results were obtained with the PLS model (four latent variables and 5-point smoothing) with a detection limit of 6.2 g kg?1, limit of quantification of 20.7 g kg?1, accuracy estimated as root mean square error of prediction of 4.8 g kg?1, mean selectivity of 0.79 g kg?1, sensitivity of 5.04 × 10?3 g kg?1, precision of 27.8 g kg?1, and signal-to-noise ratio of 1.04 × 10?3 g kg?1. These results suggest NIR spectroscopy and multivariate calibration can be effectively used to determine anthocyanin content in intact açaí and palmitero-juçara fruit.  相似文献   

2.
The nutraceutical industry is currently interested in obtaining garlic extracts using mild extraction processes to recover high levels of labile allicin. This work studied oleoresin yield and extraction selectivity for allicin in the supercritical CO2 extraction of freeze-dried aqueous garlic homogenate as a function of sample conditioning and process conditions. Agglomeration phenomena, which is responsible for substrate lumps in packed beds and flow channeling in the bed during extraction, was avoided by lowering sample moisture below 31 g kg? 1 water/substrate, and/or process temperature below 65 °C. Oleoresin yield increased slightly with extraction pressure (15–45 MPa) and dramatically with process temperature (35–65 °C), but the concentration of allicin in the extract decreased as the temperature increased. Thus, an optimal combination of intermediate temperature and pressure was selected that allowed reasonably large yields (≥ 19 g kg? 1 oleoresin/substrate) and extraction selectivities (≥ 75 mg kg? 1 allicin/oleoresin). Based on experimental results, a 4 h extraction process at 55 °C and 30 MPa using 55 kg kg? 1 CO2/substrate was recommended. Cumulative extraction plots for oleoresin and allicin were successfully adjusted using a linear driving force mass transfer model.  相似文献   

3.
The kinetics of a batch solid–liquid extraction of total phenolic compounds (PC) from milled grape seed (Vitis vinifera L. cv. “Frankovka”) using 50% ethanol at different extraction temperatures (25–80 °C) was studied. The maximum yield of PC was 0.13 kgGAE/kgdb after 200 min of extraction in agitated vessel at 80 °C. A new model based on the assumptions of a first order kinetics mechanism for the solid–liquid extraction and a linear equilibrium at the solid–liquid interface was developed. The model involves the concept of broken and intact cells in order to describe two successive extraction periods: a very fast surface washing process followed by slow diffusion of phenolic compounds from grape seeds to the solvent.The proposed model is suited to fit experimental data and to simulate the extraction of phenolic compounds, which was confirmed by the correlation coefficient (r ? 0.965), the root mean square error (RMSE ? 0.003 kgGAE/kgdb) and the mean relative deviation modulus (E ? 2.149%). The temperature influenced both equilibrium partition coefficients of phenolic compounds and transport properties, which is manifested by a relatively high value of activation energy (23–24) kJ/mol and by values of effective diffusivity in seed particles.  相似文献   

4.
Eight cheese varieties with different moisture (357–488 g kg?1), fat (183–335 g kg?1) and protein content (202–292 g kg?1) were subjected to ultrasonic cutting using a 40 kHz guillotine sonotrode. Cutting force curves were evaluated with respect to ultrasound-induced cutting work reduction and energy demand of the sonotrode. With cutting velocity and ultrasonic amplitude set to 2500 mm min?1 and 12 μm, respectively, composition had a significant effect on the response of the cheeses. Whereas cutting work reduction was mainly determined by fat-in-dry matter, the energy demanded by the sonotrode to maintain vibration was inversely interrelated to the ratio of moisture to solids-non-fat. Three selected cheeses were subjected to cutting experiments with systematically varied cutting velocity and amplitude. The results indicate that the cheeses respond differently to the cutting parameters, and that their careful adjustment is helpful for a target-orientated design of the process.  相似文献   

5.
6.
The detection limits of 24 antimicrobial agents were determined in ewes’ milk by one commercially available version of brilliant black reduction test, BRT Inhibitor Test with prediffusion AiM® (BRT AiM®). For each drug, eight concentrations were tested on 20 milk samples from individual ewes. The detection limits of the BRT AIM® method were determined by means of logistic regression models: 6 μg kg−1 amoxycillin, 6 μg kg−1 ampicillin, 51 μg kg−1 cloxacillin, 2 μg kg−1 penicillin “G”, 230 μg kg−1 cefadroxil, 1330 μg kg−1 cephalosporin “C”; 270 μg kg−1 cephalexin, 92 μg kg−1 cefoperazone, 120 μg kg−1 ceftiofur, 69 μg kg−1 cefuroxime, 6000 μg kg−1 streptomycin, 1200 μg kg−1 gentamycin, 3700 μg kg−1 neomycin, 630 μg kg−1 erythromycin, 120 μg kg−1 tylosin, 390 μg kg−1 doxycycline, 5500 μg kg−1 oxytetracycline, 6200 μg kg−1 tetracycline, 5400 μg kg−1 sulfadiazine, 3200 μg kg−1 sulfamethoxazole, 6500 μg kg−1 sulfamethoxypyridazine, 6200 μg kg−1 sulfaquinoxaline, 22000 μg kg−1 chloramphenicol and 4100 μg kg−1 trimethoprim. The BRT AiM® method presents detection limits for β-lactam antibiotics that are similar to those obtained as Maximum Residue Limits (MRLs) according to Regulation 2377/90 EEC as set out by the European Union. However, for other antimicrobial agents the estimated limits were higher than those of the EU-MRLs. It is therefore advisable to enhance the sensitivity of the method for the detection of the different antimicrobial groups or to develop a combined system of different microbiological inhibitor tests that would enable the detection of a greater number of antimicrobial agents.  相似文献   

7.
Extra virgin olive oil is a premium food product that is likely to be the target of adulteration with refined olive oils or seed oils. Refining produces steroidal alkenes (sterenes) including stigmastadiene. This paper describes a rapid GC–MS method for the determination of stigmastadiene which is faster and more sensitive than the current official procedure based on GC-FID. The method does not require a saponification procedure for cold pressed oils, uses a stigmastadiene standard for quantification, has a low limit of quantification (0.015 mg kg 1) and gives excellent confirmation of peak identity at the current regulatory limit of 0.5 mg kg 1.  相似文献   

8.
Supercritical fluid extraction (SFE) was applied for the extraction of valuable compounds from grape (Vitis labrusca B.) peel. Extraction was carried out according to an orthogonal array design (OAD) and independent variables selected were temperature, pressure and modifier concentration. SFE process was optimized by using response surface methodology (RSM) for the extract yield, total phenols, antioxidants and total anthocyanins from grape peel. Effects of extraction temperature and pressure were found to be significant on all responses. Optimal SFE conditions were identified as 45–46 °C temperature, 160–165 kg cm? 2 pressure and 6–7% ethanol as modifier for maximum extract yield (12.31%), total phenols (2.156 mg GAE/100 mL), antioxidants (1.628 mg/mL) and total anthocyanins (1.176 mg/mL). Experimental values for response variables at these optimal conditions match well with the predicted values. Grape peel extracts obtained by SFE showed more than 93% DPPH radical scavenging activities.Industrial relevanceThis study describes the response surface optimization of supercritical fluid extraction (SFE) process for the enhanced recovery of total phenols, antioxidant and anthocyanins from grape peel. SFE uses CO2 as supercritical fluid which is environment friendly solvent; allows extraction at lower temperature and the extracts obtained possess higher quality and safety. Industrially, it may be used as a promising technique for the extraction of bioactive compounds from plant materials.  相似文献   

9.
The aim of this study is to assess a new process for the valorization of fermented grape pomace using pulsed electric fields (PEF). The combination of densification and PEF treatment was applied on grape pomace of low relative humidity, without any addition of conductive liquid. The kinetics of extraction and the composition of polyphenols were evaluated throughout the subsequent hydro-alcoholic extraction at different temperatures.Optimal parameters of PEF treatment (field strength E = 1.2 kV·cm 1; energy input W = 18 kJ·kg 1; density ρ = 1.0 g·cm 3) increased the content of total polyphenols regardless of the temperature of extraction. The ratio of total anthocyanins to total flavan-3-ols at 20 °C was equal to 7.1 and 9.0 for control and PEF treated modalities, respectively. These results demonstrate the selective nature of PEF treatment in anthocyanin extraction, and thus reveal new possibilities to produce extracts with different biochemical compositions.Industrial relevanceThis study examines the feasibility of densification combined with PEF pre-treatment of relatively low humidity grape pomace for the enhancement of bioactive compounds extraction. The concentration of total phenolic compounds obtained after PEF treatment showed that the use of this technique is relevant for an industrial use, since solvent amount and extraction time can be reduced. Moreover, the selective nature of PEF opens the opportunity to produce extracts of different biochemical compositions. This process is an alternative to conventional pre-treatments of raw material (e.g. dehydration and grinding), which have impacts on product quality and are more energy consuming.  相似文献   

10.
Cereal-based food can be frequently contaminated by the presence of mycotoxins derived from Fusarium fungus, and, in particular, by deoxynivalenol (DON). Nowadays, analytical strategies for the detection of DON are well developed, but there are gaps for what concerns a correct identification, quantification and toxicological evaluation of the respective metabolites, mainly related to detoxifying actions via plant metabolism or to processing technologies and also referred to as “masked” mycotoxins.Here, we report the development of a liquid chromatography/linear ion trap mass spectrometry method capable of determining deoxynivalenol-3-glucoside (DON-3G), which is the main known DON metabolite, in different processed cereal-derived products. Samples were extracted with a mixture of methanol/water (80:20; v/v) and cleaned up using immunoaffinity columns. Chromatographic separation was performed using a core–shell C18 column with an aqueous acetic acid/methanol mixture as the mobile phase under gradient conditions. The method was in-house validated on a bread matrix as follows: matrix-matched linearity (r2 > 0.99) was established in the range of 10–200 μg kg?1; trueness expressed as recovery was close to 90%; good intermediate precision (overall RSD < 9%) and adequate detection quantitation limits (4 and 11 μg kg?1, respectively) were achieved. Furthermore, applying a metrology approach based on intralaboratory data, the estimated measurement expanded uncertainty was determined to be equal to 29%. The reliability of the method was finally demonstrated in bread, cracker, biscuit and minicake commodities, resulting in relatively low levels of DON-3G, which were not higher than 30 μg kg?1.  相似文献   

11.
Consumption of virgin olive oil (VOO) is highly recommended due to its human health benefits. Brazil is now beginning to experimentally produce VOO, and there are no data on its chemical profile. The aim of this work was to determine the phenolic compound, tocopherol and fatty acid contents of 17 monovarietal VOOs produced from olive varieties cultivated in the southeast region of Brazil during two crop years. The chemical composition of Brazilian VOO resembles that found in the literature for well-established VOOs. The analyzed compounds comprised palmitic acid (6–12%), stearic acid (1.6–2.2%), oleic acid (70–84%), linoleic acid (3.2–11.7%), α-linolenic acid (0.6–1.4%), tyrosol (NQ–155 mg kg 1), (+)-pinoresinol (2.9–23 mg kg 1), hydroxytyrosol (ND–38 mg kg 1), luteolin (ND–2.2 mg kg 1), α-tocopherol (29–233 mg kg 1), β-tocopherol (ND–9.6 mg kg 1), and γ-tocopherol (ND—19 mg kg 1). There was a significant difference in the contents of almost all of the analyzed compounds between the two crop years. Principal component analysis demonstrated that some varieties can be differentiated from one another by chemical composition. The results indicated that some Brazilian monovarietal VOOs are promising and that further studies will help to improve the quality of Brazilian VOO.  相似文献   

12.
A central composite rotatable design was employed to study the effect of ultrasound assisted extraction conditions namely sonication amplitude (10–90%), sonication cycle (0.1–1.0 s?1), solid–liquid ratio (2–10) and extraction time (5–35 min) on the total anthocyanin extraction from Garcinia indica Choisy. Overall extractions of total anthocyanin, acidity and antioxidant activity were considered as response variables. The significant (p < 0.05) response surface models with high coefficients of determination values (R2) ranging from 0.91 to 0.93 were fitted for the experimental data, which indicated that the polynomial response models fitted well for describing the extraction efficiencies of anthocyanin, acidity and antioxidant activity. Based on the design, the optimal conditions for obtaining higher extraction were extraction time 35 min, cycle ranging from 0.44 to 0.48 s?1, percentage amplitude ranging from 10 to 14%, and solid–liquid ratio 10. The graphical optimization of superimposed contour plots fulfilled the conditions to obtain total anthocyanin (Y1)  135 mg/100 g DW, total titratable acidity (Y2)  25 g/100 g DW and antioxidant activity (Y3)  14.5 M Trolox/100 g DW. The study demonstrated that response surface methodology can be utilized for deriving the optimum conditions for extraction of anthocyanin from G. indica Choisy.  相似文献   

13.
A sensitive and specific HPLC method with tandem diode array-fluorescence detection (DAD-FL) has been developed and validated for the simultaneous determination of pheophytin a (phy a) and pyropheophytin a (pyrophy a) in olive oils. Pigments were extracted with reverse phase solid phase extraction (RP-SPE) and subsequently analysed by HPLC-DAD-FL. The chromatographic analysis was carried out isocratically on ODS2 RP column using methanol–acetone (1:1 v/v) at flow-rate of 2.0 ml min−1. Specificity of the method was assured by the simultaneous detection by UV–visible (410 nm) and FL (λEx: 410 nm; λEm: 672 nm). Both compounds could be baseline separated within 7 min. The method was validated and applied in olive oil samples recently extracted as well as stored during 12 months. The limit of detection (LOD) defined at a signal-to-noise ratio of about 3 was ∼21.6 ng g−1 for pyrophy a and ∼24.6 ng g−1 for phy a under FL detection, and ∼148.0 ng g−1 for both analytes under UV–visible detection. The calibration graphs were linear (r2 > 0.9999; p < 0.01) between 0.25–14.00 ng μl−1 for pyrophy a and 0.25–19.00 ng μl−1 for phy a, under both fluorescence and UV–visible detection conditions. Recoveries of phy a and pyrophy a were over 94% as estimated by the standard addition method. Relative standard deviation for the intra-day and inter-day determination of phy a and pyrophy a were lower than 3.7% and 8.0%, respectively.  相似文献   

14.
《Food chemistry》1999,64(1):107-110
Five cassava products, commonly consumed in and around the Abraka area of Delta State, Nigeria were analysed for their cyanide levels. This study, to determine safe levels of cyanide, became necessary as the fermentation time in the processing of these products has been observed to be drastically shortened to as low as 6 h for quick economic returns. In all the products, the cyanide levels were reduced from 30.0–58.0 mg HCN equivalent kg−1 of product. These levels fall below the reported 30.0 mg HCN equivalent kg−1 safe (fresh weight) of raw cassava to 5.4–24.0 mg HCN equivalent kg−1 level for cassava products. Nevertheless, some of the products containing up to 20.0–26.5 g HCN equivalent kg−1 of products are dangerous to health as these levels are higher than the 20.0 mg HCN equivalent kg−1 safe level recommended by the Standard Organization of Nigeria. The current practice of short-time fermentation should therefore be discouraged.  相似文献   

15.
The migration of α-tocopherol (α-T) from low density polyethylene (LDPE) films, added with 20 (film A) and 40 mg g?1 (film B) to corn oil for 12 weeks at 5, 20 and 30 °C was determined. A LDPE film added with no α-T was used as control (film C). Diffusion coefficient (D) values for the film A system were 1.4 × 10?11, 7.1 × 10?11 and 30.3 × 10?11 cm2 s?1 at 5, 20 and 30 °C, respectively. Meanwhile, D values for the film B system were 1.3 × 10?11, 9.6 × 10?11 and 51.1 × 10?11 cm2 s?1 at the same temperatures. The activation energy (Ea) for the diffusion of α-T was 126.5 (film A) and 105.9 kJ mol?1 (film B). The effect of the migration of α-T on the oxidative stability of corn oil was evaluated by monitoring hexanal content by solid phase micro-extraction (SPME) and gas chromatography. The hexanal content in the oil showed that both films added with α-T resulted suitable to maintain the oxidative stability of the oil for about 16 weeks at 30 °C, compared to 12 weeks for the oil in contact with the film C.  相似文献   

16.
Concentrating cashew apple juice alters the beverage aroma and flavor, compromising consumer acceptability of the concentrated beverage. To understand the mechanisms involved in these changes, this research characterized the dynamics of the loss and emergence of volatile compounds during cashew apple juice concentration, reporting their impact on beverage sensory quality. Fresh cashew apple juice (10.3°Brix) was concentrated in a thermal-siphon type evaporator operating in a closed system. Five samples were taken throughout the concentration process with the following soluble solids contents: 11.8°Brix, 14.9°Brix, 20.2°Brix, 29.6°Brix and 42.1°Brix. Trained judges rated the aroma note intensities, described as “fresh cashew apple” and “cooked” as perceived in the fresh and concentrated beverages. The headspace volatiles of the six samples were identified and quantified by GC–MS. The results indicated the esters as the major component in the fresh juice (226.46 μg kg 1) representing 45.0% of the total mass of volatiles, followed by the terpenes (118.98 μg kg 1), acids (45.23 μg kg 1), aldehydes (39.10 μg kg 1), alcohols (18.91 μg kg 1), lactones (19.15 μg kg 1), hydrocarbons (18.02 μg kg 1) and ketones (11.05 μg kg 1). Predictive statistical models (R2 > 0.956, p  0.002) revealed that on reaching 14.9°Brix, the ester concentration declined more than 90%, the terpene content almost 100%, alcohols 85%, aldehydes 80% and hydrocarbons 90%. At 14.9°Brix, the intensity of “fresh cashew apple” aroma still predominated in the juice, but the panelists detected the presence of a weak “cooked” aroma. Concentration of the beverage to 20.2°Brix or above expressively increased the cooked aroma intensity and the concentration of hydrocarbons, alcohols and some aldehydes usually associated with off-flavors such as pentanal and decanal. This raises the possibility that some of these compounds might have been formed during juice processing. Juice with better sensory quality could possibly be obtained by concentrating the beverage to levels below 20.2°Brix, recovering the esters that evaporated off the juice until ~ 15°Brix is reached, and re-adding them to the juice concentrated.  相似文献   

17.
Lactulose has been successfully synthesized by dual-enzymatic method in organic-aqueous two-phase media using lactose and fructose as the raw materials. Cyclohexane–buffer system C6H12:buffer = 95:5 (v/v) was employed as the organic-aqueous media for the reaction. The dual-enzymatic system was consisted of immobilized lactase (IL) and immobilized glucose isomerase (IGI). Immobilized lactase was prepared by cross-linking the free lactase into Fe3O4-chitosan magnetic microspheres. The main enzymatic reaction parameters were investigated, including reaction temperature (T), pH value and reaction time (t). Under the optimum reaction conditions, i.e., lactose 0.8 g mL?1, fructose 0.1 g mL?1, IL 0.1 g mL?1, IGI 0.05 g mL?1, T = 30 °C, pH = 8.0 and t = 2 h, the obtained highest lactulose yield was approximately 151 g L?1 and the corresponding productivity was 75.5 g L?1 h?1. Experimental results indicated that the organic-aqueous media can significantly promoted the transglycosidation activity of lactase and therefore improve the lactulose yield. The possible reaction mechanism of the synthesis of lactulose using IL and IGI in two-phase system was also proposed.  相似文献   

18.
Subcritical water extraction was investigated as a green technology for the extraction of phenolic compounds from Crocus sativus petals. A Box-Behnken design was utilized to determine the optimal extraction conditions. Extraction temperature (120–160 °C), extraction time (20–60 min) and water to solid (W/S) ratio (20–40 mL/g) were considered as the variables for the extraction of phenolic compounds. A second order polynomial model was fitted to each response and the regression coefficients were determined using least square methodology. There was a good correspondence between the experimental data and their predicted counterparts. The optimum conditions of extraction were estimated to be W/S ratio of 36 mL/g, temperature of 159 °C and time of 54 min. Extraction using these optimized conditions achieved the best TPC (1616 mg/100 g), TFC (239 mg/100 g), %DPPHsc (86.05%) and FRAP value (5.1 mM). Principal components analysis (PCA) allowed a better understanding of interactions between properties of extracted phenolic antioxidants.Industrial relevanceApplication of subcritical water was shown to be a practical technique to extract the phenolic compounds of saffron petals as an underutilized bulk agro-waste. The higher phenolic antioxidants obtained in extractions carried out by this technique is of major interest from an industrial point of view, since solvent amounts were reduced and extraction times shortened. Thus, the application of this emerging technology for extraction uses and low-cost raw materials is an economical alternative to conventional extraction methods according to industry demands and a sustainable development.  相似文献   

19.
Utilization of distillery stillage from bioethanol production for lactic acid and feed production was studied. The lactic acid fermentation of the stillage was performed by Lactobacillus rhamnosus ATCC 7469 and maximal lactic acid concentration of 50.18 g L 1, yield of 0.90 g g 1, productivity of 1.48 g L 1 h 1 and viable cell number of 5 × 109 CFU mL 1 were achieved. Solid residues with biomass remains after lactic acid fermentation were assessed for animal consumption. The content of proteins and ash decreased in the residues after the fermentation, whilst the content of oil and nitrogen free extract was higher when compared to unfermented samples. The digestible (17480.64 kJ kg 1) and metabolisable (17389.08 kJ kg 1) energies as well as digestibility (966.95 g kg 1) of the fermentation residue were very high. The in vitro assessment of L. rhamnosus ATCC 7469 survival in simulated gastric conditions has shown high survival rate (87%). In addition, this bacterium has shown good antimicrobial activity against the most important pathogens and capability to produce exopolysaccharide on different sugars present in animal diet. After effective lactic acid fermentation, the residues could be recommended as a high quality feed for monogastric animals.  相似文献   

20.
The aim of this study was to ascertain the influence of pressure, temperature and time on the supercritical fluid extraction of β-carotene from the crude palm oil. The operating conditions were shown as follows: pressures of 75, 125 and 175 bar, temperatures of 80, 100 and 120 °C and extraction time of 1, 3 and 5 h. The extracts were analyzed using UV spectroscopy at a wavelength of 450 nm. Then the experimental data was compared with the data obtained using a statistical method. The results from the model showed a good agreement with the experimental data. The results (obtained from the statistical model) demonstrate that a pressure of 140 bar, temperature of 102 °C and extraction time of 3.14 h are required to obtain optimum yield of β-carotene (1.028 × 10−2%) from the extraction process, however the maximum yield of the β-carotene (1.741 × 10−2%) was experimentally obtained at a pressure of 75 bar, temperature of 120 °C and extraction time of 1 h.  相似文献   

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