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1.
Some aspects of the preservation process of vegetable soybean are discussed in this paper. Factors, like the effects of blanching duration, and brine composition, were discussed in relation with the quality attributes of the product including enzyme activity, texture and colour. It was observed that the concentration of CaCl2 influenced the texture and luminosity (L), while the pH affected luminosity (L) and green colour (– a / b ) of the processed product. Furthermore, blanching for 90 s before heat-processing was effective to inactivate 99% of the initial lipoxygenase activity. It was found that a brine containing 150 g L−1 NaCl and 2.9 g L−1 CaCl2, at pH 6.5 that was thermally treated for 9 min generated a lethality of 4 min that is enough to produce a 12-log reduction required for low acid foods and at the same time retaining desirable colour and texture.  相似文献   

2.
Liu C  Ruan H  Shen H  Chen Q  Zhou B  Li Y  He G 《Journal of food science》2007,72(4):M120-M125
ABSTRACT:  The optimization of fermentation medium for alpha-galactosidase production by Aspergillus foetidus ZU-G1 was investigated in shaker flask fermentation. A one-factor-at-a-time experiment was used to screen the preferable nutriment (carbon sources, nitrogen sources, and essential elements) for alpha-galactosidase production. A fractional factorial design was used to screen the main 5 factors, soybean meal, wheat bran, KH2PO4, FeSO4·7H2O, and the medium initial pH, that affected the production of alpha-galactosidase. The central composite experimental design was further adopted to derive a statistical model for optimizing the composition of the fermentation medium. The experimental results showed that the optimum fermentation medium for alpha-galactosidase production by Aspergillus foetidus ZU-G1 was composed of 3.2% soybean meal (w/v), 2% wheat bran (w/v), 0.1% KH2PO4 (w/v), and 0.05% FeSO4·7H2O (w/v); initial medium pH was 6.31. The results further predicted that alpha-galactosidase activity reached 64.75 U/mL after 96-h incubation in this medium, which was approximately 7 times higher than that incubated in the nonoptimized medium. The time course of alpha-galactosidase production in the optimized medium composition was also carried out to validate the model.  相似文献   

3.
The aim of the study was to determine Se concentration in selected products of animal origin (dairy products, pork, beef, chicken, giblets, fish, eggs) and to estimate the degree to which these products cover daily Se requirement in humans. Selenium concentrations were determined using the spectrofluorometric method. Mean Se concentration in the milk, yoghurt, kefir, and probiotic drinks was 0.020 μg mL−1, 0.010 μg mL−1, 0.012 μg mL−1 and 0.012 μg mL−1, respectively. Selenium concentration in cheese ranged 0.022–0.088 μg g−1 wet weight. The average selenium content of meat ranged from 0.064 (beef) to 0.094 (chicken) μg g−1 w.w. The mean Se content of giblets (liver: 0.307–0.401 μg g−1 w.w.) was significantly ( P  < 0.05) higher than in meat. The concentration of Se depends on fish species and in our study it ranged from 0.136 ± 0.023 (flounder) to 0.282 ± 0.024 μg g−1 w.w. (mackerel). The results obtained show that the analysed food provides 22.8% of the daily selenium requirement. Considering that animal products account for 40–45% of the diet daily selenium intake averages 33–37 μg.  相似文献   

4.
Investigation of respiration rate of fresh produce, under different gas composition and temperatures, and respective mathematical modelling is central for the modified atmosphere packaging design. This work investigates the effect of temperature (4, 8, 12, 16, 20 °C) and gas composition (O2 between 3 to 21% and CO2 between 0 to 15%) on respiration rate of whole mushrooms. Oxygen and carbon dioxide respiration rates increased significantly (3–4 fold) as the temperature elevated from 4 to 20 °C and were in the range of 13.23 ± 3.12 to 102.41 ± 2.132 mL kg−1 h−1) and 14.33 ± 1.56 to 97.02 ± 2.51 mL kg−1 h−1) respectively. Low O2 and high CO2 levels reduced O2 consumption and CO2 production rates of whole mushrooms on average by a circa 47–60% at all temperatures as compared to the respiration rate at ambient air. Mathematical models were developed for RO2 and RCO2, by combining the Arrhenius and Michaelis–Menten uncompetitive equations. These models predicted well, O2 consumption and CO2 production rates of whole mushrooms as a function of both temperature and gas composition.  相似文献   

5.
The essential oil of Artabotrys odoratissimus R.Br. was evaluated for antifungal activity against some storage fungi causing contamination of food stuffs. Minimum inhibitory concentration of the oil was found to be 750 μL L−1 against Aspergillus flavus Link. It was found superior over different prevalent synthetic fungicides which inhibited the growth of A. flavus between 1000–5000 μL L−1. The oil exhibited broad fungitoxic spectrum against fourteen different storage fungi. Aspergillus fumigatus was inhibited at 1000 μL L−1 whereas Cladosporium cladosporioides , Curvularia lunata , Fusarium oxysporum , Helminthosporium oryzae , Macrophomina phaseolina , Microsporum gypseum , Mucor racemosus , Penicillium italicum , Pythium debaryanum , Rhizoctonia solani , Sclerotium rolfsii and Trichoderma viride at 500 μL L−1. Aspergillus niger was found to be inhibited only 84.9% at 1000 μL L−1. In addition, the oil showed significant efficacy in arresting aflatoxin B1 secretion by the toxigenic strain (Navjot 4NSt) of A. flavus at 750 μL L−1. The efficacy of A. odoratissimus oil as aflatoxin suppressor is being reported for the first time.  相似文献   

6.
A simple flow injection (FI) manifold with spectrophotometric detection was fabricated and tested for arbutin determination. It is based on the measurement of a red-coloured product at 514 nm formed by the complexation reaction between arbutin and 4-aminoantipyrine (4-AP) in the presence of hexacyanoferrate (III) in an alkaline medium. On injecting 300 μL standard solutions at various concentrations of arbutin into the FI system under optimum conditions, a linear calibration graph over the range of 1.0–30.0 μg mL−1 arbutin was established. It is expressed by the regression equation y  = 0.2188 ± 0.0036 x  + 0.1019 ± 0.0366 ( r 2   = 0.9990, n  = 5). The detection limit (3σ) and the limit of quantitation (10σ) were 0.04 μg mL−1 and 0.13 μg mL−1, respectively. The RSD of intraday and interday precisions were found to be 1.2–1.4% and 1.7–2.7%, respectively. The method was successfully applied in the determination of arbutin in four selected fruits and three commercial whitening cream extracts with the mean recoveries of the added arbutin over the range of 96.2–99.0%. No interference effects from some common excipients used in commercial whitening creams were observed. The method is simple, rapid, selective, accurate, reproducible and relatively inexpensive.  相似文献   

7.
The contents of total chlorophyll (T-Chl), carotenoids and phenolics compounds were quantified in the biomasses of Ulva lactuca grown either in normal or artificial sea water under indoor conditions. The antioxidant and antibacterial activities of U. lactuca crude organic extracts ( Ulva- COEs) were determined. Thirty-four compounds in Ulva- COEs were characterised by thin layer chromatography and high-performance liquid chromatography. The major compounds were chlorophyll a (Chl a ) (15.60–30.90%) and b (Chl b ) (12.20–14.89%) , 9-cis β-carotene (13.12–14.47%), α-carotene (11.44–11.47%) and all-trans β-carotene (6.16–29.70%, of total carotenoids).The Ulva- COEs exhibited remarkable antioxidant activity, with an IC50 (concentration which causes a 50% of DPPH radical scavenging activity) values ranged from 16.5 and 18.7 μg mL−1, which could be compared with the synthetic antioxidants: α-tocopherol (14.4 μg mL−1), butylated hydroxyanisol (13.1 μg mL−1) and butylated hydroxyltoluene (13.1 μg mL−1). Also, Ulva- COEs exhibited great potential antibacterial activities against six bacterial strains, with minimal inhibitory concentration values ranged from 0.40 to 0.35 mg mL−1.  相似文献   

8.
Three hundred and thirteen of 2643 dried fig, two of eighty hazelnut, sixteen of twenty-eight pistachio, five of ten peanut and nineteen of twenty-three paprika samples for export from Turkey were contaminated with total aflatoxins in the range of 0.2–162.76, 5.46–6.55, 2.31–63.11, 0.75–26.36 and 1.79–6.55 μg kg−1, respectively. Samples were collected from January to August 2007 and tested for aflatoxins (B1, B2, G1 and G2) by immunoaffinity column extraction using RP-HPLC. Fifty-six of the 313 dried fig, all of the contaminated hazelnut and pistachio, two of the sixteen peanut and three of the nineteen paprika samples exceeded the regulatory limits of the European Union. The ratio of the different types of aflatoxin present in each sample exhibited great variability. For example, of 313 contaminated fig samples, 159 contained only aflatoxin B1, eighty-five contained B1 (49.7%) + G1 (50.3%), twenty-two contained only G1, twenty contained B1 (89.4%) + B2 (10.6%), thirteen contained B1 (73.7%) + B2 (10.8%) + G1 (15.5%) and fourteen contained all four types, B1 (26%) + B2 (2.5%) + G1 (66.5%) + G2 (5%).  相似文献   

9.
An headspace solid phase microextraction-gas chromatography (HS-SPME-GC) method, previously developed and validated, was applied to the determination of the methyl anthranilate (MA) content of 75 Italian citrus honeys (11 of lemon, 44 of orange and 20 of Citrus spp.). Twenty-four samples were purchased on the local market and 51 were provided by CRA-API ( Consiglio Nazionale per la Ricerca e Sperimentazione in Agricoltura-Istituto Nazionale di Apicoltura e Bachicoltura ) (Bologna, Italy). All the samples had a MA content above the limit of detection (LOD) (0.149 μg g−1) of the analytical method. The concentration range was between 0.46 and 2.52 μg g−1 and the overall average MA content was 1.19 μg g−1. The honeys with the highest mean MA content were the orange honeys followed by Citrus spp. and lemon (1.29 ± 0.461, 1.12 ± 0.511 and 0.92 ± 0.39 μg g−1, respectively). No significant differences were measured between commercial and authenticated samples.  相似文献   

10.
The antioxidant properties and toxicity profile of roasted noni ( Morinda citrifolia L . ) leaf infusion were evaluated. The 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging activity was greater than green tea infusion (81.6 ± 0.9% vs. 57.5 ± 1.8%, P  < 0.001). The mean quercetin and kaempferol contents of roasted noni leaf infusion, as prepared by the consumer, were 0.24 ± 0.01 and 0.14 ± 0.01 μg mL−1, respectively. Tannic acid content was 10 ± 1 μg mL−1. The infusion was non-mutagenic in the reverse mutation test in Salmonella typhimurium and did not induce primary DNA damage in E. coli PQ37. Further, no significant primary DNA damage was induced by 5,15-dimethylmorindol, which was the only detectable anthraquinone in noni leaves. The infusion was not cytotoxic in the 24 h brine shrimp toxicity test (LC50 > 1 mg mL−1), nor was there any evidence of acute oral toxicity from the freeze–dried infusion in Sprague–Dawley rats (LD50 > 2000 mg kg−1 b.w.).  相似文献   

11.
Synopsis We have previously screened 150 medicinal plants for the inhibition of elastase and found significant inhibitory effects of the extracts of Areca catechu L. on the ageing and inflammation of skin tissues . To isolate and identify the compounds having biological activity, they were further purified by each fraction of solvents, silica gel column chromatography, preparative TLC and reversed-phase HPLC. The peak in HPLC, which coincided with the inhibitory activity against elastase, was identified as a phenolic substance by using various colorimetric methods, UV and IR. IC50 values of this phenolic substance were 26.9 μg mL−1 for porcine pancreatic elastase (PPE) and 60.8 μg mL−1 for human neutrophil elastase (HNE). This phenolic substance showed more potent activity than that of reference compounds, oleanolic acid (76.5 μg mL−1 for PPE, 219.2 μg mL−1 for HNE) and ursolic acid (31.0 μg mL−1 for PPE, 118.6 μg mL−1 for HNE). According to the Lineweaver–Burk plots, the inhibition against both PPE and HNE by this phenolic substance was competitive inhibition with the substrate. The phenolic substance from A. catechu effectively inhibited hyaluronidase activity (IC50 : 210 μg mL−1 ).
These results suggest that the phenolic substance purified from A. catechu has an anti-ageing effect by protecting connective tissue proteins.  相似文献   

12.
Response surface methodology (RSM) was employed for the simultaneous analysis of fermentation conditions of temperature, pH and inoculum size on chemical characteristics such as ethanol, glycerol and volatile acidity, produced during mango wine production by Saccharomyces cerevisiae ( var. bayanus ). The experiments were carried out according to the central composite design to establish the optimum conditions for improving the quality of mango wine. The predicted values for optimisation process conditions were in good agreement with experimental data. The results showed that a satisfactory production of ethanol from the mango juice could be achieved reaching up to 10% (v/v), glycerol concentration is increased to 6.94 g L−1 and volatile acidity is minimised to 0.29 g L−1 at optimised fermentation conditions of temperature 22.5 °C, pH 3.8 and inoculum size 11.9%. Verification of the model indicated no difference between predicted and observed values. Sensory evaluation studies shown overall acceptance of mango wine with good quality.  相似文献   

13.
Predominant triterpenes (free oleanolic acid, β-sitosterol and β-sitosterol-3-O-β- d -glucoside) in skin and cuticular wax of grape berries have been analysed by liquid chromatography–mass spectrometry (LC-APCI-MS). The validity of the developed method was established by determining linearity, recovery, precision, accuracy, limit of detection and quantification. Detection limits were in the range of 0.12–0.25 mg L−1, and linearity values ranged up to 105 mg L−1. The repeatability of the method was good. High variability was found among the measured grape varieties based on triterpene content, quantitites of oleanolic acid of cuticular wax ranged from 31.53 mg kg−1 to 162.01 mg kg−1 of the twelve analysed samples. The highest sitosterol content was measured in the sample 'Othello' (73.12 mg kg−1), while maximum sitosterol glucoside content was also found in 'Othello' variety (13.68 mg kg−1). The results showed that the study on triterpenes could be an informative tool to characterise grape varieties.  相似文献   

14.
In this work, the effect of temperature, oxygen, red coloration process and post-harvest storage time on the respiration rate of fresh-cut Annurca apples was studied to properly develop modified atmosphere packaging. Our results showed that the red coloration process and the post-harvest storage time did not affect the respiration rate or the respiratory quotient of fresh-cut Annurca apples in the range of temperature studied (5–20 °C). A Michaelis–Menten-type equation, with the model constants described by means of an Arrhenius-type relationship, was used for predicting respiration rate on varying the temperature and O2 concentration in the head space. The maximal respiration rate (mL kg h−1) (RRmax) and the O2% corresponding to     values estimated at the reference temperature (12.5 °C), i.e. the average of the experimental temperature ranges, were, respectively, 6.77 ± 0.1 mL kg−1 h−1 and 0.68 ± 0.07% v/v, and the activation energy of the aerobic respiration rate of fresh-cut Annurca apples was estimated at 51 ± 1 kJ mol−1. The model works well to develop a modified atmosphere for fresh-cut Annurca apples.  相似文献   

15.
Anthocyanin pigment-rich sweet potato (SP) cubes were pickled by lactic fermentation by brining the cut and blanched cubes in common salt (NaCl, 2–10%) solution. They were then inoculated with a strain of Lactobacillus plantarum (MTCC 1407) and incubated for 28 days. Treatment with 8–10% brine solution was found to be organoleptically most acceptable. The final product with 8% and 10% brine solutions had a pH (2.5–2.8), titratable acidity (TA) (1.5–1.7 g kg−1), lactic acid (LA) (1.0–1.3 g kg−1), starch (56–58 g kg−1) and anthocyanin content (390 mg kg−1) on fresh weight basis. Sensory evaluation rated the anthocyanin-rich SP lacto-pickle acceptable based on texture, taste, aroma, flavour and after taste. Principal component analyses reduced the eleven original analytical and proximate variables (pH, TA, LA, starch, total sugar, anthocyanin, organic mater, ash, fat, protein and calories) to three independent components (factors), which accounted for 91% of the total variations.  相似文献   

16.
A chemically defined synthetic medium was developed on which Phytophthora infestans (Mont.) de Bary strain 1.2.4 grew extensively. The medium consisted of: 90.0 g maltose; 20.0 g L-proline; 20.0 g DL-alanine; 1.0 g KNO3; 0.50 g KH2PO4; 0.25 g MgSO4 7H2O; and 1.0 mg thiamin per liter of distilled water. The average level of growth on this medium was 0.5864 g dry weight mycelium per 50 ml medium. The glycoalkaloids, solanidine and solanine, were produced by P. infestans in this medium at an average concentration of 0.8518 mg total glycoalkaloids per 25 ml medium with a range of 0.0 to 5.9 mg per 25 ml. No glycoalkaloid production was detected when the level of growth of the fungus was below 0.35 g dry weight mycelium/50 ml medium. Glycoalkaloids were synthesized by 5 of 10 cultures grown on chick pea medium and by none of 10 cultures grown on rye seed medium.  相似文献   

17.
Polyphenol and pH influence the flavour quality of cocoa beans during roasting. Amino acids and reducing sugars are flavour precursors in cocoa beans, which develop into cocoa-specific aroma through Maillard reactions during roasting. A central composite design was applied to determine the combined effect of polyphenol and pH on the flavour precursors during cocoa roasting at 120 °C for 45 min using a lipidic model system. Polyphenol was added at 40, 80 and 120 g kg−1 and pH was adjusted to 4.5, 6 and 7.5. The response surface methodology revealed that a lower concentration of amino acids and reducing sugars was obtained at higher polyphenol concentration (120 g kg−1) and lower pH value (4.5). Based on the constraints set, the best polyphenol concentration of 43–58 g kg−1 and pH of 7.0–7.5 was found to be optimum for the formation of flavour precursors in this lipidic model study.  相似文献   

18.
Five apple juices were produced on a pilot scale by crushing the fruit, treating the mash with pectolytic enzymes, pressing, extracting water from the pomace, pasteurization, treatment of the juice with enzymes, combined gelatin/silica sol fining and final ultrafiltration. The temperature of the mash treatment was either ambient or one of 30, 40, 50 or 60 °C, in order to test whether this led to different compositional changes in the corresponding juices. The main emphasis was put on detection of D -galacturonic acid as the indicator substance for the extent of the enzymatic treatment. In the pasteurized raw juices after pressing we found values from 226 to 398 mg L−1. A distinct increase of the galacturonic acid levels could be observed during the clarification steps. Enzymatic juice treatment raised the concentrations to 580–720 mg L−1. After ultrafiltration, final values of 790–1100 mg L−1 were measured. Generally, the highest values were found in the 50 °C sample, which is the optimum temperature for pectinase activity. This was also true for the colloid concentrations and polyphenols. The influence of the temperature of the enzymatic mash treatment on other characteristic juice parameters like total titratable acidity, density, sugar, and minerals concentrations was low.  相似文献   

19.
The physicochemical properties of fractionated maize flour and the textural characteristics of a maize-based nonfermented food gel (maize tuwo ) prepared from the respective fractionated flours were evaluated. The maize flour was fractionated into four fractions: <75 μm, 75–150 μm, 150–300 μm, 300–425 μm and whole meal (<425 μm). There were variations in the selected chemical constituents of fractionated maize flour including protein (2.9–4%), ash (0.80–0.97%), crude fibre (0.73–0.91%) and damaged starch (10.1–17.4%). The fractionated maize flour gave variable bulk density (0.80–0.93 g cm−3), water absorption capacity (1.9–2.1 g g−1) and oil absorption capacity (1.7–2.1 g g−1). The colour characteristics of the fractionated maize flour and the pasting properties were all affected by the fractionation. The cohesiveness index (strain at peak compressive force) of the food gel from the flour fractions ranged between 15% and 19.5% while the softness index of the food gel ranged between 16.7 and 17.5 mm. The relative high cohesiveness and softness indexes (i.e. 19.5% and 17.4 mm respectively) of maize tuwo prepared from the flour fraction of 75–150 μm can predispose the food gel towards easier hand-mouldability and swallowability respectively; being important quality indicators for its acceptability.  相似文献   

20.
Electrical stimulation was evaluated as a method to kill Salmonella typhimurium in various salt solutions at different concentration . Salmonella typhimurium at 2 × 105 CFU/ml was treated at 22–24C for 60 min in each salt solution using electricity at 10 mA/cm2 current, 1 kHz frequency, and 50% duty cycle. Samples taken at various times were serially diluted, plated on tryptic soy agar and xylose lysine desoxycholate agar, and incubated at 37C for 18–24 h. To detect injured cells, samples were also pre-enriched in buffered peptone water at 37C for 4–5h before being plated. Results indicated all salmonellae were electrically killed at 5 min in NaCl, at 30 min in NaNO3, and at 45 min in NaC2H3O2 at 0.15 and 0.015 M concentrations. Salmonellae were also killed at 45 min in Na3PO4 and at 60 min in Na2CO3 at 0.0015 M concentration by electricity in combination with high pH .  相似文献   

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