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1.
Textural firmness is a primary determinant of consumer acceptance for evaluating freshness quality of fish fillet flesh. The objective of this study was to investigate the potential of using visible and near-infrared hyperspectral imaging (400–1000 nm) for non-destructive prediction of firmness quality of grass carp fillet as affected by frozen storage. Fillet samples were frozen at − 20 °C for 24 h and then stored at 4 °C for thawing over five days. Hyperspectral images were obtained at different thawing stages and their corresponding spectral data were extracted. Two calibration models were established between the extracted spectral data and the reference firmness values measured by the traditional mechanical method by using partial least squares regression (PLSR) and least-square support vector machine (LS-SVM) analysis. Three approaches of regression coefficients (RC) from PLSR analysis, genetic algorithm (GA) and successive projection algorithm (SPA) were utilized to recognize the most important wavelengths that possessed the greatest influence and sensitivity on the firmness prediction based upon the whole spectral range. By comparing the above-mentioned three variable selection methods, seven optimal wavelengths (450, 530, 550, 616, 720, 955 and 980 nm) were selected by GA and its corresponding simplified prediction model of GA-LS-SVM was also obtained, showing the best performance with the highest determination coefficient (R2P) of 0.941 and the lowest root mean square error estimated by prediction (RMSEP) of 1.229. The overall results of this study suggested that hyperspectral imaging technique has a potential for fast and non-destructive prediction and analysis of textural firmness of grass carp fillets as affected by frozen storage.  相似文献   

2.
With the aim of studying the optical properties of ‘Pink Lady®’ apples measured by TRS during storage in normal atmosphere and of relating them to fruit maturity and structural characteristics, 60 apples, measured at harvest by TRS at 670 nm and in the spectral range 740−1100 nm, were ranked on the basis of decreasing μa670 (increasing maturity) and randomized into 6 batches corresponding to 6 times of analysis: at harvest and after 7, 15, 29, 66 and 91 days of storage at 1 °C. At each storage time, apples were measured by TRS in the same spectral range as at harvest, and firmness, intercellular space volume (RISV), soluble solid content (SSC) and starch hydrolysis were measured; Streif Index and weight loss were computed. Overall, the μa spectra showed a maximum at 670 nm (chlorophyll-a) and at 980 nm (water), while the μ’s spectra had a decreasing trend with the wavelength increase. The μa670 and μa980 decreased with storage time as a consequence of a decrease in chlorophyll and water contents, respectively. The size and the density of the scattering centers were affected by the interplay of various phenomena: starch hydrolysis, flesh softening, water loss and RISV increase. High correlation coefficients were found between μa in the spectral region 920−1100 nm and firmness, Streif Index and RISV, while low correlation coefficients were observed between μa and SSC, and between μ’s and all the quality parameters. Using PLS analysis, good prediction for firmness, RISV and Streif Index were obtained using μa spectra; models’ performance improved when μa and μ’s are combined.  相似文献   

3.
《Meat science》2009,81(4):1205-1211
The influence of ageing and cooking on the Raman spectrum of porcine longissimus dorsi was investigated. The rich information contained in the Raman spectrum was highlighted, with numerous changes attributed to changes in the environment and conformations of the myofibrillar proteins.Predictions equations for shear force and cooking loss were developed from the Raman spectra of both raw and cooked pork. Good correlations and standard errors of prediction were obtained for both WB shear force and cooking loss, with the raw and the cooked samples showing almost identical results R2 = 0.77, root mean standard error of prediction (RMSEP)% of mean = 12% for shear force; R2 = 0.71, RMSEP% of mean = 10% for cooking loss. The Raman spectra were also able to predict the extent of cooking that occurred within the pork (R2val = 0.94, RMSEP% of range = 5.5%).Raman spectroscopy has considerable potential as a method for non-destructive and rapid determination of pork quality parameters such as tenderness. Raman spectroscopy may provide a means of determining changes during cooking and the extent to which foods have been cooked.  相似文献   

4.
Experiments were conducted to compare the colour, texture and microbiological quality of green beans that had been either high pressure sterilised (HPS) using commercially achievable pressures (a pre-heat to 86 °C followed by two treatments of 2 min at 700 MPa) or were conventionally thermally sterilised (Fo 1 to 3 min with a retort temperature of 115 °C). Samples were assessed immediately after processing and after 7 months of ambient storage. HPS treated samples were generally darker in appearance (L values shifted downwards) compared with heat treated (F0 3 min) samples. The a values for HPS samples were significantly (P < 0.05) higher than F0 3 min treated samples after processing but were not significantly different after 7 months storage (P > 0.05). HPS treated samples were typically twice as firm as F0 3 min treated samples (P < 0.05). There was some softening over storage but this differential in firmness was maintained after 7 months. Total aerobic and anaerobic plate counts and spore counts after storage were below the limits of detection in all samples apart from one canned sample where leaker spoilage had occurred.Industrial relevanceThermal sterilisation technologies are used to produce ambient stable products but frequently these products suffer deleterious quality changes such as colour and texture modification as a result of processing. There is industrial interest in any technologies with the potential to produce ambient stable products with improved retention of ‘fresh’ characteristics. High pressure sterilisation is a promising method for the production of ambient stable products with improved quality.  相似文献   

5.
The paper describes the developed hardware and software components of a computer vision system that extracts colour parameters from calibrated colour images and identifies non-destructively the different quality levels exhibited by lettuce (either whole or fresh-cut) during storage. Several colour parameters extracted by computer vision system have been evaluated to characterize the product quality levels. Among these, brown on total and brown on white proved to achieve a good identification of the different quality levels on whole and fresh-cut lettuce (P-value < 0.0001). In particular, these two parameters were able to discriminate three levels: very good or good products (quality levels from 5 to 4), samples at the limit of marketability (quality level of 3) and waste items (quality levels from 2 to 1). Quality levels were also chemically and physically characterized. Among the parameters analysed, ammonia content proved to discriminate the marketable samples from the waste in both product's typologies (either fresh-cut or whole); even the two classes of waste were well discriminated by ammonia content (P-value < 0.0001).A function that infers quality levels from the extracted colour parameters has been identified using a multi-regression model (R2 = 0.77). Multi-regression also identified a function that predicts the level of ammonia (an indicator of senescence) in the iceberg lettuce from a colour parameter provided by the computer vision system (R2 = 0.73), allowing a non-destructive evaluation of a chemical parameter that is particularly useful for the objective assessment of lettuce quality.The developed computer vision system offers flexible and simple non-destructive tool that can be employed in the food processing industry to monitor the quality and shelf life of whole and fresh-cut lettuce in a reliable, objective and quantitative way.  相似文献   

6.
Regime (direction, amount, rate, and pattern) of change in aroma active compounds was quantified as a function of four pulsed electric field (PEF) treatment times, three fruits, and 10 physical and eight sensory properties using the best-fit multiple linear regression (MLR) models. The PEF treatment times did not deteriorate 94% of the sensory properties and 70% of the physical properties and significantly change 57% of a total of 73 aroma active compounds detected for sour cherry juice, and apricot and peach nectars. The best performing MLR models belonged to 1-methyl-4-prop-1-en-2-ylcyclohexene as a function of fruit type, treatment time, and titratable acidity (= 49 mg/L; Radj2 = 95.7%; Rcv2 = 94.9%) and to 2-[(2S,5S)-5-ethenyl-5-methyloxolan-2-yl]propan-2-ol as a function of fruit type, and treatment time (SE = 157 mg/L; Radj2 = 98.2%; Rcv2 = 98.0%), respectively (n = 48; p < 0.001).Industrial relevancePulsed electric field (PEF) is one of the leading nonthermal food technologies especiallyfor processing of high acid low viscosity foods with satisfactory quality and microbial inactivation. It was shown in this study that PEF with different treatment times can successfully be applied in the pasteurization of sour cherry juice, and apricot and peach nectars with minimum loss of aroma active compounds and sensory and physical properties. Both PEF processing conditions and results can be used as a guide to determine PEF processing parameters for industrial scale processing of juices/nectars.  相似文献   

7.
This work was undertaken in order to determine the feasibility of a low intensity ultrasonic sensor to be used in the control of the cake manufacturing process. A set of 27 batters with different oil, egg and sugar contents were elaborated to obtain products with different physical characteristics. The physical properties of batters (density, viscosity and rheology) and cakes (volume, symmetry, volume index, height and density) were correlated with ultrasonic measurements. Significant correlations were obtained between the acoustic impedance and the batter consistency (R2 = 0.53), G″ (R2 = 0.66), and G1 (R2 = 0.53). The ultrasound measurement provided better correlations with physical properties of cakes than any of the conventional methods of batter measurement. This system has shown an interesting potential for industrial applications, especially in the detection of deficient batters.  相似文献   

8.
《Meat science》2013,93(4):837-840
This study aimed to measure the amount of microbial contamination caused by inspecting the lymph nodes of adult sheep carcasses for caseous lymphadenitis (CLA). Surface swabs from carcasses pre-inspection (N = 296) and post-inspection (N = 296) were obtained for enumeration of indicator organisms at three commercial abattoirs. At the scapular site, inspection doubled the probability of detecting E. coli (Pr before = 0.35, Pr after = 0.67) and increased the expected count of E. coli from 2 cfu/cm2 to 13 cfu/cm2. Inspection at the rump site increased the probability of detecting E. coli by 1.1 times (Pr before = 0.84, Pr after = 0.93) and increased the expected count from 32 cfu/cm2 to 45 cfu/cm2. Effects were also observed for Enterobacteriaceae and total viable count. The findings show that routine inspection of adult sheep carcasses for CLA has a detrimental impact on carcass microbiological traits.  相似文献   

9.
The effects of postharvest treatment with chitosan nanoparticles (CSNPs = T1) and Zataria multiflora essential oil (ZEO) incorporated in (ZEO@CSNPs = T2), on the shelf-life extension and antioxidant activities of whole cucumbers during storage were evaluated. Coated and control cucumbers were stored at 10 ± 1 °C with 90-95% RH for 21 days. Measurements of physicochemical and microbial growth were accomplished every 3 days. After 15 days, the fruit decay in the T2 coating was 2% vs. 12 and 97.7% in the T1 coated and uncoated fruit, respectively. Significant differences were obtained for weight loss, firmness, respiration rate, DPPH-radical scavenging activity, reducing power and microbial counts (P < 0.05) during storage. There were significantly higher levels of DPPH-radical scavenging activity and reducing power in T2-treated cucumbers compared with that in the T1-treated followed by the control fruit. In conclusion the ZEO loaded CSNPs coating could improve the quality of cucumber and protect the bioactive components during storage.Industrial relevanceCucumber as a good source of antioxidants is one of the most popular and widely grown vegetable crops in the world. However, it has a short shelf-life (< 14 days) that is mainly related to firmness loss, discoloration, desiccation and fungal rot. The reduction of losses is a major objective of postharvest technology for cucumbers, which tries to utilize safe and efficacious methods to control contamination and the growth of spoiling fungi.On the other hand, the nano-/micro-encapsulation of EOs allows protection of their sensitive bioactive compounds from unfavorable environmental conditions and enhances their bioactivity during food processing and storage. So, in this study a new edible coating, consisting of Zataria multiflora essential oil (ZEO) incorporated into chitosan nanoparticles (CSNPs), was introduced to extend the shelf-life of cucumber as well as protect the bioactive compounds with antioxidant properties.  相似文献   

10.
The effects of calcium and storage time on physicochemical properties and nanostructure of chelate-soluble pectin (CSP) of apricots (Prunus armeniaca L.) at 0 °C were investigated. During the storage, the firmness did not change with the contents but consistent with the morphology changes of CSP, which were characterized by atomic force microscopy (AFM). The branching structures of CSP decreased, meanwhile, the frequencies of chains with small width (<35 nm) and lengths (<500 nm) of CSP chains increased, which showed more in the control group than in the 1% calcium treated group. Compared to the control and 3% calcium treated groups, treatment with 1% calcium delayed the changes of physicochemical properties and degradation of the depolymerization of CSP during the fruit softening. The results provided us with a way to investigate the quality indexes from structural studies of nanoscale.  相似文献   

11.
The potential of Near-Infrared Transmittance (NIT) Spectroscopy for estimation of fatty acid composition in soybean seed samples was studied. Total 612 whole seed samples with wide range of variability for major fatty acids were used to develop calibration equations by applying SNV de-trend and first derivative mathematical treatment in the range of 850–1048 nm. Useful chemometric models for most important fatty acids present in soybean seed oil were developed using Modified Partial Least Squares (MPLS) regression method. In external validation oleic (r2 = 0.89, SEP = 1.61), linoleic (r2 = 0.86, SEP = 1.50) and palmitic (r2 = 0.89, SEP = 0.17) acids were predicted with good accuracy, while the predictions for linolenic acid (r2 = 0.78, SEP = 0.36) and stearic acid (r2 = 0.63, SEP = 0.11) had relatively poor accuracy. The whole-seed NIT spectroscopy equations for fatty acid estimation would be useful for improving efficiency of breeding programs aimed at altering fatty acid composition in soybean.  相似文献   

12.
This study was done in order to investigate the effect of repetitive pulsed light (RPL) treatment at certain interval on microbiological stability, quality and physicochemical changes of fresh-cut cantaloupes during storage. Fresh-cut cantaloupes packed in polypropylene bag were exposed to RPL treatment with fluences of 0.3, 0.6, 0.9 and 1.2 J/cm2 every 48 h up to 28 days of storage at 4 ± 1 °C. The microbiological quality, headspace gas composition, physical quality (firmness, fluid loss and colour), chemical quality (pH, titratable acidity, total soluble solids, total phenolic content and ascorbic acid content) and microscopic observations of fresh-cut cantaloupes were determined during storage. No significant (p > 0.05) effect was observed for firmness, colour and total soluble solids of fresh-cut cantaloupes treated with RPL throughout the storage study. Repetitive PL treatment using 0.9 J/cm2 was the most effective fluence for extending the shelf life of fresh-cut cantaloupes with extension by 20 days compared to control in term of microbiological quality while maintaining all quality parameters. Negative effect of single PL treatment (SPL) (11.7 J/cm2) on tissue structure of fresh-cut cantaloupes during storage was minimised by applying RPL treatment (0.9 J/cm2 for every 48 h interval).Industrial relevanceFresh-cut cantaloupes are becoming more popular due to the benefits of convenience and fresh-like quality provided. However, fresh-cut cantaloupes are susceptible to microbial contamination and deterioration as the fruit tissue is injured due to cutting of the product into pieces. Repetitive PL (RPL) treatment is an alternative application to single PL (SPL) treatment for extending shelf life of fresh-cut fruits by minimising the negative effect of SPL treatment on the tissue structure. This study demonstrates the usefulness of RPL treatment to further extend the shelf life of fresh-cut cantaloupes compared to SPL treatment. This is crucial for vending cut fruits through refrigerators equipped with RPL system. The RPL application contributes to reduced postharvest loss and increased convenience and availability of fresh-cut fruits to the public which benefit both producers and consumers.  相似文献   

13.
An experiment was undertaken to investigate the effect of milk fat level (0%, 2.5% and 5.0% w/w) and gel firmness level at cutting (5, 35 and 65 Pa) on indices of syneresis, while curd was undergoing stirring. The curd moisture content, yield of whey, fat in whey and casein fines in whey were measured at fixed intervals between 5 and 75 min after cutting the gel. The casein level in milk and clotting conditions was kept constant in all trials. The trials were carried out using recombined whole milk in an 11 L cheese vat. The fat level in milk had a large negative effect on the yield of whey. A clear effect of gel firmness on casein fines was observed. The best overall prediction, in terms of coefficient of determination, was for curd moisture content using milk fat concentration, time after gel cutting and set-to-cut time (R2 = 0.95).  相似文献   

14.
The aim of this study was to evaluate the effects of gamma radiation on cherry tomatoes, to assess the potential of irradiation post-harvest treatment for fruit shelf-life extension. Freshly packed cherry tomatoes (Solanum lycopersicus var. cerasiforme) were irradiated at several gamma radiation doses (0.8 kGy up to 5.7 kGy) in a 60Co chamber. Microbiological parameters, antioxidant activity and quality properties such as texture, color, pH, total soluble solids content, titratable acidity, and sensory parameters, were assessed before and after irradiation and during storage time up to 14 days at 4 °C. Inactivation studies of natural cherry tomatoes microbiota and inoculated potential foodborne pathogens (Salmonella enterica; Escherichia coli and Staphylococcus aureus) were performed. A two log reduction on the microbial load of cherry tomatoes was verified after irradiation at 3.2 kGy, and 14 days of storage at 4 °C. Moreover, a maximum reduction of 11 log on the viability of potential foodborne bacteria was obtained after irradiation at 3.2 kGy on spiked fruits. Regarding fruits quality properties, irradiation caused a decrease in firmness compared with non-irradiated fruit, although it was verified a similar acceptability among fruits non-irradiated and irradiated at 3.2 kGy. Therefore, these results suggest that the irradiation treatment could be advantageous in improving microbial safety of cherry tomatoes and shelf-life extension without affecting significantly its quality attributes.Industrial relevanceThere is an ever-increasing global demand from consumers for high-quality foods with major emphasis placed on quality and safety attributes. One of the main demands that consumers display is for minimally processed, high-nutrition/low-energy natural foods with no or minimal chemical preservatives. Extending the shelf-life, while improving the food safety, will have a positive impact on both the industry and consumers (and potential target groups such as immunocompromised patients). The present study indicated that post-harvest gamma radiation treatment of cherry tomatoes can be used as an emergent, clean and environmental friendly process to extend the shelf-life of this fruit with safety and quality.  相似文献   

15.
Effect of crystalline structure of two isolated potato starches on gelatinization and glycemic response was studied. Both starches showed to possess different fine structures. Starch 1 exhibited a typical B-type X-ray diffraction pattern, while Starch 2 exhibited an X-ray diffraction pattern suggesting the presence of imperfections of the general B-type crystalline structure (peak at 5.5° 2θ was absent), hence disarraying the structure order. This difference was reflected in the gelatinization behavior and consequently in the glycemic response. Starch 2 started to melt at lower temperature than Starch 1 (e.g. To was 60.9 and 61.84 °C, respectively, to native starches), and residual gelatinization enthalpy (ΔH) of Starch 2 was always smaller than that of Starch 1 when heated at 54–65 °C for 10 min. Glycemic response was increased as gelatinization degree (DG) increased in starches independent from the native crystalline structure (area under curve = 2.59 × DG-75.83, R2 = 0.986; maximum concentration of postprandial blood glucose = 0.042 × DG-0.23, R2 = 0.935). Results suggested that native crystalline structure of isolated potato starch affects the glycemic response of heated starches by affecting the gelatinization behavior.  相似文献   

16.
The rheological characteristics of twenty wheat flour samples obtained from four organic flour blends and a non-organic control were compared in relation to their ability to predict subsequent loaf volume in the baked bread. The flour samples considered had protein contents that varied between 11–14 g/100 g. Four different rheological methods were employed. Oscillatory stress rheometry on the protein gel extracted from the wheat flour, oscillatory stress rheometry and creep measurement on undeveloped dough samples and biaxial extensional measurements on simple flour–water doughs. None of the fundamental rheological parameters correlated with loaf volume. There was a correlation between the storage modulus of the gel protein and storage modulus for the undeveloped dough (r = 0.85). There was a weak negative correlation between protein content and biaxial extensional viscosity (r = −0.62). Stepwise multiple regression related loaf volume to dough stability time (measured on the Farinograph) and tan (phase angle) for the undeveloped dough samples (overall model r2 = 0.54). The results indicate that the four rheological tests considered could not be used as predictors of subsequent loaf volume when the bread is baked.  相似文献   

17.
In an attempt to investigate the hard-to-cook phenomenon in Dioscorea dumetorum tubers during storage, selected physical and chemical characteristics were monitored. A 3 × 5 factorial experiment with storage conditions (15 °C, 59% RH; 30 °C, 75% RH; 45 °C, 86% RH) and storage period (0, 2, 4, 7 and 14 days) as variables was carried out. Changes in cooked hardness, water absorption, water-holding capacity and solid loss of steeped tubers as well as phytate, total phenols and lignin contents were monitored. Water uptake and solid loss of steeped tubers decreased significantly (P  0.05) with storage period, suggesting that storage affects cell wall membrane permeability of the tubers. Cooked hardness analyses indicated significant difference (P  0.05) between fresh and stored tubers and its rate varied with storage time and storage conditions. Cooked hardness values correlated negatively (r = −0.922–0.857, P  0.05, d.f. = 146) with phytate and total phenols. A multiple mechanism for D. dumetorum tubers hardening is presented which includes phytate loss as a minimal contributor to cooked hardness during the first days of storage and total phenol loss via a lignification-like mechanism as a major contributor.  相似文献   

18.
The amount of ice nuclei formed during the pressure release is important for the final formation and development of ice crystals in pressure shift freezing (PSF) frozen products. In this study, a high-pressure (HP) calorimeter was used to evaluate the ratio of ice crystals instantaneously formed by rapid depressurization during PSF of pure water and pork muscle tissue. Experiments were carried out initial pressure levels of 62, 115, 157 and 199 MPa, with corresponding phase change temperatures of −5, −10, −15 and −20 °C, respectively (slightly higher than phase change point of water–ice I). The ice crystal ratio was determined based on calorimetric peak measured and heat balance. The evaluated regression relationship between observed ice crystal ratio (Rice in %) and pressure (P, MPa) was Rice–water = 0.115P + 0.00013P2 (R2 = 0.96, n = 9) for pure water, and Rice–pork = 0.080P + 0.00012P2 (R2 = 0.95, n = 11) for pork muscle. Compared to other methods, the calorimetric evaluation does not require any of the pressure-related properties of the test sample. HP calorimetry can thus be used to evaluate ice crystal ratio for PSF of foods even though their pressure related properties may be unknown.  相似文献   

19.
Mass transfer and physical attributes of red bell pepper were evaluated. Pepper strips were placed into brine of constant concentration at different temperatures (25–55 °C) with immersion times ranging from 15 to 480 min with and without ultrasound treatment. Diffusion coefficients were evaluated for calcium, sodium, citric acid, soluble and total solids, impregnation and water loss. Firmness, kinetic coefficients and color were determined for each treatment. Ultrasound increased the uptake of solutes (p < 0.05) with the exception of calcium, sodium ions, and acidity, where diffusion coefficients did not significantly differ among treatments. Loss of water, total and soluble solids in tissue significantly increased at 55 °C with 47 kHz, with diffusion coefficients of 13.23 × 10−10 m2/s, 7.26 × 10−10 m2/s and 14.42 × 10−10 m2/s, respectively. These increases may be attributed to increased cell wall permeability, facilitating transport of water and solute, as evidenced by product firmness, where ultrasound treatments had a negative effect on firmness.  相似文献   

20.
The influence of food ingredients (water, starch, fat, and sugar), individually and in combination, on the sensory perception of the pungency of capsaicin was studied in model food systems using the time-intensity method. Furthermore, the transferability of the results obtained using model food matrices to complex matrices, such as convenience salsas, was investigated. Significant differences between the samples (p < 0.05) were examined by analysis of variance (ANOVA) followed by the Tukey-HSD post hoc test. A highly complex matrix and a high starch content reduced the perception of pungency in both the model food matrices and the convenience salsa products. Therefore, the time-related maximum intensity of pungency (Imax) was affected by other factors in addition to the capsaicin concentration.The total capsaicinoid content in the salsas was quantified by high-performance liquid chromatography–mass spectrometry (HPLC–MS) and correlated to the results of the sensory evaluation. The best correlation (R2 = 0.8029) was observed for the total capsaicinoid content and the maximum intensity of pungency (Imax) in comparison to the duration of the total pungency perception TDur (R2 = 0.5176) and the area under the curve (R2 = 0.6898). The calculated regression models serve as an example of how empirical calculations can be generated and used in a specific context.  相似文献   

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