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1.
The change in browning characteristics of the slices processed from ‘Tsugaru’ apples stored at 0 °C for 5 months under controlled atmosphere (CA, 1 kPa O2 + 1 kPa CO2, 3 kPa O2 + 3 kPa CO2) or air has been investigated for 5 days at 20 °C. Respiration and ethylene production of the slices from apples stored in CA were retarded. Electrolyte leakage and browning index were lower in the slices from apples stored under CA than air. Vitamin C and phenolic contents in the slices from apples stored under air were maintained at higher level compared to the slices from apples stored under CA. Polyphenol oxidase activity in the slices was not affected by pre-slicing storage atmospheres. Therefore, the atmospheres of pre-slicing storage affected browning development in fresh-cut products of ‘Tsugaru’ apples and browning was found to be correlated with the levels of electrolyte leakage and phenolic compounds.  相似文献   

2.
The effects of an aerobic modified atmosphere packaging (MAP) (70% CO2, 15% O2 and 15% N2) with and without a CO2 3-h soluble gas stabilization (SGS) pre-treatment of chicken drumsticks were determined for various package and product quality characteristics. The CO2 dissolved into drumsticks was determined. The equilibrium between CO2 dissolved in drumsticks and CO2 in head space was reached within 48 h after packaging, showing highest values of CO2 in SGS pre-treated samples. This greater availability of CO2 resulted in lower counts of TAB and Pseudomonas in SGS than in MAP drumsticks. Package collapse was significantly reduced in SGS samples. The average of CO2 dissolved in the MAP treatment was 567 mg CO2 kg− 1 of chicken and, 361 mg CO2 kg− 1 of chicken during the MAP treatment, in SGS pre-treated samples. This difference could be the quantity of CO2 dissolved during SGS pre-treatment.  相似文献   

3.
Modified atmosphere packaging improved quality of kohlrabi stems   总被引:1,自引:0,他引:1  
Víctor H. Escalona 《LWT》2007,40(3):397-403
To improve the keeping quality of the kohlrabi stems and avoiding wilting of the leaves, modified atmosphere packaging (MAP) with oriented polypropylene and amide-polyethylene copolymer bags was applied. Avoiding wilting of the kohlrabi leaves is crucial because European consumers consider the freshness of kohlrabi leaves as a key quality parameter. Whole kohlrabies were stored within, above-mentioned sealed bags, for 14 days at 0 °C and 95% RH, followed by 3 days at 10 °C. In the MA packages gas compositions of about 5 kPa O2 and 10-15 kPa CO2 were generated. The respiratory activity, C2H4 production, firmness (of stems and leaves), sugars, organic acids contents, as well as chemical and sensory quality attributes were monitored. The respiratory rate of the kohlrabi stems in air at 0 °C was 10-11 mg CO2/kg/h with a C2H4 production lower than 0.05 μl/kg/h (traces). However, when the temperature was increased at 10 °C the respiration rate raised 3.5 folds. Acidity, pH, soluble solids, sugars and organic acids content and firmness did not show significant changes at the end of both cold storage and retail sale periods. MAP was very effective improving keeping quality of the stems and retarding wilting of the leaves. During the retail sale period at 10 °C, the bags must to be perforated to avoid anaerobic conditions.  相似文献   

4.
C. Villatoro 《LWT》2009,42(2):557-293
‘Pink Lady®’ apples (Malus domestica) fruit were harvested at commercial maturity treated with three different agrochemical products, and stored at 1 °C under either air or controlled atmosphere conditions (2.5 kPa O2 + 3 kPa CO2 and 1 kPa O2 + 2 kPa CO2) for 15 and 28 weeks. Diphenylamine, folpet and imazalil contents in both skin and flesh were simultaneously determined after cold storage plus a simulated marketing period of 1 or 7 days at 20 °C. Results showed that apples stored in 2.5 kPa O2 + 3 kPa CO2 retained higher contents of diphenylamine residues in comparison with those stored in 1 kPa O2 + 2 kPa CO2 or refrigerated air. Significant differences in imazalil skin contents were found throughout the simulated marketing period at 20 °C after storage for 28 weeks in controlled atmospheres.  相似文献   

5.
Fennel was washed on the butt‐end cut with ascorbic (1%) and citric (5%) acids and packed in polypropylene (PP) baskets sealed with PP film to generate a modified atmosphere. As a control, perforated PP was used. Storage conditions were 14 d at 0 °C followed by 4 d in air at 15 °C. Chemical and sensory quality attributes were monitored. No browning of external leaves developed. Modified atmosphere of 16 to 17% O2 and 3 to 4% CO2 was able to inhibit browning of the butt‐end cut, the main factor for keeping quality of fennel, but treatments with antioxidants did not. In all treatments, green color and firmness decreased, although under modified atmosphere the best results for keeping fennel quality were found.  相似文献   

6.
Long-life Calibra tomatoes (Lycopersicum esculentum Mill.) were minimally fresh processed in slices or wedges and packaged in polypropylene (PP) trays. Passive and active (3 kPa O2+0 kPa CO2 and 3 kPa O2+4 kPa CO2) modified atmosphere packages (MAP) were used at 0 and 5 °C. After 14 days, the gas composition within passive MAP packages was 11–13 kPa O2+5.5–6 kPa CO2 and 8–9.5 kPa O2+10.5–11.5 kPa CO2 at 0 and 5 °C, respectively. The gas composition reached in active MAP at both temperatures for both types of cuts was around 7–10.5 kPa O2 and 7–9 kPa CO2. The highest C2H4 level (15 L L–1) was found in passive MAP at 5 °C, while in active MAP at both temperatures about 6 L L–1 C2H4 accumulated. After 7 days of storage at 0 °C, the tomato pieces showed better aroma, appearance and overall quality than those stored at 5 °C. No difference between MAP treatments was found, although both led to a better appearance and overall quality than controls in air. After 14 days at 0 °C, only MAP treatments kept a good flavour, overall quality and texture, with no differences between them. After 14 days at 5 °C in all treatments, the flavour fell below a fair condition and the slices showed a slight senescence. MAP significantly reduced total plate counts (TPC) of slices at 5 °C, although only active MAP reduced TPC in wedges after 14 days at 5 °C. A visibly better appearance and overall quality was found in slices than in wedges. The main factors influencing the quality of tomato pieces were the storage duration and temperature. To keep the quality of fresh-cut tomatoes, one should consider three factors for selection: a suitable low chilling sensitive tomato cultivar, an adherent placenta and optimal maturity stage at harvest.  相似文献   

7.
L. Gašperlin  B. Lukan  B. ?lender  T. Polak 《LWT》2009,42(8):1313-1319
Mutagenic heterocyclic amines (HAs) originate in processed proteinaceous foods. The effects of the presence of skin (with vs. without) and of grilling method (two plate vs. infrared) on the content of HAs in grilled chicken pectoralis superficialis muscle (temperature, 220 °C) were investigated. HA precursors (creatine, creatinine, free amino acids and carbohydrates) and HAs of these raw and grilled breast muscles were determined. The muscles originated from 24 birds of either sex (provenance Ross; aged 40-45 days). The HA content was determined in homogenates of the upper and lower surface slices of the grilled muscles (Ti = 82 °C). A higher content of total free amino acids was seen for the muscle (27.1 mmol kg−1 raw meat) than for the skin (21.7 mmol kg−1 raw meat). The creatine, creatinine and carbohydrate levels in the skin were below the limits of detection. The contents of creatine (31.8-38.7 mmol kg−1) and creatinine (0.24-0.33 mmol kg−1) in the breast muscle were determined. Relatively high levels were seen for glucose (23 mmol kg−1 raw meat) and fructose (10 mmol kg−1 raw meat) in the muscle, with other sugars present at low levels (<2 mmol kg−1 raw meat). For the chicken muscle grilled on a two-plate grill, the contents of total HAs (PhIP, MeIQx, DiMeIQx, Harman and Norharman) were lower with the skin in place than in the muscle grilled without the skin (3.5 μg kg−1vs. 4.8 μg kg−1). Also, during infrared grilling with the skin, lower amounts of HAs were formed than with grilling on the two-plate grill (2.4 μg kg−1vs. 3.5 μg kg−1). On average, the infrared-grilled samples with skin contained 3-fold more total HAs than similar samples without the skin (2.4 μg kg−1vs. 0.8 μg kg−1), with the highest levels seen for PhIP and MeIQx.  相似文献   

8.
This study describes the extraction and characterisation of cashew apple polyphenol oxidase (PPO) and the effect of wounding on cashew apple phenolic acid composition, PPO activity and fruit browning. Purification factor was 59 at 95% (NH4)2SO4 saturation. For PPO activity, the optimal substrate was catechol and the optimum pH was 6.5. PPO Km and Vmax values were 18.8 mM and 13.6 U min−1 ml−1, respectively. Ascorbic acid, citric acid, sodium sulphite and sodium metabisulphite decreased PPO activity, while sodium chloride increased PPO activity. Wounding at 2 °C and 27 °C for 24 h increased PPO activity but storage at 40 °C reduced PPO activity. Gallic acid, protocatechuic acid and cinnamic acid (free and conjugate) were identified in cashew apple juice. Cutting and subsequent storage at 40 °C hydrolysed cinnamic acid. 5-Hydroxymethylfurfural content in cashew apple juice increased after injury and storage at higher temperatures, indicating non-enzymatic browning.  相似文献   

9.
The effect of alginate and gellan-based edible coatings on the shelf-life of fresh-cut Fuji apples packed in trays with a plastic film of a known permeability to oxygen (110 cm3 O2 m−2 bar−1 day−1) was investigated by measuring changes in headspace atmosphere, color, firmness and microbial growth during 23 days of storage at 4 °C. Concentration of O2 and CO2 in the package was measured and no significant differences between coated and uncoated fresh-cut apples were observed. Ethylene concentration in coated apples seemed to be delayed since it remained below 50 μl l−1 throughout the whole refrigerated storage period, while production of this gas was detected in uncoated apples from the very initial days of storage. Coated apple wedges exhibited ethanol and acetaldehyde formation from the second week of storage indicating fermentative metabolism. Polymers were crosslinked with a calcium chloride solution, to which the antibrowning agent N-acetylcysteine was added, being incorporated into the coatings formulation and helping to maintain firmness and color of apple wedges during the entire storage time. The application of the edible coatings also retarded the microbiological deterioration of fresh-cut apples. Alginate and gellan edible coatings effectively prolonged the shelf-life of Fuji apple wedges by 2 weeks of storage compared with the control apple slices which showed a considerable cut surface browning and tissue softening from the very early days of storage, limiting their shelf-life to less than 4 days.  相似文献   

10.
A minimal process was carried out for pitted jackfruit (Artocarpus heterophyllus L.) bulbs using additives CaCl2, ascorbic acid (AA), and sodium benzoate in combination with mild acidified conditions for storage under modified atmosphere (MA), i.e., 3 kPa O2 + 5 kPa CO2, gas mixture flushed polyethylene (GFPE) bags, polyethylene terephthalate jars with silicon membrane on lid and polyethylene bag with air. Samples devoid of any additive based pretreatment but packaged in similar MA conditions were used as experimental control. A restricted loss of around 7%, 8%, 43%, and 31% was found for total phenolics (TP), total flavonoids (TF), total carotenoids (TC), and AA contents respectively in the pretreated samples kept under GFPE bags towards the end of 35 days storage at 6 °C. Among the phytochemicals evaluated, the radical-scavenging activity showed the highest correlation (r = 0.979) with AA followed by TP, TF and TC.  相似文献   

11.
Dietary polyamines, putrescine, spermidine (SPD) and spermine (SPM), participate in an array of important physiological roles, including tumour growth. Thus, reliable information on polyamine content in foods has been needed. We therefore determined polyamine contents in chilled chicken meat and giblets (n = 20) and skin (n = 10) 24 h after slaughter. The polyamines were determined, after extraction with perchloric acid, as dansyl derivatives, using an HPLC method. Mean SPD values were 4.8, 10.2, 11.4, 48.7 and 12.1 mg kg−1 and SPM values were 36.8, 38.0, 24.3, 133 and 82.7 mg kg−1 in breast, thigh, skin, liver and heart, respectively. Significant statistical correlations between SPD and SPM contents were observed in breast, thigh, skin and liver, whereas correlations were insignificant in heart. An increase of SPD and SPM was apparent in breasts and thighs stored at −18 °C for 6 months; however, it was significant only for SPM in thighs. The losses of both SPD and SPM were statistically insignificant during storage of aerobically packaged breasts up to 9 days at +2 °C. A significant decrease of SPM to about 60% of the initial contents was observed in both vacuum-packaged and in modified atmosphere (20% CO2 and 80% O2)-stored breasts on day 21 at +2 °C. For both SPD and SPM, roasting, grilling and frying of fresh breasts caused losses of about 40–60% of the initial contents (higher than boiling and stewing). Similarly, losses of SPM, due to roasting of breasts frozen for 3 or 6 months, were higher than those caused by stewing. Putrescine was detected only sporadically and at levels close to the detection limit of 1.0 mg kg−1 (fresh matter).  相似文献   

12.
Apple slices, ozonised in water (1:2 w/v; 200 mg O3/h, for 5 min) and then soaked in a solution containing ascorbic acid (200 mg kg−1), citric acid (200 mg kg−1) and sodium benzoate (200 mg kg−1) for 10 min, were coated with edible surface coatings made up of shellac and aloe gel (AG), separately and in combination. Application of coatings was found to significantly (p < 0.05) reduce the respiration and ethylene synthesis rates as well as electrolyte leakage. The AG-coated samples showed reduced polyphenol oxidase (96.1) and peroxidase activity (211.2) followed by the samples coated with combination of shellac + AG, and shellac alone; the uncoated samples being showing maximum values (122.8, 288.5) for these enzymes in terms of units/g/min, respectively. The L*, a* and b* values, firmness, microbiological and keeping quality of the coated slices also showed reduced changes during storage for 30 days at 6 ± 1 °C.  相似文献   

13.
Diffusion of carbon dioxide through grain bulks   总被引:3,自引:0,他引:3  
The diffusion coefficient of carbon dioxide (CO2) through grain bulks was determined using a transient method with the following variables: (1) grain bulk (wheat, barley, and canola); (2) moisture content (m.c.) (dry, damp, and wet conditions); (3) temperature (5°C, 15°C, 25°C, and 40°C); (4) direction of gas flow (upwards, downwards, and horizontal); (5) porosity (two levels for each grain bulk); (6) grain kernel orientation (vertical and horizontal); (7) initial concentration in the gas chamber (20%, 40%, and 60%); and (8) dockage (0%, 4%, 8%, and 12%). The diffusion coefficients of CO2 through wheat bulks ranged from 5.9×10−6 to 7.6×10−6 m2 s−1, through barley bulks from 5.1×10−6 to 8.4×10−6 m2 s−1, and through canola bulks from 3.7×10−6 to 5.3×10−6 m2 s−1 for the test conditions studied.Increasing the m.c. decreased diffusion coefficients. An increase in temperature generally increased the diffusion coefficient of CO2. Diffusion in the downward direction resulted in higher diffusion coefficients. No significant difference in diffusion coefficients was observed between the upward and horizontal directions of flow. An increase in porosity resulted in higher diffusion coefficients. The upward diffusion coefficient of CO2 was higher for vertical grain kernel orientation than for horizontal kernel orientation for wheat and barley but for canola, the difference between the two kernel orientations was not significant. There was no significant difference in diffusion coefficients for different initial gas concentrations. The diffusion coefficient increased linearly as the dockage was increased.The amount of CO2 absorbed by barley and canola increased with an increase in m.c. in polynomial fashion. There was no significant difference in the sorption of CO2 by barley and canola when the temperature of the grain was changed from 15°C to 40°C.  相似文献   

14.
Alejandro Tomás-Callejas 《LWT》2011,44(6):1422-1428
The antimicrobial effects and quality changes of O2, He, N2 or N2O-enriched active modified atmosphere packaging -MAP- (100 kPa initial gas partial pressure) compared to a chlorinated −100 mg L−1 NaClO- passive MAP (control) in fresh-cut Red Chard baby leaves up to 8 days at 5 °C were studied. High O2 MAP (>85 kPa O2) inhibited natural microflora growth during 7 days at 5 °C. Regarding control treatment, no differences for He and N2O-enriched MAPs on microbial growth were found although control samples were previously disinfected. Initial total phenolics content (613 mg ChAE kg−1 fw) increased up to 61-93% after 6 days at 5 °C under O2, He, and N2-enriched MAPs. Vitamin C content decreased up to 67% after shelf life in control samples while lower decreases were monitored in samples stored under non-conventional MAPs. He-enriched MAP preserved the total chlorophylls content throughout shelf life. After 8 days at 5 °C the overall sensory quality of all treatments showed a moderate decrease while still being scored at the limit of usability. In conclusion, He and O2-enriched MAPs are useful tools in the preservation of fresh-cut Red Chard quality.  相似文献   

15.
The objective of this study is to analyze the influence of temperature and reduced pressure on the convective heat transfer coefficient, h, during frying of products with different area/volume ratio. h was determined from surface temperature and moisture loss experimental data during frying of potato cylinders and “churros”, at different oil temperatures (100, 120 and 140 °C) and moderate vacuum (19.5–25.9 kPa). The results obtained during vacuum frying were compared with those obtained at atmospheric pressure, both for the same oil temperature (140 °C) and for the same thermal gradient (40 °C). During frying, h changes considerably, reaching a maximum between 700–1600 Wm−2 K−1 in vacuum frying and 800–2000 Wm−2 K−1 in atmospheric frying. To quantify the effect of oil temperature, pressure and size of the product on h, a parameter called “bubbling efficiency”, BE, was defined. BE relates the bubble departure radius and the area/volume ratio of the product. An equation (the derivative of the Gompertz function) was proposed to estimate the mean heat convective coefficients for each frying condition as a function of BE (R2 = 0.957). The relation between h and BE shows a maximum corresponding to an optimal bubbling pattern. Most of the vacuum frying settings are outside this optimum, being affected by the insulation effect of bubbles covering the surface.  相似文献   

16.
The effects of different initial in-package O2 and CO2 concentrations (2.5 kPa O2 + 7 kPa CO2, 10 kPa O2 + 7 kPa CO2, 21 kPa O2, 30 kPa O2 and 70 kPa O2) on peroxidase activity, vitamin C content, total phenolics and antioxidant capacity of fresh-cut ‘Piel de Sapo’ melon have been investigated for 14 days at 4 °C. The radical scavenging activity of fresh-cut melon strongly increased after 9 days storage related to a synthesis of phenolic compounds, especially under 2.5 kPa O2 + 7 kPa CO2 atmospheres. Low O2 levels best maintained vitamin C and phenolic content during the storage. However, stressful too-low O2 and high CO2 levels induced an important increase of peroxidase activity under 2.5 kPa O2 + 7 kPa CO2 atmosphere, which was directly related to changes of vitamin C throughout storage. Therefore, 70 kPa O2 atmospheres are proposed to prevent anaerobic conditions during storage of fresh-cut melon and thus, reduce wounding stress and deteriorative changes related to high peroxidase activity in tissue.  相似文献   

17.
Tiehua Li  Min Zhang  Shaojin Wang 《LWT》2008,41(6):965-973
The effects of three storage temperatures (1, 3, and 5 °C) were determined on the quality of the edible mushroom Agrocybe chaxingu stored in modified atmosphere packages (MAP) with and without (control) silicon gum film windows. Results showed that the storage temperature had clear effects on headspace gas concentrations of O2, CO2 and ethylene, sensory characteristics, respiration rate, ascorbic acid content, soluble solid content and electrolyte leakage. The higher storage temperature (5 °C) resulted in more rapid changes in the different quality parameters for the stored mushroom except in the case of storage at 1 °C where chilling injury occurred. The MAP with silicon gum film windows at 3 °C provided the best atmosphere for mushroom A. chaxingu as shown by a fact that the MAP packs with windows at 3 °C had better quality than the control.  相似文献   

18.
The potential of 1-methylcyclopropene for controlling ripening in ‘Lateblue’ blueberry fruit was explored. After harvest, blueberry fruits were exposed to 1-MCP (0.3 and 0.6 μl l−1). After treatment, samples were stored in air at 0 °C for 35 days and in a controlled atmosphere (3 kPa O2 + 11 kPa CO2) for 60 days. Quality parameters were monitored (weight loss, total soluble solids content, titratable acidity, firmness, anthocyanin content, phenolic content, total antioxidant capacity). Blueberries treated with 1-MCP showed a reduced weight loss during storage and a lower total soluble solid content compared to untreated fruit. High titratable acidity values were observed after controlled atmosphere storage, but no significant effect of 1-MCP on this parameter was observed. 1-MCP had no significant effects on anthocyanins, phenolics or antioxidant activities.  相似文献   

19.
Dates (Pheonix dactylifera) harvested from Kutch district of Gujarat, India were processed for the development of dehydrated dates. Dates grown in the Kutch region of Gujarat are harvested before maturation, i.e. Khalal stage to prevent spoilage caused due to rains. The processing and dehydration conditions for the preparation of dehydrated dates from immature date fruits were evaluated. Processing of dates by blanching in water at 96±1 °C and subsequent dehydration at 60±2 °C for 18-20 h resulted in good quality dehydrated dates as compared to the dates dried without heat treatment. The dehydrated dates were found to be acceptable with respect to colour, flavour, taste and overall quality. The dehydrated dates contained a total sugars of 520 g kg−1, reducing sugars of 415.1 g kg−1, tannins 13.5 g kg−1 and ascorbic acid 33.7 mg kg−1. Equilibrium relative humidity (ERH) of the dehydrated dates was found to be 75.9% with an initial moisture content of 159 g kg−1. The dehydrated dates packed in 75 μ low-density polyethylene packaging material were shelf stable for 6 months at room temperature. The dehydrated dates remained acceptable during the storage period.  相似文献   

20.
The whole cell protein and macrorestriction analysis of DNA of Enterobacteriaceae isolates recovered from minced beef stored at 0, 5, 10 and 15 °C aerobically and under modified atmosphere packaging consisting of 40% CO2-30% O2-30% N2 in the presence (MAP+) and absence (MAP−) of oregano essential oil were studied. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) profiles obtained from whole cell protein analysis of the Enterobacteriaceae isolates revealed seven groups. Moreover, application of a modified PFGE protocol with XbaI restriction, resulted into 19 different fingerprints. The Enterobacteriaceae community of fresh meat consisted of Serratia liquefaciens and Serratia proteamaculans. S. liquefaciens strain VK23 was the dominant isolate of Enterobacteriaceae for the most conditions adopted, except 10 °C and 15 °C under MAP + and 10 °C under MAP−. In the latter cases, Hafnia alvei represented the dominant fingerprint. Citrobacter freundii was recovered from minced beef stored aerobically, while H. alvei and Proteus vulgaris were recovered under MAP. Storage conditions affected the Enterobacteriaceae community; modified atmosphere packaging increased both species and strain diversity.  相似文献   

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