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1.
Skinless tilapia (Dreochromis niloticus x D. aureus) fillets were covered with a gelatin coating containing benzoic acid as an antimicrobial agent. Benzoic acid content of fish fillets was used to estimate the amount of gelatin coated on fillet surface, and it was found that the gelatin contents were between 16.3 mg and 17.3 mg per g of fillets. Aerobic and anaerobic microbial loads, volatile basic nitrogen (VBN) contents, and sensory evaluation were used as indicators to survey the feasibility of an antimicrobial gelatin coating to prolong the shelf‐life of tilapia fillets under refrigeration. After 7 days of storage under refrigeration, tilapia fillets coated with gelatin containing benzoic acid had acceptable VBN contents, increased moderately in microbial loads, and showed no significant sensory difference (P < 0.05) from fresh fillets. The results indicate that an antimicrobial gelatin coating is suitable for preservation of tilapia fillets.  相似文献   

2.
The effect of chitosan (0.5%)/Jicama starch (0%–4%)‐based edible coating on the quality of Nile tilapia (Oreochromis niloticus) fillets was evaluated over ice storage time. All samples were periodically analysed for pH value, thiobarbituric acid (TBA), total volatile basic nitrogen (TVB‐N), electrical conductivity (EC), total viable counts (TVC), total psychrotrophic counts (TPC), drip loss, colour, hardness and sensory characteristics. Results demonstrated that the quality of Nile tilapia fillets was preserved by the film containing chitosan and/or Jicama starch. Compared with chitosan coating alone (0.5% chitosan/0.25% glycerol) (< 0.05), T3 (0.5% chitosan/1% Jicama starch/0.25% glycerol) had a better effect on the drip loss, TBA, TVC, TPC, hardness and sensory characteristics of the samples, thus indicating that low Jicama starch concentration (1%) enriched the coating ability of chitosan in extending the shelf life of Nile tilapia fillets.  相似文献   

3.
Potential for toxin development by Clostridium botulinum type E was investigated in retail-type packages of fresh tilapia fillets packaged in high barrier film under selected atmospheres [100% air, a modified atmosphere (MA) containing 75%CO2:25%N2, and vacuum] and stored under refrigeration (4°C) and abuse temperatures (8 and 16°C). Toxin development coincided with sensory spoilage at 16°C storage for fillets packaged in either MA, or vacuum. At 8°C, toxin development in fillets packaged in either of the atmospheres occurred 7-23 days after sensory spoilage. At 4°C, none of MA-packaged fillets became toxic until 10 days after onset of sensory spoilage. Toxin development did not precede sensory spoilage in any treatments or temperatures studied.  相似文献   

4.
The effect of modified atmospheres (MAs) (75% CO2:25% N2; 50% CO2: 50% N2; and 25% CO2: 75% N2) and 100% air on shelf life of fresh tilapia fillets packaged in high barrier film bags was evaluated at refrigeration temperature (4.0°). Fillets packaged in 100% air spoiled after 9 days, as indicated by sensory characteristics, and had increased surface pH, TMA content, K-value and high microbial counts. When levels of CO2 were increased from 25 to 75% in the package atmosphere, the shelf life of MA-packaged tilapia fillets was extended 4–21 days more than that of fillets packaged under 100% air. Although fillets packaged under 75% CO2:25% N2 were judged by sensory characteristics to be acceptable for more than 25 days, their K-value was high (93.1%). K-values were independent of spoilage and correlated only with length of storage of the MA-packaged fillets.  相似文献   

5.
In the present study the combined effect of an O2 absorber and oregano essential oil (0.4% v/w) on shelf life extension of rainbow trout fillets (Onchorynchus mykiss) stored under refrigeration (4 °C) was investigated. The study was based on microbiological [TVC, Pseudomonas spp., Lactic Acid Bacteria, H2S-producing bacteria including Shewanella putrefaciens, Enterobacteriaceae and Clostridium spp.), physicochemical (pH, PV, TBA, TVBN and Drip loss) and sensory (odor, taste) changes occurring in the product as a function of treatment and storage time. Aerobically-packaged rainbow trout fillets stored at 4 °C were taken as control samples. Results showed that TVC exceeded 7 log cfu/g on day 4 of storage for control samples, day 7–8 for samples containing oregano oil, day 9 for samples containing the O2 absorber and day 12–13 for samples containing the O2 absorber and oregano oil. Pseudomonas spp., Enterobacteriaceae and LAB were only partially inhibited by the O2 absorber and/or the oregano oil. In all cases the inhibition effect was more pronounced when the combination of O2 absorber with oregano essential oil was used. pH decreased from an initial value of 6.65–6.09 and subsequently increased to 6.86 due to formation of protein decomposition products. % Drip loss ranged between 7% and 11–12% at the end of the product shelf life. PV values ranged between 11.4 and 27.0 meq O2/kg oil while malondialdehyde (MDA) ranged between 9.6 and 24.5 mg/kg. TVBN ranged between 10.6 and 54.6 mg/kg at the time of sensory rejection. Sensory shelf life was 4 days for the control samples, 7–8 days for samples containing oregano oil, 13–14 days for samples containing the O2 absorber and 17 days for samples containing the O2 absorber plus oregano oil.  相似文献   

6.
Two distinct strategies were combined to preserve fresh fish (Merluccius merluccius) under refrigeration at 4 °C for 12 days: (i) the application of an antimicrobial edible coating enriched with oregano essential oil (OEO) or carvacrol (CV) and (ii) the reduction of initial microbial load by good handling practise and the use of sodium hypochlorite (NaOCl). The action of antimicrobial coatings alone retarded the growth of Enterobacteriaceae, lactic acid bacteria (LAB) and H2S producing bacteria on fish samples. The reduction of initial microbial load by itself only affected the evolution of LAB, but not the rest of the bacterial groups. When using both techniques combined, edible antimicrobial coatings were significantly more effective with additional and significant delays in the growth of mesophilic, psychrotrophic and Pseudomonas bacteria. Thus, the use of both strategies combined resulted in a reduction of the counts of all bacterial groups after 12 days of storage which ranged from 1.5 log and 8 log, in Pseudomonas and H2S producing bacteria, respectively. Moreover, no significant differences were observed when comparing the microbiological evolution of samples treated with OEO compared to those only treated with CV.  相似文献   

7.
The effect of ?1.5 °C brine super‐chilling on the quality of the modified atmosphere‐packaged Lateolabrax japonicus fish fillets was studied. The result showed that the total viable mesophilic count (TVC) and H2S‐producing bacterial count (HC) of samples were super‐chilled, and then modified atmosphere‐packaged (Sc + Map) were lower than that of Map (Samples were not super‐chilled but modified atmosphere packaged), and values of total volatile base nitrogen (TVB‐N), thiobarbituric acid (TBA), pH and myofibril fragmentation index (MFI) for Sc + Map increased more slowly than those for Map. Colour of skin and flesh of fish fillets was not affected by brine super‐chilling, except the whiteness of the skin of fish fillets. Sc + Map could extend the shelf life of fish fillets for 4 days longer than Map.  相似文献   

8.
Films were prepared by incorporating different levels of antibacterial agents such as oregano oil, sodium lactate (NaL) and ɛ-polylysine (ɛ-PL) into sorbitol-plasticized whey protein isolate (WPI) films. The moisture uptake behaviour and the water vapour permeability (WVP) of the films were only affected by NaL, as the water sorption and permeability increased with addition of NaL into the protein matrix. An increase of the glass transition temperature of the sorbitol regions, as assessed by Dynamic Mechanical Thermal Analysis (DMTA), was caused by the addition of ɛ-PL, while incorporation of the oregano oil caused plasticization of the film that was depicted by a decrease in the transition temperature of the polymer-rich regions. On the other hand, incorporation of NaL into the films did not significantly alter their thermo-mechanical properties. However, the addition of NaL or ɛ-PL in the film forming solution resulted in a decline of maximum tensile strength (σmax). Wrapping of beef cuts with the antimicrobial films resulted in a significant reduction of the bacterial population levels. The maximum specific growth rate (μmax) of total flora (Total Viable Count, TVC) and pseudomonads was significantly reduced (P<0.05), with the use of antimicrobial films containing relatively high levels of oregano oil (1.5% w/w in the film forming solution) or ɛ-PL (0.75% w/w in the film forming solution), while the growth of Lactic Acid Bacteria (LAB) was completely inhibited.  相似文献   

9.
应用电子鼻采集贮藏过程冷鲜罗非鱼片顶空挥发性气味,同步进行感官评价、微生物和理化分析。结果表明:传感器响应信号随着鱼片气味浓度增大而增大,且对不同新鲜度气味有良好响应。线性判别(LDA)比主成分分析(PCA)更能有效区分鱼片的不同新鲜度、微生物及挥发性盐基氮含量,表明电子鼻可快速检测鱼片的品质劣变进程。通过负荷加载分析和相关分析表明,W2W、W1W、W1S、W2S对区分冷鲜罗非鱼片不同新鲜度的贡献较大,并与感官可接受性、菌落总数和挥发性盐基氮的相关性良好,可作为今后研制鱼用电子鼻系统精选传感器的理论参考。  相似文献   

10.
The margin of safety between shelf-life (onset of sensory spoilage) and potential time to toxin production by Clostridium botulinum type E in retail type packages of fresh marine cod fillets packaged in high barrier film under selected atmospheres [100% air, a modified atmosphere (MA) containing 75% CO2:25% N2, and vacuum] and stored under refrigeration (4C) and temperature-abuse conditions (8 and 16C) was investigated. Margin of safety data of MA-packaged marine cod fillets was also compared with MA-packaged aquacultured tilapia, catfish, and salmon fillets. Sensory spoilage preceded onset of toxin presence for the marine cod fillets packaged in any of the atmospheres and storage temperatures tested. At 4C, none of the marine cod fillets packaged in either atmosphere developed toxin, even 20 days after spoilage, as determined by sensory characteristics. During storage at refrigeration and mild (8C) temperature-abuse conditions, MA-packaged marine cod showed a greater margin of safety compared to aquacultured tilapia, catfish, and salmon packaged under the same atmospheres and conditions. Fat content appeared to potentially influence the margin of safety in MA-packaged aquacultured fresh fish fillets during storage.  相似文献   

11.
Half‐carcasses of rabbit packed under four different modified atmospheres (MA; A: 30% CO2 + 70% O2; B: 30% CO2 + 30% O2 + 40% N2; C: 40% CO2 + 60% N2; D: 80% CO2 + 20% O2) and stored at 1 °C over 20 days, were assessed in relation to bacteria (total viable counts (TVC), lactic acid bacteria (LAB), Enterobacteriaceae and Pseudomonas) and rancidity development as 2‐thiobarbituric acid reactive substances (TBARS). None of the MA tested produced mean counts greater than 5 log CFU cm?2 for TVC and LAB, or greater 2 log CFU cm?2 for Pseudomonas and Enterobacteriaceae. All MA showed an inhibitory effect on microbial growth, especially on growth of the spoilage bacteria Pseudomonas and Enterobacteriaceae. This inhibition was more relevant in atmospheres with higher CO2 concentrations (types C and D). Significant differences in rancidity levels between MA types (p < 0.01) were observed 10 days post‐packing. In general these values were higher in MA type A, which showed a significant increase in TBARS values (p < 0.05) over time. Copyright © 2005 Society of Chemical Industry  相似文献   

12.
Antimicrobial films were prepared by incorporating different levels of oregano oil (0.5%, 1.0%, and 1.5% w/w in the film forming solution) into sorbitol-plasticized whey protein isolate (WPI) films. The moisture uptake behavior and the water vapor permeability (WVP) were not affected by the addition of oregano oil at any of the concentrations used. A reduction of the glass transition temperature (∼10–20 °C), as determined by dynamic mechanical thermal analysis (DMTA), was caused by addition of oil into the protein matrix. A decrease of Young modulus (E) and maximum tensile strength (σmax) accompanied with an increase in elongation at break (%EB) was observed with increasing oil concentration up to a level of 1.0% (w/w). Wrapping of beef cuts with the antimicrobial films resulted in smaller changes in total color difference (ΔΕ) and saturation difference (Δchroma) during refrigeration (5 °C, 12 days). The maximum specific growth rate (μmax) of total flora (total viable count, TVC) and pseudomonads were significantly reduced (P < 0.05) by a factor of two with the use of antimicrobial films (1.5% w/w oil in the film forming solution), while the growth of lactic acid bacteria was completely inhibited. These results pointed to the effectiveness of oregano oil containing whey protein films to increase the shelf life of fresh beef.  相似文献   

13.
Using A New Measure To Define Shelf Life Of Fresh Whitefish   总被引:1,自引:0,他引:1  
An acceptor set size measure was successfully employed to examine shelf life trade-offs when fresh lake whitefish fillets (Coregonus clupeaformis) were dipped in 0.0, 2.5 or 5.0% (w/v) potassium sorbate, packaged in low, intermediate, or higher barrier bags, placed in 100% CO2 modified atmosphere packaging system and held under refrigeration at less than 3°C. When sorbate was varied, shifts in acceptor size indicated that fillets dipped in 5.0% sorbate had the longest shelf life, exceeding 14 days. No significant difference was found when film permeability was varied. For all barrier films, shelf life exceeded 15 days although the low barrier bag had smaller acceptor sizes.  相似文献   

14.
BACKGROUND: Color of muscle foods plays a major role in consumer perception of meat quality. Carbon monoxide (CO) has been successfully used for improving color of packaged meat and fish products. In this study, we wanted to investigate pre‐mortem treatment of live tilapia using 100% CO for its ability to improve the color of frozen whole tilapia. We compared untreated and CO‐treated whole, gutted tilapia, frozen for 2 and 4 months at ? 20 °C. Frozen tilapia samples were thawed overnight at 4 °C, filleted and analyzed for their color, heme peak wavelength and CO concentration. RESULTS: Euthanasia using CO significantly increased redness (a* value) and lightness (L* value) of tilapia white and red muscle. Frozen storage significantly (P < 0.05) decreased redness of both CO‐treated and untreated tilapia. However, even after 4 months of frozen storage, a*‐value of CO‐treated tilapia was similar to fresh untreated tilapia fillets. Heme peak wavelengths of CO‐euthanized tilapia were higher than in untreated tilapia and there was no significant (P > 0.05) decrease in heme peak wavelengths of CO‐treated tilapia white and red muscle during frozen storage. The CO content of frozen euthanized tilapia fillets was significantly (P > 0.05) higher than in untreated fillets. In general, red muscle tissue of euthanized tilapia had a higher concentration of CO than white muscle. CONCLUSION: Color stability of tilapia fillets was significantly improved by pre‐mortem CO treatment. The color of CO‐treated fillets was retained during frozen storage compared to untreated fillets. Hence, pre‐mortem CO treatment could be used as a new method for improving color of tilapia. Copyright © 2008 Society of Chemical Industry  相似文献   

15.
A novel antimicrobial packaging system was prepared by incorporating TiO2 or Ag nanoparticles into poly(lactic acid) (PLA) matrix. The effect of PLA, PLA/TiO2, and PLA/TiO2 + Ag film on the physicochemical and microbiological properties of Yunnan cottage cheese stored at 5 ± 1 °C for 25 days was investigated. The low density polyethylene (LDPE) film was used as the control. The weight loss, pH value, lactic acid bacteria count (LAB), texture, sensory quality, and antimicrobial activity were determined. Cheeses packed by PLA/TiO2 and PLA/TiO2+Ag film provided better retention in pH value, LAB, sensory quality, and antimicrobial activity compared with those packed by PLA and LDPE film. Migration of Ti and Ag nanoparticles was lower than the limit of 10 mg/kg as defined by EFSA for food contact materials. The results indicated that the incorporation of TiO2 or Ag nanoparticles into PLA matrix could maintain cheese quality and prolong its shelf life to 25 days.

Practical applications

Yunnan cottage cheese is one of the most popular cheeses in China. However, the shelf life of unpacked Yunnan cottage cheese is only 5–7 days under refrigerated condition. PLA film incorporated with antimicrobial TiO2 or Ag nanoparticles has great potential to prolong cheese shelf life. The novel packaging material may be an effective alternative for cheese preservation.  相似文献   

16.
真空包装鲈鱼片在冷藏与微冻贮藏过程中的新鲜度评价   总被引:3,自引:0,他引:3  
以淡水鲈鱼为对象,采用真空包装方法,研究鲈鱼片在冷藏(4 ℃)和微冻(-2 ℃)条件下的新鲜度变化情况。以菌落总数、pH值、挥发性盐基氮(total volatile basic nitrogen,TVB-N)值、K值为指标,结合电子鼻对冷藏和微冻鲈鱼片的气味进行检测,并对所获得信息进行主成分分析,综合评价其新鲜度。结果表明,随着贮藏时间的延长,不同温度贮藏的鲈鱼片其菌落总数和K值均呈上升趋势,温度越低,上升越慢;贮藏初期pH值呈先下降后升高的趋势;电子鼻分析结果与菌落总数、K值结果保持一致,能有效区分不同新鲜度的鲈鱼片。综合各指标变化,与冷藏相比,真空包装鲈鱼片微冻贮藏能保持较好新鲜度,货架期更长。  相似文献   

17.
A combination of conventional methods and genetic identification (PCR sequencing) was used to study the dynamics of the bacterial population during the spoilage of modified atmosphere packaged (MAP) Atlantic horse mackerel (Trachurus trachurus) fillets. The cultivable microflora in Atlantic horse mackerel samples packaged in a modified atmosphere (48% CO2, 50% N2 and 2% O2) at refrigeration temperature (6 °C) was measured on days 1, 5 and 7 using non-selective (Long and Hammer agar) and selective media (Kligler's iron agar, STAA and MRS). The microflora was genetically characterised using partial amplification of 16S rRNA gene sequences from 309 bacterial isolates obtained from Long and Hammer agar. At the end of the shelf life (5 days), the total viable counts (TVC) on Long and Hammer agar were not significantly different to the LAB counts on MRS agar (p > 0.05). The molecular approach showed that Photobacterium, Arthrobacter, Chryseobacterium and Pseudoclavibacter (44.5% of total) dominated the microbial composition of the fish at the beginning of storage. However, Serratia, Shewanella and Yersinia dominated at the late spoilage stages (over 57.2% of the total). Carnobacterium was the most important species of the lactic acid bacteria (LAB) and was identified at the beginning and end of the storage period. Vibrio spp. was only found at the end of the shelf life. This research demonstrates that the microbial biodiversity in MAP Atlantic horse mackerel is enormous and the dominant species change over the storage time. The results presented here on the dominant communities in fish products will make it possible to accurately select the best preservation practices.  相似文献   

18.
This study examined the effects of different levels of flaxseed oil in increasing the α-linolenic (LNA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids contents in tilapias raised in captivity. Nile tilapia were raised in captivity for a period of five months, receiving increasing levels (0%; 1.25%; 2.50%; 3.75% and 5.00%) of flaxseed oil in substitution for sunflower oil (control). No significant differences (P>0.05) of moisture or total lipids contents were found among fillets from tilapia fed the different diets. Analyses of the fatty acid methyl esters (FAMEs) were quantitatively measured by capillary gas chromatography against a C23:0 internal standard. Increases of the concentration of LNA, EPA and DHA (in mg/g of total lipids), were well established in the fillets, with a significant difference (P<0.05) among all the treatments, as the replacement of the sunflower oil by flaxseed oil was increased.  相似文献   

19.
The microflora of common carp (Cyprinus carpio) skin, gill and intestine were analysed and the antimicrobial activities of garlic oil and nine constituents of essential oils (allyl isothiocyanate, carvacrol, cinnamaldehyde, citral, cuminnaldehyde, eugenol, isoeugenol, linalool and thymol) against the carp isolates were studied to identify compounds that might extend the shelf-life of carp fillet. A total of 90 isolated strains were identified to belong to seven genera: Acinetobacter (6), Alcaligenes (2), Bacillus (2), Flavobacterium (20), Micrococcus (2), Moraxella (6) and Pseudomonas (4), and two families Enterobacteriaceae (14) and Vibrionaceae (34). The dominant micro-organisms of carp were found to be Flavobacterium (37%) and Vibrionaceae (33%) in skin, Flavobacterium (33%) in gill and Vibrionaceae (63%) and Flavobacterium (37%) in intestine. Against these isolates, thymol, carvcarol and cinnamaldehyde had the strongest antimicrobial activities, followed by isoeugenol, eugenol, garlic oil, and then citral. The antimicrobial properties of the other constituents tested (cuminnaldehyde, linalool and allyl isothiocyanate) were low. In tests of mixed compounds, a combination of carvacrol and thymol had the highest antimicrobial activity. Moraxella, Flavobacterium and Vibrionaceae were more sensitive to the compounds, whereas Alcaligenes strains were resistant. Dipping carp fillets in a solution of 0.5% carvacrol and 0.5% thymol before storage at 5°C and 10°C reduced both the total microbial load by about 100-fold and the Volatile Bases Nitrogen (VB-N), as compared with controls. In addition, dipping treatment delayed bacterial growth and extended the shelf-life of the fillets from 4 to 12 days at low temperature (5°C). However, the treated and control fillets showed little difference during storage at 10°C. Data from sensory evaluation showed that dipped fillets in 1% (carvacrol+thymol) extended the shelf-life of carp fillets by 8 and 4 days at 5° and 10°C, respectively. Thus, carvacrol and thymol dipping can improve the microbial stability of fish fillets by removing bacteria and by inhibiting bacterial growth.  相似文献   

20.
Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 °C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography‐mass spectrometry (GC‐MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H2S producing bacteria were characterized based on maximum growth rates (μmax), maximal microbial concentration (Nmax) and at the moment of microbial shelf life (Svalues), calculated from Gompertz‐fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest μmax. The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC‐MS in spoiled chicken samples, ethanol (EtOH), 1‐butanol‐3‐methyl (1But‐3M), and acetic acid (C2) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But‐3M and C2 was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But‐3M, and C2) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But‐3M, and C2 as rapid evaluation for poultry quality testing using SPME‐GC‐MS.  相似文献   

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