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1.
新鲜和经温和加工的鱼类产品越来越受人们欢迎,包括更容易患上食源性疾病的人,这带来了新的食品安全问题。新鲜和经温和加工的鱼类产品由于一群微生物的作用而变质,其中有能力控制和产生代谢产物的优势腐败菌,直接影响了产品的感官特性,导致消费者的排斥。近年来,人们付出了相当大的努力研究了鱼类产品中的优势腐败菌,以及寻找能够抑制鱼类产品中优势腐败菌的天然防腐剂和保鲜技术,以提高产品的质量和保质期。本文概述了国内外一些鱼类产品在低温条件下存在的优势腐败菌,以及3种鱼类产品中优势腐败菌概况,介绍了部分天然防腐剂及保鲜技术在鱼类产品中的应用情况,展望了鱼类产品中优势腐败菌、天然防腐剂及保鲜技术的研究方向。  相似文献   

2.
The aim was to study spoilage during the refrigerated storage of cooked pork loin processed by the sous vide method. Samples were packaged under vacuum into polyamide-polypropylene pouches, cooked at an oven temperature/time of 70 °C/12 h, chilled at 3 °C and stored at 2 °C for 0, 5 or 10 weeks. Microbial (psychrotrophs, lactic acid bacteria, Enterobacteriaceae, moulds and yeasts), physical–chemical (pH, water activity, TBARS, acidity, L*a*b* colour, texture profile analysis and shear force) and sensory (appearance, odour, flavour, texture and acceptance) parameters were determined. The results showed that sensory spoilage preceded microbiological spoilage of sous vide pork loin. Counts bellow 1 log cfu/g of psychrotrophs, anaerobic psychrotrophs, Enterobacteriaceae and lactic acid bacteria were detected in any control week, while moderate counts (2–3 log cfu/g) of moulds and yeasts were found. Minor changes in water activity, lipid oxidation, CIELab colour, hardness, cohesiveness or gumminess were associated with spoilage of pork loin, only decreases of lactic acid, springiness and shear force were observed. The pork loin was unacceptable after 10 weeks. This loss of acceptance was mainly due to the deterioration of meaty flavour and odour, although the loss of appearance, juiciness and firmness also contributed. Moderate warmed-over and rancidity were detected. The sensory analysis was the most effective method for determining the shelf life of the sous vide pork-based dishes.  相似文献   

3.
The purpose of this study was to investigate the effect of applying two Lactobacillus protective cultures on microbiological, chemical and odour changes during storage of refrigerated vacuum‐packed rainbow trout (Oncorrynchus mykiss) fillets. Lactobacillus sakei CECT 4808 and Lb. curvatus CECT 904T were inoculated individually or in combination into rainbow trout fillets. The samples were vacuum‐packed and stored at 4 ± 0.5 °C and were assessed during a 20‐day storage period for microbiological (Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria (LAB), H2S‐producing bacteria, yeasts and moulds) and chemical (pH, total volatile basic nitrogen, lipid oxidation) parameters and off‐odour. Samples inoculated with Lb. sakei and with both strains had significantly (P≤0.05) lower counts of all microbiological spoilage indicator organisms (Enterobacteriaceae, Pseudomonas spp., H2S‐producing bacteria, yeasts and moulds) than those inoculated with Lb. curvatus or the controls. All chemical parameters examined and off‐odour scores were also significantly (P≤0.05) improved in the samples inoculated with Lb. sakei or with both strains compared with those inoculated with Lb. curvatus or the controls. Lb. sakei generally showed a better preservative effect (P≤0.05) than the combination of strains. Inoculation with Lb. sakei CECT 4808 could provide an additional hurdle to improve shelf‐life of refrigerated vacuum‐packaged trout fillets, as inoculation with this strain resulted in extension of shelf‐life by 5 days. Furthermore, this strain showed some antioxidative ability, which could retard lipid oxidation in fish. Copyright © 2006 Society of Chemical Industry  相似文献   

4.
The effectiveness of electron beam irradiation on the shelf life of mozzarella cheese was evaluated using five different irradiation doses and a control cheese. Shelf life tests were run at 10 °C by determining the cell load of spoilage micro‐organisms monitored on the consecutive days during storage. By fitting the experimental data through a modified version of the Gompertz equation, the shelf life of samples irradiated to the different doses was calculated. Results show significant increases in the shelf life of the investigated cheese. There were slight differences in the functional properties such as stretching, oiling off, melting between irradiated and unirradiated cheeses at 260 °C in oven. Our results indicated that the electron irradiation at the dose of 2.0 kGy may inhibit the growth of spoilage micro‐organisms such as coliforms and Pseudomonas sp. without affecting the sensorial characteristics of the product.  相似文献   

5.
Counts of aerobic mesophilic micro‐organisms and aerobic mesophilic spore‐forming bacteria were determined in 91 ultra‐high‐temperature (UHT) commercial Brazilian samples. Forty‐six spore‐forming bacteria were identified and characterised in terms of their spoilage potential. Among the 20 brands evaluated, 45% had counts of aerobic mesophilic micro‐organisms higher than 1.0 × 102 cfu/mL. The sporulated bacteria were identified as Bacillus subtilis/amyloliquefaciens, Bacillus licheniformis, Bacillus pumilus and Bacillus megaterium, and 31% and 33% showed proteolytic and lipolytic activity, respectively. Our findings indicate that there is a potential risk of UHT milk samples becoming spoiled during their commercial shelf life.  相似文献   

6.
The best packaging conditions for rocket salad were assessed by subsequent experimental trials. In the first step, a preliminary screening of different packaging materials was performed and two micro‐perforated oriented polypropylene films with different micro‐hole diameters (90 and 110 μm) were selected as best packaging solutions. In the subsequent experimental step, modified headspace conditions were applied without any improvement on product quality. In the last step, the effects of an ethylene adsorbent were analysed. Rocket salad packaged in both films with the ethylene adsorbent recorded a shelf life of about 16 days, compared to the control samples that remained acceptable for 13 days. During storage, the microbial quality (mesophilic and psychrotrophic bacteria, pseudomonadaceae, lactic acid bacteria, yeasts, total coliforms and enterobacteriacae), the pH, the colour changes and the main sensory parameters were also monitored.  相似文献   

7.
The quality of four types of fresh-cut produce, packaged in consumer-sized packages under an equilibrium modified atmosphere and stored at 7 degrees C, was assessed by establishing the relation between the microbial outgrowth and the corresponding production of nonvolatile compounds and related sensory disorders.In vitro experiments, performed on a lettuce-juice-agar, demonstrated the production of nonvolatile compounds by spoilage causing lactic acid bacteria and Enterobacteriaceae. Pseudomonas fluorescens and yeasts, however, were not able to produce detectable amounts of nonvolatile metabolites.The type of spoilage and quality deterioration in vivo depended on the type of vegetable. Mixed lettuce and chicory endives, leafy tissues, containing naturally low concentrations of sugars, showed a spoilage dominated by Gram-negative microorganisms, which are not producing nonvolatile compounds. Sensory problems were associated with visual properties and the metabolic activity of the plant tissue. Mixed bell peppers and grated celeriac, on the other hand, demonstrated a fast and intense growth of spoilage microorganisms, dominated by lactic acid bacteria and yeasts. This proliferation resulted in detectable levels of organic acids and the rejection by the trained sensory panel was based on the negative perception of the organoleptical properties (off-flavour, odour and taste).The applied microbiological criteria corresponded well with detectable changes in sensory properties and measurable concentrations of nonvolatile compounds, surely in the cases where lactic acid bacteria and yeasts were provoking spoilage. Consequently, the freshness of minimally processed vegetables, sensitive for outgrowth of lactic acid bacteria and yeasts (e.g., carrots, celeriac, bell peppers, mixtures with non-leafy vegetables) can be evaluated via analysis of the produced nonvolatile compounds.  相似文献   

8.
Quality changes of aerobically packed cod fillets stored under superchilling and abusive temperature conditions were characterized by the growth of specific spoilage organisms (SSO) and the production of microbial metabolites measured by an electronic nose along with traditional sensory and chemical analysis (total volatile basic nitrogen [TVB‐N], pH). A new process based on quick contact freezing and cold air blasting was used to achieve superchilling of fillets before chilled (0.5 °C) or superchilled (‐1.5 °C) storage. Photobacterium phosphoreum dominated under temperature abusive conditions coinciding with high levels of TVB‐N and increased electronic nose responses indicating increased levels of alcohols and aldehydes at sensory rejection. Dominating growth of Pseudomonas spp. in 1 batch was associated with the origin, the catching method, and the cooling conditions during processing. The superchilling process followed by superchilled storage (‐1.5 °C) extended the sensory shelf life of the fillets for at least 3 d compared with traditional process, resulting in a total shelf life of 15 d. High content of TVB‐N was observed in superchilled fillets at sensory rejection. P. phosphoreum counts were lower under superchilling conditions (6.0 to 6.8 log colony‐forming units [CFU]/g), compared with the traditionally processed chilled fillets (7.2 log CFU/g). However, H2S‐producing bacteria appeared to grow steadily under superchilling conditions reaching counts as high as 7.6 log CFU/g at sensory rejection.  相似文献   

9.
Minimally processed carrots have a short shelf‐life because of white blush formation (caused primarily by surface dehydration) and microbiological spoilage (caused mostly by lactic acid bacteria). The use of polymeric packaging films combined with edible coatings might have an additive or synergistic effect to extend the shelf‐life of minimally processed carrots because of the formation of a double barrier to gases and water vapour. A 3 × 3 factorial experiment using a polymeric packaging film of three different levels of permeability and a cellulose‐based edible coating (Nature Seal®) at different concentrations was conducted on minimally processed carrots to investigate any possible synergistic effect over 12 days of storage at 10 °C. No such effect was found. The polymeric packaging film effectively prevented microbiological growth and spoilage but was unable to control white blush formation. On the other hand, the edible coating partially controlled white blush formation but enhanced microbiological spoilage. The polymeric packaging film functioned primarily as a gas barrier, whereas the edible coating probably functioned as a moisture barrier. White blush formation was found to be the most important shelf‐life determinant for minimally processed carrots. Copyright © 2003 Society of Chemical Industry  相似文献   

10.
Pathogens and spoilage organisms occuring in meat products were screened in laboratory media, according to a method of Eklund (1983), in order to determine the specific inhibitory effect of lactate on growth of these microorganisms under optimum growth conditions (pH 6.5, 20°C). In general, Gram-positive bacteria were more sensitive towards lactate than Gram-negative bacteria. It was shown especially, that strains that were able to grow at water activities of 0.95 and below in the presence of NaCl (Staphylococcus aureus, Listeria monocytogenes, Brochothrix thermosphacta) were inhibited by sodium lactate (NaL). It appeared, that yeasts were resistant to large amounts of NaL (> 10% w/v). However, NaL had a specific inhibitory effect on growth of these organisms when compared to the effect of NaCl. These results indicate that lactate addition to food products with a pH near neutrality offers good prospects for shelf life prolongation.  相似文献   

11.
The impact of minimal processing technology on the sensory quality and the growth of micro‐organisms in eight varieties of cauliflower packaged in four different films (one PVC and three P‐Plus) was measured and quantified during more than 25 days of storage at 4 °C. Other important parameters such as weight loss and gas concentration in the packages were also determined. The composition of the atmosphere in the packages of minimally processed cauliflower depended on both the permeability of the film used for the packaging and the variety of cauliflower. When establishing shelf‐life, loss of sensory quality was the deciding factor rather than loss of microbiological quality. The initial microbial load proved more important than the composition of the atmosphere inside the packages. In sensory evaluation the most important aspect was colour. In instrumental evaluation, coordinate b* was the main means of estimating shelf‐life. The combination of P‐Plus 120 film and varieties of cauliflower of large size and great vigour allowed the atmosphere inside the packages to have an O2 level below 10% and a CO2 level above 10%. That atmosphere composition proved essential for maintaining the sensory quality of minimally processed cauliflower. In these conditions, samples attained a shelf‐life of more than 25 days. However, the different behaviours of the cauliflower varieties make it necessary to establish particular packaging conditions. The use of less permeable films than those used in this study, or the use of actively modified atmospheres, could be an alternative for those varieties that require special packaging conditions when processed using this technology. Copyright © 2006 Society of Chemical Industry  相似文献   

12.
Two hundred samples of minimally processed, frozen, and prepacked potato chips, peas, corn, and a variety of combined vegetables from supermarkets in Gaborone, Botswana, were examined microbiologically. Determination of aerobic mesophilic plate count, aerobic psychrotrophic plate count, lactic acid bacteria, yeasts and molds, coliforms, Listeria spp., and Staphylococcus aureus were done. Chips had the lowest mean log values for all of the microorganisms enumerated except yeasts and molds. The mean log values for single vegetables ranged from 3.6 to 9.1, 3.4 to 8.9, 2.9 to 5.6, and 2.1 to 6.5 log CFU/ g aerobic mesophilic plate count, aerobic psychrotrophic plate count, lactic acid bacteria, and yeasts and molds, respectively. The microbial profiles of peas and corn were almost similar (P < 0.001). The mean values for combined vegetables were clustered within 4.6 and 5.4 and 4.2 and 5.2 log CFU/g aerobic mesophilic plate count and aerobic psychrotrophic plate count, respectively. All of the vegetables had a coliform population distribution ranging from 0 to < 10(4) most probable number per g. The predominant gram-negative bacteria isolated included members of Enterobacteriaceae and Pseudomonaceae (86.2%). Escherichia coli was not detected in all of the samples. The organisms isolated included those responsible for spoilage in frozen vegetables, namely Pseudomonas, Klebsiella, Corynebacterium, lactic acid bacteria, and Flavobacterium. The predominant lactic acid bacteria were Lactobacillus spp. (55.9%). Other spoilage organisms were yeasts, and Cryptococcus spp. (55.4%) was predominant. Pathogens, namely Listeria monocytogenes, were also isolated at a rate of 2 to 10%, of which 4% was from corn, 2% each from peas and country crop, and 10% from stir-fry. Bacillus cereus was also isolated and accounted for 7.7% of the microorganisms from corn. S. aureus was isolated from all of the vegetables. Enterotoxigenic strains were from corn, peas, mixed vegetables, and stir-fry, and all of them produced enterotoxin A. In addition, the isolates from stir-fry vegetables also produced enterotoxins B and C. The study reveals the presence of pathogens and emerging opportunistic pathogens in the ready-to-use or ready-to-eat vegetables. If E. coli is the only indicator for safety and acceptability, consumers may be exposed to foodborne diseases. Inclusion of other groups as indicator organisms is suggested. Retailers are urged to invest in standby generators to maintain the cold chain.  相似文献   

13.
Abstract: The shelf life of packaged fresh red meats is most frequently determined by the activity of microorganisms, which results in the development of off‐odors, gas, and slime, but it is also influenced by biochemical factors such as lipid radical chain and pigment oxidation causing undesirable flavors and surface discoloration. The predominant bacteria associated with spoilage of refrigerated meats are Pseudomonas, Acinetobacter/Moraxella (Psychrobacter), Shewanella putrefaciens, lactic acid bacteria, Enterobacteriaceae, and Brochothrix thermosphacta. The spoilage potential of these organisms and factors influencing their impact on meat quality are discussed. High O2‐modified atmosphere (80% O2+ 20% CO2) packaging (MAP) is commonly used for meat retail display but vacuum packaging remains the major MAP method used for meat distribution. Two‐step master packaging (outer anoxic‐20% CO2+ 80% N2/inner gas‐permeable film) is used for centralized MAP distribution, but CO use (0.4%) in low O2 packaging systems is limited by consumer uncertainty that CO may mask spoilage. Active packaging where the film contributes more than a gas/physical barrier is an important technology and has been studied widely. Its application in combination with MAP is very promising but impediments remain to its widespread industrial use. The influence of processing technologies including modified atmospheres on lipid oxidation and discoloration of meats are analyzed. Because both organic acids and antioxidants have been evaluated for their effects on microorganism growth, in concert with the prevention of lipid oxidation, work in this area is examined.  相似文献   

14.
The fermentation profiles, shelf‐life and consumer acceptance of traditional West African sour sorghum beer (pito) fermented with pure commercial starter cultures of lactic acid bacteria (L. delbrueckii) and yeast (Saccharomyces cerevisiae) were evaluated. The beers from this ‘pure culture’ approach were compared with the spontaneous fermentation of pito wort. Lactic acid formation, pH change and extract utilisation were monitored during fermentation. Lactic acid content was used as a measure of sourness to establish the spoilage level of over‐sourness. Further, regression models relating sourness to the time the drink was kept were used to predict the shelf‐life. Consumer acceptance of the product was evaluated using a novel nine‐point hedonic scale. The pure culture and traditionally fermented beers followed similar lactic acid and fermentation profiles but strain‐specific differences were observed. Similar levels of pH, lactic acid level and extract utilisation were achieved. An improvement in shelf‐life of two days was found over traditionally fermented pito. There was no statistical difference between the two pito products for overall liking and taste. However, there was a preference for the aroma of the pure culture pito. It is suggested that the use of pure cultures will facilitate the scale‐up of pito production. © 2019 The Institute of Brewing & Distilling  相似文献   

15.
A study was undertaken to determine populations and profiles of yeast species on fresh and processed poultry products upon purchase from retail supermarkets and after storage at 5 degrees C until shelf life expiration, and to assess the potential role of these yeasts in product spoilage. Fifty samples representing 15 commercial raw, marinated, smoked, or roasted chicken and turkey products were analyzed. Yeast populations were determined by plating on dichloran rose bengal chloramphenicol (DRBC) agar and tryptone glucose yeast extract (TGY) agar. Proteolytic activity was determined using caseinate and gelatin agars and lipolytic activity was determined on plate count agar supplemented with tributyrin. Populations of aerobic microorganisms were also determined. Initial populations of yeasts (log10 cfu/g) ranged from less than 1 (detection limit) to 2.89, and increased by the expiration date to 0.37-5.06, indicating the presence of psychrotrophic species. Highest initial populations were detected in raw chicken breast, wings, and ground chicken, as well as in turkey necks and legs, whereas roasted chicken and turkey products contained less than 1 log10 cfu/g. During storage, yeast populations increased significantly (P < or = 0.05) in whole chicken, ground chicken, liver, heart and gizzard, and in ground turkey and turkey sausage. Isolates (152 strains) of yeasts from poultry products consisted of 12 species. Yarrowia lipolytica and Candida zeylanoides were predominant, making up 39 and 26% of the isolates, respectively. Six different species of basidiomycetous yeasts representing 24% of the isolates were identified. Most Y. lipolytica strains showed strong proteolytic and lipolytic activities, whereas C. zeylanoides was weakly lipolytic. Results suggest that yeasts, particularly Y. lipolytica, may play a more prominent role than previously recognized in the spoilage of fresh and processed poultry stored at 5 degrees C.  相似文献   

16.
夏天龙  姜梅  王宏勋  赵国娇 《食品科学》2014,35(18):252-257
用Gompertz模型对不同温度条件下真空包装鲜切紫薯中酵母菌和乳酸菌的生长曲线进行一级模型拟合,并通过计算准确因子(Af)和偏差因子(Bf)验证的生长模型的准确性;利用平方根模型和Arrhenius模型构建酵母菌和乳酸菌的二级模型,比较两种模型的优劣性;依据真空紫薯感官评价判定紫薯的腐败限控量,对其货架期预测模型进行构建和验证。结果表明,Gompertz模型能较好地拟合不同温度条件下2 种菌的生长情况(R2在0.9左右),数学检验参数Af、Bf接近1.0,均在接受范围;通过不同二级模型动力学参数的比较,2 种菌均为用平方根模型拟合二级模型较优;紫薯选用酵母菌作为指示菌预测货架期较好,其腐败限控量为6.64 (lg(CFU/g)),选定4 ℃条件构建并验证货架期预测模型可靠性,实测值为7.0 d,预测值为7.737 d,预测效果良好。  相似文献   

17.
Fresh fish and shellfish are highly perishable products due to their biological composition. Under normal refrigerated storage conditions, the shelf life of these products is limited by enzymatic and microbiological spoilage. However, with increasing consumer demands for fresh products with extended shelf life and increasing energy costs associated with freezing and frozen storage, the fish‐processing industry is actively seeking alternative methods of shelf life preservation and marketability of fresh, refrigerated fish and at the same time economizing on energy costs. Additional methods that could fulfill these objectives include chemical decontamination, low‐dose irradiation, ultra‐high pressure, and modified atmosphere packaging (MAP). This review focuses on the biochemical and microbiological composition of fresh fish/shellfish, the spoilage patterns in these products, factors influencing spoilage, and the combination treatments that can be used in conjunction with refrigeration to extend the shelf life and keeping quality of fresh fish/shellfish. The safety concerns of minimally processed/MAP fish, specifically with respect to the growth of Clostridium botulinum type E, is also addressed.  相似文献   

18.
Fish skin has both positive and negative effects on the shelf‐life of the fish. This study aimed to investigate the spoilage process of the skin and flesh of refrigerated farmed turbot (Scophthalmus maximus) with vacuum packaging. Microbial community changes were analyzed by combining culture‐dependent and culture‐independent methods. The results indicated that the shelf‐life of vacuum‐packaged refrigerated turbot was 16 d; skin mucus was the interference factor of turbot quality. The culture‐dependent analysis demonstrated that the total viable counts and the population of H2S‐producing bacteria, Pseudomonas spp., Enterobacteriaceae spp., and lactic acid bacteria in skin had a range of 0.45 to 1.40 log (CFU/g) higher than the microbial numbers in flesh after 16 d in storage. 16S high throughout sequencing results demonstrated that the compositions of spoilage microbes were similar in skin and flesh. Shewanella spp., followed by Carnobacterium spp., was the dominant spoilage organism at day 16. Quorum sensing (QS) signaling activity increased during the storage. Exogenous N‐butanoyl‐L‐homoserinelactone(C4‐HSL) and N‐hexanoyl‐Lhomoserine lactone (C6‐HSL) significantly accelerated the spoilage process of refrigerated turbot, while the addition of 4, 5‐Dihydroxypentane‐2, 3‐dione (DPD) prolonged the lag phase duration. Therefore, QS may be involved in the spoilage process of refrigerated turbot.  相似文献   

19.
Pomegranate kernels were stored in plastic pouches in a modified gas atmosphere under refrigeration. The storage life of this product (3–4 weeks at 1°C) was limited by off-flavours produced by microbial metabolism; yeasts and acetic acid bacteria were the predominant spoilage organisms.  相似文献   

20.
Japanese rice wine, sake, is a traditional alcoholic beverage in Japan. Similar to the case with beer, sake is known to be microbiologically stable and most microorganisms fail to grow in sake. This is principally due to its high ethanol concentration that reaches approximately 20% (v/v) in undiluted sake products and 15% (v/v) in finished products. Despite the high level of ethanol content, spoilage incidents occasionally occur in sake, due to the presence of highly ethanol‐tolerant lactobacilli, known as hiochi‐bacteria. Hiochi‐bacteria are generally composed of two groups of lactobacilli, hiochi‐lactobacilli and true hiochi‐bacilli. The former group of lactobacilli is less ethanol‐and heat‐tolerant, and therefore rarely poses a problem to sake products. In contrast, the true hiochi‐bacilli exhibit extraordinarily high ethanol tolerance and cause spoilage incidents in sake, conferring acidity and off‐flavors, such as diacetyl, in spoiled products. From a taxonomic standpoint, the true hiochi‐bacilli mainly consist of two Lactobacillus species, L. fructivorans and L. homohiochi. The strains of true hiochi‐bacilli prefer sake‐like environments, and the presence of ethanol and mevalonic acid, in combination with low pH milieu, is essential or stimulatory for the growth of these bacteria. Interestingly, the type strain of L. fructivorans does not show such characteristics, suggesting the true hiochi‐bacilli are profoundly adapted to sake environments. Although beer spoilage lactic acid bacteria do not have close taxonomic relationships with true hiochi‐bacilli, there are striking similarities between these two groups of spoilage lactic acid bacteria. In this review, unique features of sake and beer spoilage lactic acid bacteria are discussed in comparative terms.  相似文献   

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