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Spoilage
Terms modified by Spoilage Selected AbstractsEFFECT OF PROCESSING ON BACTERIAL POPULATION OF CUTTLE FISH AND CRAB AND DETERMINATION OF BACTERIAL SPOILAGE AND RANCIDITY DEVELOPING ON FROZEN STORAGEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2007THAILAMBAL ANANTHA SUBRAMANIAN ABSTRACT Processing techniques like cooking and freezing exhibited significant (P < 0.001) reduction in the bacterial load of cuttlefish, Sepia pharaonis, and marine crab, Portunus pelagicus. Raw cuttle fish had 2.4 × 107 cfu/g which on cooking reduced to 9.7 × 106 cfu/g. Freezing reduced the bacterial load further as cooked frozen product had only 9.9 × 104 cfu/g. Similarly, raw crab had 2.6 × 107 cfu/g which on cooking reduced to 6.5 × 106 cfu/g. A further reduction in bacterial load was seen after freezing as cooked frozen crab exhibited only 7.3 × 104 cfu/g. Escherichia coli and Staphylococcus aureus were present in the limit of acceptability for fish and fish products. Salmonella typhimurium and Vibrio cholerae were absent even in raw stage. Biochemical analysis performed on stored frozen products of cuttle fish and crab exhibited a significant (P , 0.05) increase in bacterial spoilage and rancidity with increasing days of storage. Total volatile base nitrogen, trimethylamine, thiobarbituric acid and free fatty acid contents in frozen products of cuttle fish and crab increased significantly with 120 days of frozen storage. [source] Psychrophilic and psychrotrophic clostridia: sporulation and germination processes and their role in the spoilage of chilled, vacuum-packaged beef, lamb and venisonINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2010Katharine H. Adam Summary Spoilage of beef, lamb and venison by psychrophilic and psychrotrophic clostridial species renders meat unacceptable resulting in financial losses and reduced consumer confidence. A number of clostridial strains, including Clostridium algidicarnis, Clostridium algidixylanolyticum, Clostridium estertheticum, Clostridium frigidicarnis and Clostridium gasigenes, have been implicated in red meat spoilage. Unlike other spoilers, these clostridia are able to grow in anaerobic conditions and at chilled temperatures (some at ,1.5 °C the optimal storage temperature for chilled red meat). The spoilage they cause is characterised by softening of the meat, production of large amounts of drip (exudates), offensive odours and in the case of C. estertheticum and C. gasigenes production of gas. Spoilage occurs following the introduction of clostridial spores into vacuum packages during processing. Germination of spores is necessary for the growth of vegetative cells, which cause spoilage. Current mitigation strategies focus on good management practice within meat processing plants. However, this is not always sufficient to prevent spoilage. This review summarises the issues associated with meat spoilage because of psychrotolerant clostridia and discusses areas that require further study. [source] Whey-cheese production using freeze-dried kefir culture as a starterJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2007D. Dimitrellou Abstract Aims:, The aim of the present study was to evaluate the use of a freeze-dried kefir culture in the production of a novel type of whey-cheese similar to traditional Greek Myzithra-cheese, to achieve improvement of the quality characteristics of the final product and the extension of shelf-life. Methods and Results:, The use of kefir culture as a starter led to increased lactic acid concentrations and decreased pH values in the final product compared with whey-cheese without starter culture. The effect of the starter culture on production of aroma-related compounds responsible for cheese flavour was also studied using the solid phase microextraction gas chromatography/mass spectrometry technique. Spoilage in unsalted kefir-whey-cheese was observed on the thirteenth and the twentieth day of preservation at 10 and 5°C, respectively, while the corresponding times for unsalted whey-cheese preservation were 11 and 14 days. Conclusions:, The cheeses produced were characterized as high-quality products during the preliminary sensory evaluation. An indication of increased preservation time was attributed to the freeze-dried kefir culture, which also seemed to suppress growth of pathogens. Significance and Impact of the Study:, The results suggested the use of kefir culture as a means to extend the shelf-life of dairy products with reduced or no salt content. [source] Characterization by Volatile Compounds of Microbial Deep Spoilage in Iberian Dry-Cured HamJOURNAL OF FOOD SCIENCE, Issue 6 2010Alberto Martín Abstract:, In the present study, volatile compounds of spoiled dry-cured Iberian ham with deep spoilage or "bone taint" were analyzed and correlated with level of spoilage and the microorganisms detected. Volatile compounds extracted by a solid phase micro-extraction technique were assayed by gas chromatography/mass spectrometry. The spoiled hams were evaluated sensorially, and the correlations among volatile compounds, spoilage level, and microbial counts were studied. The spoiled hams had higher concentrations of hydrocarbons, alcohols, acids, esters, pyrazines, sulfur compounds, and other minor volatile compounds than unspoiled hams. The sensorial analysis showed that the spoilage level of hams correlated with several volatile compounds, most of them associated with Gram-positive catalase positive cocci and,Enterobacteriaceae,counts. Cyclic compounds such as cyclohexanone, some ethers, and pyrazines should be considered as indicators to monitor incipient microbial deep spoilage in the elaboration of this meat product. [source] Inactivation Kinetics of Foodborne Spoilage and Pathogenic Bacteria by OzoneJOURNAL OF FOOD SCIENCE, Issue 3 2000J.-G. Kim ABSTRACT: Ozone was tested against Pseudomonas fluorescens, Escherichia coli O157:H7, Leuconostoc mesenteroides, and Listeria monocytogenes. When kinetic data from a batch reactor were fitted to a dose-response model, a 2-phased linear relationship was observed. A continuous ozone reactor was developed to ensure a uniform exposure of bacterial cells to ozone and a constant concentration of ozone during the treatment. Survivors plots in the continuous system were linear initially, followed by a concave downward pattern. Exposure of bacteria to ozone at 2.5 ppm for 40 s caused 5 to 6 log decrease in count. Resistance of tested bacteria to ozone followed this descending order: E. coli O157:H7, P. fluorescens, L. mesenteroides, and L. monocytogenes. [source] Physiological characteristics of the biocontrol yeast Pichia anomala J121FEMS YEAST RESEARCH, Issue 3 2002Elisabeth Fredlund Abstract The yeast Pichia anomala J121 prevents mold spoilage and enhances preservation of moist grain in malfunctioning storage systems. Development of P. anomala J121 as a biocontrol agent requires in-depth knowledge about its physiology. P. anomala J121 grew under strictly anaerobic conditions, at temperatures between 3°C and 37°C, at pH values between 2.0 and 12.4, and at a water activity of 0.92 (NaCl) and 0.85 (glycerol). It could assimilate a wide range of C- and N-sources and produce killer toxin. A selective medium containing starch, nitrate, acetic acid, and chloramphenicol was developed for P. anomala. P. anomala was equally sensitive as Candida albicans to common antifungal compounds. Growth ability at a range of environmental conditions contributes to the competitive ability of the biocontrol yeast P. anomala J121. [source] Silage quality when Moringa oleifera is ensiled in mixtures with Elephant grass, sugar cane and molassesGRASS & FORAGE SCIENCE, Issue 4 2009B. Mendieta-Araica Abstract Fourteen different silages were prepared using mixtures of Moringa (Moringa oleifera), Elephant grass (Pennisetum purpureum cv Taiwan) or sugar cane (Saccharum officinarum). Molasses from sugar cane was used in the amounts of either 10 or 50 g kg,1 fresh matter (FM) in treatments without sugar cane. A completely randomized design with three replicates of each treatment was used. The silages were prepared in 1800 mL micro silos and opened after 120 d. The presence of Moringa and Elephant grass in the silage changed the pH by ,0·8 and +0·7, respectively (P < 0·001), indicating a favourable effect of Moringa on silage pH. Overall differences were found among treatments for dry matter content, crude protein and acetic acid concentrations, weight loss, CO2 production and silage pH after spoilage (P < 0·001). Weight loss was proportionately 0·034 and 0·014 in silages with and without sugar cane respectively (P < 0·001). Overall, differences (P < 0·05) were also found for neutral-detergent fibre and lactic acid concentrations, lactic acid bacteria counts, clostridial counts and time to spoilage of the silages. Treatments containing Moringa had higher lactic acid concentrations (+16 g kg,1 DM; P < 0·01) compared to treatments without but the presence of Moringa decreased time to spoilage by 67 h (P < 0·05). No differences were found in propionic acid concentration or fungal growth of the silages. It is concluded that Moringa can be used as a component of high quality silages which also contain high concentrations of crude protein. [source] Fermentation characteristics and aerobic stability of grass silage inoculated with Lactobacillus buchneri, with or without homofermentative lactic acid bacteriaGRASS & FORAGE SCIENCE, Issue 4 2001F. Driehuis Aerobic spoilage by yeasts and moulds is a major cause of reduced nutritional value of silage and increases the risk of potential pathogenic microorganisms. Recent studies have shown that inoculation with Lactobacillus buchneri inhibits yeast growth and reduces the susceptibility to aerobic spoilage of various ensiled forages. The aim of this study was to determine whether these effects are retained when L. buchneri is added in combination with homofermentative lactic acid bacteria. In three experiments, silages were produced from perennial ryegrass [240,421 g kg,1 dry matter (DM)] inoculated with L. buchneri or L. buchneri plus a mixture of Pediococcus pentosaceus and Lactobacillus plantarum (inoculant PL). Uninoculated silage and silage inoculated with PL alone served as controls. Silages were examined for pH and DM loss in the course of ensilage and chemical and microbiological composition and aerobic stability after 3,4 months. L. buchneri plus PL and PL alone increased the initial rate of pH decline. L. buchneri alone and L. buchneri plus PL enhanced aerobic stability and, in general, reduced yeast and mould counts. In addition, these inoculants increased the final pH and DM loss and the concentrations of acetic acid and 1,2-propanediol (or propionic acid and 1-propanol instead of 1,2-propanediol), and decreased the concentration of lactic acid. The effects of L. buchneri on fermentation products increased with decreasing DM content. In silages of less than 270 g kg,1 DM, L. buchneri increased the ammonia-N concentration. It is suggested that this was associated with the relatively high final pH resulting from the high metabolic activity of L. buchneri in these silages. [source] Epidemiology and carcinogenesis of hepatocellular carcinomaHPB, Issue 1 2005TRISHE Y.-M. Abstract The incidence of hepatocellular carcinoma (HCC) shows marked variation worldwide but the magnitude of this tumor is reflected by the occurrence of at least 1 million new cases annually and the uniformly dismal outlook with median survivals of <25 months after resection and <6 months with symptomatic treatment. The strikingly uneven distribution of this tumor parallels the prevalence of hepatitis B infection with rising incidence in western countries attributed to hepatitis C infection. Chronic hepatitis and cirrhosis constitute the major preneoplastic conditions in the majority of HCCs and may be related to other etiologic agents such as environmental chemical carcinogens including nitrites, hydrocarbons, solvents, organochlorine pesticides, and the chemicals in processed foods, cleaning agents, cosmetics and pharmaceuticals, as well as plant toxins such as aflatoxins produced by fungi that cause spoilage of grain and food in the tropics. Genetic diseases such as genetic hematochromatosis, Wilson's disease, ,-1-antitrypsin deficiency, and the inborn errors of metabolism including hereditary tyrosinemia and hepatic porphyria, are known to be associated with HCC. Numerous genetic alterations and the modulation of DNA methylation are recognized in HCC and it is likely that these genetic and epigenetic changes combine with factors involved in chronic hepatocyte destruction and regeneration to result in neoplastic growth and multiple molecular pathways may be involved in the production of subsets of hepatocellular tumors. [source] Influence of potassium sorbate on the growth of yeasts and moulds in yogurtINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 2 2009MAHA A M AL-ASHMAWY Yeasts and moulds are little affected by low pH and may cause spoilage of yogurt during storage. In the present study, potassium sorbate was added as a preservative in concentrations of 0.05%, 0.1% and 0.2%. The unpreserved yogurt showed unfavourable characteristics: yeast and mould counts and acidity increased. The addition of potassium sorbate, however, inhibited yeast and mould levels, with normal characteristic properties extending more than 14 days. Potassium sorbate is thus seen as valuable for preserving yogurt. [source] Psychrophilic and psychrotrophic clostridia: sporulation and germination processes and their role in the spoilage of chilled, vacuum-packaged beef, lamb and venisonINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2010Katharine H. Adam Summary Spoilage of beef, lamb and venison by psychrophilic and psychrotrophic clostridial species renders meat unacceptable resulting in financial losses and reduced consumer confidence. A number of clostridial strains, including Clostridium algidicarnis, Clostridium algidixylanolyticum, Clostridium estertheticum, Clostridium frigidicarnis and Clostridium gasigenes, have been implicated in red meat spoilage. Unlike other spoilers, these clostridia are able to grow in anaerobic conditions and at chilled temperatures (some at ,1.5 °C the optimal storage temperature for chilled red meat). The spoilage they cause is characterised by softening of the meat, production of large amounts of drip (exudates), offensive odours and in the case of C. estertheticum and C. gasigenes production of gas. Spoilage occurs following the introduction of clostridial spores into vacuum packages during processing. Germination of spores is necessary for the growth of vegetative cells, which cause spoilage. Current mitigation strategies focus on good management practice within meat processing plants. However, this is not always sufficient to prevent spoilage. This review summarises the issues associated with meat spoilage because of psychrotolerant clostridia and discusses areas that require further study. [source] Thymol and modified atmosphere packaging to control microbiological spoilage in packed fresh cod hamburgersINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2009Maria Rosaria Corbo Summary A study on the use of mild technologies to produce packaged fish hamburgers was presented. In particular, the antimicrobial effect of some natural compounds (carvacrol, eugenol, thymol, green tea extract, rosemary extract, grapefruit seed extract and lemon extract), at various concentrations (500,10 000 ppm), was screened in vitro against the main fish spoilage micro-organisms (Shewanella putrefaciens and Photobacterium phosphoreum). Lemon extract and thymol, in combination with modified atmosphere packaging, showed the greatest inhibition activity, therefore, thymol was subsequently used as an ingredient for producing fish hamburgers. Results pointed out that this combination is effective in controlling the growth of microbial species mainly involved in fresh fish spoilage; in particular, it significantly (P < 0.05) reduced the growth rate of bacterial population, performing about 4.8 log CFU g,1 and 6.5 log CFU g,1 reduction of the hydrogen sulphide producing bacteria and psychrotrophic aerobic specific spoilage organisms cell load, respectively, if compared with the control. [source] The use of packaging techniques to maintain freshness in fresh-cut fruits and vegetables: a reviewINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009Mª Alejandra Rojas-Graü Summary Browning and other discolourations, softening, surface dehydration, water loss, translucency, off-flavour and off-odour development, as well as microbial spoilage are some of the most frequent causes of quality loss in fresh-cut products. Nowadays, the use of innovative modified atmospheres and edible coatings stands out among other techniques in the struggle for maintaining freshness and safety of fresh-cut fruits and vegetables. A few studies have demonstrated the effectiveness of these techniques when applied to different fresh-cut commodities. However, treatment and storage conditions for fresh-cut fruits are still being largely explored to better keep their fresh-like quality attributes. This review discusses the recent advances in the use of innovative modified atmosphere packaging (MAP) systems to maintain freshness of fresh-cut fruits and vegetables. Furthermore, special attention is devoted to the development of coatings that can be used as a complement or alternative to MAP. [source] Isolation and identification of Alicyclobacillus acidocaldarius by 16S rDNA from mango juice and concentrateINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2005Pieter A. Gouws Summary In this study we investigate the spoilage of ultra high temperature UHT mango juice as well as a carbonated fruit juice blend to identify organisms contributing to the spoilage. The mango concentrate, the final product, as well as the other ingredients used during manufacturing, were tested for the presence of Alicyclobacillus by polymerase chain reaction (PCR) and sequencing analyses. Microbiological examination of the mango pureé and spoiled fruit juices, using YSG agar [yeast extract 2 g, glucose 1 g, soluble starch 2 g, pH 3.7 (adjust with 2N H2SO4), H2O 1000 mL, bacto agar 15 g] incubated at 55 °C, detected sporeforming, acid dependent and thermotolerant bacteria. The hyper variable region of the 16S rDNA was amplified. The nucleotide sequence of the PCR fragments was determined using the ABI Prism 310 automated DNA sequencer and the collected sequencing data were analysed and compared with the non-redundant database using NCBI-BLAST. Alicyclobacillus acidocaldarius were isolated and identified by 16S rDNA gene sequences analyses. The results indicated that the mango purèe, as well as the final product of mango juice and the fruit juice blend, were positive for Alicyclobacillus. The preventative measures of low pH, pasteurization of mango juice and the subsequent use of aseptic packaging were not regarded as sufficient to prevent the outgrowth of Alicyclobacillus spoilage organisms. [source] Oligonucleotide microarrays for the detection and identification of viable beer spoilage bacteriaJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2008D.G. Weber Abstract Aims:, The design and evaluation of an oligonucleotide microarray in order to detect and identify viable bacterial species that play a significant role in beer spoilage. These belong to the species of the genera Lactobacillus, Megasphaera, Pediococcus and Pectinatus. Methods and Results:, Oligonucleotide probes specific to beer spoilage bacteria were designed. In order to detect viable bacteria, the probes were designed to target the intergenic spacer regions (ISR) between 16S and 23S rRNA. Prior to hybridization the ISR were amplified by combining reverse transcriptase and polymerase chain reactions using a designed consenus primer. The developed oligonucleotide microarrays allows the detection of viable beer spoilage bacteria. Conclusions:, This method allows the detection and discrimination of single bacterial species in a sample containing complex microbial community. Furthermore, microarrays using oligonucleotide probes targeting the ISR allow the distinction between viable bacteria with the potential to grow and non growing bacteria. Significance and Impact of the Study:, The results demonstrate the feasibility of oligonucleotide microarrays as a contamination control in food industry for the detection and identification of spoilage micro-organisms within a mixed population. [source] Bacteriological and chemical changes occurring in Bunker-stored silage covered with biodegradable coatingJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2007P. Denoncourt Abstract Aims:, To evaluate the efficacy of a biodegradable silage coating for the ability to protect timothy (Phleum pratensa) type silage against spoilage and its quality under natural conditions. Methods and Results:, Triplicate mini-silos of silage were prepared for three treatments (1: uncoated; 2: coated with biodegradable coating and 3: sealed with plastic), two types of storage (unprotected or protected from rain) and 10 sampling times (0, 7, 14, 21, 28, 35, 42, 56, 63 and 70 days postensiling). Triplicate mini-silos were opened at each sampling time for microbiological (total aerobic bacteria, lactic acid bacteria, moulds and yeasts) and biochemical analyses [pH, dry matter (DM), water-soluble sugars (WSC), lactic (LA), acetic, propionic and butyric acids content]. The study showed that at day 70, counts of moulds and yeasts in silages protected against rain and coated with biodegradable coating were 5·98 log CFU g,1 when compared with 5·92 and 3·62 log CFU g,1 in samples from plastic-sealed silage and uncoated silage, respectively. The pH was low and stable pH (4·34) when compared with uncoated (7·17) and plastic sealed (8·34) silages (P 0·05). A DM, WSC and LA content of 421·7, 13·4 and 20·9 g kg,1 was, respectively, observed. For silage stored outdoors, a level of moulds and yeasts of 3·77 log CFU g,1 of silage was also observed in silages coated with biodegradable coating after 28 days of storage. A stable pH showing a mean value of 4 was also observed. The pH, DM, WSC and LA content were, respectively, 4·18, 341·1, 13·34 and 31·8 g kg,1 in these samples. After 70 days of storage, the level of moulds and yeasts on silage sealed with biodegradable coating was 7·73 log CFU g,1. A DM, WSC and LA content of 291·9, 5·56 and 10·0 g kg,1 was, respectively, observed. Conclusions:, When compared with uncoated silage, the application of biodegradable coating can preserve the quality of silage for up to a month when exposed to rain and up to 70 days when protected from rain. Significance and Impact of the Study:, Results emphasize the possibility of the use of a biodegradable coating as an alternative to plastic film for sealing horizontal bunker silos. [source] Biogenic amine formation and microbial spoilage in chilled garfish (Belone belone belone) , effect of modified atmosphere packaging and previous frozen storageJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2006P. Dalgaard Abstract Aims:, To evaluate biogenic amine formation and microbial spoilage in fresh and thawed chilled garfish. Methods and Results:, Storage trials were carried out with fresh and thawed garfish fillets at 0 or 5°C in air or in modified atmosphere packaging (MAP: 40% CO2 and 60% N2). During storage, sensory, chemical and microbial changes were recorded and histamine formation by isolates from the spoilage microflora was evaluated at 5°C. Photobacterium phosphoreum was responsible for histamine formation (>1000 ppm) in chilled fresh garfish. The use of MAP did not reduce the histamine formation. Strongly histamine-producing P. phosphoreum isolates formed 2080,4490 ppm at 5°C, whereas below 60 ppm was formed by other P. phosphoreum isolates. Frozen storage inactivated P. phosphoreum and consequently reduced histamine formation in thawed garfish at 5°C markedly. Conclusions:,Photobacterium phosphoreum can produce above 1000 ppm of histamine in chilled fresh garfish stored both in air and in MAP. Freezing inactivates P. phosphoreum, extends shelf life and markedly reduces histamine formation in thawed MAP garfish during chilled storage. Significance and Impact of the Study:, At 5°C, more than 1000 ppm of histamine was formed in garfish; thus even when it is chilled this product represents a histamine fish-poisoning risk. [source] Effects of high-pressure processing on Listeria monocytogenes, spoilage microflora and multiple compound quality indices in chilled cold-smoked salmonJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2004R. Lakshmanan Abstract Aims:, To evaluate the effect of high-pressure processing (HPP) on Listeria monocytogenes, microbial and chemical changes and shelf-life in chilled cold-smoked salmon (CSS). Methods and Results:, First, challenge tests with L. monocytogenes were carried out using HPP of the product at 0·1 (control), 150, 200 and 250 MPa. Secondly, storage trials with the naturally contaminated product and HPP at 0·1 (control) and 200 MPa were realized. Shelf-life, microbial changes and chemical changes were determined and existing predictive models and multiple compound quality indices evaluated. HPP with 250 MPa did not inactivate L. monocytogenes but significant lag phases of 17 and 10 days were observed at ca 5 and 10°C, respectively. HPP with 200 MPa had a marked effect on both colour and texture of CSS. Conclusions:, High-pressure processing was unable to prevent growth of L. monocytogenes or spoilage of chilled CSS. Existing mathematical models allowed growth rates of L. monocytogenes and shelf-life of samples without high-pressure treatments to be predicted. Significance and Impact of the Study:, High-pressure processing seems more appropriate for new types of salmon products than for a classical product like CSS where consumers expect specific quality attributes. [source] Dormant ascospores of Talaromyces macrosporus are activated to germinate after treatment with ultra high pressureJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2004J. Dijksterhuis Abstract Aims:, Ascospores of Talaromyces macrosporus are constitutively dormant and germinate after a strong external shock, classically a heat treatment. This fungus is used as a model system to study heat resistance leading to food spoilage after pasteurization. This study evaluates the effect of high pressure on the germination behaviour of these spores. Methods and Results:, Ascospore containing bags were subjected to ultra high pressure and spores were plated out on agar surfaces. Untreated suspensions showed invariably very low germination. Increased germination of ascospores occurred after short treatments at very high pressure (between 400 and 800 MPa). Activation is partial compared with heat activation and did not exceed 6·9% (65 times that of untreated suspensions) of the spore population. Maximum activation was attained shortly (10 s,3 min) after the pressure was applied and accompanied by cell wall deformations as judged by scanning electron microscopy. The spores observed in this study were harvested from cultures that were 39,58 days old. The maturity of spores at similar developmental stages was measured by assessing the heat resistance of ascospores. Between 20 and 40 days heat resistance increased 2·4-fold, but only an additional increase of 1·3-fold was observed at later stages (40,67 days). Conclusions:, Our investigations show that high pressure constitutes a second type of shock that can activate heat-resistant ascospores to germinate. Activation is maximal after very short treatments and accompanied with changes in the cell wall structure. High-pressure activation is not the result of immaturity of the ascospores. Significance and Impact of the Study: These observations are relevant for the application of high pressure as a novel pasteurization method. [source] Molecular characterization of lactic acid populations associated with wine spoilageJOURNAL OF BASIC MICROBIOLOGY, Issue 1 2004L. Beneduce We have investigated the prevalence of spoilage lactic acid bacteria (LAB) in table wines produced in the Apulia region. The occurrence of LAB was evaluated in wines produced with low sulphur dioxide doses and not supplemented with selected malolactic starters such as Oenococcus oeni. About 150 strains were isolated from wine must and a molecular characterization was performed using PCR-based techniques. Most of the strains analysed belonged to Lactobacillus plantarum species. However, some of the strains were identified as Pediococcus damnosus and Leuconostoc sp. The amplified fragments of Pediococcus damnosus were cloned and sequenced. The coding sequence was highly homologous to that of the ropy plasmid confirming that the isolated strain was a ropy+Pediococcus damnosus. In all the samples analysed, the final must pH value reached was relatively high (from 3.78 to 3.90). The high pH values had probably negatively influenced (counteracted) the activity of sulphur dioxide added, allowing proliferation of spoilage wine microorganisms. [source] ANTIMICROBIAL, PHYSICAL AND MECHANICAL PROPERTIES OF CHITOSAN-BASED FILMS INCORPORATED WITH THYME, CLOVE AND CINNAMON ESSENTIAL OILSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 6 2009M.H. HOSSEINI ABSTRACT Chitosan-based films containing thyme, clove and cinnamon essential oils at 0.5, 1 and 1.5% v/v were prepared to examine their antibacterial, physical and mechanical properties. Scanning electron microscopy was carried out to explain structure,property relationships. Films containing thyme essential oil revealed larger inhibition zones than those containing clove and cinnamon essential oils against gram-positive and gram-negative bacteria tested. Films were more effective against gram-positive bacteria than gram-negative. Incorporating thyme and clove essential oils into chitosan-based films increased moisture content (from 17.80,28.38%), solubility in water (25.97,30.62%), water vapor transmission rate (0.00233,0.00571 g/s/m2) and elongation at break (25.31,42.70%) of films. Cinnamon-enriched films had opposite changes such as increase in tensile strength (from 12.2,21.35 MPa) and decrease in moisture content (17.80,9.36%) and solubility in water (25.9,14.21%) of films. PRACTICAL APPLICATIONS Microbial growth on food surfaces is a major cause of food spoilage. Combining antimicrobial agents such as plant essential oils directly into a food packaging polymer is a form of active packaging. These films possess the potential for improving microbial stability of foods by acting on the food surface upon contact. Because of the effect of direct addition of plant essential oils to food on sensory characteristics of packaged food, incorporation of essential oils into films may have additional applications in food packaging. [source] EFFECT OF PROCESSING ON BACTERIAL POPULATION OF CUTTLE FISH AND CRAB AND DETERMINATION OF BACTERIAL SPOILAGE AND RANCIDITY DEVELOPING ON FROZEN STORAGEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2007THAILAMBAL ANANTHA SUBRAMANIAN ABSTRACT Processing techniques like cooking and freezing exhibited significant (P < 0.001) reduction in the bacterial load of cuttlefish, Sepia pharaonis, and marine crab, Portunus pelagicus. Raw cuttle fish had 2.4 × 107 cfu/g which on cooking reduced to 9.7 × 106 cfu/g. Freezing reduced the bacterial load further as cooked frozen product had only 9.9 × 104 cfu/g. Similarly, raw crab had 2.6 × 107 cfu/g which on cooking reduced to 6.5 × 106 cfu/g. A further reduction in bacterial load was seen after freezing as cooked frozen crab exhibited only 7.3 × 104 cfu/g. Escherichia coli and Staphylococcus aureus were present in the limit of acceptability for fish and fish products. Salmonella typhimurium and Vibrio cholerae were absent even in raw stage. Biochemical analysis performed on stored frozen products of cuttle fish and crab exhibited a significant (P , 0.05) increase in bacterial spoilage and rancidity with increasing days of storage. Total volatile base nitrogen, trimethylamine, thiobarbituric acid and free fatty acid contents in frozen products of cuttle fish and crab increased significantly with 120 days of frozen storage. [source] INHIBITION OF MICROORGANISMS IN SALAD DRESSING BY SUCROSE AND METHYLGLUCOSE FATTY ACID MONOESTERSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 4 2003CHING-MIAO YANG The antimicrobial activity of sucrose and methylglucose esters of medium to long chain fatty acids was studied with two microorganisms involved in the spoilage of salad dressings, Zygosaccharomyces bailii and Lactobacillus fructivorans. The microorganisms were inhibited to various degrees by 0.1, 0.5, and 1.0% synthesized sucrose or methylglucose monoesters using a modified broth dilution method. Sucrose monoesters were most inhibitory when the esterified fatty acid was myristic (C14) or palmitic acid (C16). Methylglucose monoesters with lauric (C12) or myristic acid (C14) exhibited greater inhibition than those with longer chain fatty acids. The least inhibition was generally observed with sucrose and methylglucose oleate (C18:1). Sucrose monoesters were usually more inhibitory than methylglucose monoesters of the same fatty acid, especially for palmitic and stearic (C18) acids. In salad dressing, 1% sucrose monoesters of lauric, myristic, or palmitic acid significantly (P < 0.05) inhibited the growth of Z. bailii and L. fructivorans, and were comparable with or more effective than 0.1% sodium benzoate. Z. bailii growth was nearly completely inhibited by sucrose laurate, myristate and palmitate by 9 days of salad dressing storage. Sucrose monoesters did not delay the lag phase of L. [source] STORAGE QUALITY of ETHYLENE TREATED ,ANJOU' and ,BOSC WINTER PEARSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 5 2000S.R. DRAKE ,Anjou' and ,Bosc' pears (Pyrus communis, L.) were harvested one to two days prior to commercial harvest from three orchards in the Wenatchee growing district of Washington. Harvested fruit were treated with 300 ppm ethylene for three days at 20C. Ethylene treatment enhanced yellow color on fruit peel and the reduction of flesh firmness, and increased spoilage after 90 days in either regular atmosphere (RA) storage or controlled atmosphere (CA) storage regardless of cultivar. Ethylene-treated fruit, of both cultivars, stored in CA had a longer storage life than fruit stored in RA. the safe storage period of ethylene-treated ,Anjou'and ,Bosc' pears was 90 and 45 days, respectively, in RA and 120 and 90 days, respectively, in CA. [source] FREE-SPACE MICROWAVE MEASUREMENT of LOW MOISTURE CONTENT IN POWDERED FOODSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2000RAM M. NARAYANAN A free-space microwave transmission technique has been developed and tested for rapid inline noninvasive measurement of the moisture content of various types of food powders. the basis of this technique is the relation between the attenuation of X-band microwave radiation through a sample of the food powder to its moisture content by weight. Since food powders generally lose their utility and desirable properties, such as flowability and resistance to spoilage, at lower levels of moisture content, typically 3,7%, special techniques must be developed in order to accurately characterize the moisture content at these low levels. One such technique is to use frequency averaging to enhance the accuracy of the measurements to avoid multiple reflection effects prevalent in low-loss low-moisture attenuation measurements. This technique was implemented in the moisture content estimation. Overall accuracies in moisture content estimation are generally less than 1%, although in some cases, accuracies are in the vicinity of 5%. [source] THE EFFECT OF MODIFIED ATMOSPHERE PACKAGING ON THE QUALITY AND SHELF LIFE OF FRANKFURTER TYPE-SAUSAGESJOURNAL OF FOOD QUALITY, Issue 2010NALAN GOKOGLU ABSTRACT The effects of modified atmosphere packaging on the quality and shelf life of frankfurter-type sausages, prepared exclusively from beef meat, were investigated. Sausages were packed under varying modified atmosphere conditions (30% CO2/70% N2; 70% CO2/30% N2; 100% CO2; 80% CO2/20% O2) and vacuum, and stored at 4C for 28 days. Lower pH values were observed in the samples packed under modified atmospheres compared to vacuum. Inhibition effect of carbon dioxide concentration on the oxidation was seen. Carbon dioxide caused microbial inhibition. The lowest total viable count was found in the samples packed under 100% CO2. It was concluded that modified atmosphere packaging had significant effect on the quality and shelf life of frankfurter-type sausages compared to vacuum packaging. The most suitable atmosphere among the tested atmospheres was that with 70% CO2, 30% N2 atmosphere. The shelf life of sausages under this atmosphere was 28 days. PRACTICAL APPLICATIONS Meat and meat products are susceptible to spoilage. Several preservation techniques are used to extend their shelf life. Packaging of fresh meat is a common application to protect its quality. Modified atmosphere packaging (MAP) means to replace the air in a package of food with some different mixture of gases. The success in MAP is to choose the suitable gas combination, packaging system, package application and the package material. Proper gas combination to keep meat quality should be provided. Several studies have been performed to extent shelf life of pork sausages and local-type sausages using modified atmosphere packaging technique. However there is no data on beef sausages. The results of this research will form the basis for further studies and also will be beneficial for industry. [source] EFFECT OF HEADSPACE OXYGEN AND FILMS OF DIFFERENT OXYGEN TRANSMISSION RATE ON TOXIN PRODUCTION BY CLOSTRIDIUM BOTULINUM TYPE E IN RAINBOW TROUT FILLETS STORED UNDER MODIFIED ATMOSPHERESJOURNAL OF FOOD SAFETY, Issue 3 2000ISABELLE DUFRESNE ABSTRACT Studies were conducted to determine the effect of various levels of headspace oxygen (0,100%, balance CO2) or film oxygen transmission rate (OTR) on the time to toxicity in modified atmosphere packaged (MAP) fresh trout fillets challenged with C. botulinum type E (102 spore/g) and stored under moderate temperature abuse conditions (12C). In all cases, trout were toxic within 5 days, irrespective of the initial levels of oxygen in the package headspace. However, spoilage preceded toxigenesis. Packaging of trout fillets in low gas barrier films, with OTRs ranging from 4,000 to 10,000 cc/m2/day at 24C and 0% relative humidity, also had no effect on time to toxicity in all MAP trout fillets. All fillets were toxic within 4,5 days and spoilage again preceded toxigenesis. This study has shown that the addition of headspace O2, either directly to a package or indirectly by using a low gas barrier film, had no influence on the time to toxigenesis or spoilage. Additional barriers, other than headspace O2 or film transmission rate, need to be considered to ensure the safety of MAP trout fillets, particularty at moderate temperature abuse conditions. [source] Characterization by Volatile Compounds of Microbial Deep Spoilage in Iberian Dry-Cured HamJOURNAL OF FOOD SCIENCE, Issue 6 2010Alberto Martín Abstract:, In the present study, volatile compounds of spoiled dry-cured Iberian ham with deep spoilage or "bone taint" were analyzed and correlated with level of spoilage and the microorganisms detected. Volatile compounds extracted by a solid phase micro-extraction technique were assayed by gas chromatography/mass spectrometry. The spoiled hams were evaluated sensorially, and the correlations among volatile compounds, spoilage level, and microbial counts were studied. The spoiled hams had higher concentrations of hydrocarbons, alcohols, acids, esters, pyrazines, sulfur compounds, and other minor volatile compounds than unspoiled hams. The sensorial analysis showed that the spoilage level of hams correlated with several volatile compounds, most of them associated with Gram-positive catalase positive cocci and,Enterobacteriaceae,counts. Cyclic compounds such as cyclohexanone, some ethers, and pyrazines should be considered as indicators to monitor incipient microbial deep spoilage in the elaboration of this meat product. [source] Stabilizing Smoked Salmon (Oncorhynchus gorbuscha) Tissue after Extraction of OilJOURNAL OF FOOD SCIENCE, Issue 3 2010Cindy Bower ABSTRACT:, Alaska salmon oils are rich in n-3 polyunsaturated fatty acids and are highly valued by the food and pharmaceutical industries. However, the tissue that remains after oil extraction does not have an established market. Discarded pink salmon (Oncorhynchus gorbuscha) tissues were preserved using a combination of smoke-processing and acidification with lactic acid bacteria (LAB). All samples were analyzed for moisture, protein, ash, and lipid contents. Bacterial cell counts, pH, and lactic acid concentrations were recorded as a measure of LAB viability. Neither raw nor smoked salmon were free from spoilage during 60 d of storage. Only fermented samples successfully stabilized below pH 4.7, while retaining lactic acid concentrations over 15 g/L during storage. When smoked, fermented salmon head tissues were dried, the pH of the resulting high-protein "cracker" was significantly lower than when crackers were prepared only from the smoked (but not fermented) salmon material. Both cracker varieties retained valuable polyunsaturated fatty acids. This research suggests that salmon-head tissues discarded after oil extraction represent a good source of protein and high-value fatty acids in a shelf-stable form. Practical Application: Alaska salmon oils are rich in n-3 polyunsaturated fatty acids and are highly valued by the food and pharmaceutical industries. However, the tissue that remains after oil extraction does not have an established market. Material produced from salmon tissue discarded after oil extraction may represent a valuable resource for preparing high-protein crackers and other fish-based food products. In addition to providing a unique smoke-flavoring, the smoked, fermented fish material may also impart antioxidant factors thereby extending the shelf life of the product. [source] High Relative Humidity In-Package of Fresh-Cut Fruits and Vegetables: Advantage or Disadvantage Considering Microbiological Problems and Antimicrobial Delivering Systems?JOURNAL OF FOOD SCIENCE, Issue 4 2008J.F. Ayala-Zavala ABSTRACT:, This hypothesis article states that the high relative humidity (RH) of packaged fresh-cut fruits or vegetables that is associated with spoilage can be used as an advantageous way to deliver antimicrobial compounds using cyclodextrins (CDs) as carriers. CDs can function as antimicrobial delivery systems as they can release antioxidant and antimicrobial compounds (guest molecules) as the humidity levels increase in the headspace. Hydrophobic antimicrobial guests can be complexed with CDs due to the amphiphatic nature of the host. Then, at high RH values, due to the water,CDs interaction, host,guest interactions are weakened; consequently, the antimicrobial molecule is released and should protect the product against the microbial growth. Potential antimicrobial compounds capable of forming complexes with CDs are discussed, as well as possible applications to preserve fresh-cut produce and future research in this area. [source] | |||||||||||||||||||