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PubMed2003

Combinations of pulsed white light and UV-C or mild heat treatment to inactivate conidia of Botrytis cinerea and Monilia fructigena.

The use of pulses of intense white light to inactivate conidia of the fungi Botrytis cinerea and Monilia fructigena, responsible for important economical losses during postharvest storage and transport of strawberries and sweet cherries, was investigated in this study. In the first stage, a light treatment applying pulses of 30 micros at a frequency of 15 Hz was investigated, resulting in a treatment duration varying from 1 to 250 s. The conidia of both fungi showed similar behaviour to pulsed light, with a maximal inactivation of 3 and 4 log units for B. cinerea and M. fructigena, respectively. The inactivation of the conidia increased with increasing treatment intensity, but no complete inactivation was achieved. The sigmoidal inactivation pattern obtained by the pulsed light treatment was described using a modification of the model of Geeraerd et al. [Int. J. Food Microbiol. 59 (2000) 185]. Hereto, the shoulder length was incorporated explicitly and relative values for the microbial populations were used. In the second stage, combinations of light pulses and ultraviolet-C or heat were applied. The UV light used in the experiments is the short-wave band or UV-C, running from 180 to 280 nm with a peak at 254 nm (UV-B runs from 280 to 320 nm and UV-A from 320 to 380 nm). The UV-C doses were 0.025, 0.05 and 0.10 J/cm(2), and the temperatures for the thermal treatment ranged from 35 to 45 degrees C during 3-15 min. When combining UV-C and light pulses, there was an increase in inactivation for both B. cinerea and M. fructigena, and synergism was observed. There was no effect of the order of the treatments. For the heat-light pulses combination, there was a difference between both fungi. The order of the treatments was highly significant for B. cinerea, but not for M. fructigena. Combining heat and light treatments improved the inactivation, and synergism between both methods was again observed. Complete inactivation of M. fructigena conidia was obtained after, e.g., a 40-s pulsed light treatment and 15 min at 41 degrees C, or after an 80-s light treatment and 10 min at 41 degrees C.

Botrytis↗
PubMed2004

Inhibition of pathogens on fresh produce by ultraviolet energy.

Ultraviolet energy at a wavelength of 253.7 nm (UVC) was investigated for its bactericidal effects on the surface of Red Delicious apples, leaf lettuce and tomatoes inoculated with cultures of Salmonella spp. or Escherichia coli O157:H7. Inoculated samples were subjected to different doses ranging from 1.5 to 24 mW/cm(2) of UVC and enumerated on tryptic soy agar plus 0.05 g/l nalidixic acid to determine effective log reductions of microbial populations. UVC applied to apples inoculated with E. coli O157:H7 resulted in the highest log reduction of approximately 3.3 logs at 24 mW/cm(2). Lower log reductions were seen on tomatoes inoculated with Salmonella spp. (2.19 logs) and green leaf lettuce inoculated with both Salmonella spp. and E. coli O157:H7 (2.65 and 2.79, respectively). No significant statistical difference (p>0.05) was seen in the ability of UVC to inactivate a higher population of either Salmonella spp. or E. coli O157:H7 on the surface of green leaf lettuce. No significant difference was seen among the use of different doses applied to the surface of fresh produce for reduction of E. coli O157:H7 or Salmonella spp. (p>0.05). The use of UVC may prove to be beneficial in protecting the safety of fruits and vegetables in conjunction with Good Agricultural Practices and Good Manufacturing Practices.

Colony Count, Microbial↗
PubMed2003

Combining nonthermal technologies to control foodborne microorganisms.

Novel nonthermal processes, such as high hydrostatic pressure (HHP), pulsed electric fields (PEFs), ionizing radiation and ultrasonication, are able to inactivate microorganisms at ambient or sublethal temperatures. Many of these processes require very high treatment intensities, however, to achieve adequate microbial destruction in low-acid foods. Combining nonthermal processes with conventional preservation methods enhances their antimicrobial effect so that lower process intensities can be used. Combining two or more nonthermal processes can also enhance microbial inactivation and allow the use of lower individual treatment intensities. For conventional preservation treatments, optimal microbial control is achieved through the hurdle concept, with synergistic effects resulting from different components of the microbial cell being targeted simultaneously. The mechanisms of inactivation by nonthermal processes are still unclear; thus, the bases of synergistic combinations remain speculative. This paper reviews literature on the antimicrobial efficiencies of nonthermal processes combined with conventional and novel nonthermal technologies. Where possible, the proposed mechanisms of synergy is mentioned.

Biotechnology↗
PubMed1999

The safety and social acceptance of novel foods.

The regulatory processes employed in the UK and the European Union to assess the safety of novel foods and novel food ingredients, including those resulting from the application of recombinant DNA technology (genetically modified foods), are described. Examples are given of yeasts that have been genetically modified and can be used in food and drink manufacture and food enzymes derived from genetically modified microorganisms that have been deemed safe for use by the UK regulatory system. Social acceptance of such novel foods or food ingredients is not uniform in countries of the developed world. Consumer concerns can be based on ethical considerations (scientists "playing God") or safety worries ("more testing needs to be done"). The general acceptance of such foods and food ingredients in Europe is still unclear.

Consumer Behavior↗
PubMedDate not supplied

Design and optimization of hot-filling pasteurization conditions: Cupuaçu (Theobroma grandiflorum) fruit pulp case study.

Cupuaçu (Theobroma grandiflorum) is an Amazonian tropical fruit with a great economic potential. Pasteurization, by a hot-filling technique, was suggested for the preservation of this fruit pulp at room temperature. The process was implemented with local communities in Brazil. The process was modeled, and a computer program was written in Turbo Pascal. The relative importance among the pasteurization process variables (initial product temperature, heating rate, holding temperature and time, container volume and shape, cooling medium type and temperature) on the microbial target and quality was investigated, by performing simulations according to a screening factorial design. Afterward, simulations of the different processing conditions were carried out. The holding temperature (T(F)) and time (t(hold)) affected pasteurization value (P), and the container volume (V) influenced largely the quality parameters. The process was optimized for retail (1 L) and industrial (100 L) size containers, by maximizing volume average quality in terms of color lightness and sensory "fresh notes" and minimizing volume average total color difference and sensory "cooked notes". Equivalent processes were designed and simulated (P(91)( degrees )(C) = 4.6 min on Alicyclobacillus acidoterrestris spores) and final quality (color, flavor, and aroma attributes) was evaluated. Color was slightly affected by the pasteurization processes, and few differences were observed between the six equivalent treatments designed (T(F) between 80 and 97 degrees C). T(F) >/= 91 degrees C minimized "cooked notes" and maximized "fresh notes" of cupuaçu pulp aroma and flavor for 1 L container. Concerning the 100 L size, the "cooked notes" development can be minimized with T(F) >/= 91 degrees C, but overall the quality was greatly degraded as a result of the long cooling times. A more efficient method to speed up the cooling phase was recommended, especially for the industrial size of containers.

Bacillus↗
PubMed1990

Lipid test.

Explore the source record for details and available documents.

Eggs↗
PubMed1972

Foood additives.

Explore the source record for details and available documents.

Coloring Agents↗
PubMed1998

Light inactivation of food-related pathogenic bacteria using a pulsed power source.

The effects of high intensity light emissions, produced by a novel pulsed power energization technique (PPET), on the survival of bacterial populations of verocytotoxigenic Escherichia coli (serotype 0157:H7) and Listeria monocytogenes (serotype 4b) were investigated. Using this PPET approach, many megawatts (MW) of peak electrical power were dissipated in the light source in an extremely short energization time (about 1 microsecond). The light source was subjected to electric field levels greater than could be achieved under conventional continuous operation, which led to a greater production of the shorter bacteriocidal wavelengths of light. In the exposure experiments, pre-determined bacterial populations were spread onto the surface of Trypone Soya Yeast Extract Agar and were then treated to a series of light pulses (spectral range of 200-530 nm) with an exposure time ranging from 1 to 512 microseconds. While results showed that as few as 64 light pulses of 1 microsecond duration were required to reduce E. coli 0157:H7 populations by 99.9% and Listeria populations by 99%, the greater the number of light pulses the larger the reduction in cell numbers (P < 0.01). Cell populations of E. coli 0157:H7 and Listeria were reduced by as much as 6 and 7 log10 orders at the upper exposure level of 512 microseconds, respectively. Survival data revealed that E. coli 0157:H7 was less resistant to the lethal effects of radiation (P < 0.01). These studies have shown that pulsed light emissions can significantly reduce populations of E. coli 0157:H7 and L. monocytogenes on exposed surfaces with exposure times which are 4-6 orders of magnitude lower than those required using continuous u.v. light sources.

Disinfection↗
PubMed1980

Bananas--physiology and biochemistry of storage and ripening for optimum quality.

Bananas (Musa spp.) are a major food crop of the humid tropics, and although edible cultivars are diverse and numerous, most of our knowledge of the physiology and biochemistry of these fruits relates to a few dessert cultivars of the AAA type, mainly of the Cavendish subgroup, which dominate the export trade between tropical and temperate zones. The preclimacteric period of banana fruits after harvest determines their transportability, and its duration is very sensitive to changes in fruit maturity, storage temperature, ethylene concentration, and other factors; progress in measurement and resolution of each of these effects is described. Changes in composition of the ripening fruits, especially in the development of flavor volatiles, are reviewed. Progress in understanding the integration of the biochemical changes controlling ripening in banana fruits is discussed. Recent work on storage, ripening, and factors relating to sensory assessment of fruit quality is discussed for cultivars of Musa types not used in major export trades.

Amino Acids↗
PubMed2002

Characteristics and performance of the Sunna high dose dosemeter using green photoluminescence and UV absorption readout methods.

Growth in the use of ionising radiation for medical sterilisation and the potential for wide-scale international food irradiation have created the need for robust, mass-producible, inexpensive, and highly accurate radiation dosemeters. The Sunna dosemeter, lithium fluoride injection-moulded in a polyethylene matrix, can be read out using either green photoluminescence or ultraviolet (UV) absorption. The Sunna dosemeter can be mass-produced inexpensively with high precision. Both the photoluminescent and the UV absorption reader are simple and inexpensive. Both methods of analysis display negligible humidity effects, minimal dose rate dependence, acceptable post-irradiation effects, and permit measurements with a precision of nearly 1% 1sigma. The UV method shows negligible irradiation temperature effects from -30 degrees C to +60 degrees C. The photoluminescence method shows negligible irradiation temperature effects above room temperature for sterilisation dose levels and above. The dosimetry characteristics of these two readout methods are presented along with performance data in commercial sterilisation facilities.

Humidity↗
PubMed1997

The influence of micronization, dehulling, and enzyme supplementation on the nutritional value of peas for laying hens.

Two experiments were conducted to determine the effects of micronization (infrared heat treatment), dehulling, or enzyme supplementation on the nutritive value of three cultivars (Impala, Radley, and Sirius) of peas in laying hens. In Experiment 1, 280 White Leghorn hens were fed diets containing micronized and dehulled peas for a period of 12 wk. The dietary inclusion of peas was 600 g/kg (correction was made for the amounts of hulls in those diets that contained dehulled peas). Egg production (P < or = 0.05), feed conversion (P > or = 0.05), and egg mass output (P < or = 0.05) were lower for birds fed untreated peas. Daily feed intake, egg weight, and albumen quality were not affected. Egg production, feed conversion, and egg mass output were similar for layers fed diets containing micronized peas and those fed the wheat-soybean control diet. Except for daily feed intake, which was reduced (P < or = 0.05), dehulling did not affect (P > or = 0.05) the feeding value of peas. The efficacy of dietary inclusion of a crude enzyme (pectinase) was evaluated in another experiment (8 wk). Pectinase was included in the experimental diets at 0, 50, and 100 U/kg and fed to 252 layers. The inclusion level of peas in these diets was 650 g/kg. There was no effect (P > or = 0.05) of enzyme supplementation on all production traits. Egg production, feed conversion, and egg mass output were 81.9, 83.6, and 83.0%; 1.61, 1.59, and 1.59 and 50.0, 51.2, and 50.3 at 0, 50, and 100 U/kg levels, respectively. It can be concluded that of the treatments tested only micronization had a positive effect on the feeding value of peas for laying hens.

Animal Feed↗
PubMed2001

What views and uses of radiation sources in the 21st century?

Considering that in 1899 neither biotechnology nor the electronic revolution were foreseen, some humility might be advisable when one looks into the crystal ball for the future role of radiation sources. In the past 50 years, nuclear medicine, nuclear weapons, and nuclear power have had a huge impact in the world. In the next 50 years, nuclear weapons may be phased out, nuclear power revived, and nuclear medicine may continue, especially for diagnostic purposes. Conflicts between great powers and blocks will no longer be about territorial or ideological domination but about trade, finance, information, and the environment and the weapons used will not be bombs but investments, credits, and control of information. Nuclear power-still based on fission-will be relaunched and get more uses, e.g., to propel ships, to produce heat for industry and for space heating, and perhaps to desalinate water. The public will be more at ease with radiation as it is better educated, as nuclear safety continuously improves and new types of nuclear power plants emerge, as waste sites fail to cause any problems, and as no other energy source is found to deliver so much energy at reasonable cost with negligible impact on climate and environment. One kilogram of oil corresponds to 4 kWh of electricity. One kilogram of uranium fuel corresponds to 50,000 kWh, and 1 kg of plutonium 6,000,000 kWh! In nuclear medicine, radiation may give way to other treatments as the understanding of cancer advances. On the other hand, the extreme ease with which sources of radiation can be identified is unmatched and likely to make them useful tools as tracers and markers in medicine-and other fields-for a long time. For certain uses--perhaps food irradiation--radiation sources, such as cobalt, may be replaced by accelerators which may be switched on and off at will. As more sources are used, registration and control of them must be made very effective around the whole world. Very high natural emissions of radon will continue to call for cautionary measures, but many other nonradiating substances will be identified as hazardous to health and call for vigorous intervention.

Forecasting↗