Progress 10/01/01 to 09/30/06
Outputs
A program was developed to calculate together the survival/degradation curves of five organisms-vitamins combinations during heat treatments and posted as freeware on the web. The program also allows to compare, simultaneously, the effect of up to five different thermal histories (temperature profiles) on the accomplished sterility of heat preserved food products. Mathematical models have been developed to stimulate processes and systems where the number of organisms decreases and then increases, or vice versa. Examples are disinfected water where after the agent's dissipation and the survivors might grow incomplete thermal processes, and certain slow cooking procedures in which part of the meat is incubated in the interior while the microorganisms are being destroyed in the exterior. A new approach to microbial inactivation and/or growth based on purely statistical consideration has been examined and initial results indicate that it can produce survival and growth
curves that are consistent with almost all those being reported in the literature, including those that show peek growth or a minimum survival ratio. Non linear kinetics has also been applied to chemical reactions. It has been demonstrated that non-isothermal loss of vitamins in processed and stored foods can be predicted with satisfactory accuracy from isothermal kinetic data.
Impacts
The web pages from with the downloadable programs to calculate microbial inactivation and growth under non-isothermal conditions had several hundred visits each. The method to examine and predict non-isothermal inactivation data is now taught in food processing courses at several universities in the United States and abroad. The most common underlying survival model, based on the Weibull distribution, originally developed in the project is not being used by many microbiologists in the United States and other countries. The demonstration that non linear kinetics can be implemented in predicting microbial growth, nutrients loss and the efficacy of preservation methods will improve the safety and nutritional quality of processed foods. They will also provide food researchers in various disciplines with an explanation of the discrepancies between the predictor of conventional theories and the microbiological and biochemical changes that foods actually undergo during their
processing, transportation and storage.
Publications
- Corradini, M.G. and Peleg, M. 2006. Prediction of vitamin loss during non-isothermal heat processes and storage with non-linear kinetic models. Trends in Food Science & technology 17:24-34.
- Corradini, M.G., Normand, M.D. and Peleg, M. 2006. On expressing the equivalence of non-isothermal and isothermal heat sterilization processes. J. Sci. Food Agric. 86:785-792.
- Corradini, M.G. and Peleg, M. 2006. On modeling and simulating transitions between microbial growth and inactivation or vice versa. Intnl. J. Food Microbiol. 108:22-35.
- Peleg, M. 2006. On fundamental issues in texture evaluation and texturization. Food Hydrocolloids. 20:405-414.
- Corradini, M.G., Amezquita, A., Normand M.D. and Peleg, M. 2006. Modeling and predicting non-isothermal microbial growth using general purpose software. Intnl. J. Food Microbiol 106:223-328.
- Corradini, M.G. and Peleg, M. 2005. Consistency of dispersed food systems and its evaluation by squeezing flow viscometry. J. Texture Studies 36:605-629.
- Corradini,, M.G., Normand, M.D. and Peleg, M. 2005. Calculating the efficacy of heat sterilization processes. J. Food Engr, 67:59-69. Peleg, M., Normand, M.D. and Corradini, M.G. 2005. Generating microbial survival curves during thermal processing in real time. Journal of Applied Microbiology 98:406-417.
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Progress 10/01/04 to 09/30/05
Outputs
The Methodology developed for simulating and predicting microbial inactivation under non-isothermal conditions has been extended to growth curves. Two programs written in MS Excel(R) were posted on the Web. They allow the simulation/prediction of growth patterns characterized by short and long "lag times". The predictive ability of the models was confirmed using published data. We have also introduced and tested a new sterilization efficacy measure in the form of an equivalent time at a reference temperature to replace the traditional "Fo value", whenever the survival of an organism or spore does not follow the first order kinetics. [There is growing evidence that the majority of organisms indeed do not obey the log linear model.] We have also made the initial steps into expanding some of our approach and non-linear models to other biological/biochemical processes like enzymes inactivatio and vitamins loss.
Impacts
Our program enables us to model, calculate and predict correctly the microbial growth patterns with a minimum number of primary parameter (three instead of four or more as in the traditional models) and without having to rely on any preconceived rate models whose general validity has yet to be convincingly confirmed. The models themselves (of both inactivation and growth) can serve as a basis of devices that will translate time-temperature records into microbial growth or decay, thus ensuing the safety of processed, transported and stored foods.
Publications
- Corradini, M.G. and Peleg, M. 2005. Estimating non-isothermal bacterial growth in foods from isothermal experimental data. Journal of Applied Microbiology 99:187-200.
- Peleg, M. 2005. Mixtures of food powders and particulates. In: Onwulata, C.I. (Ed.) Encapsulated and Powdered Foods. CRC Taylor & Francis, New
- Corradini, M.G. and Peleg, M. 2004. Demonstration of the Weibull-Log logistic survival model's applicability to non isothermal inactivation of E. coli K12 MG1655. Journal of Food Protection 67:2617-2621.
- Periago, P.M., van Zuijlen, A., Fernandez, P.S., Klapwijk, P.M., ter Steeg, P.F., Corradini, M.G. and Peleg, M. 2004. Estimation of the non-isothermal inactivation patterns of Bacillus sporothermodurans IC4 spores in soups from their isothermal survival data. Intntl. J. of Food Micro. 95:205-218.
- Peleg, M., Corradini, M.G. and Normand, M.D. 2004 Kinetic models of complex biochemical reactions and biological processes. Chemie Ingenieur Technik 76:413-423.
- Corradini, M. G. and Peleg, M. 2004. A model of non-isothermal degradation of nutrients, pigments and enzymes. J. Science Food Agric. 84:217-226.
- Peleg, M. 2004. Analysing the effectiveness of thermal preservation processes. In: Richardson, P. (Ed.): Improving thermal processing. Woodhead Publishing, Cambridge, UK. pp. 411-426. [See Peleg (2003) in last year's report: Modelling applied to processes: the case of thermal preservaton - Reprinted with very minor changes upon the publisher's request.]
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Progress 10/01/03 to 09/30/04
Outputs
A non-isothermal microbial inactivation model previously proposed has been expanded. Since the program used in its development was Mathematica (R)(Wolfram Research, Champaign, IL), an advanced mathematical software, rarely used in the food industry (and even food research), we have written a new version of the model that can be used with Microsoft Excel (R), which is much more popular. The new program is based on converting the original model's differential rate equation into a difference equation, which can be solved incrementally. This allows for the generation of theoretical survival curves of one or more targeted organisms or spores in real time. In turn, this new program will enable us to replace the currently used 'F0 value', which is based on idealization of the inactivation kinetics, with a more realistic estimate of the actual survival ratio. The procedure can also be implemented in industrial heat processes control systems using the digitally recorded
temperature as an input.
Impacts
Two versions of the program written in MS Excel(R) have been posted on the web at http://www-unix.oit.umass.edu/~aew2000/ as freeware for use by the Food and other industries, which use heat to destroy microorganisms and spores. A similar program to assess the efficacy of chemical disinfections with volatile agents (like in water chlorination) was also posted. The three programs were set to generate survival curves during sterilization, pasteurization and chemical treatment with a dissipating agent using realistic (published) survival parameters of common organisms. Unlike the current methods to calculate 'sterility' they are based on the non-linear kinetics of microbial inactivation (of which the linear kinetics is just a special simple case) and the actual survival parameters of the organism or spore to be eliminated.
Publications
- Peleg, M. and Normand, M.D. 2004. Calculating microbial survival parameters and predicting survival curves from non-isothermal inactivation data. Crit. Rev. Food Sci. Nutr. 44:409-418.
- Corradini, M.G. and Peleg, M. 2003. A model of microbial survival curves inw ater treated with a volatile disinfectant. J. Appl. Microbiol. 95:1268-1276.
- Peleg, M. 2003. Modeling applied to processes: the case of thermal preservation. In: Zeuthen, P. and Bogh-Sorensen, L. (Eds.):Food preservation techniques. Woodhead Publishing, Cambridge, UK. pp. 507-523.
- Peleg, M. 2003. Microbial survival curves: Inerpretation, mathematical modeling and utiliztion. Comments on Theoretical Biology 8:357-387.
- Corradini, M.G. and Peleg, M. 2003. A theoretical note on the estimation of the number of recoveralbe spores from surivival curves having an activation shoulder. Food Research Intnl. 36:107-113.
- Peleg, M., Normand, M.D. and Campanella, O.H. 2003 Estimating microbial inactivation parameters from survival curves obtained under varying conditions - The linear case. Bulletin Mathemat. Biol. 65:219-234.
- Gonzalez Martinez, C. Corradini, M.G. and Peleg, M. 2003. Effect of moisture on the mechanical properties of pork rind ('chicharon').Food Sci.Technol. Intnl. 9:249-255.
- Peleg, M. 2003. Calculation of the non-isothermal inactivation patterns of microbes having sigmoidal isothermal semi-logarithmic survival curves. Crit. Rev. Food Sci. Nutr. 43:645-658.
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Progress 10/01/02 to 09/30/03
Outputs
Squeezing flow viscometry, and complementary rheologic methods were used to assess the consistency of chickpeas and similar pastes which are difficult to asses by conventional methods because of artifacts. Similar procedures were employed to evaluate the texture of albumen foams and how added gums can affect their stability. We have continued to develop the new class of microbial inactivation models and extended them to non-thermal destruction processes and to bacterial spores showing an "activation shoulder". We also developed a mathematical method to caculate microbial survival parameters from non-isothermal inactivation data.
Impacts
The demonstration of the applicability of squeezing flow viscometry to foams would facilitate their textural evaluation in the food industry using simple testing procedures and relatively inexpensive equipment. The new class of microbial inactivation models can help to assess the actual efficacy and safety of traditional and novel preservation technologies in cases where the traditional caculation methods are inapplicable, because the assumptions on which they are based are violated.
Publications
- Chanasattru, W., Corradini, M.G. and Peleg, M. 2002. Determination of practically significant differences in the sensorily perceived consistency of semi liquid foods. J. Texture Studies 33:445-460.
- Kampf, N. and Peleg, M. 2002. Characterization of chickpea (Cicer arietum L.) pastes using squeezing flow viscometry. Rheologica Acta 41:549-556.
- Kampf, N., Gonzalez Martinez, C., Corradini, M.G. and Peleg, M. 2003. Effect of two gums on the development, rheological properties and stability of egg albumen foams. Rheologica Acta 42:259-268.
- Peleg, M. 2002. A model of survival curves having an 'activation shoulder'. J. Food Sci. 67:2438-2443.
- Peleg, M. 2002. Simulation of E. coli inactivation by carbon dioxide under pressure. J. Food Sci. 67:896-901.
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Progress 10/01/01 to 09/30/02
Outputs
We have continued using squeezing flow viscometry as means of rheological characterization of semi-liquid foods practically intact. This enabled us to prepare samples with practically identical flavor and appearance which differed only in their consistency. Using these, we have estimated the consistency threshold of their sensory perception. We have extended our mathematical method to interpret and predict microbial survival curves to additional non-thermal preservation processes and to non-isothermal data sources. This required the development of new mathematical models and writing new programs to solve their respective differential equations numerically .
Impacts
The squeezing flow procedures will enable testing foods,which are currently very difficult to evaluate by conventional methods because of irreversible damage to the specimen. The method to predict survival curves will enable more rational evaluation of the efficacy of current preservation methods and the development of more effective new ones.
Publications
- Corradini, M.G., Engel, R. and Peleg, M. 2001. Sensory thresholds of consistency of semi liquid foods: Evaluation by squeezing flow viscometry. J. Texture Studies 32:143-154.
- Campanella, O.H. and Peleg, M. 2001. Theoretical comparison of a new and the traditional method to calculate C. botulinum survival during thermal inactivation. J. Sci. Food Agric. 81:1069-1076.
- Peleg, M., Penchina, C.M. and Cole, M.B. 2001. Estimation of the survival curve of Listeria monocytogenes during non-isothermal heat treatments. Food Res. Intnl. 34:383-388.
- Campanella, O. H. and Peleg, M. 2002. Squeezing flow viscometry for non-elastic semi liquid foods - Theory and Applications. Crit. Rev. Food Sci. Nutr. 42:241-264.
- Peleg, M. 2002. Modeling and simulation of microbial survival during treatments with a dissipating lethal chemical agent. Food Res. Intnl. 35:327-336.
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Progress 10/01/00 to 09/30/01
Outputs
New Project
Impacts
(N/A)
Publications
- No publications reported this period
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