Cost, quality, and safety: A nonlinear programming approach to optimize the temperature during supply chain of leafy greens

Leafy green vegetables are highly susceptible to microbial contamination because they are minimally processed. Pathogenic bacteria of concern include Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes. Leafy greens are a highly perishable commodity, and in some cases have a postharvest shelf-life limited to one week. This study provides an approach to optimize storage temperature of leafy greens in the supply chain, considering the cost of refrigeration, sensory quality parameters (i.e., fresh appearance, wilting, browning, and off-odor), and microbial safety using nonlinear programming (NLP). The loss of sensory quality parameters was expressed as Arrhenius equations and pathogen growth were represented by three-phase linear (primary) and square-root (secondary) models. The objective function was refrigeration cost, which was to be minimized. The constraints were growth of pathogens and the loss of sensory characteristics. An interactive graphical user interface was developed in MATLAB. Pathogen growth is of more concern than loss of sensory quality in fresh-cut Iceberg lettuce when considering a shelf-life of up to two days, and the model indicates is difficult to maintain sensory qualities for longer shelf-life values. Browning is of maximum concern for fresh-cut Iceberg and Romaine lettuce, whereas off-odor is the biggest concern for fresh-cut chicory.

[1]  D. Schaffner.  Utilization of mathematical models to manage risk of holding cold food without temperature control. , 2013, Journal of food protection.

[2]  A. Barczak,et al.  Temperature abuse timing affects the rate of quality deterioration of commercially packaged ready-to-eat baby spinach. Part I: sensory analysis and selected quality attributes. , 2014 .

[3]  L. Gould,et al.  Outbreaks attributed to fresh leafy vegetables, United States, 1973–2012 , 2015, Epidemiology and Infection.

[4]  A. P. Ruhil,et al.  Prediction of sensory quality of UHT milk : A comparison of kinetic and neural network approaches , 2009 .

[5]  E. Ryser,et al.  Listeria monocytogenes transfer during mechanical dicing of celery and growth during subsequent storage. , 2014, Journal of food protection.

[6]  J. Sofos,et al.  Quantitative risk assessment for Listeria monocytogenes in selected categories of deli meats: impact of lactate and diacetate on listeriosis cases and deaths. , 2009, Journal of food protection.

[7]  Donald G. Mercer,et al.  Determination of acceptability and shelf life of ready-to-use lettuce by digital image analysis , 2004 .

[8]  J.G.A.J. van der Vorst,et al.  Simulation modelling and risk assessment as tools to identify the impact of climate change on microbiological food safety – The case study of fresh produce supply chain , 2010 .

[9]  R. Akkerman,et al.  An optimization approach for managing fresh food quality throughout the supply chain , 2011 .

[10]  A. Ponce,et al.  Effects of abusive temperatures on the postharvest quality of lettuce leaves: ascorbic acid loss and microbial growth , 2006 .

[11]  Joaquim R. R. A. Martins,et al.  pyOpt: a Python-based object-oriented framework for nonlinear constrained optimization , 2011, Structural and Multidisciplinary Optimization.

[12]  M. Pierson,et al.  Evaluation and definition of potentially hazardous foods , 2003 .

[13]  R. C. Whiting,et al.  When is simple good enough: a comparison of the Gompertz, Baranyi, and three-phase linear models for fitting bacterial growth curves , 1997 .

[14]  Pascal Delaquis,et al.  Development of a dynamic growth-death model for Escherichia coli O157:H7 in minimally processed leafy green vegetables. , 2011, International journal of food microbiology.

[15]  C. Nguyen-the,et al.  Effects of carbon dioxide on the fate of Listeria monocytogenes, of aerobic bacteria and on the development of spoilage in minimally processed fresh endive. , 1996, International journal of food microbiology.

[16]  Fernando Pérez-Rodríguez,et al.  Growth of Escherichia coli O157:H7 and Listeria monocytogenes in packaged fresh-cut romaine mix at fluctuating temperatures during commercial transport, retail storage, and display. , 2014, Journal of food protection.

[17]  G. Ayoola,et al.  Food security in Nigeria: Institutional support through micro-credit for soyabean production , 2004 .

[18]  Yaguang Luo,et al.  Effectiveness of two-sided UV-C treatments in inhibiting natural microflora and extending the shelf-life of minimally processed 'Red Oak Leaf' lettuce. , 2006, Food microbiology.

[19]  R. Buchanan,et al.  Development of growth and survival models for Salmonella and Listeria monocytogenes during non-isothermal time-temperature profiles in leafy greens , 2017 .

[20]  J Olley,et al.  Relationship between temperature and growth rate of bacterial cultures , 1982, Journal of bacteriology.

[21]  S. Roura,et al.  Delayed Cooling or Suboptimal Storage Temperatures Reduce Butterhead Lettuce Shelf-Life , 2014 .

[22]  V. Rubatzky,et al.  SPECIALTY SALAD GREENS: POSTHARVEST PHYSIOLOGY AND SHELF-LIFE , 1998 .

[23]  James N. BeMiller,et al.  Bread Staling: Molecular Basis and Control. , 2003, Comprehensive reviews in food science and food safety.

[24]  F. Devlieghere,et al.  Shelf-life of minimally processed lettuce and cabbage treated with gaseous chlorine dioxide and cysteine. , 2008, International journal of food microbiology.

[25]  A. Allende,et al.  Microbial and sensory quality of commercial fresh processed red lettuce throughout the production chain and shelf life. , 2004, International journal of food microbiology.

[26]  D. Oh,et al.  Predictive model for growth of Listeria monocytogenes in untreated and treated lettuce with alkaline electrolyzed water , 2010 .

[27]  P. Skandamis,et al.  Modeling transfer of Escherichia coli O157:H7 and Listeria monocytogenes during preparation of fresh-cut salads: impact of cutting and shredding practices. , 2015, Food microbiology.

[28]  Washington,et al.  Parameters for determining inoculated pack/challenge study protocols. , 2010, Journal of food protection.

[29]  T. O’Hare,et al.  The effects of 1-methylcyclopropene on the shelf life of minimally processed leafy asian vegetables , 2003 .

[30]  E. Szabo,et al.  Survey for psychrotrophic bacterial pathogens in minimally processed lettuce , 2000, Letters in applied microbiology.

[31]  S. Zorrilla,et al.  The influence of sodium chloride reduction on physicochemical, biochemical, rheological and sensory characteristics of Mozzarella cheese , 2014 .

[32]  M. Pirovani,et al.  Modeling changes of sensory attributes for individual and mixed fresh-cut leafy vegetables , 2005 .