Shelf-life prediction models for ready-to-eat fresh cut salads: Testing in real cold chain

Theofania Tsironi; Efimia Dermesonlouoglou; Marianna Giannoglou; Eleni Gogou; George Katsaros; Petros Taoukis

doi:10.1016/j.ijfoodmicro.2016.09.032

Shelf-life prediction models for ready-to-eat fresh cut salads: Testing in real cold chain

Int J Food Microbiol. 2017 Jan 2:240:131-140. doi: 10.1016/j.ijfoodmicro.2016.09.032. Epub 2016 Oct 3.

Authors

Theofania Tsironi¹, Efimia Dermesonlouoglou¹, Marianna Giannoglou¹, Eleni Gogou¹, George Katsaros¹, Petros Taoukis²

Affiliations

¹ National Technical University of Athens, School of Chemical Engineering, Laboratory of Food Chemistry and Technology, Greece.
² National Technical University of Athens, School of Chemical Engineering, Laboratory of Food Chemistry and Technology, Greece. Electronic address: taoukis@chemeng.ntua.gr.

PMID: 27745710
DOI: 10.1016/j.ijfoodmicro.2016.09.032

Abstract

The aim of the study was to develop and test the applicability of predictive models for shelf-life estimation of ready-to-eat (RTE) fresh cut salads in realistic distribution temperature conditions in the food supply chain. A systematic kinetic study of quality loss of RTE mixed salad (lollo rosso lettuce-40%, lollo verde lettuce-45%, rocket-15%) packed under modified atmospheres (3% O₂, 10% CO₂, 87% N₂) was conducted. Microbial population (total viable count, Pseudomonas spp., lactic acid bacteria), vitamin C, colour and texture were the measured quality parameters. Kinetic models for these indices were developed to determine the quality loss and calculate product remaining shelf-life (SL_R). Storage experiments were conducted at isothermal (2.5-15°C) and non-isothermal temperature conditions (T_eff=7.8°C defined as the constant temperature that results in the same quality value as the variable temperature distribution) for validation purposes. Pseudomonas dominated spoilage, followed by browning and chemical changes. The end of shelf-life correlated with a Pseudomonas spp. level of 8 log(cfu/g), and 20% loss of the initial vitamin C content. The effect of temperature on these quality parameters was expressed by the Arrhenius equation; activation energy (E_a) value was 69.1 and 122.6kJ/mol for Pseudomonas spp. growth and vitamin C loss rates, respectively. Shelf-life prediction models were also validated in real cold chain conditions (including the stages of transport to and storage at retail distribution center, transport to and display at 7 retail stores, transport to and storage in domestic refrigerators). The quality level and SL_R estimated after 2-3days of domestic storage (time of consumption) ranged between 1 and 8days at 4°C and was predicted within satisfactory statistical error by the kinetic models. T_eff in the cold chain ranged between 3.7 and 8.3°C. Using the validated models, SL_R of RTE fresh cut salad can be estimated at any point of the cold chain if the temperature history is known. Shelf-life models of validated applicability can serve as an effective tool for shelf-life assessment and the development of new products in the fresh produce food sector.

Keywords: Eruca sativa L; Field test; Kinetic modelling; Lactuca sativa L; Microbial growth; Ready-to-eat salad; Shelf-life.

MeSH terms

Cold Temperature
Colony Count, Microbial
Food Microbiology / methods
Food Preservation / methods*
Food Storage / methods*
Kinetics
Lactobacillaceae / growth & development*
Lactuca / microbiology*
Models, Biological
Pseudomonas / growth & development*
Refrigeration*
Vegetables / microbiology*