Effect of electrical field strength applied by PEF processing and storage temperature on the outgrowth of yeasts and moulds naturally present in a fresh fruit smoothie

R.A.H. Timmermans*, A.L. Nederhoff, M.N. Nierop Groot, M.A.J.S. van Boekel, H.C. Mastwijk

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

9 Citations (Scopus)

Abstract

Pulsed electrical field (PEF) technology offers an alternative to thermal pasteurisation of high-acid fruit juices, by extending the shelf life of food products, while retaining its fresh taste and nutritional value. Substantial research has been performed on the effect of electrical field strength on the inactivation kinetics of spoilage and pathogenic micro-organisms and on the outgrowth of spoilage micro-organisms during shelf life. However, studies on the effect of electrical field strength on the inactivation and outgrowth of surviving populations during shelf life are missing. In this study, we assessed the influence of electrical field strength applied by PEF processing and storage temperature on the outgrowth of surviving yeast and mould populations naturally present in fresh fruit smoothie in time. Therefore, an apple-strawberry-banana smoothie was treated in a continuous-flow PEF system (130 L/h), using similar inlet and outlet conditions (preheating temperature 41 °C, maximum temperature 58 °C) to assure that the amount of energy across the different conditions was kept constant. Smoothies treated with variable electrical field strengths (13.5, 17.0, 20.0 and 24.0 kV/cm) were compared to smoothies without treatment for outgrowth of yeasts and moulds. Outgrowth of yeasts and moulds stored at 4 °C and 7 °C was analysed by plating and visual observation and yeast growth was modelled using the modified logistic growth model (Zwietering model). Results showed that the intensity of the electrical field strength had an influence on the degree of inactivation of yeast cells, resulting in a faster outgrowth over time at lower electrical field strength. Outgrowth of moulds over time was not affected by the intensity of the electrical field strength used.Application of PEF introduces a trade-off between type of spoilage: in untreated smoothie yeasts lead to spoilage after 8 days when stored at 4 or 7 °C, whereas in PEF treated smoothie yeasts were (partly) inactivated and provided outgrowth opportunities for moulds, which led to spoilage by moulds after 14 days (7 °C) or 18 days (4 °C).

Original languageEnglish
Pages (from-to)21-30
JournalInternational Journal of Food Microbiology
Volume230
DOIs
Publication statusPublished - 2016

Fingerprint

electric field
raw fruit
Fruits
strength (mechanics)
Spoilage
molds (fungi)
Yeast
storage temperature
Fruit
Fungi
Yeasts
yeasts
Temperature
Processing
spoilage
Food Storage
shelf life
inactivation
Fruit juices
Pasteurization

Keywords

  • Competition
  • Electrical field strength
  • Global modeling
  • Pulsed electric field (PEF)
  • Shelf life
  • Visual spoilage
  • Yeast and moulds

Cite this

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title = "Effect of electrical field strength applied by PEF processing and storage temperature on the outgrowth of yeasts and moulds naturally present in a fresh fruit smoothie",
abstract = "Pulsed electrical field (PEF) technology offers an alternative to thermal pasteurisation of high-acid fruit juices, by extending the shelf life of food products, while retaining its fresh taste and nutritional value. Substantial research has been performed on the effect of electrical field strength on the inactivation kinetics of spoilage and pathogenic micro-organisms and on the outgrowth of spoilage micro-organisms during shelf life. However, studies on the effect of electrical field strength on the inactivation and outgrowth of surviving populations during shelf life are missing. In this study, we assessed the influence of electrical field strength applied by PEF processing and storage temperature on the outgrowth of surviving yeast and mould populations naturally present in fresh fruit smoothie in time. Therefore, an apple-strawberry-banana smoothie was treated in a continuous-flow PEF system (130 L/h), using similar inlet and outlet conditions (preheating temperature 41 °C, maximum temperature 58 °C) to assure that the amount of energy across the different conditions was kept constant. Smoothies treated with variable electrical field strengths (13.5, 17.0, 20.0 and 24.0 kV/cm) were compared to smoothies without treatment for outgrowth of yeasts and moulds. Outgrowth of yeasts and moulds stored at 4 °C and 7 °C was analysed by plating and visual observation and yeast growth was modelled using the modified logistic growth model (Zwietering model). Results showed that the intensity of the electrical field strength had an influence on the degree of inactivation of yeast cells, resulting in a faster outgrowth over time at lower electrical field strength. Outgrowth of moulds over time was not affected by the intensity of the electrical field strength used.Application of PEF introduces a trade-off between type of spoilage: in untreated smoothie yeasts lead to spoilage after 8 days when stored at 4 or 7 °C, whereas in PEF treated smoothie yeasts were (partly) inactivated and provided outgrowth opportunities for moulds, which led to spoilage by moulds after 14 days (7 °C) or 18 days (4 °C).",
keywords = "Competition, Electrical field strength, Global modeling, Pulsed electric field (PEF), Shelf life, Visual spoilage, Yeast and moulds",
author = "R.A.H. Timmermans and A.L. Nederhoff and {Nierop Groot}, M.N. and {van Boekel}, M.A.J.S. and H.C. Mastwijk",
year = "2016",
doi = "10.1016/j.ijfoodmicro.2016.04.014",
language = "English",
volume = "230",
pages = "21--30",
journal = "International Journal of Food Microbiology",
issn = "0168-1605",
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TY - JOUR

T1 - Effect of electrical field strength applied by PEF processing and storage temperature on the outgrowth of yeasts and moulds naturally present in a fresh fruit smoothie

AU - Timmermans, R.A.H.

AU - Nederhoff, A.L.

AU - Nierop Groot, M.N.

AU - van Boekel, M.A.J.S.

AU - Mastwijk, H.C.

PY - 2016

Y1 - 2016

N2 - Pulsed electrical field (PEF) technology offers an alternative to thermal pasteurisation of high-acid fruit juices, by extending the shelf life of food products, while retaining its fresh taste and nutritional value. Substantial research has been performed on the effect of electrical field strength on the inactivation kinetics of spoilage and pathogenic micro-organisms and on the outgrowth of spoilage micro-organisms during shelf life. However, studies on the effect of electrical field strength on the inactivation and outgrowth of surviving populations during shelf life are missing. In this study, we assessed the influence of electrical field strength applied by PEF processing and storage temperature on the outgrowth of surviving yeast and mould populations naturally present in fresh fruit smoothie in time. Therefore, an apple-strawberry-banana smoothie was treated in a continuous-flow PEF system (130 L/h), using similar inlet and outlet conditions (preheating temperature 41 °C, maximum temperature 58 °C) to assure that the amount of energy across the different conditions was kept constant. Smoothies treated with variable electrical field strengths (13.5, 17.0, 20.0 and 24.0 kV/cm) were compared to smoothies without treatment for outgrowth of yeasts and moulds. Outgrowth of yeasts and moulds stored at 4 °C and 7 °C was analysed by plating and visual observation and yeast growth was modelled using the modified logistic growth model (Zwietering model). Results showed that the intensity of the electrical field strength had an influence on the degree of inactivation of yeast cells, resulting in a faster outgrowth over time at lower electrical field strength. Outgrowth of moulds over time was not affected by the intensity of the electrical field strength used.Application of PEF introduces a trade-off between type of spoilage: in untreated smoothie yeasts lead to spoilage after 8 days when stored at 4 or 7 °C, whereas in PEF treated smoothie yeasts were (partly) inactivated and provided outgrowth opportunities for moulds, which led to spoilage by moulds after 14 days (7 °C) or 18 days (4 °C).

AB - Pulsed electrical field (PEF) technology offers an alternative to thermal pasteurisation of high-acid fruit juices, by extending the shelf life of food products, while retaining its fresh taste and nutritional value. Substantial research has been performed on the effect of electrical field strength on the inactivation kinetics of spoilage and pathogenic micro-organisms and on the outgrowth of spoilage micro-organisms during shelf life. However, studies on the effect of electrical field strength on the inactivation and outgrowth of surviving populations during shelf life are missing. In this study, we assessed the influence of electrical field strength applied by PEF processing and storage temperature on the outgrowth of surviving yeast and mould populations naturally present in fresh fruit smoothie in time. Therefore, an apple-strawberry-banana smoothie was treated in a continuous-flow PEF system (130 L/h), using similar inlet and outlet conditions (preheating temperature 41 °C, maximum temperature 58 °C) to assure that the amount of energy across the different conditions was kept constant. Smoothies treated with variable electrical field strengths (13.5, 17.0, 20.0 and 24.0 kV/cm) were compared to smoothies without treatment for outgrowth of yeasts and moulds. Outgrowth of yeasts and moulds stored at 4 °C and 7 °C was analysed by plating and visual observation and yeast growth was modelled using the modified logistic growth model (Zwietering model). Results showed that the intensity of the electrical field strength had an influence on the degree of inactivation of yeast cells, resulting in a faster outgrowth over time at lower electrical field strength. Outgrowth of moulds over time was not affected by the intensity of the electrical field strength used.Application of PEF introduces a trade-off between type of spoilage: in untreated smoothie yeasts lead to spoilage after 8 days when stored at 4 or 7 °C, whereas in PEF treated smoothie yeasts were (partly) inactivated and provided outgrowth opportunities for moulds, which led to spoilage by moulds after 14 days (7 °C) or 18 days (4 °C).

KW - Competition

KW - Electrical field strength

KW - Global modeling

KW - Pulsed electric field (PEF)

KW - Shelf life

KW - Visual spoilage

KW - Yeast and moulds

U2 - 10.1016/j.ijfoodmicro.2016.04.014

DO - 10.1016/j.ijfoodmicro.2016.04.014

M3 - Article

VL - 230

SP - 21

EP - 30

JO - International Journal of Food Microbiology

JF - International Journal of Food Microbiology

SN - 0168-1605

ER -