TY - JOUR

T1 - Development of predictive models evaluating the spoilage-delaying effect of a bioprotective culture on different yeast species in yogurt

AU - Nielsen, Line

AU - Rolighed, Maria

AU - Buehler, Ariel

AU - Knøchel, Susanne

AU - Wiedmann, Martin

AU - Marvig, Cecilie

N1 - Funding Information: We acknowledge Tina Hornbæk (Chr. Hansen A/S, Hoersholm, Denmark) for critical reading of the manuscript. The authors Maria Rolighed and Cecilie Marvig are employed by Chr. Hansen A/S, a company that develops and commercializes bacterial cultures. This work was supported by the Department of Dairy Bioprotection of Chr. Hansen A/S, the Department of Food Science of the University of Copenhagen, and the Department of Food Science of Cornell University. The authors have not stated any other conflicts of interest. Funding Information: We acknowledge Tina Hornb?k (Chr. Hansen A/S, Hoersholm, Denmark) for critical reading of the manuscript. The authors Maria Rolighed and Cecilie Marvig are employed by Chr. Hansen A/S, a company that develops and commercializes bacterial cultures. This work was supported by the Department of Dairy Bioprotection of Chr. Hansen A/S, the Department of Food Science of the University of Copenhagen, and the Department of Food Science of Cornell University. The authors have not stated any other conflicts of interest. Publisher Copyright: © 2021 American Dairy Science Association

PY - 2021

Y1 - 2021

N2 - Yeast spoilage of fermented dairy products causes challenges for the dairy industry, including economic losses due to wasted product. Food cultures with bioprotective effects are becoming more widely used to help ensure product quality throughout product shelf life. To assist the dairy industry when evaluating product quality throughout shelf life and the effect of bioprotective cultures, we aimed to build stochastic models that provide reliable predictions of yeast spoilage in yogurt with and without bioprotective culture. Growth characterizations of Debaryomyces hansenii, Yarrowia lipolytica, Saccharomyces cerevisiae, and Kluyveromyces marxianus at storage temperatures of 7, 12, and 16°C during a 30-d storage period were conducted in yogurt with and without a bioprotective culture containing Lacticaseibacillus rhamnosus strains. The kinetic growth parameters were calculated using the Buchanan growth model, and these parameters were used as baseline values in Monte Carlo models to translate the yeast growth into spoilage levels. The models were developed using 100,000 simulations and they predicted yeast spoilage levels in yogurt by the 4 yeast types. Each modeled yogurt batch was set to be contaminated with yeast at a concentration drawn from a normal distribution with a mean of 1 log10 cfu/mL and standard deviation of 1 log10 cfu/mL and stored for 30 d at a temperature drawn from a normal distribution with a mean of 6.1°C and a standard deviation of 2.8°C. Considering a spoilage level of 5 log10 cfu/mL, the predicted number of spoiled samples was reduced 3-fold during the first 10 d and by 2-fold at the end of shelf life when a bioprotective culture was added to the yogurt. The models were evaluated by sensitivity analyses, where the main effect factors were maximum yeast population, storage temperature, and yeast strain. The models were validated by comparing the model output to actual observed spoilage data from a European dairy using the bioprotective culture. When the model prediction, based on a mixture of the 4 specific yeast strains, was compared with spoilage data from the European dairy, the observed effect of bioprotective cultures was considerably higher than predicted, potentially influenced by the presence of contaminating strains more sensitive to a bioprotective culture than those characterized here. The developed Monte Carlo models can predict yeast spoilage levels in yogurt at specific production settings and how this may be affected by various parameters and addition of bioprotective cultures.

AB - Yeast spoilage of fermented dairy products causes challenges for the dairy industry, including economic losses due to wasted product. Food cultures with bioprotective effects are becoming more widely used to help ensure product quality throughout product shelf life. To assist the dairy industry when evaluating product quality throughout shelf life and the effect of bioprotective cultures, we aimed to build stochastic models that provide reliable predictions of yeast spoilage in yogurt with and without bioprotective culture. Growth characterizations of Debaryomyces hansenii, Yarrowia lipolytica, Saccharomyces cerevisiae, and Kluyveromyces marxianus at storage temperatures of 7, 12, and 16°C during a 30-d storage period were conducted in yogurt with and without a bioprotective culture containing Lacticaseibacillus rhamnosus strains. The kinetic growth parameters were calculated using the Buchanan growth model, and these parameters were used as baseline values in Monte Carlo models to translate the yeast growth into spoilage levels. The models were developed using 100,000 simulations and they predicted yeast spoilage levels in yogurt by the 4 yeast types. Each modeled yogurt batch was set to be contaminated with yeast at a concentration drawn from a normal distribution with a mean of 1 log10 cfu/mL and standard deviation of 1 log10 cfu/mL and stored for 30 d at a temperature drawn from a normal distribution with a mean of 6.1°C and a standard deviation of 2.8°C. Considering a spoilage level of 5 log10 cfu/mL, the predicted number of spoiled samples was reduced 3-fold during the first 10 d and by 2-fold at the end of shelf life when a bioprotective culture was added to the yogurt. The models were evaluated by sensitivity analyses, where the main effect factors were maximum yeast population, storage temperature, and yeast strain. The models were validated by comparing the model output to actual observed spoilage data from a European dairy using the bioprotective culture. When the model prediction, based on a mixture of the 4 specific yeast strains, was compared with spoilage data from the European dairy, the observed effect of bioprotective cultures was considerably higher than predicted, potentially influenced by the presence of contaminating strains more sensitive to a bioprotective culture than those characterized here. The developed Monte Carlo models can predict yeast spoilage levels in yogurt at specific production settings and how this may be affected by various parameters and addition of bioprotective cultures.

KW - bioprotective culture

KW - Monte Carlo simulation

KW - yeast spoilage

KW - yogurt

U2 - 10.3168/jds.2020-20076

DO - 10.3168/jds.2020-20076

M3 - Journal article

C2 - 34127268

AN - SCOPUS:85107851575

VL - 104

SP - 9570

EP - 9582

JO - Journal of Dairy Science

JF - Journal of Dairy Science

SN - 0022-0302

IS - 9

ER -