title: Quantifying the spoilage and shelf-life of yoghurt with fruits.
abstract: The aim of the present study was to develop a predictive model to quantify the spoilage of yoghurt with fruits. Product samples were stored at various temperatures (5-20 °C). Samples were subjected to microbiological (total viable counts, lactic acid bacteria-LAB, yeasts and moulds) and physico-chemical analysis (pH, titratable acidity and sugars). LAB was the dominant micro-flora. Yeasts population increased at all temperatures but a delay was observed during the first days of storage. Titratable acidity and pH remained almost constant at low temperatures (5 and 10 °C). However, at higher temperatures (>10 °C), an increase in titratable acidity and reduction in pH was observed. Sugar concentration (fructose, lactose and glucose) decreased during storage. A mathematical model was developed for shelf-life determination of the product. It was successfully validated at a temperature (17 °C) not used during model development. The results showed that shelf-life of this product could not be established based only on microbiological data and use of other parameters such as sensory or/and physico-chemical analysis is required. Shelf-life determination by spoilage tests is time-consuming and the need for new rapid techniques has been raised. The developed model could help dairy industries to establish shelf-life predictions on yoghurt with fruits stored under constant temperature conditions.
authors.affiliation: Agricultural University of Athens, Department of Food Science and Technology, Laboratory of Food Quality Control and Hygiene, Iera Odos 75, GR-11855 Athens, Greece. mmat@aua.gr
authors.forename: M
authors.initials: M
authors.lastname: Mataragas
authors.forename: V
authors.initials: V
authors.lastname: Dimitriou
authors.forename: P N
authors.initials: PN
authors.lastname: Skandamis
authors.forename: E H
authors.initials: EH
authors.lastname: Drosinos
mesh_terms: D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods / Q000592:standards*; D005638:Fruit / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007778:Lactobacillus / Q000254:growth & development; D008954:Models, Biological; D011237:Predictive Value of Tests; D013696:Temperature; D015003:Yeasts / Q000254:growth & development; D015014:Yogurt / Q000382:microbiology*