Microbial Quality and Shelf Life of Processed Blueberry Product.


Fan, L.,* A. Martynenko, C. Doucette, T. Hughes and S. Fillmore. 2016. Microbial Quality and Shelf Life of Processed Blueberry Product. Poster presentation at the ISEKI Food Conference. July 5-8th. Vienna, Austria.


Spoilage of processed food products caused by spoilage microorganisms has been reported repeatedly. Among them are heat-resistant molds, which usually contaminate fruits on or near the ground and survive heat treatments used for fruit processing. Heat-resistant fungi can grow and spoil the products during shelf life stored at room temperature and result in great economic losses. In this study, blueberry puree products were developed using cavitation technology. Microbial quality including total plate counts, yeast and molds counts and heat-resistant molds of frozen blueberry materials and processed products following pasteurization at 86, 88, 90, 92, 94 and 96°C (at industrial settings) were determined. Shelf life study of pasteurized blueberry products included periodical checks of microbial quality, soluble solids (Brix %), titratable acidity (citric acid %), pH, viscosity (cP) and flow rate (cm/30 s) for up to 24 weeks at room temperature. Our results indicated that heat-resistant molds, originally present at 2.03 log CFU/200g in raw blueberries were inactivated by the selected pasteurization temperatures. Standard spiral plater method was unable to detect heat-resistant molds in blueberry samples, therefore pour plate method was applied, which enabled large amount of samples to be analyzed with accuracy and consistency. Shelf life study showed the absence of microbial growth in the range of temperatures from 90 to 96°C for 24 weeks along with non-significant changes of quality characteristics of blueberry products. Our research findings provide the food industry with useful information on developing other processed fruit products and ensuring food safety and quality.

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