Effects of Moisture Contents and Storage Temperatures on the Physical, Chemical and Microbiological Qualities of Non-Sulfitted Dried Apricots

Abstract

This study was conducted to determine the changes in the physicochemical and microbiological qualities of the non-sulfited sun dried apricots (NSDAs) at three different moisture contents (MCs, 13.7, 23.5 and 27.0%) and at four different storage temperatures (4, 10, 20, and 30 degrees C) for 12 months in bulk and packaged samples. NSDAs were subjected to physical (moisture, water activity, pH and reflectance colour values), chemical (browning formation, beta-carotene, and acidity), and microbial (counts for total aerobic mesophilic and psycrofilic bacteria, yeast and mould, xerofilic mould and yeast, osmophilic yeast, lactic acid bacteria, Enterobacteriaceae, Staphylococcus-Micrococcus spp.) analyses at one-month time intervals. Results indicated that while the fastest brown colour formation occurred in the samples containing 23.5% MC and stored at 30 degrees C, the browning decelerated below 10 degrees C. No significant change was observed in beta-carotene contents of NSDAs during storage (P>0.05). After rehydration, osmophilic yeast count of NSDAs increased by 2.5 log colony-forming units (cfu/g). Significant reductions were observed in the microbial loads of the samples at 23.5 and 27.0% MCs with the decreasing water activity (P<0.05) during storage and increasing storage temperatures. However, yeast and mould counts exceeded 5.0 log cfu/g of the samples containing 27.0% MC after 2-months storage at 20 degrees C. Overall, we suggest that MC and storage temperature for NSDAs should be below 23.5% and 20 degrees C to achieve high microbial and physicochemical qualities for a year, respectively.