Effect of alginate and propolis-based edible coating on moisture loss and microbial status of raspberries, cherries, and blueberries during storage

University of Ruse “Angel Kanchev”, Branch-Razgrad, 7200 Razgrad, Bulgaria

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Abstract

Raspberries, strawberries, and cherries are among the most perishable fruits in terms of moisture loss and microbial spoilage during storage, especially at room temperature. The present study aims to evaluate the effect of an edible sodium alginate-based coating, applied alone or in combination with a glycerol extract of propolis, on moisture retention and microbial stability in these three fruit types. For each fruit group, three samples were prepared: a control (without coating), a sample with alginate coating, and a sample with alginate and propolis extract. The fruits were stored at room temperature for a period of 168 h. Moisture loss was monitored daily, and at the end of the storage period, the total count of aerobic mesophilic microorganisms was determined. Soft fruits such as raspberries, strawberries, and cherries are highly valued by consumers for their fresh taste, rich content of bioactive compounds, and beneficial health properties. However, these fruits are extremely susceptible to mechanical damage, moisture loss, and microbial contamination, which significantly limit their postharvest shelf life. When stored at room temperature, moisture loss leads to fruit shrinkage, loss of freshness and texture, while microbial growth accelerates spoilage and decay processes.