The Effect of Freezing Storage on Microbiological Quality of Some Spice Plants
2007
Wójcik-Stopczyńska, Barbara | Jadczak, Dorota
In the study four spice plants were tested: basil, marjoram, savory and the leafy type of parsley. A microbiological analysis included fresh plant material - shoots with leaves (whole and cut into 2-3cm pieces) and frozen pieces (after freezing and storage for 12 months at -25°C). In the fresh whole plants a total number of mesophilic aerobic bacteria ranged from 3.9 in marjoram to 6.7 log- CFU·g⁻¹ in parsley, moulds - from 2.2 in basil and savory to 4.1 logCFU·g⁻¹ in parsley and yeasts - from 2.1 in basil and savory to 3.5 logCFU·g⁻¹ in parsley. Cutting of plants caused a significant increase in the number of these microorganisms. Freezing and freezing storage induced differentiated decreasing of microbiological contamination of tested material. After 12 months of freezing storage an average survival percentage of bacteria was 10%, of moulds and yeasts respectively 44% and 48%, in relation to number of these microorganisms in fresh cut spice plants before freezing. Final counts of bacteria, moulds and yeasts ranged respectively 3.3-6.1, 2.3-3.7 and 2.1-4.1 logCFU·g⁻¹. Neither in the fresh material nor in the frozen one were pathogenic bacteria found. The titre of coliforms in all tested samples of basil, savory and marjoram was >0.1g but it was lower (0.01g) in fresh and frozen parsley. Microbiological quality of frozen parsley was low (total count of microorganisms >6.0 logCFU·g⁻¹). Moreover there was a high number of moulds and yeasts (>3.0 logCFU·g⁻¹) in frozen marjoram. The microbiological quality of frozen basil and savory was quite good. The count of microorganisms in fresh plant material before freezing influenced microbiological quality of frozen spice plants.
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