Volume 207, 17 August 2015, Pages 66–70
Highlights
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- Post-consumer mold growth in maple syrup reduces product quality.
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- In the 2014 season, samples were collected from 68 producers across Ontario.
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- Water activity, pH, and °Bx were determined.
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- Some 23 species were isolated, dominated by fungi known from high sugar foods.
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- Mold damage was mainly associated with high aw, cold packing and sanitation.
Abstract
Maple
syrup is a high value artisanal product produced mainly in Canada and a
number of States primarily in the northeast USA. Mold growth (Wallemia sebi)
on commercial product was first reported in syrup in 1908. Since then,
few data have been published. We conducted a systematic examination for
fungi in maple syrup from 68 producers from all of the syrup-producing
areas of Ontario, Canada. The mean pH of the samples was pH 6.82, sugar
content averaged 68.0 ± 0.89 °Brix and aw averaged
0.841 ± 0.011. Some 23 species of fungi were isolated based on
morphology and molecular techniques. The most common fungus in the maple
syrup samples was Eurotium herbariorum, followed by Penicillium chrysogenum, Aspergillus penicillioides, Aspergillus restrictus, Aspergillus versicolor and two species of Wallemia. Cladosporium cladosporioides
was also common but only recovered when fungi known from high sugar
substrates were also present in the mold damaged sample. The rarely
reported yeast Citeromyces matrinsis was found in samples from three producers. There appear to be three potential causes for mold damage observed. High aw
was associated with about one third of the mold damage. Independently,
cold packing (bottling at ~ 25 °C) was a risk factor. However, syrup of
good quality and quite low aw values was contaminated. We
hypothesize that sanitation in the bottling line and other aspects of
the bottling process may be partial explanations. Clarifying this
requires further study.
Keywords
- Maple syrup;
- Fungi;
- Yeasts;
- Water activity;
- °Brix;
- pH
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