*3.4. Correlation between Experimental Measures*

### 3.4.1. Correlation between Fungal Respiration and Ergosterol Content

There was a significant correlation between ergosterol content and cumulative respiration data for *F. graminearum* inoculation in wheat grain. Spearman rank order correlation suggested a strong positive correlation between these two variables (Table 3). When considering individual aw treatments the correlation was stronger during the colonisation period but this decreased when both aw levels are considered together. The overall correlation coefficient among water activities for the length of the experiment was 88.58%.

**Table 3.** Spearman rank order correlation coefficient between cumulative fungal respiration and ergosterol content. *p*-values of all coefficients were < 0.001.


3.4.2. Correlation between Mycotoxin Contamination Levels and Indicators of Colonisation

Correlations between the growth indicators used in this study and the mycotoxin production is shown in Table 4. For DON, all of the indicators used (i.e., volume, ergosterol and cumulative DML) showed a positive correlation. The correlations ranged from 0.8149 to 0.9528 and were dependent on the aw treatment, with higher correlations at 0.95 aw than 0.97 aw. The cumulative DML and the ergosterol content were found to be the indicators most correlated to DON contamination level.

**Table 4.** Correlation (Spearman's) factors of the mycotoxin content with volumetric colonisation, ergosterol, and Cumulative dry matter loss. DON: Deoxynivalenol, ZEN: Zearalenone, DML: dry matter loss. Correlation to the volume was performed using data from the days 2, 4 and 6 of growth, time when the samples were fully colonised.


For ZEN, all indicators except for the volume of growth obtained at 0.95 aw correlated well with the mycotoxin content. The average correlation ranged from 0.4150 to 0.8193. Higher correlation factors were observed at 0.97 aw when compared to 0.95 aw. The best correlated indicators for ZEN were the cumulative DML at 0.97 aw and both cumulative DML and Ergosterol at 0.95 aw.

Overall, DON and ZEN production showed a good correlation at 0.95 aw (0.6417) and 0.97 aw (0.7604).
