# Postharvest Evaluations of Blackcurrant Fruits with Chitosan and Ultraviolet A Treatments
## 3 Results and Discussion
### Microbial Population Changes Under Postharvest Treatments  
The results (Figure 3) on yeast and mold populations of blackcurrants during storage indicated on day 0, chitosan with or without UVA treatment already had an impact on  
\begin{table}
\begin{tabular}{c c c c c c} \hline \multicolumn{6}{c}{**Blackcurrant Physical Characteristics During Storage**} \\ \hline \multicolumn{6}{c}{\({}^{\circ}\)**Brix**} \\ \hline Treatment & D0 & D3 & D7 & D11 & D15 \\ \hline UVA & 14.9 \(\pm\) 0.0 a & 15.1 \(\pm\) 0.3 a & 15.9 \(\pm\) 0.0 b & 15.7 \(\pm\) 0.4 b & 15.7 \(\pm\) 0.4 a \\ \hline Chitosan & 14.1 \(\pm\) 0.0 a & 14.6 \(\pm\) 0.4 a & 15.4 \(\pm\) 0.5 ab & 14.8 \(\pm\) 0.1 ab & 14.6 \(\pm\) 0.0 a \\ \hline UVA-Chito & 15.1 \(\pm\) 0.0 a & 15.2 \(\pm\) 0.7 a & 15.2 \(\pm\) 0.4 ab & 16.3 \(\pm\) 0.2 b & 15.9 \(\pm\) 0.2 b \\ \hline Control & 14.7 \(\pm\) 0.5 a & 15.0 \(\pm\) 0.0 a & 14.3 \(\pm\) 0.3 a & 14.6 \(\pm\) 0.3 a & 14.6 \(\pm\) 0.4 a \\ \hline \multicolumn{6}{c}{\(p\)-value} \\ \hline \multicolumn{6}{c}{pH} \\ \hline Treatment & D0 & D3 & D7 & D11 & D15 \\ \hline UVA & 2.9 \(\pm\) 0.0 a & 3.0 \(\pm\) 0.1 a & 3.0 \(\pm\) 0.1 a & 3.0 \(\pm\) 0.1 a & 3.1 \(\pm\) 0.0 a \\ \hline Chitosan & 3.0 \(\pm\) 0.0 a & 2.9 \(\pm\) 0.1 a & 3.0 \(\pm\) 0.0 a & 2.9 \(\pm\) 0.1 a & 3.1 \(\pm\) 0.0 a \\ \hline UVA-Chito & 2.9 \(\pm\) 0.1 a & 2.9 \(\pm\) 0.0 a & 3.0 \(\pm\) 0.1 a & 3.0 \(\pm\) 0.1 a & 3.1 \(\pm\) 0.0 a \\ \hline Control & 3.0 \(\pm\) 0.1 a & 2.9 \(\pm\) 0.1 a & 3.0 \(\pm\) 0.1 a & 3.0 \(\pm\) 0.1 a & 3.0 \(\pm\) 0.1 a \\ \hline \multicolumn{6}{c}{\(p\)-value} \\ \hline \multicolumn{6}{c}{Citric Acid (\%)} \\ \hline Treatment & D0 & D3 & D7 & D11 & D15 \\ \hline UVA & 1.6 \(\pm\) 0.8 a & 1.4 \(\pm\) 0.3 a & 2.0 \(\pm\) 0.1 a & 1.9 \(\pm\) 0.1 a & 2.0 \(\pm\) 0.1 a \\ \hline Chitosan & 1.9 \(\pm\) 0.9 a & 2.0 \(\pm\) 0.6 a & 1.6 \(\pm\) 0.8 a & 1.6 \(\pm\) 0.7 a & 2.  
y a small number of input yeast and mold populations. The reduction in yeast and mold populations at the beginning stage might have been because of the coating of chitosan. On day 3, chitosan's impact on yeast and mold populations was not significantly different from that of chitosan combined with UVA, and the population was below 24 Log CFU/g on average. Both the control and UVA had higher yeast and mold populations (>28 Log CFU/g on average) on day 3. The UVA-chitosan influences were significantly different from the chitosan treatments on day 7. Chitosan combined with UVA had higher efficiency of antifungal activity, although the influences were not significantly different from chitosan itself on both day 12 and day 15. On the other hand, UVA had few inhibition capabilities compared with the control treatment before day 12. The UVA treatment's impact on yeast and mold populations was only significantly different from that of the control treatment at the later stages (day 12 to day 15) of postharvest. During storage, large amounts of yeast and mold populations were detected in both the UVA and control treatments. Generally, UVA had less impact on controlling fungal populations, whereas chitosan or chitosan combined with UVA (UVA-Chito) had a strong inhibition effect in blackcurrant postharvest treatments. High-molecular-weight chitosan fractions could destabilize the fungal cell membranes, and low-molecular-weight fractions of chitosan could penetrate fungal cells and disturb cell processes [42]. In this study, low-molecular-weight chitosan was used. Its higher solubility and lower viscosity made it easier to coat small blackcurrant berries. Further alternative LED lights may be applicable in the future with light spectrums such as UVC. The integration of UVC has been extensively studied for postharvest contamination and preservation, specifically controlling yeast and mold growth during storage [43].  
Meanwhile, the aerobic populations of microbes on blackcurrants during postharvest were absent to low (0-0.3 LogCFU/g) during postharvest, and there were no changes across storage.