# The Inactivation of Microscopic Fungi in Bakery Products Using Hurdle Technology--A Case Study
## 3 Results
### Characterization of Microscopic Fungi in the Production Environment and in the Product
During their microscopic observation, pseudomycelium as well as elongated or oval cells capable of vegetative reproduction by budding were observed. The yeast _Hymphicia burtonii_ on the surface of the product also formed a characteristic powdery, white, spreading coating (Figure 2). In order to eliminate microscopic fungi from the surface of various types of baked goods packaged in MAP, several modifications were made to both the packaging and product preparation processes. Influence of the Composition of the Gas Mixture Used in MAP Technology and the Use of Ethanol on the Development of Microscopic Fungi in Bakery Products  
Microscopic fungal growth was observed in almost every type of baked good packaged in a modified atmosphere but without the addition of ethanol. The data collected in Table 6 indicate the day of contamination occurrence (first number in the column) and the number of contaminated samples (the digit after the slash). In most samples, there was visible growth of single, spotty, creamy-white yeast colonies, and in the case of hot dogs, there were also more extensive, often colorful colonies of molds. In ciabatta, these appeared after 7-9 days regardless of the type of gases contained in the packages. However, in the remaining types of products (both hot dogs and wheat kaiser rolls) packaged with 100% CO\({}_{2}\), the development of microscopic fungi was completely inhibited. In contrast, in packages with 70% CO\({}_{2}\)/30% N\({}_{2}\) and 100% N\({}_{2}\), the time at which the first infections appeared was 12-33 days. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Type of Bread**} & \multicolumn{2}{c}{**Gases in**} & \multicolumn{4}{c}{**Ethanol Concentration [\%]**} \\  & **Packaging** & **0** & **1.5** & **4.5** & **9.0** \\ \hline \multirow{3}{*}{Ciabatta} & 70\% CO\({}_{2}\)/30\% N\({}_{2}\) & 9/3 & 11/1 (16/3) & 49/0 & 49/0 \\  & 100\% CO\({}_{2}\) & 7/2 (9/3) & 49/0 & 49/0 & 49/0 \\  & 100\% N\({}_{2}\) & 7/3 & 17/1 & 49/0 & 49/0 \\ \hline \multirow{3}{*}{Wheat hot dog} & 70\% CO\({}_{2}\)/30\% N\({}_{2}\) & 25/1 (32/3) & 35/0 & 35/0 & 35/0 \\  & 100\% CO\({}_{2}\) & 35/0 & 35/0 & 35/0 & 35/0 \\  & 100\% N\({}_{2}\) & 12/1 (17/3) & 35/0 & 35/0 & 35/0 \\ \hline \multirow{3}{*}{Graham hot dog} & 70\% CO\({}_{2}\)/30\% N\({}_{2}\) & 26/1 (35/2) & 35/0 & 35/0 & 35/0 \\  & 100\% CO\({}_{2}\) & 35/0 & 35/0 & 35/0 & 35/0 \\  & 100\% N\({}_{2}\) & 12/1(14/3) & 35/0 & 35/0 & 35/0 \\ \hline \multirow{3}{*}{Wheat kaiser roll} & 70\% CO\({}_{2}\)/30\% N\({}_{2}\) & 20/1 & 23/2 & 35/0 & 35/0 \\  & 100\% CO\({}_{2}\) & 35/0 & 30/1 & 35/0 & 35/0 \\ \cline{1-1}  & 100\% N\({}_{2}\) & 33/1 & 35/0 & 35/0 & 35/0 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The occurrence of microscopic fungi on baked goods packed in different atmospheric conditions and ethanol concentrations during storage (day of the contamination occurrence/number of infected samples). Figure 2: Macroscopic observation of yeast growth on the ciabatta surface. Only the absence of infection in any sample was considered a positive result, as it reflects the level of acceptance adopted in industrial reality. The use of 100% CO\({}_{2}\) was effective in protecting the products, but severe packaging deformation was observed. Package collapse results from the decrease in gas volume due to CO\({}_{2}\) absorption. In addition, the oxygen concentration was checked in samples packaged without added ethanol. It was found that there were no exceedances of residual oxygen standards in the packaging. Its value was below 0.5%. The addition of ethanol at a concentration of 1.5% completely protected the hot dogs (wheat and graham) from microscopic fungal growth, in all three gas modifications. However, in the case of ciabatta as well as the wheat kaiser roll, there were single infected samples. Increasing the ethanol concentration to \(\geq\)4.5% contributed to the complete inhibition of microscopic fungal growth in all samples tested.