# The Inactivation of Microscopic Fungi in Bakery Products Using Hurdle Technology--A Case Study
## 4 Discussion
Among the genera that contaminate bread, the following are listed: _Alternaria_ and _Cidosporium_--often found in the air, _Aspergillus_ and _Penicillium_--so-called storage molds, and _Rhizopus_, _Mucor_, or _Geotrichum_. One of the most common species is _Rhizopus stolonifer_, called \"bread mold\" [13; 19; 22; 23; 24]. In the work presented herein, among the isolated strains of mold, two genera predominated--_Aspergillus_ and _Penicillium_--which are also mentioned by other authors [25; 26; 27] as the main cause of bread spoilage. Various types of yeast were also identified in the analyzed samples. In the not-fully-thawed MAP-packaged products, high condensation of moisture in the packaging was observed. This contributed to a very intensive development of yeast forming white, rather extensive colonies macroscopically similar to mold, which were identified as _Hypophichia burtoni_. According to [PERSON] and [PERSON] [28], this yeast is capable of developing at low \(\mathrm{a_{w}}\) = 0.85, where it forms white or pink spots on the surface of products. It is a species that is very often isolated from baked goods and can rapidly multiply to form a pseudomycelium. Together with _Pichia anomala_ and _Saccharomyces fibuligera_, they cause spoilage of pre-baked, MAP-packed baked goods, which is known as \"chalk mold\" [29; 30]. As [PERSON] (2015) [31] points out, modified atmosphere packaging can extend the shelf life of bakery products but is ineffective against spoilage by chalk mold. In the presented work, two species of _C. guillermondii_ and _C. parapysilosis_, which are known as potential human pathogens, were also isolated from the surface of the examined samples. So-called non-albicans _Candida_ have recently found increasing interest as a growing cause of infection [32]. Although not considered a source of foodborne infection, both isolated species were found in more than 20% of bread samples collected in Europe [28]. Unlike mold, where the risks associated with mycotoxin production are known, the health significance of yeast-contaminated foods is not well recognized. However, there are some reports indicating that the above-mentioned yeast species can also cause disease in humans [33]. The use of half-baking technology in combination with MAP packaging technology makes it possible to effectively extend the shelf life of baked goods, which improves the economics of production. However, a limiting factor in the shelf life of such semi-bakedproducts is their susceptibility to the occurrence of microbial infections, mainly related to the growth of microscopic fungi. Three different modifications of the gas composition were used in the study. The best results were achieved for packages containing only CO\({}_{2}\), where fungal growth was observed only on ciabatta. However, this resulted in the collapse of the packaging and ultimately the shrinking of the foil around the products. Therefore, it is necessary to add nitrogen, which has a filling function in the packaging. The effectiveness of carbon dioxide in MAP-packaged bakery products was confirmed by [PERSON] et al. (2003) [PERSON] et al. (2003), who observed no mold growth after 28 days of storing samples at 25 \({}^{\circ}\)C. The gas acts as a fungistatic agent by inhibiting metabolism and disrupting enzymatic activity and can also react with proteins [1]. In the other two variants, where a mixture of 70% CO\({}_{2}\)/30% N\({}_{2}\) or 100% N\({}_{2}\) was used, infected samples were present in all types of products. [PERSON] et al. (2002) [PERSON] et al. (2002) conclude that the use of MAP technology to extend the shelf life of baked goods has some drawbacks. According to them, the highly porous structure does not allow for the complete elimination of oxygen and its migration from the product to the package; therefore, the oxygen concentration may increase in the package. Meanwhile, the results obtained in the course of repeated tests several times contradict the described results. They did not confirm the migration of oxygen from the product into the package.