# The Inactivation of Microscopic Fungi in Bakery Products Using Hurdle Technology--A Case Study
###### Abstract  
The issue of the microbiological spoilage of bakery products with an extended shelf life declared by the producer was the reason for searching for an effective solution. The aim of the investigation was to find the sources of infection, identify microorganisms causing product spoilage, and propose ways to eliminate the problem without the use of chemical preservatives in the product. It was found that the dominant contaminating microorganisms are yeasts of the genus _Hynbiophia_ sp., _Saccharomyces_ sp., and _Candidai_ spp., as well as molds--_Apergillus_ spp. and _Pentiillium_ spp. The microbiological quality of the production environment was assessed, and as a remedial action, a disinfection process was carried out. The influence of gas composition in MAP (modified atmosphere packaging) and the use of ethanol during packaging on the incidence of yeast or mold occurrence was checked. The effectiveness of using sourdough was also tested. The best results were achieved by using sourdough obtained with selected starter cultures and using a gas mixture for packaging in the proportion of 70% carbon dioxide and 30% nitrogen, without the addition of ethanol. These conditions ensured the expected shelf life of bakery products while maintaining their quality.  
bakery products; microscopic fungi; modified atmosphere packaging (MAP); starter cultures Article  
The Insumicroorganisms. These include innovative ways of packaging products or preservatives that prevent the growth of bacteria, mold, and yeast. In the case of packaging, it is possible to use the already mentioned modified atmosphere, where inert gases like CO\({}_{2}\) or N\({}_{2}\) are used [3,4]. However, the use of synthetic chemicals is currently poorly perceived by consumers due to the \"clean label\" market trend. The lack of consumer acceptance of synthetic additives is forcing manufacturers to use alternatives that will meet the relevant technological functions as well as market requirements. One possible solution is the use of natural additives in the form of essential oils, plant extracts, and starter cultures containing lactic acid bacteria [5, 6, 7, 8, 9, 10].  
In the process of food preservation, a single agent is often used, the dosage of which most often exceeds the required level. Increasingly, hurdle technology is being used, where several preserving agents are applied. By doing so, it is possible to achieve a higher level of food safety and at the same time better quality despite the use of lower quantities of preservative agents [11].  
The microbiological quality of food is also greatly influenced by the production environment, such as surfaces, air, substrates used, and personnel. Although bread is free from microorganisms after baking, contamination is possible during the process of packaging, storage, or transportation [12,13]. One possible solution is to use cooling spirals with air handling units equipped with HEPA filters and a cleaning-in-place (CIP) system. To further protect the product, carbon dioxide can be injected into the coils. In further processing, packaging rooms can be designed to meet \"clean room\" requirements and be equipped with airlocks for workers. Such a room layout works best for long-run production. At the company under review, 30 different products are packed in the MAP packing room. Mainly, there is a hot dog, which is subjected to freezing during one of the stages of the production process. Such a production scheme precludes the use of technology in which the product is transported directly to the packing room after baking.  
The aim of the research was to determine the sources of microbial contamination occurring in baked goods produced using HB technology and MAP packaging, identify spoilage microorganisms and search for solutions aimed at microbiological protection of the products meeting the expectations of customers reluctant to use chemical preservatives.