## 1 Introduction  
Bread and other bakery products are important diet components in many parts of the world. The baking mainly uses white wheat flour obtained after removing wheat (_Tritcium aestivum_ L.) bran and germ, which are sources of fibre, phytochemicals, and important nutrients. Because of this, the final product contains less dietary fibre and phenolic compounds. Foods enriched with natural antioxidants are being developed to recompense for this loss. Functional foods consumed as part of a regular diet provide biologically active ingredients that provide health benefits [1]. Unfortunately, bread is a perishable food that goes through physical, chemical, sensory, and microbiological changes during storage. One of the biggest problems in baking is the growth of toxigenic fungi, mainly from the genera _A Aspergillus_ and _Penicillium_[2]. The growth of fungi leads to quality changes in food, but it can also have negative health effects, as some of these microorganisms produce mycotoxins. They are a public health problem due to their widespread occurrence in the world's food supply [3]. To avoid spoilage of food products by fungi, preservatives are used. However, they have some disadvantages, including altering the aftertaste of light flour products, delaying dough fermentation [4], and not being inert to the consumer. There are reports in the literature of the occurrence of urticaria and contact dermatitis after consuming products with sorbic acid, which is approved for preserving bread [5]. In addition, chemical preservatives are ineffective against some common fungal species in bread, such as _Penicillium paneum_ and _P. roqueforti_[2].  
The threat to food health safety posed by the presence of toxigenic fungi and the demand for natural products has prompted the search for new methods of preserving baked goods and eliminating harmful microorganisms and their metabolites. There is great interest in natural ingredients with multifunctional properties with potential uses in food production. Plant extracts have been widely studied as potential biopreservatives, as plants contain many important antimicrobial compounds, including phenolic compounds, glucosinolates, alkaloids, cyanogenic glycosides, and oxylipins [6; 7].  
In this context, _Calendula officinalis_ (common marigold), a member of the _Asteraceae_ family, is a valuable product with rich medicinal and functional properties. Many secondary metabolites are responsible for the biological activity of marigolds, such as flavonoids, triterpenoids, and polyphenols, found mainly in flower extract [8; 9]. These compounds are responsible for antioxidant activity, exhibit neuroprotective effects, prevent degenerative diseases such as diabetes and cardiovascular diseases, and have anticancer, anti-inflammatory, and antimicrobial effects [10]. Extracts from _Calendula officinalis_ petals have proven antimicrobial activity against many pathogens, including _Pseudomonas aeruginosa_, _Staphylococcus aureus_[11], _Escherichia coli_, _Bacillus subtilis_, _Klebsiella aerogenes_, _Enterococcus faecalis_, _Candida albicans_, _C. glabrata_, _Aspergillus flavus_, _A. fumigatus_, and _A. niger_[12].  
Reports from other researchers indicate that, depending on the plant species, the best solvents for extracting bioactive compounds are acetone, ethanol, and methanol [13; 14]. However, according to current trends, analytical procedures should strive to be minimal, as simple as possible to perform, low-cost, and environmentally friendly. Therefore, the study presented in this paper decided to use deionized water as a solvent to extract bioactive compounds from marigolds. Water extract preparation is a relatively easy and inexpensive process, which is important from the consumer's point of view.  
This study aimed to evaluate the fungistatic properties of the _Calendula officinalis_ water extract against fungi _Aspergillus niger_ and _Penicillium_ sp. and to determine the effect of extract addition on the quality of wheat bread.