**1. Introduction**

Meat and meat products have excellent nutritional properties, being sources of protein, fat, essential amino acids, minerals and vitamins [1,2]. However, due to its higher lipid profile and sodium content, apart from other contaminants present after obtaining and processing, meat consumption has lately been connected to the development of different diseases around the world, mainly diabetes, obesity, cardiovascular problems and cancer [3]. Therefore, the increasing demand for healthier meat products has driven to the meat industry and scientific community to look for new meat products with less fat and salt content, with dietary fiber addition, and even probiotics inclusion, or natural antioxidants and vegetable proteins addition [4–6].

The reduction of fat or salt and substitution by other vegetable sources or ingredients to improve the functional and nutritional properties has been widely tested in emulsified sausages like frankfurters considering these sausages may contain up to 30% pork fat, 40% of which is saturated fatty acids [7,8]. However, since they are highly demanded and consumed, maintaining the sensory quality in the improvement of nutritional value is essential [9].

In this sense, di fferent oil sources like olive, canola, linseed and fish oil as well as cereal and seed fibers (rice, chia, linseed) or vegetables, legumes and fruits, even algae, have been included in frankfurters considering the nutritional properties but also the technological issues associated to the emulsion formation [10–16]. One alternative to improve the nutritional profile of meat products could be the edible mushrooms since they have been reported to be a rich source of essential nutrients, with a high content in protein (16.47–36.96%), low level of lipids, and high dietary fiber content (24.4–46.62% in dry weight, DW) [17]. Because of their interesting flavor, medicinal and quality nutritional aspects, they have been used as food supplement to prevent malnutrition [18]. Apart from that, the strong umami taste of mushroom often referred to as a meaty taste [19,20] could contribute to reduce the salt content in meat formulations [21].

Moreover, cultivation of edible mushrooms is an easily and economically viable process, due to their ability to grow on di fferent wastes such as cereal, cotton, fruit, vegetable, sawdust and leaf [22]. Several successful attempts to use mushroom flour in some bakery products have been reported [23–25] but less information is available about its incorporation in meat products with di fferent results [8,26]. Due to the above reasons, mushrooms could be considered a promising naturally functional ingredient to improve nutritional quality of meat products, being *Agaricus bisporus* (Ab; champignon) and *Pleurotus ostreatus* (Po; oyster mushroom) the most worldwide cultivated species [27]. The aim of this investigation was evaluate the e ffect of partial replacement of fat and salt by addition of edible mushroom (Ab and Po) flour in frankfurter type sausages on the physicochemical, microbiological and sensorial parameters during cold storage.

#### **2. Materials and Methods**
