**1. Introduction**

Sunflower is the fourth crop in the world for oil production after palm, soybean and rapeseed oil [1]. Sunflower meal is the main by-product of the sunflower oil production, representing up to 36% of the mass of the processed seed [2]. The protein content of sunflower seeds is about 20%, whereas the protein content of sunflower meal ranges from 30% to 50% [3]. In addition to protein, sunflower meal contains other valuable nutrients such as vitamins, minerals and polyphenols [2,4]. For this reason, although sunflower meal is mainly used as animal feed [5], it has potential for human consumption [6].

Sunflower meal has been upcycled into a versatile food-grade defatted sunflower seed powder (SUN) [7] with many potential food applications. Grasso et al. [8] showed that SUN has valuable technological properties, such as high water holding capacity. Total phenolic content and antioxidant capacity and nutritional improvements with the use of SUN in biscuits and muffins have recently been reported [8,9]. Nevertheless, the application of SUN in food from animal origin remains to be explored. The use of SUN in popular and highly consumed gel/emulsion meat products such as frankfurters is of particular interest because the SUN's reported technological properties and nutritional qualities could benefit these products formulations, obtaining healthier meat derivatives. Indeed, several meat products have been reformulated to be healthier using several strategies and ingredients to replace pork back fat [10–12]. Examples of animal fat replacements in frankfurters include the use of several plant-based ingredients (but also animal-derived ones such as collagen have been used), such as rye

bran and collagen [13], chia seeds [14], pineapple dietary fibres and water [15]. Other animal fat replacements used in meat matrices are mushrooms in pork sausages [16] and grape seed oil emulsified with gelatin and alginate in meat emulsions [17]. However, to the best of our knowledge, there are no studies available on the incorporation of sunflower by-products into popular meat products such as frankfurters.

In this context, this work examined the potential of SUN application as an animal fat replacer on the reformulation of healthier frankfurters. Nutritional composition, sensory acceptability, technological properties (processing loss, colour, pH and texture) and lipid structural characteristics (using ATR–FTIR spectroscopy) were evaluated.

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