**1. Introduction**

Bakery products are staple foods, widely consumed in large quantities worldwide, with an important role in human nutrition [1]. Due to the increased awareness of health issues, the bakery industry is moving to provide functional and healthy foods, mainly via fortification with satiating and active ingredients, such as proteins, fibres, minerals, vitamins, and bioactive peptides [2] in response to an increasingly demanding consumer.

The incorporation of ingredients that exhibit functional properties, in addition to traditional nutrients, is an interesting alternative to the development of innovative bakery foods. Brazilian bread cheese is known worldwide, but the incorporation of dairy products (such as yogurt and curd cheese) in bread formulations is not common in the bakery markets.

Nutritional benefits of dairy products (DP) include increasing the amount of minerals with good assimilability (mainly Ca and P), vitamins (A and B12), protein, and essential amino acids (lysine, methionine, and tryptophan). Technology benefits may also be considered and can include improvement of dough handling properties and bread quality (flavour, crumb structure, and texture). These benefits result from the effect of protein and milk fat on the bread structure [3].

Good nutrition, especially adequate, easily digestible protein and mineral intake, is a determinant factor for the human health. Protein and minerals are considered key nutritional components in a well-balanced diet with an important contribution to maintain muscle mass and bone structure [4]. Some studies have reported the technological properties of dairy products as potential ingredients into a wide variety of products [5], such as infant formulas [6], that could aid in achieving dietary requirements for children and seniors.

Yoghurt (Yg) is a fermented milk product that consists of a casein network formed at the isoelectric point [7], being the acid obtained by the activity of the specific lactic acid bacteria (LAB), *Streptococcus thermophilus* and *Lactobacillus delbrueckii ssp. bulgaricus* cultures. Yg is considered the most popular dairy product worldwide for its nutritional and health benefits, since it is a rich source of protein (casein), vitamins (B2, B6, and B12), and minerals (such as Ca, P, and K), and contributes to good microbiota. This product is a potential ingredient for bakeries, representing an interesting alternative for new bakery products [8], and can be incorporated into bread formulations as a fresh product.

Curd cheese (Cc) is a co-product obtained by the thermal denaturation and subsequent precipitation of the soluble whey proteins. These products are considered to have a high protein nutritional value, representing of 20–30% of the proteins present in bovine milk. This complex mixture of globular protein molecules (α-lactalbumin and β-lactoglobulin) presents a higher protein efficiency ratio than wheat proteins [9] and is considered to be an important source of essential amino acids (leucine, isoleucine, and valine). Previous work has shown significant increments in protein, ash, and mineral contents (Ca, K, Mg, and P) in bread with whey protein concentrate [10]. However, some authors reported that whey protein exerted some negative effects on bread quality by depressing the loaf volume and increasing the crumb firmness [11].

The aim of the present study was to evaluate the influence of yoghurt and curd cheese addition as potential ingredients for the design of new bread formulations and assess their effect on wheat dough (WD) rheology and bread quality, as well as the aging kinetics and nutritional profile.

Different contents of yoghurt and curd cheese were added to wheat flour dough, and the impact on dough rheology was assessed by small amplitude oscillatory measurements (SAOS) and extension properties. Dough microstructure was also evaluated. The breads produced were also characterized in terms of microstructure, texture profile, and shelf life. Sensory analysis was performed to evaluate the acceptability of the developed breads. The maximum addition of each dairy product was discussed in terms of the potential applications for the market.
