**1. Introduction**

Ice cream is a frozen milk-based dessert as a frozen aerated emulsion (O/W) containing partially combined fat globules, air bubbles, and ice crystals. Ice cream includes milk, milk cream, emulsifiers, sweeteners, stabilizers, and flavorings [1]. Ice cream generally contains high dairy or non-dairy fat (10–16%) [2,3]. As one of the most important ingredients in ice cream, milk fat interacts with other ingredients to improve texture, mouthfeel, creaminess, and overall sensation of lubricity [4]. Ice cream is a popular dessert, especially during hot weather, with an annual global consumption of around 2 L per person [5]. However, the demand for low-calorie foods has increased in recent years. Therefore, many studies have been carried out to develop new additives and new products in the food industry to meet this demand. In order to ensure the stability of ice cream, some special additives with stabilizer and emulsifier properties are required, and these additives are used in ice cream production.

**Citation:** Atik, I.; Tekin Cakmak, Z.H.; Avcı, E.; Karasu, S. The Effect of Cold Press Chia Seed Oil By-Products on the Rheological, Microstructural, Thermal, and Sensory Properties of Low-Fat Ice Cream. *Foods* **2021**, *10*, 2302. https://doi.org/10.3390/ foods10102302

Academic Editors: Marco Poiana, Francesco Caponio and Antonio Piga

Received: 21 August 2021 Accepted: 22 September 2021 Published: 28 September 2021

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Stabilizers are preferred in ice cream production because they provide specific and important functions such as increasing the viscosity and smoothness of the ice cream mix, improving aeration, reducing ice recrystallization, and the rate of structural collapse during melting [2,6]. Emulsifiers are substances that provide a fine dispersion of foods by reducing surface tension [7]. Emulsifiers minimize the formation of ice crystals by increasing the volume capacity of the ice cream and its resistance to melting. Stabilizers and emulsifiers also provide the ice cream with dryness and hardness, as well as a smooth structure and the desired oily feeling [8–10].

Chia (*Salvia hispanica* L.) seed, belonging to the *Lamiaceae* family, has a high amount of oil (25–38%), carbohydrates (26–41%), high dietary fiber (18–30%), and protein (19–23%) [11].Chia seeds have emulsifying and stabilizing properties due to their high protein content and water-soluble branching polysaccharides. They have the potential to be used as a natural emulsifier and stabilizer in many food compositions [12,13]. Researchers have studied the effect of chia seed gel mucilage on ice cream as a stabilizer and emulsifier [14–18]. In our study, different from these studies, a cold press oil by-product was used in the preparation of ice cream. In addition, in our study, the by-product ratio was determined under optimum conditions, and comprehensive properties such as rheological, microstructural, emulsion stability, thermal and sensory properties in the low-fat and high-fat control samples were analyzed in this study. It was also used for the first time in this study for 3-ITT analysis and thermal loop rheology of ice cream samples. Our research paper contains differences from other studies both in terms of material and analysis methods.

Fat substitutes can be used to reduce the amount of fat in foods and replace it with oil-like substances and reduce the caloric value with new additives. Fat substitutes can provide many of the properties that fat gives to foods and be classified as carbohydratederived fat substitutes, protein-derived fat substitutes, synthetic fat substitutes, and fat compound substitutes. When these substances are used instead of fat in foods, the fat in the food can be partially or completely reduced, and the energy from fat is minimized but provides palatable products [19]. Recently, cold-pressed oil industry by-products have also been used as fat substitutes [20–22]. Cold-press oil by-products such as cold-press oils include a high amount of protein, carbohydrate, fiber contents, and nutritive components without any solvent trace, and these by-products can be used as a natural fat replacer, emulsifier, stabilizer, and a natural antioxidant source in food emulsions [23,24].

Chia-seed by-products derived from the cold-press oil industry have the potential to be utilized as a building strengthener and fat replacer due to their ability to develop relatively viscous solutions. Furthermore, Capitani et al. [25] reported that the residual meal/by-product obtained from the oil-extracting process of chia seeds was determined as a good source of total dietary fiber, consisting mostly of insoluble dietary fiber. Therefore, chia seed by-products can improve food texture, utilize a role as texturing and stabilizing agen<sup>t</sup> due to high dietary fiber content. Akcicek and Karasu [20] used the cold-pressed chia seed oil by-products as a fat replacer in a low-fat salad dressing. However, chia seed oil byproducts as a fat replacer, stabilizer, and emulsifier in a low-fat ice-cream formulation have not been investigated. Many studies are present in the literature about the development of low-fat ice cream formulations [7,26–30].

The main purpose of this study is to produce ice cream with an optimum feature of low-fat content by using cold-pressed chia seed oil by-products without causing any change in the rheological and melting properties of ice cream. In this study, the optimization process was carried out based on the rheological analysis results of the ice creams produced with different formulations. The rheological and melting properties of the ice creams produced after the optimization process were investigated. Thus, production parameters with optimum rheological and melting properties were determined.
