# Plant-Origin Additives from _Boswellia_ Species in Emulgel Formulation for Radiotherapy Skin Care
## 4 Discussion
### Correlation Matrix of Instrumental Analysis Results and Sensory Analysis  
The use of sensory analysis to determine not only the maximum concentration but also the impact of the addition of plant extracts on the sensory characteristics of a product--while maintaining its antioxidant properties without deteriorating these characteristics, which as important for consumers--is being studied in the food industry [54; 55]. This is due to the fact that plant extracts, especially those rich in phenolic compounds, may have taste, color, and odor, and all such aspects should be taken into consideration prior to any use in the formulation of foods. In the case of cosmetic and pharmaceutical preparations, sensory characteristics such as smell, consistency, spreadability, and greeiness after application are important to consumers, especially for people with skin diseases or injuries [32; 35]. When it comes to assessing the antioxidant capacity of topical preparations containing plant extracts in their formulations, the authors approach the issue in two ways. The first method involves evaluating the extracts and the prepared formulations separately. The extracts are analyzed for their antioxidant capacity (usually via the DPPH or FRAP method), and their chemical composition is determined. The release of phenolic compounds from the gel matrix is also studied [56]. For the formulations, however, in vivo tests on probands are carried out, which include instrumental tests on the skin concerning skin melanin level, skin erythema, skin moisture content, skin sebum content, and skin elasticity [57]. The second method involves the assessment of the antioxidant potential of extracts and formulations using the same in vitro methods, although this approach is less popular in the literature. An example of such research is the work of [PERSON] et al. [43], where emulsions containing plant extracts for antioxidant activity tests were diluted 1:2.5 in a suitable buffer for each assay. All diluted formulations were mixed for 20 min prior to the measurements of their antioxidant activity. In this research, the second approach was used, i.e., the assessment of antioxidant properties for both plant raw materials and formulations. For the emulsions and emulsgels, the in vitro method of obtaining filtrates proposed in studies of bigels [38] containing _Centella asatica_ was used. Additionally, an attempt to correlate the impact of plant-origin additives on the product functional properties determined via instrumental methods with the sensory characteristics determined in the sensory analysis was made. In addition to the basic physicochemical characteristics, the analyzed functional properties included those regarding the effectiveness of the preparation as a potential product in post-radiotherapy skin care, i.e., % inhibition and the content of polyphenols in the formulation composition. The obtained results are presented in the form of a correlation matrix in Table 5.  
The presence of an essential oil and/or a select CO\({}_{2}\) extract rich in volatile ingredients (such terpenids, as well as aliphatic octyl acetate [44]) in the formulation influences the product's odor, which is correlated with hydration (correlation coefficient 0.625 \(p\geq 0.1\)) and spreadability (correlation coefficient 0.760 \(p\geq 0.05\)). The literature data [30; 44] indicate the presence of moisturizing ingredients such as polysaccharides, proteins, and boswellic acids, which help maintain the proper level of hydration. _Boswellia_ species also have a proven anti-inflammatory effect, which affects the condition of dry, irritated skin, and skin with dermatoses [58]. In addition, it has been reported that _Boswellia_ can be an effective topical agent with which to soften facial lines and relax the skin [59]. However, in the case of the correlation between odor and spreadability, it can be presumed that the probands spread the formulation with an intense odor faster more effectively and also more willingly. The odor dissipates faster during vigorous movements.