**2. Materials and methods**

#### **2.1 Sample preparation**

Fresh Chinese Chestnuts were collected from the local market of Nainital, Uttarakhand, India. The chestnuts were first washed to eliminate any dust or fine particles. They were then sun dried for 3–4 days at 32°C. The ingredient's shelf life was extended by drying as there was no water activity and no moisture present. The flaxseeds were purchased from the local store in the city of Bazpur, Uttarakhand, India. After dry roasted, they were later ground into powder. The chocolate compound bar was bought from the local market of Lucknow city of Uttar Pradesh, India.

**Figure 5.** *Preparation of mix.*

The chocolate compound was tempered at 42°C for further use in the process of product development. To eliminate variations in their composition and avoid quality differences, the procurement was completed in a single lot. In **Figure 5**, the stages of product development are shown.
