Development and Characterization of Chicken Eggshell-Derived Untreated and Treated-Biogenic Hydroxyapatite-Fortified Candy and Consumer Acceptance by Using the Just-About-Right Method

This study focused on producing chicken eggshell-derived hydroxyapatite (HAp) from local bakeries in Rawalpindi, Pakistan, following a series of cleaning steps, including membrane removal, alkaline treatment, washing, crushing, sieving, calcination (1000 °C), and ultrasonication to get untreated (raw) and treated-biogenic (subjected to calcination and ultrasonication) HAps. FTIR spectra showed PO43– peaks at 875 and 714 cm–1 (treated-biogenic) and 755 cm–1 (untreated) HAps. AAS showed calcium content ranging from 97.27 ± 1.13 ppm (untreated) to 140.5 ± 0.09 ppm (treated-biogenic) HAps. Particle size was observed at the 442 nm peak in untreated, whereas the peaks were at 58.5 and 255 nm in treated-biogenic HAp. SEM analysis revealed a smooth layer of HAp crystal lattice in both samples, whereas XRD confirmed crystalline behavior at 2θ. In addition, both untreated and treated-biogenic HAps with different concentrations (0, 0.2, 0.4, and 0.5%) were incorporated into seven candy formulations with codes (C, C1, C2, C3, C4, C5, and C6). The absence of Salmonella was reported in both HAps. The candy’s hardness increased as HAp concentration increased. Further, the highest mean scores of appearance and taste were observed at 7.76 and 7.70 in C1. However, C2 recorded aroma (7.98), aftertaste (8.07), and mouthfeel (7.66) mean scores when compared with the control. The C4 formulation showed the highest acceptability in terms of appearance (7.46 ± 0.13) when using untreated HAp; however, this level of acceptability was still lower when compared to the C2 formulation (7.75 ± 0.46). Using JAR scales, consumer responses (%) investigated the penalties and mean drop of the candies with Spearman’s correlation of each attribute. Also, a diagnostic chart of penalty analysis of each formulation was displayed.