This study was aimed to investigate the potential use of pre-treated cuttlebone powder (CBP) as an alternative calcium source by evaluating the physicochemical properties of CBP pre-treated with distilled water (CBP1), 1% acetic acid (CBP2), and 2% sodium hydroxide (NaOH) solutions (CBP3). Proximate analysis revealed ash as the major component of all samples. The presence of phenols, flavonoids, alkaloids, and glycosides were detected but tannins appeared to be absent in cuttlebones. Mineral analysis indicated that CBP was rich in calcium, which means the material may be considered as a potential calcium source for food products or calcium supplements. The bulk density of CBP2 was significantly lower (p < .05) than those of CBP1 and CBP3, and the water holding capacity (WHC) of CBP1 was significantly higher (p < .05) than those of CBP2 and CBP3. The high bulk density, water and oil holding capacities of CBP demonstrated its potential use as a functional food ingredient. K E Y W O R D Salternative calcium, bioactive compounds, pre-treated cuttlebone powder 2 of 14 | HUEY Et al.51.8% of urban Malaysian postmenopausal women suffer from osteoporosis (Khan et al., 2014). A number of diseases, such as growth disorder in children and osteoporosis in adults, are common health problems related to calcium deficiency and the inability of the body to absorb calcium (Asikin et al., 2019). According to the Ministry of Health and Malaysia (MOH) (2017), the recommended nutrient intake (RNI) of calcium for Malaysian adult males aged 20-59 years and females aged 20-49 years is 1,000 mg/day.The food industry produces large volumes of wastes as a result of the production, preparation, and consumption of food (Aschemann-Witzel et al., 2015). Food waste may result in significant economic losses and pollution problems (Aschemann-Witzel et al., 2015).According to Food and Agriculture Organization (FAO) ( 2019), the catches of cuttlefishes have been ranging from 11,000 to 15,000 tons for each year throughout the world. The cuttlebones are usually discarded as processing waste materials by the food industry and household (Fatimah Zaharah & Rabeta, 2018). Hence, the cheap and readily available cuttlebones by-products in the fisheries and aquaculture industries provide the opportunity for the more effective utilization of cuttlebones as a valuable product due to their potentially high source of calcium. Information on the physicochemical properties of cuttlebones is lacking. Diaz et al. (2015) revealed that the methanolic extracts of squid and cuttlefish bone powder exhibit anticancer activity against HepG2 liver cancer cells. Thus, the research of the chemical composition and functional properties of cuttlebones may provide information to consumers about the nutritional values of cuttlebone and maximize the application of cuttlebones as a potential functional food ingredient. | MATERIAL S AND ME THODS | MaterialsCuttlefish (Sepia latimanus) was purchased from a wet market at Gelugor, Penang. The samples were stored in an ice box to preserv...