Process Development and Characteristics of Biocalcium from Skipjack Tuna (Katsuwonus pelamis) Eyeball Scleral Cartilage

Abstract

Scleral cartilage biocalcium (SCBC) powder from skipjack tuna (Katsuwonus pelamis) eyeball scleral cartilage (STESC) was produced using hexane and isopropanol (1:1) for defatting, followed by protein removal using alcalase at different concentrations (1.5-4.5%) for various times (0-180 min). Calcined scleral cartilage (CSC) was also prepared and characterized. The lowest fat remaining in STESC was attained after 6 cycles of defatting (P < 0.05). The use of 1.5% alcalase for 90 min resulted in the highest soluble protein removed, while showed the lowest loss in hydroxyproline. Higher value of calcium (39.90%), phosphorus (18.97%) and L* (87.97) were detected in the CSC powder, compared to SCBC powder (23.28%, 10.99% and 81.77, respectively) (P < 0.05). However, a*, b*, and ∆E* of CSC powder were lower than SCBC counterpart. The mean particle sizes of both powders had a negligible difference (P > 0.05). XRD-diffractogram of both powders con rmed the presence of hydroxyapatite. CSC showed the loss of water, amide I, II, III, and other organic functional group peaks in Fourier transform infrared spectra. Also, smaller number and abundance of volatile compounds were found in CSC powder. STESC showed a higher calcium solubility in gastrointestinal tract than CSC (P < 0.05). Therefore, scleral cartilage of tuna eyeball could be used as an alternative source for producing biocalcium. Statement Of NoveltyThis is the rst report on biocalcium from skipjack tuna eyeball scleral cartilage. Simple process including pretreatment using mixed solvents for defatting and enzymatic hydrolysis for protein removal was successfully developed.

Chemical Compositions and Characteristics of Biocalcium from Pre-Cooked Tuna Bone as Influenced by Sodium Chloride Pretreatment and Defatting by Asian Seabass Lipase

“…Lightness (L*), redness/greenness (a*), and yellowness/blueness (b*) were recorded. The differences in color (∆E*) were also computed [10].…”

“…A scanning electron microscope (SEM) equipped with an electron-dispersive X-ray spectroscope (EDX) (SEM-EDX) (X-Max80; Oxford, UK) was used [10]. The samples were coated with gold and determined with the secondary electron mode at a 20 kV accelerating voltage.…”

“…Those bones are rich in calcium (41.2-49.2%) and collagen [9]. Several processing methods, including non-collagenous protein removal, fat removal, bleaching, softening, drying, and grinding, have been developed [4,10]. Alkaline pretreatment with a 2 M NaOH solution (50 • C, 30 min) is generally employed for non-collagenous protein removal [4].…”

“…This process is effective for the removal of remaining meat and blood in pre-cooked tuna bone. For fat removal or defatting processes, various solvents such as hexane, isopropanol and their mixture are applied, followed by evaporation to obtain defatted bone with less or no fat [4,10].…”

“…Increasing sodium chloride concentration enhances the repulsive force between the protein molecules, leading to augmented protein solubilization [11]. Furthermore, fish bone also contains fats or lipids, which can oxidize and develop an undesirable odor/flavor, especially a fishy odor in biocalcium [4,10]. A defatting process with lipase from fish viscera is a potential alternative for fat removal from fish bone.…”