Protein hydrolysates from two forms of salmon frames named “chunk” and “mince” were produced and characterized. Both samples were subjected to hydrolysis using alcalase and papain at 1%–3% (w/w protein) for 0–240 min. Hydrolysate prepared with either protease at 3% for 180 min had the solid yield of 24.05%–26.39%. Hydrolysates contained 79.20%–82.01% proteins, 6.03%–6.34% fat, 9.81%–11.09% ash, and 4.02%–5.80% moisture. Amino acid profile showed that all hydrolysates had glutamic acid/glutamine (113.45–117.56 mg/g sample), glycine (77.86–86.18 mg/g sample), aspartic acid/asparagine (76.04–78.67 mg/g sample), lysine (61.97–65.99 mg/g sample), and leucine (54.30–57.31 mg/g sample) as the predominant amino acids. The size distributions determined by gel filtration chromatography varied, depending on proteases and the form of frame used for the hydrolysis. Different hydrolysates showed varying antioxidant capacities. Thus, protein hydrolysates from salmon frame could be used as a nutritive supplement in the protein deficient foods. Practical applications Frames of salmon are by‐products from salmon fish processing industries. The frames contained the remaining meat, hence they can be used for the preparation of protein hydrolysates. Generally, hydrolysates from fish by‐products have been regarded as a promising food supplement, because they are rich in amino acids. Additionally, hydrolysates possess antioxidant activity, which is of health benefit. To produce the hydrolysate with less time consumption, the use of frame chunk instead of minced frame can be of better choice. Thus, frame of salmon, especially in chunk form, could be used as a raw material for production of protein hydrolysate using alcalase. The hydrolysate produced from salmon frame could serve as an alternative nutritive supplement to tackle the nutrition inadequacies in foods.

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Alkaline treatment has been extensively implemented in the extraction process of hydroxyapatite (HAp) extraction from various kinds of bio-materials, such as animal bone and scales. The main purpose of such treatment is to remove proteinaceous substances from raw materials. The influence of the alkaline treatment that could alter not only the organic contents but also chemical composition—specifically the Ca/P mole ratios of bio-calcium, HAp, and the biphasic apatite powders derived from salmon bone, a by-product from the salmon industry—was investigated. Both HAp and biphasic apatite powders were obtained from the calcination of bio-calcium powders with and without alkaline treatment, respectively. An X-ray diffraction analysis confirmed the presence of hydroxyapatite and β-tricalcium phosphate (β-TCP) in the calcined bone powder without alkaline treatment while only a single phase of hydroxyapatite was observed in the alkaline-treated sample. Calcium and phosphorus contents were measured by an inductively coupled plasma optical emission spectrometer (ICP-OES). A variation of Ca/P ratios was observed among all samples, depending on the chemical and heat treatment conditions. Organic molecules, such as protein, fat, hydroxyproline, and TBARS, were significantly lowered in bio-calcium powders with the alkaline treatment. This work represents important research on chemical treatment prior to the raw material conversion process, which significantly influences chemical and phase compositions of the bio-calcium and hydroxyapatite powder derived from salmon bone waste.

Biocalcium (BC) powder from the bones of precooked skipjack tuna was produced and characterized, compared to calcined bone (CB) powder. Higher calcium (40.35%) and phosphorous (15.28%) contents were found in the CB powder, compared to BC powder (26.91 and 12.63%, respectively). Nevertheless, similar Ca/P ratio was observed (1.62–1.65). Mean particle sizes of both powders were 17.07–20.29 µm. BC powder had higher b* (yellowness) with slightly lower L* (lightness) values than the CB counterpart (p < .05). Both samples showed a characteristic peak of hydroxyapatite in X‐ray diffraction patterns, in which the crystallinities of the BC and CB powders were 45.19 and 74.69%, respectively. Amides I, II, and III peaks in Fourier transform infrared spectrum, hydroxyproline, and protein were detected only in the BC powder. BC powder had a low abundance of volatile compounds, including aldehydes, alcohols, and ketones. A negligible amount of volatiles was found in the CB powder. Practical applications Calcium supplementation has been increasingly used to alleviate the lack of calcium in the human body, particularly inadequate levels of calcium and poor absorption. Calcium associated with peptides or biocalcium (BC) has a higher advantage in terms of absorption than calcium alone. Precooked skipjack tuna is considered a promising source for BC production due to its abundance. BC with improved color and odor along with increased solubility in gastrointestinal tract can be used as an alternative calcium supplement to tackle the inadequate intake of dietary calcium.