Gyoon-Woo Lee’s research while affiliated with Gyeongsang National University and other places

Four roe protein isolates (RPIs) from skipjack tuna were prepared using isoelectric solubilization (pH 11 and 12) and precipitation (pH 4.5 and 5.5) (ISP) at different pH points to evaluate their physicochemical and functional properties and in vitro bioactivities. Moisture (<6.3%) and protein (71%–77%) content were maintained. Sulfur, sodium, phosphorus, and potassium were the major elements, and glutamic acid and leucine were the prevalent amino acids (12.2–12.8 and 9.6–9.8 g/100 g protein, respectively) in RPIs. RPI-1 showed the highest buffering capacity at pH 7–12. RPIs and casein showed similar water-holding capacities. At pH 12, RPI-1(pH 11/4.5) showed the highest solubility, followed by RPI-3(pH 12/4.5), RPI-2(pH 11/5.5), and RPI-4(pH 12/5.5) (p < .05). Oil-in-water emulsifying activity indices of RPI-1 and RPI-3 significantly differed. At pH 2 and 7–12, pH-shift treatment improved the food functionality of RPIs, which was superior to positive controls (casein and hemoglobin). RPI-1 showed ABTS+ radical scavenging (102.7 μg/ml) and angiotensin-converting enzyme inhibitory activities (44.0%).

The objective of this study was to investigate physicochemical properties of protein concentrate from skipjack tuna roe by a cook‐dried (boiled or steamed‐dried) process, and to evaluate their food functional properties. The yields of boil‐dried concentrate (BDC) and steam‐dried concentrate (SDC) prepared from skipjack tuna roe were 22.4 for BDC and 24.4% for SDC. Their protein yields were 16.8 and 18.4%, respectively. In terms of major minerals of the BDC and SDC, sulfur (853.2 and 816.6 mg/100 g) exhibited the highest levels followed by potassium, sodium and phosphorus. The prominent amino acids of roe protein concentrates (RPCs) were Glu, Asp, Leu and Val. The BDC and SDC showed a higher buffer capacity than egg white (EW) at the pH‐shift range. The pH‐shift treatment significantly improved the water holding capacities of RPCs, except pH 6. But they had a low solubility across the pH‐shift range. The foaming capacities (104%–119%) of BDC and SDC were significantly lower than those of EW (p < .05), and their foam stabilities were not observed. Emulsifying activity index (m²/g protein) of RPCs and EW was 2.3 for BDC, 11.1 for SDC and 18.0 for EW. RPCs in the food and seafood processing industries will be available as egg white alternative protein sources and will be available as ingredients of surimi‐based products in particular.

This study evaluated the protein recovery, functional properties and biological activity of isolate processed water (IPW) generated in the preparation of protein isolates from fish roes (BH, bastard halibut Paralichthys olivaceus; ST, skipjack tuna Katsuwonus pelamis; YT, yellowfin tuna Thunnus albacares) by an isoelectric solubilization and precipitation process. The IPWs contained 2.7-5.4 mg/mL of protein, and the protein losses were 8-21% (P<0.05). The form capacity of IPW-3 for BH and ST, and IPW-4 for YT was 155, 194, and 164%, respectively. The emulsifying activity index (27-43 m2/g) of the YT-IPWs was the strongest, followed by ST (7-29 m2/g) and BH (10-19 m2/g). The 2,2-diphenyl-1-picrylhydrazyl scavenging activities of IPW-1 and -3 were higher than those of IPW-2 and -4. The 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid scavenging activity (IC50, mg/mL) of IPW-2 and -4 was 0.03 mg/mL for BH, 0.04-0.08 mg/mL for ST, and 0.04-0.07 mg/mL for YT. BH IPW-3 had the strongest reducing power (0.41 mg/mL) and superoxide dismutase-like activity (1.68 mg/mL). The angiotensin-I converting enzyme inhibitory activity of IPW-3 was the highest for ST (1.52 mg/mL), followed by BH and YT. The common predominant amino acids in the IPWs were the essential amino acids Val, Leu, Lys, and Arg and the non-essential amino acids Ser, Glu, and Ala.

This study evaluated the protein recovery and functional properties and biological activity of boiled and steamed process water (BPW and SPW, respectively) generated from the preparation of concentrated roe of bastard halibut (BH; Paralichthys olivaceus), skipjack tuna (ST; Katsuwonus pelamis), and yellowfin tuna (YT; Thunnus albacares) using the cook-dry process. The protein loss from the water extracts (EXT) of 100 g of roe protein was 15.05-19.71% and was significantly (P<0.05) higher than that of BPW (5.47-10.34%) and SPW (3.88-8.18%). The foam capacity of BPW (166-203%) and SPW (15-194%) was better than that of EXT. The emulsifying activity index of the original samples was lower than those (15.40-107.86 m2/g) of diluted protein samples. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and the reducing power of BPW and SPW were stronger than those of EXT. The 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) radical scavenging activity of EXT (0.028-0.045mg/mL) was significantly higher those of BPW and SPW. The angiotensin I-converting enzyme (ACE) inhibitory activity of SPW was the highest for BH (1.04 mg/mL), followed by YT and ST. The predominant amino acids in SPW were Glu, Ala, Leu, and His. These results demonstrate that processing water containing diluted organic components, including protein, can be consumed directly by humans as a functional reinforcing material after appropriate concentration processes.

Three kinds of roe protein concentrates (RPCs: boil-dried concentrate, BDC; steam-dried concentrate, SDC; freeze-dried concentrate, FDC) were prepared from yellowfin tuna to produce value added products for food applications. The buffer capacities of the RPCs were higher under alkaline than under acidic conditions. The water holding capacities of the RPCs were in range 4.5–4.7 g/g protein at pH 6.0. The protein solubility of the FDC (14.2%) was higher than those of the BDC (5.4%) and SDC (5.5%) at pH 6.0. The foaming capacity of the FDC (156.8%) was higher than those of the BDC (109.7%) and SDC (109.4%); the FDC foam was stable for 60 min. The oil-in-water emulsifying activity index of the FDC (12.2m2/g protein) exceeded those of the BDC and SDC (2.2m2/g protein). Protein concentrates from yellowfin tuna roe may be useful as a potential protein source and as a high-value food ingredient.

Clamshells, which comprise more than 50% of a clam’s weight, are a major byproduct of the clam industry and are mainly composed of insoluble calcium carbonate. This study investigates the use of clamshells as a natural calcium resource. Highly soluble powdered calcium lactate (LCCL) was prepared from the calcined powdered shells of littleneck clams (LCCP) using response surface methodology (RSM) to predict optimum conditions. These conditions, as derived from pH, solubility, and yield of 11 LCCLs manufactured according to the RSM model, were 1.80 M lactic acid and 1.13 M LCCP. The actual values of pH (6.98), solubility (93.99%), and yield 351.23%) under the optimized conditions were as predicted. The derived LCCL exhibited a strong buffering capacity in the range of pH 2.78-3.90 when combined with less than 2 mL of 1 N HCl. The ranges of calcium content and solubility of LCCL were 7.7-17.5 g/100 g and 96.6-98.9%, respectively. Fourier transform infrared spectroscopy (FT-IR) of the LCCL identified it as calcium lactate pentahydrate, and field emission scanning electron microscopy (FESEM) revealed an irregular and rod-like microstructure. These results confirm the potential use of clamshells, converted to highly soluble organic acid calcium, as an additive to enhance calcium content in food ingredients.

The fractionation of serine protease inhibitor (SPI) from fish roe extracts was carried out using polyethylene glycol-4000(PEG4000) precipitation. The protease inhibitory activity of extracts and PEG fractions from Alaska pollock (AP), bastardhalibut (BH), skipjack tuna (ST), and yellowfin tuna (YT) roes were determined against target proteases. All of the roeextracts showed inhibitory activity toward bromelain (BR), chymotrypsin (CH), trypsin (TR), papain-EDTA (PED), andalcalase (AL) as target proteases. PEG fractions, which have positive inhibitory activity and high recovery (%), were thePEG1 fraction (0–5%,w/v) against cysteine proteases (BR and PA) and the PEG4 fraction (20–40 %,w/v) against serineproteases (CH and TR). The strongest specific inhibitory activity toward CH and TR of PEG4 fractions was AP (9278 and1170 U/mg) followed by ST (6687 and 2064 U/mg), YT (3951 and 1536 U/mg), and BH (538 and 98 U/mg). Theinhibitory activity of serine protease in extracts and PEG fractions from fish roe was stronger than that of cysteineprotease toward common casein substrate. Therefore, SPI is mainly distributed in fish roe and PEG fractionationeffectively isolated the SPI from fish roes. Recovery of serine protease inhibitor from fish roes by polyethylene glycol precipitation. Available from: https://www.researchgate.net/publication/305637522_Recovery_of_serine_protease_inhibitor_from_fish_roes_by_polyethylene_glycol_precipitation [accessed Jul 26, 2016].

To facilitate the effective use of butter clam shell as a natural calcium resource, we determined the optimal conditions for calcium lactate (BCCL) preparation with high solubility using response surface methodology (RSM). The polynomial models developed by RSM for pH, solubility and yield were highly effective in describing the relationships between factors (P<0.05). Increased molar ratios of calcined powder (BCCP) from butter clam shell led to reduced solubility, yield, color values and overall quality. The critical values of multiple response optimization to independent variables were 1.75 M and 0.94 M for lactic acid and BCCP, respectively. The actual values (pH 7.23, 97.42% for solubility and 423.22% for yield) under optimization conditions were similar to the predicted values. White indices of BCCLs were in the range of 86.70–90.86. Therefore, organic acid treatment improved color value. The buffer-ing capacity of BCCLs was strong, at pH 2.82 to 3.80, upon the addition of less than 2 mL of 1 N HCl. The calcium content and solubility of BCCLs were 6.2–16.7 g/100 g and 93.6-98.5%, respectively. Fourier transform analysis of infrared spectroscopy data identified BCCL as calcium lactate pentahydrate, and the analysis of microstructure by field emission scanning electron microscopy revealed an irregular form.

Isoelectric solubilization/precipitation (ISP) processing allows selective, pH-induced water solubility of proteinswith concurrent separation of lipids and removal of materials not intended for human consumption such asbone, scales, skin, etc. Recovered proteins retain functional properties and nutritional value. Four roe proteinisolates (RPIs) from yellowfin tuna roe were prepared under different solubilization and precipitation condition(pH 11/4.5, pH 11/5.5, pH 12/4.5 and pH 12/5.5). RPIs contained 2.3–5.0 % moisture, 79.1–87.8 % protein, 5.6–7.4%lipidand3.0–3.8 % ash. Protein content of RPI-1 and RPI-2 precipitated at pH 4.5 and 5.5 after alkalinesolubilization at pH 11, was higher than those of RPI-3 and RPI-4 after alkaline solubilization at pH 12 (P< 0.05).Lipid content (5.6–7.4 %) of RPIs was lower than that of freeze-dried concentrate (10.6 %). And leucine and lysineof RPIs were the most abundant amino acids (8.8–9.4 and 8.5–8.9 g/100 g protein, respectively). S, Na, P, K asminerals were the major elements in RPIs. SDS-PAGE of RPIs showed bands at 100, 45, 25 and 15 K. Moisture andprotein contents of process water as a 2’nd byproduct were 98.9–99.0 and 1.3–1.8 %, respectively. Therefore,yellowfin tuna roe isolate could be a promising source of valuable nutrients for human food and animal feeds.

Roe is the term used to describe fish eggs (oocytes) gathered in skeins and is one of the most valuable food products from fishery sources. Thus, means of processing are required to convert the underutilized yellowfin tuna roes (YTR) into more marketable and acceptable forms as protein concentrate. Roe protein concentrates (RPCs) were prepared by cooking condition (boil-dried concentrate, BDC and steam-dried concentrate, SDC, respectively) and un-cooking condition (freeze-dried concentrate, FDC) from yellowfin tuna roe. The yield of RPCs was in the range from 22.2 to 25.3 g/100 g of roe. RPCs contained protein (72.3–77.3 %), moisture (4.3–5.6 %), lipid (10.6–11.3 %) and ash (4.3–5.7 %) as the major constituents. The prominent amino acids of RPCs were aspartic acid, 8.7–9.2, glutamic acid, 13.1–13.2, and leucine, 8.5–8.6 g/100 g of protein. Major differences were not observed in each of the amino acid. K, S, Na, and P as minerals were the major elements in RPCs. No difference noted in sodium dodecyl sulfate polyacrylamide gel electrophoresis protein band (15–100 K) possibly representing partial hydrolysis of myosin. Therefore, RPCs from YTR could be use potential protein ingredient for human food and animal feeds.