Buffer capacity (a), water‐holding capacity (b), and solubility (c) of protein isolates recovered from skipjack tuna roe (RPIs) using isoelectric solubilization and precipitation without (control) and with pH‐shift treatment. Values are expressed as the mean ± SD of triplicate determinations. Means with different letters within the sample and pH are significantly different at p < .05 by Duncan's multiple range test. Hb, hemoglobin

Buffer capacity (a), water‐holding capacity (b), and solubility (c) of protein isolates recovered from skipjack tuna roe (RPIs) using isoelectric solubilization and precipitation without (control) and with pH‐shift treatment. Values are expressed as the mean ± SD of triplicate determinations. Means with different letters within the sample and pH are significantly different at p < .05 by Duncan's multiple range test. Hb, hemoglobin

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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, phos...

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... , 180 mesh SDC . Tyrosinase 저해활성 tyrosinase Cha et al. (2020) . , 300 L 900 L mushroom tyrosinase (50 Unit/mL) 1.5 mL 50 mM phosphate buffer (pH 6.8) 30 min , 300 L of 10 mM 3,4-dihydroxy-L-phenylalanine (L-DOPA) ...
... Angiotensin I-converting enzyme (ACE) Cha et al. (2020) . ...
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In the present study, protein hydrolysates were prepared from olive flounder Paralichthys olivaceus roe concentrate using different commercial proteases, and their functional properties and bioactivities were examined. Protamex (PR; 21.6%) showed the highest degree of hydrolysis, followed by alcalase (AL; 21.1%) and aroase AP-10 (AA; 20.2%). With regard to foaming activity, trypsin, chymotrypsin (CH), and bromelain (BR) had values ranging 181–188%, followed by neutrase (152%) and AA (141%). CH (36%) and BR (70%) maintained foam stability for up to 15 min. The oil-in-water emulsifying activity index of CH (10.6 m2/g) was the highest among all the hydrolysates. Notably, the 2,2′-azino-bis-3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS+) radical scavenging activities (IC50) were significantly higher in pantidase NP-2 (68.1 μg/mL) and flavourzyme (FL, 69.8 μg/mL) than in other hydrolysates. The tyrosinase inhibitory activities of FL, PR, and AA were inhibited by 12.5–19.8%. Aangiotensin I converting enzyme inhibitory activity of the control was 80.9%, and that of the hydrolysates of CH, AA, PR, and AL, which exhibited higher inhibitory activity, ranged 87.6–90.7%. CH, BR, and AA AP-10 hydrolysates exhibited superior bioactivity and functional properties. Therefore, these hydrolysates can be used as food ingredients in novel types of functional food-enhancing seafood and food processing industries.
... Consequently, this alteration in charge affects the membrane's interaction with the desired compounds, either facilitating attraction or causing repulsion [39]. At low pH values (pH = 6), the highest resistances occur (Fig. 3b-d), mainly because the proteins have their isoelectric point in acidic pHs, usually around 3 to 6 [40]. At this point, the protein load approaches zero, which increases precipitation and aggregation, increasing resistance to elution through membranes [41]; additionally, the repulsion by the membrane is reduced, which promotes fouling and plugging of the pores [42]. ...
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Problem Earthworm is a valuable source of biologically and pharmacologically active compounds, with applications in the treatment of various types of diseases; however, the main application they have been given is in the production of organic fertilizer. One of the alternatives for obtaining bioactive compounds is by means of enzymatic hydrolysis. Aim This study proposes the optimization of the fractionation of the antioxidant enzymatic hydrolysate from Californian red worm (Eisenia fetida) protein. Methodology For this purpose, the worms were separated and hydrolyzed using the enzyme Alcalase 2.4L for 4000s. The obtained hydrolysate was fractionated by means of a crossflow tangential ultrafiltration system, with a 3 kDa molecular weight cut-off ceramic membrane. A response surface design of the composite central factorial type was implemented to evaluate the effect of pH, transmembrane pressure, and flow factors on the response variables transmission, volume reduction factor (VRF) and permeate flow resistance. The transmissions focused on the antioxidant peptides, measured by three conventional methods such as TEAC, FRAP, ORAC, also known as TTEAC, TFRAP and TORAC, respectively. The evaluated resistances were the total resistance (Rtotal), fouling resistance (Rfouling), and gel resistance (Rgel). Result The results showed that the three factors evaluated affect all the response variables either in their linear or quadratic terms or by some interaction. For each response variable, a mathematical model was obtained, with statistical significance and a non-significant lack of adjustment. The models obtained were used for a multi-objective optimization process in which transfers were maximized, and resistances were minimized. The efficiency of the optimum ultrafiltration process was 25 %. Conclusion The neutral-alkaline pH is ideal for the ultrafiltration process of bioactive peptides, as it is where the highest transmissions of peptides with antioxidative capacity are found. Under optimal conditions, the 3 kDa membrane permeate was found to exhibit higher antioxidant capacity than the retentate and feed. Based on this, the fraction of less than 3 kDa emerges as a potential multifunctional ingredient, thanks to its antioxidant properties.
... The protein solubility of the selected TLPPs was examined using the method described by Cha et al. (2020) with slight modifications. In brief, a 10-mg portion of TLPPs was dissolved in 10 mL of DW and the pH of the suspension was adjusted in the range of 2 to 13 using 0.1 mol/L HCl or 0.1 mol/L NaOH. ...
... The foaming capacity (FC) and foaming stability (FS) of the TLPPs were performed using the method of Cha et al. (2020). In brief, the foam was generated by whipping the TLPP solution (10 mg/mL) at 10,000 rpm for 3 min using a homogenizer before being transferred to a 50 mL accredited cylinder. ...
... The relative protein solubility (%) of TLPPs, EW, and SP in the pH range of 2 to 12 is depicted in Figure 2. The minimum solubilities of the TLPPs were observed at pHs 3-8 (0.13-34.96%) which could be attributed to the proximity between the pH of the solution and the isoelectric point of the protein. This consequently enhanced protein precipitation (Cha et al., 2020). These findings agreed well with those from a study of proteins derived from salmon, cod, and herring byproducts which demonstrated the lowest protein solubilities at pHs 4-8 for the same reason (Abdollahi and Undeland, 2018). ...
Article
Tuna livers (TL), which are often discarded as waste, are a valuable source of protein for human consumption. However, the preparation method used affects the nutritional and functional characteristics of protein powders. This work aimed to investigate the effects of different preparation methods on the physical, chemical, and functional properties of tuna liver protein powders (TLPPs) following heat (H) treatment, heat and ultrasound-assisted (HU) extraction, alkaline pH shift (APS) process, and supercritical carbon dioxide fluid (SC-CO2 ) extraction. H at 85°C (H85), HU at 80 kHz and 100 W (HU-80-100), APS at pH 11.5 (APS 11.5), and SC-CO2 at 350 bars (SC-CO2 -350) resulted in the remarkably highest total protein content among the different preparation conditions. All TLPPs, except for APS 11.5, showed lighter color characteristics. The most abundant amino acids in all TLPPs were glutamic acid, aspartic acid and alanine. The protein solubility and foaming capacity were efficiently improved by SC-CO2-350. Nevertheless, the emulsion properties and oil holding capacity were greatly enhanced by H85 and HU-80-100, and a significant foaming stability and water holding capacity were found in APS 11.5. Therefore, the TLPPs obtained following different preparation methods are unique and could be potentially utilized as a source of protein ingredients in several food systems.
... ㆍ ㆍ ㆍ ㆍ ㆍ ㆍ 2 화, 비타민 및 무기질소재와 같은 기능성 식품소재 (Galla et al., 2012b;Kim et al., 2016) 또는 단백질 및 지질추출소재 (Heu et al., 2006;Mahmoud et al., 2008)로서의 이용에 관한 연구 (Guerard et al., 2010;Kadam and Prabhasankar, 2010)를 통해 식품 또는 식품소재로 개발될 경우 그 가치는 5배 이상 증가할 것이라고 예상하였다 (Liu et al., 2015). 최근 수산가공 부산물의 식량자원화 또는 소재화를 위해, 고 영양원이면서 저 활용 식품자원인 어류 알의 식품기능성과 생 리활성에 대한 관심 또한 높아지고 있으나 (Intarasirisawat et al., 2014;Park et al., 2016;Cha et al., 2020;Yoon et al., 2020Yoon et al., , 2023Kang et al., 2023), 명태, 대구, 숭어, 가다랑어 등 일부의 어류 알만이 염장 발효식품인 알젓의 형태로 소비되고 있을 뿐, 대부분의 어류 알은 식품소재로 이용되지 못하고 있다. 이러한 일면에서 어류 알로부터 영양 강화를 위한 단백질 소 재로 이용하고자 하는 노력 (Yoon et al., 2019Cha et al., 2020;Kwon et al., 2022;Kang et al., 2023) (Galla et al., 2012b;Mohamed et al., 2012;Park et al., 2016), 특히 단백질 용해도(protein solubility)는 거품, 유화 및 겔 형성과 같은 식품단백질 기능성에 영향을 미치는 중요인자 이기도 하다 (Kristinsson and Rasco, 2000;Mohan et al., 2007;Azadian et al., 2012). ...
... 최근 수산가공 부산물의 식량자원화 또는 소재화를 위해, 고 영양원이면서 저 활용 식품자원인 어류 알의 식품기능성과 생 리활성에 대한 관심 또한 높아지고 있으나 (Intarasirisawat et al., 2014;Park et al., 2016;Cha et al., 2020;Yoon et al., 2020Yoon et al., , 2023Kang et al., 2023), 명태, 대구, 숭어, 가다랑어 등 일부의 어류 알만이 염장 발효식품인 알젓의 형태로 소비되고 있을 뿐, 대부분의 어류 알은 식품소재로 이용되지 못하고 있다. 이러한 일면에서 어류 알로부터 영양 강화를 위한 단백질 소 재로 이용하고자 하는 노력 (Yoon et al., 2019Cha et al., 2020;Kwon et al., 2022;Kang et al., 2023) (Galla et al., 2012b;Mohamed et al., 2012;Park et al., 2016), 특히 단백질 용해도(protein solubility)는 거품, 유화 및 겔 형성과 같은 식품단백질 기능성에 영향을 미치는 중요인자 이기도 하다 (Kristinsson and Rasco, 2000;Mohan et al., 2007;Azadian et al., 2012). 한편, 거품성(foaming capacity, FC) 및 거품안정성(foam stability, FS)은 식품의 신선감(refreshment), 부드러운 촉감(softening) 그리고 방향성분의 분산과 같은 독특 한 특성을 부여하며 (Mutilangi et al., 1996;Damodaran, 1997;Klompong et al., 2007), 그리고 유화능(emulsifying activity index, EAI)과 유화 안정성(emulsion stability index, ESI)은 water-oil 계면에서 단백질이 oil을 흡착하여 유화층의 형성 및 이를 유지시키는 능력을 말한다 (Karaca et al., 2011). ...
... 또한 식품소재의 생리활성(bioactivity)에는 DPPH (2,2-diphenyl-1-picrylhydrazyl) 라디칼 (Klompong et al., 2007) 및 ABTS + (2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) 라디칼 소거활성 (You et al., 2010) 그리고 SOD (superoxide dismutase) 유사활성과 환원력(reducing power) 등의 항산화활성과 ACE (angiotensin-I converting enzyme) 저해활성을 (Mohan et al., 2007;Lee et al., 2016;Yoon et al., 2019). 앞서의 연구에서는 넙치 알을 대상으로 하 여, 가열건조 농축물의 식품성분 (Kwon et al., 2022)과 식품기 능성 , 그리고 ISP 공정을 통해 회수한 분리 단백질의 식품성분 특성 Alvarez et al., 2018;Yoon et al., 2019;Cha et al., 2020). ...
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We investigated the functional properties and in vitro bioactivity of protein isolates (RPIs) recovered from olive floun�der Paralichthys olivaceus roes by isoelectric solubilization/precipitation process, according to pH-shift treatments. The buffer capacity of RPIs was shown to be stronger in alkaline pH than in acidic pH. Water holding capacity of RPIs was in range of 4.5–5.2 g/g protein with no significant differences (P>0.05). The foaming capacity and emulsifying activ�ity index of RPIs did not show any significant differences between RPI-1 (pH 11/4.5) and 3 (pH 12/4.5), however they were superior to RPI-2 (pH 11/5.5) and 4 (pH 12/5.5). The 2,2′-azino-bis-3-ethylbenzo-thiazoline-6-sulfonic acid radical scavenging activity of RPI-3 (2.5 mg protein/mL) was 102.4 μg/mL, and the angiotensin I converting enzyme inhibitory activity was 30.8%. Among the RPIs, RPI-3 was relatively superior in protein functional properties such as buffer capacity, foaming capacity, emulsification, and anti-oxidative activity. Therefore, we suggest that RPI prepared from olive flounder roes could serve as a potential food resource.
... Then, the gel was stained with Bio-Rad Coomassie Blue R-250 followed by destaining several times. The bands obtained from the samples were compared with reference to the migration of the wide range molecular weight standard [32]. ...
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Fish head byproducts derived from surimi processing contribute about 15% of the total body weight, which are beneficial to health because they contain essential nutrients. In this study, olive flounder (OF) was the target species in order to maximize the byproduct utilization. In RAW 264.7 macrophages, the seven hydrolysates from OF head byproducts were examined for their inhibitory potential against inflammation and the oxidative stress induced by lipopolysaccharides (LPS). The pepsin hydrolysate (OFH–PH) demonstrated strong anti-inflammatory activity via the down-regulation of NO production, with an IC50 value of 299.82 ± 4.18 µg/mL. We evaluated the inhibitory potential of pro-inflammatory cytokines and PGE2 to confirm these findings. Additionally, iNOS and COX-2 protein expressions were confirmed using western blotting. Furthermore, the results from the in vivo zebrafish model demonstrated that OFH–PH decreased the LPS-elevated heart rate, NO production, cell death, and intracellular ROS level, while increasing the survival percentage. Hence, the obtained results of this study serve as a platform for future research and provide insight into the mediation of inflammatory disorders. These results suggest that OFH–PH has the potential to be utilized as a nutraceutical and functional food ingredient.
... The powder exhibited highest solubility at pH 3 (Fig. 2), with no significant differences in solubility between pH 4 and 9. Poor solubility found at pH 2 was related to the aggregation of proteins under strong electrostatic interaction. This result concurred with a previous report that soybean protein had good solubility over a wide range of pH from 3 to 9 [52] and revealed the advantage of powder over animal protein that easily precipitated at pH between 4 and 8 [28]. Values are mean ± standard error (n = 3). ...
... Conversely, in V-MWD and CAD processing with low temperature, the changes in these four components are not significant in some treatments. Besides the effect of heat intensity on β-sheets and α-helix, there is almost a general impact of germination, increase in β-sheets and decrease in α-helix, corresponding to partial denaturation and unfolding of proteins which could lead to enhanced protein solubility and emulsifying properties (Cha et al., 2020;Setia et al., 2019). ...
... Solubility is an important and useful functional property in food preparation, which has an impact on some other factors such as surface activity, emulsification, foaming, and gelation (Cha et al., 2020;Ghavidel & Prakash, 2006). The protein solubility of raw and treated lentil flours using MW-IRD, V-MWD, roasting, and CAD at different drying conditions are presented in Table 1. ...
... OFR, Olive flounder roe; RPI-1 and RPI-2, Roe protein isolate adjusted to pH 4.5 and 5.5, respectively, after alkaline solubilization at pH 11; RPI-3 and RPI-4, Roe protein isolate adjusted to pH 4.5 and 5.5, respectively, after alkaline solubilization at pH 12. Data are given as mean values±SD (n = 3 (Sathivel et al., 2004), herring (Sathivel et al., 2004), salmon Alaska pollock , (Sathivel et al., 2009) surimi (Huda et al., 2001) . (Li et al., 2004;Mahmoodani et al., 2014;Lee et al., 2016b;Yoon et al., 2018b;Cha et al., 2020). RPIs Table 3 . ...
... RPIs (154.0-304.2 mg/100 g) (148.0 mg/100 g) ISP 2 , / 2 N NaOH HCl NaCl (Lee et al., 2016b;Cha et al., 2020). ...
... sea bream (Orban et al., 2000) Baltic herring (Tahvonen et al., 2000) 2 . Lee et al. (2016b) , , , (Lee et al., 2016b;Cha et al., 2020). ISP OFR Table 3. Mineral contents of roe protein isolates recovered from olive flounder Paralichthys olivaceus by isoelectric solubilization and precipitation process Minerals (mg/100 g) OFR 1 RPI-1 (pH 11/4.5) ...
Article
Four roe protein isolates (RPIs) from olive flounder Paralichthys olivaceus roes (OFR) were recovered by isoelectric solubilization (pH 11 and 12) and precipitation (pH 4.5 and 5.5) and investigated for their food characteristics. RPIs contained 4.5–9.6% moisture, 64.1-69.5% protein, 16.1-19.8% lipid, and 1.0-3.9% ash. The protein yields of RPIs ranged from 50.1 to 56.8%, which was significantly different depending on the recovery conditions. A difference was observed in the SDS-PAGE protein band (25–100 kDa) between the alkaline solubilization at pH 11 (RPI-1 and 2) and pH 12 (RPI-3 and 4). The major amino acids of RPIs were Leu, Lys, Asp, Glu and Ala and major mineral components were sulfur, sodium, phosphorus, and magnesium, which were significantly different from OFR (P<0.05). Additionally, the lead and cadmium content was below the chemical hazard standard of the Korean food standards code. The Hunter color and whiteness of RPIs also showed significant differences according to the treatment conditions of the ISP process (P<0.05). This suggests that protein isolates recovered from olive flounder roes have high potential as nutritional supplements.
... , (130-180 μg/mL; Yoon et al., 2020), (82 μg/ mL; Yoon et al., 2018d) (103 μg/ mL; Cha et al., 2020), (160-170 μg/mL; Kim et al., 2016) , (33-97 μg/ml, Lee et al., 2017), (28-45 μg/mL) (55-110 μg/ml, Yoon et al., 2017) . , peptide , peptide , , (Wu et al., 2003). ...
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Boil-dried concentrate (BDC) and steam-dried concentrate (SDC) were prepared from olive flounder Paralichthys olivaceus roe using the cook-dried process, and their food functionality and in vitro bioactivity were examined. The buffer capacity of BDC and SDC was found to be stronger in the alkaline region than in the acidic region, and the buffer capacity of SDC was superior to that of BDC. The water holding capacities of these concentrates were 7.6 and 7.4 g/g protein, respectively, both of which were significantly lower than that of freeze-dried concentrate (FDC). The solubility of BDC (13.4%) and SDC (12.7%), foaming capacity of BDC (107.7%) and SDC (110.6%), and oil-in-water emulsifying activity index of BDC (7.7 m2/g) and SDC (9.7 m2/g) were all significantly lower than the corresponding values for FDC (P<0.05). The lower food functionality of BDC and SDC compared with FDC can be attributed to the high-temperature denaturation of proteins during the cook-dried process. The 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activities (IC50) of SDC (2.5 mg protein/mL) was 60.4 μg/mL, and the angiotensin I converting enzyme inhibitory activity was 80.9%. Olive flounder roe concentrates have good antioxidant and antihypertensive activities, and can be used as materials or ingredients in the processing of seafood and other foods to enhance protein contents and food functionality.
... Protein solubility was sharply increased below and above the isoelectric point. These findings were similar to those reported for protein isolates prepared from skipjack tuna roe (Cha et al., 2020), sea cucumber (Stichopus japonicus) viscera , sea urchin gonad , skipjack tuna roe (Cha et al., 2020), and large yellow croaker fish . The solubility of proteins is mainly determined by their surface hydrophobicity and hydrophilicity (Kristinsson et al., 2005). ...
... Protein solubility was sharply increased below and above the isoelectric point. These findings were similar to those reported for protein isolates prepared from skipjack tuna roe (Cha et al., 2020), sea cucumber (Stichopus japonicus) viscera , sea urchin gonad , skipjack tuna roe (Cha et al., 2020), and large yellow croaker fish . The solubility of proteins is mainly determined by their surface hydrophobicity and hydrophilicity (Kristinsson et al., 2005). ...